drivers/md/raid5.c

   1 /*
   2  * raid5.c : Multiple Devices driver for Linux
   3  *         Copyright (C) 1996, 1997 Ingo Molnar, Miguel de Icaza, Gadi Oxman
   4  *         Copyright (C) 1999, 2000 Ingo Molnar
   5  *         Copyright (C) 2002, 2003 H. Peter Anvin
   6  *
   7  * RAID-4/5/6 management functions.
   8  * Thanks to Penguin Computing for making the RAID-6 development possible
   9  * by donating a test server!
  10  *
  11  * This program is free software; you can redistribute it and/or modify
  12  * it under the terms of the GNU General Public License as published by
  13  * the Free Software Foundation; either version 2, or (at your option)
  14  * any later version.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * (for example /usr/src/linux/COPYING); if not, write to the Free
  18  * Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  19  */
  20
  21 /*
  22  * BITMAP UNPLUGGING:
  23  *
  24  * The sequencing for updating the bitmap reliably is a little
  25  * subtle (and I got it wrong the first time) so it deserves some
  26  * explanation.
  27  *
  28  * We group bitmap updates into batches.  Each batch has a number.
  29  * We may write out several batches at once, but that isn't very important.
  30  * conf->seq_write is the number of the last batch successfully written.
  31  * conf->seq_flush is the number of the last batch that was closed to
  32  *    new additions.
  33  * When we discover that we will need to write to any block in a stripe
  34  * (in add_stripe_bio) we update the in-memory bitmap and record in sh->bm_seq
  35  * the number of the batch it will be in. This is seq_flush+1.
  36  * When we are ready to do a write, if that batch hasn't been written yet,
  37  *   we plug the array and queue the stripe for later.
  38  * When an unplug happens, we increment bm_flush, thus closing the current
  39  *   batch.
  40  * When we notice that bm_flush > bm_write, we write out all pending updates
  41  * to the bitmap, and advance bm_write to where bm_flush was.
  42  * This may occasionally write a bit out twice, but is sure never to
  43  * miss any bits.
  44  */
  45
  46 #include <linux/blkdev.h>
  47 #include <linux/kthread.h>
  48 #include <linux/raid/pq.h>
  49 #include <linux/async_tx.h>
  50 #include <linux/module.h>
  51 #include <linux/async.h>
  52 #include <linux/seq_file.h>
  53 #include <linux/cpu.h>
  54 #include <linux/slab.h>
  55 #include <linux/ratelimit.h>
  56 #include <linux/nodemask.h>
  57 #include <linux/flex_array.h>
  58 #include <trace/events/block.h>
  59
  60 #include "md.h"
  61 #include "raid5.h"
  62 #include "raid0.h"
  63 #include "bitmap.h"
  64
  65 #define UNSUPPORTED_MDDEV_FLAGS (1L << MD_FAILFAST_SUPPORTED)
  66
  67 #define cpu_to_group(cpu) cpu_to_node(cpu)
  68 #define ANY_GROUP NUMA_NO_NODE
  69
  70 static bool devices_handle_discard_safely = false;
  71 module_param(devices_handle_discard_safely, bool, 0644);
  72 MODULE_PARM_DESC(devices_handle_discard_safely,
  73                  "Set to Y if all devices in each array reliably return zeroes on reads from discarded regions");
  74 static struct workqueue_struct *raid5_wq;
  75
  76 static inline struct hlist_head *stripe_hash(struct r5conf *conf, sector_t sect)
  77 {
  78         int hash = (sect >> STRIPE_SHIFT) & HASH_MASK;
  79         return &conf->stripe_hashtbl[hash];
  80 }
  81
  82 static inline int stripe_hash_locks_hash(sector_t sect)
  83 {
  84         return (sect >> STRIPE_SHIFT) & STRIPE_HASH_LOCKS_MASK;
  85 }
  86
  87 static inline void lock_device_hash_lock(struct r5conf *conf, int hash)
  88 {
  89         spin_lock_irq(conf->hash_locks + hash);
  90         spin_lock(&conf->device_lock);
  91 }
  92
  93 static inline void unlock_device_hash_lock(struct r5conf *conf, int hash)
  94 {
  95         spin_unlock(&conf->device_lock);
  96         spin_unlock_irq(conf->hash_locks + hash);
  97 }
  98
  99 static inline void lock_all_device_hash_locks_irq(struct r5conf *conf)
 100 {
 101         int i;
 102         local_irq_disable();
 103         spin_lock(conf->hash_locks);
 104         for (i = 1; i < NR_STRIPE_HASH_LOCKS; i++)
 105                 spin_lock_nest_lock(conf->hash_locks + i, conf->hash_locks);
 106         spin_lock(&conf->device_lock);
 107 }
 108
 109 static inline void unlock_all_device_hash_locks_irq(struct r5conf *conf)
 110 {
 111         int i;
 112         spin_unlock(&conf->device_lock);
 113         for (i = NR_STRIPE_HASH_LOCKS; i; i--)
 114                 spin_unlock(conf->hash_locks + i - 1);
 115         local_irq_enable();
 116 }
 117
 118 /* Find first data disk in a raid6 stripe */
 119 static inline int raid6_d0(struct stripe_head *sh)
 120 {
 121         if (sh->ddf_layout)
 122                 /* ddf always start from first device */
 123                 return 0;
 124         /* md starts just after Q block */
 125         if (sh->qd_idx == sh->disks - 1)
 126                 return 0;
 127         else
 128                 return sh->qd_idx + 1;
 129 }
 130 static inline int raid6_next_disk(int disk, int raid_disks)
 131 {
 132         disk++;
 133         return (disk < raid_disks) ? disk : 0;
 134 }
 135
 136 /* When walking through the disks in a raid5, starting at raid6_d0,
 137  * We need to map each disk to a 'slot', where the data disks are slot
 138  * 0 .. raid_disks-3, the parity disk is raid_disks-2 and the Q disk
 139  * is raid_disks-1.  This help does that mapping.
 140  */
 141 static int raid6_idx_to_slot(int idx, struct stripe_head *sh,
 142                              int *count, int syndrome_disks)
 143 {
 144         int slot = *count;
 145
 146         if (sh->ddf_layout)
 147                 (*count)++;
 148         if (idx == sh->pd_idx)
 149                 return syndrome_disks;
 150         if (idx == sh->qd_idx)
 151                 return syndrome_disks + 1;
 152         if (!sh->ddf_layout)
 153                 (*count)++;
 154         return slot;
 155 }
 156
 157 static void return_io(struct bio_list *return_bi)
 158 {
 159         struct bio *bi;
 160         while ((bi = bio_list_pop(return_bi)) != NULL) {
 161                 bi->bi_iter.bi_size = 0;
 162                 trace_block_bio_complete(bdev_get_queue(bi->bi_bdev),
 163                                          bi, 0);
 164                 bio_endio(bi);
 165         }
 166 }
 167
 168 static void print_raid5_conf (struct r5conf *conf);
 169
 170 static int stripe_operations_active(struct stripe_head *sh)
 171 {
 172         return sh->check_state || sh->reconstruct_state ||
 173                test_bit(STRIPE_BIOFILL_RUN, &sh->state) ||
 174                test_bit(STRIPE_COMPUTE_RUN, &sh->state);
 175 }
 176
 177 static void raid5_wakeup_stripe_thread(struct stripe_head *sh)
 178 {
 179         struct r5conf *conf = sh->raid_conf;
 180         struct r5worker_group *group;
 181         int thread_cnt;
 182         int i, cpu = sh->cpu;
 183
 184         if (!cpu_online(cpu)) {
 185                 cpu = cpumask_any(cpu_online_mask);
 186                 sh->cpu = cpu;
 187         }
 188
 189         if (list_empty(&sh->lru)) {
 190                 struct r5worker_group *group;
 191                 group = conf->worker_groups + cpu_to_group(cpu);
 192                 list_add_tail(&sh->lru, &group->handle_list);
 193                 group->stripes_cnt++;
 194                 sh->group = group;
 195         }
 196
 197         if (conf->worker_cnt_per_group == 0) {
 198                 md_wakeup_thread(conf->mddev->thread);
 199                 return;
 200         }
 201
 202         group = conf->worker_groups + cpu_to_group(sh->cpu);
 203
 204         group->workers[0].working = true;
 205         /* at least one worker should run to avoid race */
 206         queue_work_on(sh->cpu, raid5_wq, &group->workers[0].work);
 207
 208         thread_cnt = group->stripes_cnt / MAX_STRIPE_BATCH - 1;
 209         /* wakeup more workers */
 210         for (i = 1; i < conf->worker_cnt_per_group && thread_cnt > 0; i++) {
 211                 if (group->workers[i].working == false) {
 212                         group->workers[i].working = true;
 213                         queue_work_on(sh->cpu, raid5_wq,
 214                                       &group->workers[i].work);
 215                         thread_cnt--;
 216                 }
 217         }
 218 }
 219
 220 static void do_release_stripe(struct r5conf *conf, struct stripe_head *sh,
 221                               struct list_head *temp_inactive_list)
 222 {
 223         int i;
 224         int injournal = 0;      /* number of date pages with R5_InJournal */
 225
 226         BUG_ON(!list_empty(&sh->lru));
 227         BUG_ON(atomic_read(&conf->active_stripes)==0);
 228
 229         if (r5c_is_writeback(conf->log))
 230                 for (i = sh->disks; i--; )
 231                         if (test_bit(R5_InJournal, &sh->dev[i].flags))
 232                                 injournal++;
 233         /*
 234          * When quiesce in r5c write back, set STRIPE_HANDLE for stripes with
 235          * data in journal, so they are not released to cached lists
 236          */
 237         if (conf->quiesce && r5c_is_writeback(conf->log) &&
 238             !test_bit(STRIPE_HANDLE, &sh->state) && injournal != 0) {
 239                 if (test_bit(STRIPE_R5C_CACHING, &sh->state))
 240                         r5c_make_stripe_write_out(sh);
 241                 set_bit(STRIPE_HANDLE, &sh->state);
 242         }
 243
 244         if (test_bit(STRIPE_HANDLE, &sh->state)) {
 245                 if (test_bit(STRIPE_DELAYED, &sh->state) &&
 246                     !test_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
 247                         list_add_tail(&sh->lru, &conf->delayed_list);
 248                 else if (test_bit(STRIPE_BIT_DELAY, &sh->state) &&
 249                            sh->bm_seq - conf->seq_write > 0)
 250                         list_add_tail(&sh->lru, &conf->bitmap_list);
 251                 else {
 252                         clear_bit(STRIPE_DELAYED, &sh->state);
 253                         clear_bit(STRIPE_BIT_DELAY, &sh->state);
 254                         if (conf->worker_cnt_per_group == 0) {
 255                                 list_add_tail(&sh->lru, &conf->handle_list);
 256                         } else {
 257                                 raid5_wakeup_stripe_thread(sh);
 258                                 return;
 259                         }
 260                 }
 261                 md_wakeup_thread(conf->mddev->thread);
 262         } else {
 263                 BUG_ON(stripe_operations_active(sh));
 264                 if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
 265                         if (atomic_dec_return(&conf->preread_active_stripes)
 266                             < IO_THRESHOLD)
 267                                 md_wakeup_thread(conf->mddev->thread);
 268                 atomic_dec(&conf->active_stripes);
 269                 if (!test_bit(STRIPE_EXPANDING, &sh->state)) {
 270                         if (!r5c_is_writeback(conf->log))
 271                                 list_add_tail(&sh->lru, temp_inactive_list);
 272                         else {
 273                                 WARN_ON(test_bit(R5_InJournal, &sh->dev[sh->pd_idx].flags));
 274                                 if (injournal == 0)
 275                                         list_add_tail(&sh->lru, temp_inactive_list);
 276                                 else if (injournal == conf->raid_disks - conf->max_degraded) {
 277                                         /* full stripe */
 278                                         if (!test_and_set_bit(STRIPE_R5C_FULL_STRIPE, &sh->state))
 279                                                 atomic_inc(&conf->r5c_cached_full_stripes);
 280                                         if (test_and_clear_bit(STRIPE_R5C_PARTIAL_STRIPE, &sh->state))
 281                                                 atomic_dec(&conf->r5c_cached_partial_stripes);
 282                                         list_add_tail(&sh->lru, &conf->r5c_full_stripe_list);
 283                                         r5c_check_cached_full_stripe(conf);
 284                                 } else
 285                                         /*
 286                                          * STRIPE_R5C_PARTIAL_STRIPE is set in
 287                                          * r5c_try_caching_write(). No need to
 288                                          * set it again.
 289                                          */
 290                                         list_add_tail(&sh->lru, &conf->r5c_partial_stripe_list);
 291                         }
 292                 }
 293         }
 294 }
 295
 296 static void __release_stripe(struct r5conf *conf, struct stripe_head *sh,
 297                              struct list_head *temp_inactive_list)
 298 {
 299         if (atomic_dec_and_test(&sh->count))
 300                 do_release_stripe(conf, sh, temp_inactive_list);
 301 }
 302
 303 /*
 304  * @hash could be NR_STRIPE_HASH_LOCKS, then we have a list of inactive_list
 305  *
 306  * Be careful: Only one task can add/delete stripes from temp_inactive_list at
 307  * given time. Adding stripes only takes device lock, while deleting stripes
 308  * only takes hash lock.
 309  */
 310 static void release_inactive_stripe_list(struct r5conf *conf,
 311                                          struct list_head *temp_inactive_list,
 312                                          int hash)
 313 {
 314         int size;
 315         bool do_wakeup = false;
 316         unsigned long flags;
 317
 318         if (hash == NR_STRIPE_HASH_LOCKS) {
 319                 size = NR_STRIPE_HASH_LOCKS;
 320                 hash = NR_STRIPE_HASH_LOCKS - 1;
 321         } else
 322                 size = 1;
 323         while (size) {
 324                 struct list_head *list = &temp_inactive_list[size - 1];
 325
 326                 /*
 327                  * We don't hold any lock here yet, raid5_get_active_stripe() might
 328                  * remove stripes from the list
 329                  */
 330                 if (!list_empty_careful(list)) {
 331                         spin_lock_irqsave(conf->hash_locks + hash, flags);
 332                         if (list_empty(conf->inactive_list + hash) &&
 333                             !list_empty(list))
 334                                 atomic_dec(&conf->empty_inactive_list_nr);
 335                         list_splice_tail_init(list, conf->inactive_list + hash);
 336                         do_wakeup = true;
 337                         spin_unlock_irqrestore(conf->hash_locks + hash, flags);
 338                 }
 339                 size--;
 340                 hash--;
 341         }
 342
 343         if (do_wakeup) {
 344                 wake_up(&conf->wait_for_stripe);
 345                 if (atomic_read(&conf->active_stripes) == 0)
 346                         wake_up(&conf->wait_for_quiescent);
 347                 if (conf->retry_read_aligned)
 348                         md_wakeup_thread(conf->mddev->thread);
 349         }
 350 }
 351
 352 /* should hold conf->device_lock already */
 353 static int release_stripe_list(struct r5conf *conf,
 354                                struct list_head *temp_inactive_list)
 355 {
 356         struct stripe_head *sh, *t;
 357         int count = 0;
 358         struct llist_node *head;
 359
 360         head = llist_del_all(&conf->released_stripes);
 361         head = llist_reverse_order(head);
 362         llist_for_each_entry_safe(sh, t, head, release_list) {
 363                 int hash;
 364
 365                 /* sh could be readded after STRIPE_ON_RELEASE_LIST is cleard */
 366                 smp_mb();
 367                 clear_bit(STRIPE_ON_RELEASE_LIST, &sh->state);
 368                 /*
 369                  * Don't worry the bit is set here, because if the bit is set
 370                  * again, the count is always > 1. This is true for
 371                  * STRIPE_ON_UNPLUG_LIST bit too.
 372                  */
 373                 hash = sh->hash_lock_index;
 374                 __release_stripe(conf, sh, &temp_inactive_list[hash]);
 375                 count++;
 376         }
 377
 378         return count;
 379 }
 380
 381 void raid5_release_stripe(struct stripe_head *sh)
 382 {
 383         struct r5conf *conf = sh->raid_conf;
 384         unsigned long flags;
 385         struct list_head list;
 386         int hash;
 387         bool wakeup;
 388
 389         /* Avoid release_list until the last reference.
 390          */
 391         if (atomic_add_unless(&sh->count, -1, 1))
 392                 return;
 393
 394         if (unlikely(!conf->mddev->thread) ||
 395                 test_and_set_bit(STRIPE_ON_RELEASE_LIST, &sh->state))
 396                 goto slow_path;
 397         wakeup = llist_add(&sh->release_list, &conf->released_stripes);
 398         if (wakeup)
 399                 md_wakeup_thread(conf->mddev->thread);
 400         return;
 401 slow_path:
 402         local_irq_save(flags);
 403         /* we are ok here if STRIPE_ON_RELEASE_LIST is set or not */
 404         if (atomic_dec_and_lock(&sh->count, &conf->device_lock)) {
 405                 INIT_LIST_HEAD(&list);
 406                 hash = sh->hash_lock_index;
 407                 do_release_stripe(conf, sh, &list);
 408                 spin_unlock(&conf->device_lock);
 409                 release_inactive_stripe_list(conf, &list, hash);
 410         }
 411         local_irq_restore(flags);
 412 }
 413
 414 static inline void remove_hash(struct stripe_head *sh)
 415 {
 416         pr_debug("remove_hash(), stripe %llu\n",
 417                 (unsigned long long)sh->sector);
 418
 419         hlist_del_init(&sh->hash);
 420 }
 421
 422 static inline void insert_hash(struct r5conf *conf, struct stripe_head *sh)
 423 {
 424         struct hlist_head *hp = stripe_hash(conf, sh->sector);
 425
 426         pr_debug("insert_hash(), stripe %llu\n",
 427                 (unsigned long long)sh->sector);
 428
 429         hlist_add_head(&sh->hash, hp);
 430 }
 431
 432 /* find an idle stripe, make sure it is unhashed, and return it. */
 433 static struct stripe_head *get_free_stripe(struct r5conf *conf, int hash)
 434 {
 435         struct stripe_head *sh = NULL;
 436         struct list_head *first;
 437
 438         if (list_empty(conf->inactive_list + hash))
 439                 goto out;
 440         first = (conf->inactive_list + hash)->next;
 441         sh = list_entry(first, struct stripe_head, lru);
 442         list_del_init(first);
 443         remove_hash(sh);
 444         atomic_inc(&conf->active_stripes);
 445         BUG_ON(hash != sh->hash_lock_index);
 446         if (list_empty(conf->inactive_list + hash))
 447                 atomic_inc(&conf->empty_inactive_list_nr);
 448 out:
 449         return sh;
 450 }
 451
 452 static void shrink_buffers(struct stripe_head *sh)
 453 {
 454         struct page *p;
 455         int i;
 456         int num = sh->raid_conf->pool_size;
 457
 458         for (i = 0; i < num ; i++) {
 459                 WARN_ON(sh->dev[i].page != sh->dev[i].orig_page);
 460                 p = sh->dev[i].page;
 461                 if (!p)
 462                         continue;
 463                 sh->dev[i].page = NULL;
 464                 put_page(p);
 465         }
 466 }
 467
 468 static int grow_buffers(struct stripe_head *sh, gfp_t gfp)
 469 {
 470         int i;
 471         int num = sh->raid_conf->pool_size;
 472
 473         for (i = 0; i < num; i++) {
 474                 struct page *page;
 475
 476                 if (!(page = alloc_page(gfp))) {
 477                         return 1;
 478                 }
 479                 sh->dev[i].page = page;
 480                 sh->dev[i].orig_page = page;
 481         }
 482         return 0;
 483 }
 484
 485 static void raid5_build_block(struct stripe_head *sh, int i, int previous);
 486 static void stripe_set_idx(sector_t stripe, struct r5conf *conf, int previous,
 487                             struct stripe_head *sh);
 488
 489 static void init_stripe(struct stripe_head *sh, sector_t sector, int previous)
 490 {
 491         struct r5conf *conf = sh->raid_conf;
 492         int i, seq;
 493
 494         BUG_ON(atomic_read(&sh->count) != 0);
 495         BUG_ON(test_bit(STRIPE_HANDLE, &sh->state));
 496         BUG_ON(stripe_operations_active(sh));
 497         BUG_ON(sh->batch_head);
 498
 499         pr_debug("init_stripe called, stripe %llu\n",
 500                 (unsigned long long)sector);
 501 retry:
 502         seq = read_seqcount_begin(&conf->gen_lock);
 503         sh->generation = conf->generation - previous;
 504         sh->disks = previous ? conf->previous_raid_disks : conf->raid_disks;
 505         sh->sector = sector;
 506         stripe_set_idx(sector, conf, previous, sh);
 507         sh->state = 0;
 508
 509         for (i = sh->disks; i--; ) {
 510                 struct r5dev *dev = &sh->dev[i];
 511
 512                 if (dev->toread || dev->read || dev->towrite || dev->written ||
 513                     test_bit(R5_LOCKED, &dev->flags)) {
 514                         pr_err("sector=%llx i=%d %p %p %p %p %d\n",
 515                                (unsigned long long)sh->sector, i, dev->toread,
 516                                dev->read, dev->towrite, dev->written,
 517                                test_bit(R5_LOCKED, &dev->flags));
 518                         WARN_ON(1);
 519                 }
 520                 dev->flags = 0;
 521                 raid5_build_block(sh, i, previous);
 522         }
 523         if (read_seqcount_retry(&conf->gen_lock, seq))
 524                 goto retry;
 525         sh->overwrite_disks = 0;
 526         insert_hash(conf, sh);
 527         sh->cpu = smp_processor_id();
 528         set_bit(STRIPE_BATCH_READY, &sh->state);
 529 }
 530
 531 static struct stripe_head *__find_stripe(struct r5conf *conf, sector_t sector,
 532                                          short generation)
 533 {
 534         struct stripe_head *sh;
 535
 536         pr_debug("__find_stripe, sector %llu\n", (unsigned long long)sector);
 537         hlist_for_each_entry(sh, stripe_hash(conf, sector), hash)
 538                 if (sh->sector == sector && sh->generation == generation)
 539                         return sh;
 540         pr_debug("__stripe %llu not in cache\n", (unsigned long long)sector);
 541         return NULL;
 542 }
 543
 544 /*
 545  * Need to check if array has failed when deciding whether to:
 546  *  - start an array
 547  *  - remove non-faulty devices
 548  *  - add a spare
 549  *  - allow a reshape
 550  * This determination is simple when no reshape is happening.
 551  * However if there is a reshape, we need to carefully check
 552  * both the before and after sections.
 553  * This is because some failed devices may only affect one
 554  * of the two sections, and some non-in_sync devices may
 555  * be insync in the section most affected by failed devices.
 556  */
 557 int raid5_calc_degraded(struct r5conf *conf)
 558 {
 559         int degraded, degraded2;
 560         int i;
 561
 562         rcu_read_lock();
 563         degraded = 0;
 564         for (i = 0; i < conf->previous_raid_disks; i++) {
 565                 struct md_rdev *rdev = rcu_dereference(conf->disks[i].rdev);
 566                 if (rdev && test_bit(Faulty, &rdev->flags))
 567                         rdev = rcu_dereference(conf->disks[i].replacement);
 568                 if (!rdev || test_bit(Faulty, &rdev->flags))
 569                         degraded++;
 570                 else if (test_bit(In_sync, &rdev->flags))
 571                         ;
 572                 else
 573                         /* not in-sync or faulty.
 574                          * If the reshape increases the number of devices,
 575                          * this is being recovered by the reshape, so
 576                          * this 'previous' section is not in_sync.
 577                          * If the number of devices is being reduced however,
 578                          * the device can only be part of the array if
 579                          * we are reverting a reshape, so this section will
 580                          * be in-sync.
 581                          */
 582                         if (conf->raid_disks >= conf->previous_raid_disks)
 583                                 degraded++;
 584         }
 585         rcu_read_unlock();
 586         if (conf->raid_disks == conf->previous_raid_disks)
 587                 return degraded;
 588         rcu_read_lock();
 589         degraded2 = 0;
 590         for (i = 0; i < conf->raid_disks; i++) {
 591                 struct md_rdev *rdev = rcu_dereference(conf->disks[i].rdev);
 592                 if (rdev && test_bit(Faulty, &rdev->flags))
 593                         rdev = rcu_dereference(conf->disks[i].replacement);
 594                 if (!rdev || test_bit(Faulty, &rdev->flags))
 595                         degraded2++;
 596                 else if (test_bit(In_sync, &rdev->flags))
 597                         ;
 598                 else
 599                         /* not in-sync or faulty.
 600                          * If reshape increases the number of devices, this
 601                          * section has already been recovered, else it
 602                          * almost certainly hasn't.
 603                          */
 604                         if (conf->raid_disks <= conf->previous_raid_disks)
 605                                 degraded2++;
 606         }
 607         rcu_read_unlock();
 608         if (degraded2 > degraded)
 609                 return degraded2;
 610         return degraded;
 611 }
 612
 613 static int has_failed(struct r5conf *conf)
 614 {
 615         int degraded;
 616
 617         if (conf->mddev->reshape_position == MaxSector)
 618                 return conf->mddev->degraded > conf->max_degraded;
 619
 620         degraded = raid5_calc_degraded(conf);
 621         if (degraded > conf->max_degraded)
 622                 return 1;
 623         return 0;
 624 }
 625
 626 struct stripe_head *
 627 raid5_get_active_stripe(struct r5conf *conf, sector_t sector,
 628                         int previous, int noblock, int noquiesce)
 629 {
 630         struct stripe_head *sh;
 631         int hash = stripe_hash_locks_hash(sector);
 632         int inc_empty_inactive_list_flag;
 633
 634         pr_debug("get_stripe, sector %llu\n", (unsigned long long)sector);
 635
 636         spin_lock_irq(conf->hash_locks + hash);
 637
 638         do {
 639                 wait_event_lock_irq(conf->wait_for_quiescent,
 640                                     conf->quiesce == 0 || noquiesce,
 641                                     *(conf->hash_locks + hash));
 642                 sh = __find_stripe(conf, sector, conf->generation - previous);
 643                 if (!sh) {
 644                         if (!test_bit(R5_INACTIVE_BLOCKED, &conf->cache_state)) {
 645                                 sh = get_free_stripe(conf, hash);
 646                                 if (!sh && !test_bit(R5_DID_ALLOC,
 647                                                      &conf->cache_state))
 648                                         set_bit(R5_ALLOC_MORE,
 649                                                 &conf->cache_state);
 650                         }
 651                         if (noblock && sh == NULL)
 652                                 break;
 653
 654                         r5c_check_stripe_cache_usage(conf);
 655                         if (!sh) {
 656                                 set_bit(R5_INACTIVE_BLOCKED,
 657                                         &conf->cache_state);
 658                                 r5l_wake_reclaim(conf->log, 0);
 659                                 wait_event_lock_irq(
 660                                         conf->wait_for_stripe,
 661                                         !list_empty(conf->inactive_list + hash) &&
 662                                         (atomic_read(&conf->active_stripes)
 663                                          < (conf->max_nr_stripes * 3 / 4)
 664                                          || !test_bit(R5_INACTIVE_BLOCKED,
 665                                                       &conf->cache_state)),
 666                                         *(conf->hash_locks + hash));
 667                                 clear_bit(R5_INACTIVE_BLOCKED,
 668                                           &conf->cache_state);
 669                         } else {
 670                                 init_stripe(sh, sector, previous);
 671                                 atomic_inc(&sh->count);
 672                         }
 673                 } else if (!atomic_inc_not_zero(&sh->count)) {
 674                         spin_lock(&conf->device_lock);
 675                         if (!atomic_read(&sh->count)) {
 676                                 if (!test_bit(STRIPE_HANDLE, &sh->state))
 677                                         atomic_inc(&conf->active_stripes);
 678                                 BUG_ON(list_empty(&sh->lru) &&
 679                                        !test_bit(STRIPE_EXPANDING, &sh->state));
 680                                 inc_empty_inactive_list_flag = 0;
 681                                 if (!list_empty(conf->inactive_list + hash))
 682                                         inc_empty_inactive_list_flag = 1;
 683                                 list_del_init(&sh->lru);
 684                                 if (list_empty(conf->inactive_list + hash) && inc_empty_inactive_list_flag)
 685                                         atomic_inc(&conf->empty_inactive_list_nr);
 686                                 if (sh->group) {
 687                                         sh->group->stripes_cnt--;
 688                                         sh->group = NULL;
 689                                 }
 690                         }
 691                         atomic_inc(&sh->count);
 692                         spin_unlock(&conf->device_lock);
 693                 }
 694         } while (sh == NULL);
 695
 696         spin_unlock_irq(conf->hash_locks + hash);
 697         return sh;
 698 }
 699
 700 static bool is_full_stripe_write(struct stripe_head *sh)
 701 {
 702         BUG_ON(sh->overwrite_disks > (sh->disks - sh->raid_conf->max_degraded));
 703         return sh->overwrite_disks == (sh->disks - sh->raid_conf->max_degraded);
 704 }
 705
 706 static void lock_two_stripes(struct stripe_head *sh1, struct stripe_head *sh2)
 707 {
 708         local_irq_disable();
 709         if (sh1 > sh2) {
 710                 spin_lock(&sh2->stripe_lock);
 711                 spin_lock_nested(&sh1->stripe_lock, 1);
 712         } else {
 713                 spin_lock(&sh1->stripe_lock);
 714                 spin_lock_nested(&sh2->stripe_lock, 1);
 715         }
 716 }
 717
 718 static void unlock_two_stripes(struct stripe_head *sh1, struct stripe_head *sh2)
 719 {
 720         spin_unlock(&sh1->stripe_lock);
 721         spin_unlock(&sh2->stripe_lock);
 722         local_irq_enable();
 723 }
 724
 725 /* Only freshly new full stripe normal write stripe can be added to a batch list */
 726 static bool stripe_can_batch(struct stripe_head *sh)
 727 {
 728         struct r5conf *conf = sh->raid_conf;
 729
 730         if (conf->log)
 731                 return false;
 732         return test_bit(STRIPE_BATCH_READY, &sh->state) &&
 733                 !test_bit(STRIPE_BITMAP_PENDING, &sh->state) &&
 734                 is_full_stripe_write(sh);
 735 }
 736
 737 /* we only do back search */
 738 static void stripe_add_to_batch_list(struct r5conf *conf, struct stripe_head *sh)
 739 {
 740         struct stripe_head *head;
 741         sector_t head_sector, tmp_sec;
 742         int hash;
 743         int dd_idx;
 744         int inc_empty_inactive_list_flag;
 745
 746         /* Don't cross chunks, so stripe pd_idx/qd_idx is the same */
 747         tmp_sec = sh->sector;
 748         if (!sector_div(tmp_sec, conf->chunk_sectors))
 749                 return;
 750         head_sector = sh->sector - STRIPE_SECTORS;
 751
 752         hash = stripe_hash_locks_hash(head_sector);
 753         spin_lock_irq(conf->hash_locks + hash);
 754         head = __find_stripe(conf, head_sector, conf->generation);
 755         if (head && !atomic_inc_not_zero(&head->count)) {
 756                 spin_lock(&conf->device_lock);
 757                 if (!atomic_read(&head->count)) {
 758                         if (!test_bit(STRIPE_HANDLE, &head->state))
 759                                 atomic_inc(&conf->active_stripes);
 760                         BUG_ON(list_empty(&head->lru) &&
 761                                !test_bit(STRIPE_EXPANDING, &head->state));
 762                         inc_empty_inactive_list_flag = 0;
 763                         if (!list_empty(conf->inactive_list + hash))
 764                                 inc_empty_inactive_list_flag = 1;
 765                         list_del_init(&head->lru);
 766                         if (list_empty(conf->inactive_list + hash) && inc_empty_inactive_list_flag)
 767                                 atomic_inc(&conf->empty_inactive_list_nr);
 768                         if (head->group) {
 769                                 head->group->stripes_cnt--;
 770                                 head->group = NULL;
 771                         }
 772                 }
 773                 atomic_inc(&head->count);
 774                 spin_unlock(&conf->device_lock);
 775         }
 776         spin_unlock_irq(conf->hash_locks + hash);
 777
 778         if (!head)
 779                 return;
 780         if (!stripe_can_batch(head))
 781                 goto out;
 782
 783         lock_two_stripes(head, sh);
 784         /* clear_batch_ready clear the flag */
 785         if (!stripe_can_batch(head) || !stripe_can_batch(sh))
 786                 goto unlock_out;
 787
 788         if (sh->batch_head)
 789                 goto unlock_out;
 790
 791         dd_idx = 0;
 792         while (dd_idx == sh->pd_idx || dd_idx == sh->qd_idx)
 793                 dd_idx++;
 794         if (head->dev[dd_idx].towrite->bi_opf != sh->dev[dd_idx].towrite->bi_opf ||
 795             bio_op(head->dev[dd_idx].towrite) != bio_op(sh->dev[dd_idx].towrite))
 796                 goto unlock_out;
 797
 798         if (head->batch_head) {
 799                 spin_lock(&head->batch_head->batch_lock);
 800                 /* This batch list is already running */
 801                 if (!stripe_can_batch(head)) {
 802                         spin_unlock(&head->batch_head->batch_lock);
 803                         goto unlock_out;
 804                 }
 805
 806                 /*
 807                  * at this point, head's BATCH_READY could be cleared, but we
 808                  * can still add the stripe to batch list
 809                  */
 810                 list_add(&sh->batch_list, &head->batch_list);
 811                 spin_unlock(&head->batch_head->batch_lock);
 812
 813                 sh->batch_head = head->batch_head;
 814         } else {
 815                 head->batch_head = head;
 816                 sh->batch_head = head->batch_head;
 817                 spin_lock(&head->batch_lock);
 818                 list_add_tail(&sh->batch_list, &head->batch_list);
 819                 spin_unlock(&head->batch_lock);
 820         }
 821
 822         if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
 823                 if (atomic_dec_return(&conf->preread_active_stripes)
 824                     < IO_THRESHOLD)
 825                         md_wakeup_thread(conf->mddev->thread);
 826
 827         if (test_and_clear_bit(STRIPE_BIT_DELAY, &sh->state)) {
 828                 int seq = sh->bm_seq;
 829                 if (test_bit(STRIPE_BIT_DELAY, &sh->batch_head->state) &&
 830                     sh->batch_head->bm_seq > seq)
 831                         seq = sh->batch_head->bm_seq;
 832                 set_bit(STRIPE_BIT_DELAY, &sh->batch_head->state);
 833                 sh->batch_head->bm_seq = seq;
 834         }
 835
 836         atomic_inc(&sh->count);
 837 unlock_out:
 838         unlock_two_stripes(head, sh);
 839 out:
 840         raid5_release_stripe(head);
 841 }
 842
 843 /* Determine if 'data_offset' or 'new_data_offset' should be used
 844  * in this stripe_head.
 845  */
 846 static int use_new_offset(struct r5conf *conf, struct stripe_head *sh)
 847 {
 848         sector_t progress = conf->reshape_progress;
 849         /* Need a memory barrier to make sure we see the value
 850          * of conf->generation, or ->data_offset that was set before
 851          * reshape_progress was updated.
 852          */
 853         smp_rmb();
 854         if (progress == MaxSector)
 855                 return 0;
 856         if (sh->generation == conf->generation - 1)
 857                 return 0;
 858         /* We are in a reshape, and this is a new-generation stripe,
 859          * so use new_data_offset.
 860          */
 861         return 1;
 862 }
 863
 864 static void flush_deferred_bios(struct r5conf *conf)
 865 {
 866         struct bio_list tmp;
 867         struct bio *bio;
 868
 869         if (!conf->batch_bio_dispatch || !conf->group_cnt)
 870                 return;
 871
 872         bio_list_init(&tmp);
 873         spin_lock(&conf->pending_bios_lock);
 874         bio_list_merge(&tmp, &conf->pending_bios);
 875         bio_list_init(&conf->pending_bios);
 876         spin_unlock(&conf->pending_bios_lock);
 877
 878         while ((bio = bio_list_pop(&tmp)))
 879                 generic_make_request(bio);
 880 }
 881
 882 static void defer_bio_issue(struct r5conf *conf, struct bio *bio)
 883 {
 884         /*
 885          * change group_cnt will drain all bios, so this is safe
 886          *
 887          * A read generally means a read-modify-write, which usually means a
 888          * randwrite, so we don't delay it
 889          */
 890         if (!conf->batch_bio_dispatch || !conf->group_cnt ||
 891             bio_op(bio) == REQ_OP_READ) {
 892                 generic_make_request(bio);
 893                 return;
 894         }
 895         spin_lock(&conf->pending_bios_lock);
 896         bio_list_add(&conf->pending_bios, bio);
 897         spin_unlock(&conf->pending_bios_lock);
 898         md_wakeup_thread(conf->mddev->thread);
 899 }
 900
 901 static void
 902 raid5_end_read_request(struct bio *bi);
 903 static void
 904 raid5_end_write_request(struct bio *bi);
 905
 906 static void ops_run_io(struct stripe_head *sh, struct stripe_head_state *s)
 907 {
 908         struct r5conf *conf = sh->raid_conf;
 909         int i, disks = sh->disks;
 910         struct stripe_head *head_sh = sh;
 911
 912         might_sleep();
 913
 914         if (!test_bit(STRIPE_R5C_CACHING, &sh->state)) {
 915                 /* writing out phase */
 916                 if (s->waiting_extra_page)
 917                         return;
 918                 if (r5l_write_stripe(conf->log, sh) == 0)
 919                         return;
 920         } else {  /* caching phase */
 921                 if (test_bit(STRIPE_LOG_TRAPPED, &sh->state)) {
 922                         r5c_cache_data(conf->log, sh, s);
 923                         return;
 924                 }
 925         }
 926
 927         for (i = disks; i--; ) {
 928                 int op, op_flags = 0;
 929                 int replace_only = 0;
 930                 struct bio *bi, *rbi;
 931                 struct md_rdev *rdev, *rrdev = NULL;
 932
 933                 sh = head_sh;
 934                 if (test_and_clear_bit(R5_Wantwrite, &sh->dev[i].flags)) {
 935                         op = REQ_OP_WRITE;
 936                         if (test_and_clear_bit(R5_WantFUA, &sh->dev[i].flags))
 937                                 op_flags = REQ_FUA;
 938                         if (test_bit(R5_Discard, &sh->dev[i].flags))
 939                                 op = REQ_OP_DISCARD;
 940                 } else if (test_and_clear_bit(R5_Wantread, &sh->dev[i].flags))
 941                         op = REQ_OP_READ;
 942                 else if (test_and_clear_bit(R5_WantReplace,
 943                                             &sh->dev[i].flags)) {
 944                         op = REQ_OP_WRITE;
 945                         replace_only = 1;
 946                 } else
 947                         continue;
 948                 if (test_and_clear_bit(R5_SyncIO, &sh->dev[i].flags))
 949                         op_flags |= REQ_SYNC;
 950
 951 again:
 952                 bi = &sh->dev[i].req;
 953                 rbi = &sh->dev[i].rreq; /* For writing to replacement */
 954
 955                 rcu_read_lock();
 956                 rrdev = rcu_dereference(conf->disks[i].replacement);
 957                 smp_mb(); /* Ensure that if rrdev is NULL, rdev won't be */
 958                 rdev = rcu_dereference(conf->disks[i].rdev);
 959                 if (!rdev) {
 960                         rdev = rrdev;
 961                         rrdev = NULL;
 962                 }
 963                 if (op_is_write(op)) {
 964                         if (replace_only)
 965                                 rdev = NULL;
 966                         if (rdev == rrdev)
 967                                 /* We raced and saw duplicates */
 968                                 rrdev = NULL;
 969                 } else {
 970                         if (test_bit(R5_ReadRepl, &head_sh->dev[i].flags) && rrdev)
 971                                 rdev = rrdev;
 972                         rrdev = NULL;
 973                 }
 974
 975                 if (rdev && test_bit(Faulty, &rdev->flags))
 976                         rdev = NULL;
 977                 if (rdev)
 978                         atomic_inc(&rdev->nr_pending);
 979                 if (rrdev && test_bit(Faulty, &rrdev->flags))
 980                         rrdev = NULL;
 981                 if (rrdev)
 982                         atomic_inc(&rrdev->nr_pending);
 983                 rcu_read_unlock();
 984
 985                 /* We have already checked bad blocks for reads.  Now
 986                  * need to check for writes.  We never accept write errors
 987                  * on the replacement, so we don't to check rrdev.
 988                  */
 989                 while (op_is_write(op) && rdev &&
 990                        test_bit(WriteErrorSeen, &rdev->flags)) {
 991                         sector_t first_bad;
 992                         int bad_sectors;
 993                         int bad = is_badblock(rdev, sh->sector, STRIPE_SECTORS,
 994                                               &first_bad, &bad_sectors);
 995                         if (!bad)
 996                                 break;
 997
 998                         if (bad < 0) {
 999                                 set_bit(BlockedBadBlocks, &rdev->flags);
1000                                 if (!conf->mddev->external &&
1001                                     conf->mddev->sb_flags) {
1002                                         /* It is very unlikely, but we might
1003                                          * still need to write out the
1004                                          * bad block log - better give it
1005                                          * a chance*/
1006                                         md_check_recovery(conf->mddev);
1007                                 }
1008                                 /*
1009                                  * Because md_wait_for_blocked_rdev
1010                                  * will dec nr_pending, we must
1011                                  * increment it first.
1012                                  */
1013                                 atomic_inc(&rdev->nr_pending);
1014                                 md_wait_for_blocked_rdev(rdev, conf->mddev);
1015                         } else {
1016                                 /* Acknowledged bad block - skip the write */
1017                                 rdev_dec_pending(rdev, conf->mddev);
1018                                 rdev = NULL;
1019                         }
1020                 }
1021
1022                 if (rdev) {
1023                         if (s->syncing || s->expanding || s->expanded
1024                             || s->replacing)
1025                                 md_sync_acct(rdev->bdev, STRIPE_SECTORS);
1026
1027                         set_bit(STRIPE_IO_STARTED, &sh->state);
1028
1029                         bi->bi_bdev = rdev->bdev;
1030                         bio_set_op_attrs(bi, op, op_flags);
1031                         bi->bi_end_io = op_is_write(op)
1032                                 ? raid5_end_write_request
1033                                 : raid5_end_read_request;
1034                         bi->bi_private = sh;
1035
1036                         pr_debug("%s: for %llu schedule op %d on disc %d\n",
1037                                 __func__, (unsigned long long)sh->sector,
1038                                 bi->bi_opf, i);
1039                         atomic_inc(&sh->count);
1040                         if (sh != head_sh)
1041                                 atomic_inc(&head_sh->count);
1042                         if (use_new_offset(conf, sh))
1043                                 bi->bi_iter.bi_sector = (sh->sector
1044                                                  + rdev->new_data_offset);
1045                         else
1046                                 bi->bi_iter.bi_sector = (sh->sector
1047                                                  + rdev->data_offset);
1048                         if (test_bit(R5_ReadNoMerge, &head_sh->dev[i].flags))
1049                                 bi->bi_opf |= REQ_NOMERGE;
1050
1051                         if (test_bit(R5_SkipCopy, &sh->dev[i].flags))
1052                                 WARN_ON(test_bit(R5_UPTODATE, &sh->dev[i].flags));
1053
1054                         if (!op_is_write(op) &&
1055                             test_bit(R5_InJournal, &sh->dev[i].flags))
1056                                 /*
1057                                  * issuing read for a page in journal, this
1058                                  * must be preparing for prexor in rmw; read
1059                                  * the data into orig_page
1060                                  */
1061                                 sh->dev[i].vec.bv_page = sh->dev[i].orig_page;
1062                         else
1063                                 sh->dev[i].vec.bv_page = sh->dev[i].page;
1064                         bi->bi_vcnt = 1;
1065                         bi->bi_io_vec[0].bv_len = STRIPE_SIZE;
1066                         bi->bi_io_vec[0].bv_offset = 0;
1067                         bi->bi_iter.bi_size = STRIPE_SIZE;
1068                         /*
1069                          * If this is discard request, set bi_vcnt 0. We don't
1070                          * want to confuse SCSI because SCSI will replace payload
1071                          */
1072                         if (op == REQ_OP_DISCARD)
1073                                 bi->bi_vcnt = 0;
1074                         if (rrdev)
1075                                 set_bit(R5_DOUBLE_LOCKED, &sh->dev[i].flags);
1076
1077                         if (conf->mddev->gendisk)
1078                                 trace_block_bio_remap(bdev_get_queue(bi->bi_bdev),
1079                                                       bi, disk_devt(conf->mddev->gendisk),
1080                                                       sh->dev[i].sector);
1081                         defer_bio_issue(conf, bi);
1082                 }
1083                 if (rrdev) {
1084                         if (s->syncing || s->expanding || s->expanded
1085                             || s->replacing)
1086                                 md_sync_acct(rrdev->bdev, STRIPE_SECTORS);
1087
1088                         set_bit(STRIPE_IO_STARTED, &sh->state);
1089
1090                         rbi->bi_bdev = rrdev->bdev;
1091                         bio_set_op_attrs(rbi, op, op_flags);
1092                         BUG_ON(!op_is_write(op));
1093                         rbi->bi_end_io = raid5_end_write_request;
1094                         rbi->bi_private = sh;
1095
1096                         pr_debug("%s: for %llu schedule op %d on "
1097                                  "replacement disc %d\n",
1098                                 __func__, (unsigned long long)sh->sector,
1099                                 rbi->bi_opf, i);
1100                         atomic_inc(&sh->count);
1101                         if (sh != head_sh)
1102                                 atomic_inc(&head_sh->count);
1103                         if (use_new_offset(conf, sh))
1104                                 rbi->bi_iter.bi_sector = (sh->sector
1105                                                   + rrdev->new_data_offset);
1106                         else
1107                                 rbi->bi_iter.bi_sector = (sh->sector
1108                                                   + rrdev->data_offset);
1109                         if (test_bit(R5_SkipCopy, &sh->dev[i].flags))
1110                                 WARN_ON(test_bit(R5_UPTODATE, &sh->dev[i].flags));
1111                         sh->dev[i].rvec.bv_page = sh->dev[i].page;
1112                         rbi->bi_vcnt = 1;
1113                         rbi->bi_io_vec[0].bv_len = STRIPE_SIZE;
1114                         rbi->bi_io_vec[0].bv_offset = 0;
1115                         rbi->bi_iter.bi_size = STRIPE_SIZE;
1116                         /*
1117                          * If this is discard request, set bi_vcnt 0. We don't
1118                          * want to confuse SCSI because SCSI will replace payload
1119                          */
1120                         if (op == REQ_OP_DISCARD)
1121                                 rbi->bi_vcnt = 0;
1122                         if (conf->mddev->gendisk)
1123                                 trace_block_bio_remap(bdev_get_queue(rbi->bi_bdev),
1124                                                       rbi, disk_devt(conf->mddev->gendisk),
1125                                                       sh->dev[i].sector);
1126                         defer_bio_issue(conf, rbi);
1127                 }
1128                 if (!rdev && !rrdev) {
1129                         if (op_is_write(op))
1130                                 set_bit(STRIPE_DEGRADED, &sh->state);
1131                         pr_debug("skip op %d on disc %d for sector %llu\n",
1132                                 bi->bi_opf, i, (unsigned long long)sh->sector);
1133                         clear_bit(R5_LOCKED, &sh->dev[i].flags);
1134                         set_bit(STRIPE_HANDLE, &sh->state);
1135                 }
1136
1137                 if (!head_sh->batch_head)
1138                         continue;
1139                 sh = list_first_entry(&sh->batch_list, struct stripe_head,
1140                                       batch_list);
1141                 if (sh != head_sh)
1142                         goto again;
1143         }
1144 }
1145
1146 static struct dma_async_tx_descriptor *
1147 async_copy_data(int frombio, struct bio *bio, struct page **page,
1148         sector_t sector, struct dma_async_tx_descriptor *tx,
1149         struct stripe_head *sh, int no_skipcopy)
1150 {
1151         struct bio_vec bvl;
1152         struct bvec_iter iter;
1153         struct page *bio_page;
1154         int page_offset;
1155         struct async_submit_ctl submit;
1156         enum async_tx_flags flags = 0;
1157
1158         if (bio->bi_iter.bi_sector >= sector)
1159                 page_offset = (signed)(bio->bi_iter.bi_sector - sector) * 512;
1160         else
1161                 page_offset = (signed)(sector - bio->bi_iter.bi_sector) * -512;
1162
1163         if (frombio)
1164                 flags |= ASYNC_TX_FENCE;
1165         init_async_submit(&submit, flags, tx, NULL, NULL, NULL);
1166
1167         bio_for_each_segment(bvl, bio, iter) {
1168                 int len = bvl.bv_len;
1169                 int clen;
1170                 int b_offset = 0;
1171
1172                 if (page_offset < 0) {
1173                         b_offset = -page_offset;
1174                         page_offset += b_offset;
1175                         len -= b_offset;
1176                 }
1177
1178                 if (len > 0 && page_offset + len > STRIPE_SIZE)
1179                         clen = STRIPE_SIZE - page_offset;
1180                 else
1181                         clen = len;
1182
1183                 if (clen > 0) {
1184                         b_offset += bvl.bv_offset;
1185                         bio_page = bvl.bv_page;
1186                         if (frombio) {
1187                                 if (sh->raid_conf->skip_copy &&
1188                                     b_offset == 0 && page_offset == 0 &&
1189                                     clen == STRIPE_SIZE &&
1190                                     !no_skipcopy)
1191                                         *page = bio_page;
1192                                 else
1193                                         tx = async_memcpy(*page, bio_page, page_offset,
1194                                                   b_offset, clen, &submit);
1195                         } else
1196                                 tx = async_memcpy(bio_page, *page, b_offset,
1197                                                   page_offset, clen, &submit);
1198                 }
1199                 /* chain the operations */
1200                 submit.depend_tx = tx;
1201
1202                 if (clen < len) /* hit end of page */
1203                         break;
1204                 page_offset +=  len;
1205         }
1206
1207         return tx;
1208 }
1209
1210 static void ops_complete_biofill(void *stripe_head_ref)
1211 {
1212         struct stripe_head *sh = stripe_head_ref;
1213         struct bio_list return_bi = BIO_EMPTY_LIST;
1214         int i;
1215
1216         pr_debug("%s: stripe %llu\n", __func__,
1217                 (unsigned long long)sh->sector);
1218
1219         /* clear completed biofills */
1220         for (i = sh->disks; i--; ) {
1221                 struct r5dev *dev = &sh->dev[i];
1222
1223                 /* acknowledge completion of a biofill operation */
1224                 /* and check if we need to reply to a read request,
1225                  * new R5_Wantfill requests are held off until
1226                  * !STRIPE_BIOFILL_RUN
1227                  */
1228                 if (test_and_clear_bit(R5_Wantfill, &dev->flags)) {
1229                         struct bio *rbi, *rbi2;
1230
1231                         BUG_ON(!dev->read);
1232                         rbi = dev->read;
1233                         dev->read = NULL;
1234                         while (rbi && rbi->bi_iter.bi_sector <
1235                                 dev->sector + STRIPE_SECTORS) {
1236                                 rbi2 = r5_next_bio(rbi, dev->sector);
1237                                 if (!raid5_dec_bi_active_stripes(rbi))
1238                                         bio_list_add(&return_bi, rbi);
1239                                 rbi = rbi2;
1240                         }
1241                 }
1242         }
1243         clear_bit(STRIPE_BIOFILL_RUN, &sh->state);
1244
1245         return_io(&return_bi);
1246
1247         set_bit(STRIPE_HANDLE, &sh->state);
1248         raid5_release_stripe(sh);
1249 }
1250
1251 static void ops_run_biofill(struct stripe_head *sh)
1252 {
1253         struct dma_async_tx_descriptor *tx = NULL;
1254         struct async_submit_ctl submit;
1255         int i;
1256
1257         BUG_ON(sh->batch_head);
1258         pr_debug("%s: stripe %llu\n", __func__,
1259                 (unsigned long long)sh->sector);
1260
1261         for (i = sh->disks; i--; ) {
1262                 struct r5dev *dev = &sh->dev[i];
1263                 if (test_bit(R5_Wantfill, &dev->flags)) {
1264                         struct bio *rbi;
1265                         spin_lock_irq(&sh->stripe_lock);
1266                         dev->read = rbi = dev->toread;
1267                         dev->toread = NULL;
1268                         spin_unlock_irq(&sh->stripe_lock);
1269                         while (rbi && rbi->bi_iter.bi_sector <
1270                                 dev->sector + STRIPE_SECTORS) {
1271                                 tx = async_copy_data(0, rbi, &dev->page,
1272                                                      dev->sector, tx, sh, 0);
1273                                 rbi = r5_next_bio(rbi, dev->sector);
1274                         }
1275                 }
1276         }
1277
1278         atomic_inc(&sh->count);
1279         init_async_submit(&submit, ASYNC_TX_ACK, tx, ops_complete_biofill, sh, NULL);
1280         async_trigger_callback(&submit);
1281 }
1282
1283 static void mark_target_uptodate(struct stripe_head *sh, int target)
1284 {
1285         struct r5dev *tgt;
1286
1287         if (target < 0)
1288                 return;
1289
1290         tgt = &sh->dev[target];
1291         set_bit(R5_UPTODATE, &tgt->flags);
1292         BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
1293         clear_bit(R5_Wantcompute, &tgt->flags);
1294 }
1295
1296 static void ops_complete_compute(void *stripe_head_ref)
1297 {
1298         struct stripe_head *sh = stripe_head_ref;
1299
1300         pr_debug("%s: stripe %llu\n", __func__,
1301                 (unsigned long long)sh->sector);
1302
1303         /* mark the computed target(s) as uptodate */
1304         mark_target_uptodate(sh, sh->ops.target);
1305         mark_target_uptodate(sh, sh->ops.target2);
1306
1307         clear_bit(STRIPE_COMPUTE_RUN, &sh->state);
1308         if (sh->check_state == check_state_compute_run)
1309                 sh->check_state = check_state_compute_result;
1310         set_bit(STRIPE_HANDLE, &sh->state);
1311         raid5_release_stripe(sh);
1312 }
1313
1314 /* return a pointer to the address conversion region of the scribble buffer */
1315 static addr_conv_t *to_addr_conv(struct stripe_head *sh,
1316                                  struct raid5_percpu *percpu, int i)
1317 {
1318         void *addr;
1319
1320         addr = flex_array_get(percpu->scribble, i);
1321         return addr + sizeof(struct page *) * (sh->disks + 2);
1322 }
1323
1324 /* return a pointer to the address conversion region of the scribble buffer */
1325 static struct page **to_addr_page(struct raid5_percpu *percpu, int i)
1326 {
1327         void *addr;
1328
1329         addr = flex_array_get(percpu->scribble, i);
1330         return addr;
1331 }
1332
1333 static struct dma_async_tx_descriptor *
1334 ops_run_compute5(struct stripe_head *sh, struct raid5_percpu *percpu)
1335 {
1336         int disks = sh->disks;
1337         struct page **xor_srcs = to_addr_page(percpu, 0);
1338         int target = sh->ops.target;
1339         struct r5dev *tgt = &sh->dev[target];
1340         struct page *xor_dest = tgt->page;
1341         int count = 0;
1342         struct dma_async_tx_descriptor *tx;
1343         struct async_submit_ctl submit;
1344         int i;
1345
1346         BUG_ON(sh->batch_head);
1347
1348         pr_debug("%s: stripe %llu block: %d\n",
1349                 __func__, (unsigned long long)sh->sector, target);
1350         BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
1351
1352         for (i = disks; i--; )
1353                 if (i != target)
1354                         xor_srcs[count++] = sh->dev[i].page;
1355
1356         atomic_inc(&sh->count);
1357
1358         init_async_submit(&submit, ASYNC_TX_FENCE|ASYNC_TX_XOR_ZERO_DST, NULL,
1359                           ops_complete_compute, sh, to_addr_conv(sh, percpu, 0));
1360         if (unlikely(count == 1))
1361                 tx = async_memcpy(xor_dest, xor_srcs[0], 0, 0, STRIPE_SIZE, &submit);
1362         else
1363                 tx = async_xor(xor_dest, xor_srcs, 0, count, STRIPE_SIZE, &submit);
1364
1365         return tx;
1366 }
1367
1368 /* set_syndrome_sources - populate source buffers for gen_syndrome
1369  * @srcs - (struct page *) array of size sh->disks
1370  * @sh - stripe_head to parse
1371  *
1372  * Populates srcs in proper layout order for the stripe and returns the
1373  * 'count' of sources to be used in a call to async_gen_syndrome.  The P
1374  * destination buffer is recorded in srcs[count] and the Q destination
1375  * is recorded in srcs[count+1]].
1376  */
1377 static int set_syndrome_sources(struct page **srcs,
1378                                 struct stripe_head *sh,
1379                                 int srctype)
1380 {
1381         int disks = sh->disks;
1382         int syndrome_disks = sh->ddf_layout ? disks : (disks - 2);
1383         int d0_idx = raid6_d0(sh);
1384         int count;
1385         int i;
1386
1387         for (i = 0; i < disks; i++)
1388                 srcs[i] = NULL;
1389
1390         count = 0;
1391         i = d0_idx;
1392         do {
1393                 int slot = raid6_idx_to_slot(i, sh, &count, syndrome_disks);
1394                 struct r5dev *dev = &sh->dev[i];
1395
1396                 if (i == sh->qd_idx || i == sh->pd_idx ||
1397                     (srctype == SYNDROME_SRC_ALL) ||
1398                     (srctype == SYNDROME_SRC_WANT_DRAIN &&
1399                      (test_bit(R5_Wantdrain, &dev->flags) ||
1400                       test_bit(R5_InJournal, &dev->flags))) ||
1401                     (srctype == SYNDROME_SRC_WRITTEN &&
1402                      dev->written)) {
1403                         if (test_bit(R5_InJournal, &dev->flags))
1404                                 srcs[slot] = sh->dev[i].orig_page;
1405                         else
1406                                 srcs[slot] = sh->dev[i].page;
1407                 }
1408                 i = raid6_next_disk(i, disks);
1409         } while (i != d0_idx);
1410
1411         return syndrome_disks;
1412 }
1413
1414 static struct dma_async_tx_descriptor *
1415 ops_run_compute6_1(struct stripe_head *sh, struct raid5_percpu *percpu)
1416 {
1417         int disks = sh->disks;
1418         struct page **blocks = to_addr_page(percpu, 0);
1419         int target;
1420         int qd_idx = sh->qd_idx;
1421         struct dma_async_tx_descriptor *tx;
1422         struct async_submit_ctl submit;
1423         struct r5dev *tgt;
1424         struct page *dest;
1425         int i;
1426         int count;
1427
1428         BUG_ON(sh->batch_head);
1429         if (sh->ops.target < 0)
1430                 target = sh->ops.target2;
1431         else if (sh->ops.target2 < 0)
1432                 target = sh->ops.target;
1433         else
1434                 /* we should only have one valid target */
1435                 BUG();
1436         BUG_ON(target < 0);
1437         pr_debug("%s: stripe %llu block: %d\n",
1438                 __func__, (unsigned long long)sh->sector, target);
1439
1440         tgt = &sh->dev[target];
1441         BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
1442         dest = tgt->page;
1443
1444         atomic_inc(&sh->count);
1445
1446         if (target == qd_idx) {
1447                 count = set_syndrome_sources(blocks, sh, SYNDROME_SRC_ALL);
1448                 blocks[count] = NULL; /* regenerating p is not necessary */
1449                 BUG_ON(blocks[count+1] != dest); /* q should already be set */
1450                 init_async_submit(&submit, ASYNC_TX_FENCE, NULL,
1451                                   ops_complete_compute, sh,
1452                                   to_addr_conv(sh, percpu, 0));
1453                 tx = async_gen_syndrome(blocks, 0, count+2, STRIPE_SIZE, &submit);
1454         } else {
1455                 /* Compute any data- or p-drive using XOR */
1456                 count = 0;
1457                 for (i = disks; i-- ; ) {
1458                         if (i == target || i == qd_idx)
1459                                 continue;
1460                         blocks[count++] = sh->dev[i].page;
1461                 }
1462
1463                 init_async_submit(&submit, ASYNC_TX_FENCE|ASYNC_TX_XOR_ZERO_DST,
1464                                   NULL, ops_complete_compute, sh,
1465                                   to_addr_conv(sh, percpu, 0));
1466                 tx = async_xor(dest, blocks, 0, count, STRIPE_SIZE, &submit);
1467         }
1468
1469         return tx;
1470 }
1471
1472 static struct dma_async_tx_descriptor *
1473 ops_run_compute6_2(struct stripe_head *sh, struct raid5_percpu *percpu)
1474 {
1475         int i, count, disks = sh->disks;
1476         int syndrome_disks = sh->ddf_layout ? disks : disks-2;
1477         int d0_idx = raid6_d0(sh);
1478         int faila = -1, failb = -1;
1479         int target = sh->ops.target;
1480         int target2 = sh->ops.target2;
1481         struct r5dev *tgt = &sh->dev[target];
1482         struct r5dev *tgt2 = &sh->dev[target2];
1483         struct dma_async_tx_descriptor *tx;
1484         struct page **blocks = to_addr_page(percpu, 0);
1485         struct async_submit_ctl submit;
1486
1487         BUG_ON(sh->batch_head);
1488         pr_debug("%s: stripe %llu block1: %d block2: %d\n",
1489                  __func__, (unsigned long long)sh->sector, target, target2);
1490         BUG_ON(target < 0 || target2 < 0);
1491         BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
1492         BUG_ON(!test_bit(R5_Wantcompute, &tgt2->flags));
1493
1494         /* we need to open-code set_syndrome_sources to handle the
1495          * slot number conversion for 'faila' and 'failb'
1496          */
1497         for (i = 0; i < disks ; i++)
1498                 blocks[i] = NULL;
1499         count = 0;
1500         i = d0_idx;
1501         do {
1502                 int slot = raid6_idx_to_slot(i, sh, &count, syndrome_disks);
1503
1504                 blocks[slot] = sh->dev[i].page;
1505
1506                 if (i == target)
1507                         faila = slot;
1508                 if (i == target2)
1509                         failb = slot;
1510                 i = raid6_next_disk(i, disks);
1511         } while (i != d0_idx);
1512
1513         BUG_ON(faila == failb);
1514         if (failb < faila)
1515                 swap(faila, failb);
1516         pr_debug("%s: stripe: %llu faila: %d failb: %d\n",
1517                  __func__, (unsigned long long)sh->sector, faila, failb);
1518
1519         atomic_inc(&sh->count);
1520
1521         if (failb == syndrome_disks+1) {
1522                 /* Q disk is one of the missing disks */
1523                 if (faila == syndrome_disks) {
1524                         /* Missing P+Q, just recompute */
1525                         init_async_submit(&submit, ASYNC_TX_FENCE, NULL,
1526                                           ops_complete_compute, sh,
1527                                           to_addr_conv(sh, percpu, 0));
1528                         return async_gen_syndrome(blocks, 0, syndrome_disks+2,
1529                                                   STRIPE_SIZE, &submit);
1530                 } else {
1531                         struct page *dest;
1532                         int data_target;
1533                         int qd_idx = sh->qd_idx;
1534
1535                         /* Missing D+Q: recompute D from P, then recompute Q */
1536                         if (target == qd_idx)
1537                                 data_target = target2;
1538                         else
1539                                 data_target = target;
1540
1541                         count = 0;
1542                         for (i = disks; i-- ; ) {
1543                                 if (i == data_target || i == qd_idx)
1544                                         continue;
1545                                 blocks[count++] = sh->dev[i].page;
1546                         }
1547                         dest = sh->dev[data_target].page;
1548                         init_async_submit(&submit,
1549                                           ASYNC_TX_FENCE|ASYNC_TX_XOR_ZERO_DST,
1550                                           NULL, NULL, NULL,
1551                                           to_addr_conv(sh, percpu, 0));
1552                         tx = async_xor(dest, blocks, 0, count, STRIPE_SIZE,
1553                                        &submit);
1554
1555                         count = set_syndrome_sources(blocks, sh, SYNDROME_SRC_ALL);
1556                         init_async_submit(&submit, ASYNC_TX_FENCE, tx,
1557                                           ops_complete_compute, sh,
1558                                           to_addr_conv(sh, percpu, 0));
1559                         return async_gen_syndrome(blocks, 0, count+2,
1560                                                   STRIPE_SIZE, &submit);
1561                 }
1562         } else {
1563                 init_async_submit(&submit, ASYNC_TX_FENCE, NULL,
1564                                   ops_complete_compute, sh,
1565                                   to_addr_conv(sh, percpu, 0));
1566                 if (failb == syndrome_disks) {
1567                         /* We're missing D+P. */
1568                         return async_raid6_datap_recov(syndrome_disks+2,
1569                                                        STRIPE_SIZE, faila,
1570                                                        blocks, &submit);
1571                 } else {
1572                         /* We're missing D+D. */
1573                         return async_raid6_2data_recov(syndrome_disks+2,
1574                                                        STRIPE_SIZE, faila, failb,
1575                                                        blocks, &submit);
1576                 }
1577         }
1578 }
1579
1580 static void ops_complete_prexor(void *stripe_head_ref)
1581 {
1582         struct stripe_head *sh = stripe_head_ref;
1583
1584         pr_debug("%s: stripe %llu\n", __func__,
1585                 (unsigned long long)sh->sector);
1586
1587         if (r5c_is_writeback(sh->raid_conf->log))
1588                 /*
1589                  * raid5-cache write back uses orig_page during prexor.
1590                  * After prexor, it is time to free orig_page
1591                  */
1592                 r5c_release_extra_page(sh);
1593 }
1594
1595 static struct dma_async_tx_descriptor *
1596 ops_run_prexor5(struct stripe_head *sh, struct raid5_percpu *percpu,
1597                 struct dma_async_tx_descriptor *tx)
1598 {
1599         int disks = sh->disks;
1600         struct page **xor_srcs = to_addr_page(percpu, 0);
1601         int count = 0, pd_idx = sh->pd_idx, i;
1602         struct async_submit_ctl submit;
1603
1604         /* existing parity data subtracted */
1605         struct page *xor_dest = xor_srcs[count++] = sh->dev[pd_idx].page;
1606
1607         BUG_ON(sh->batch_head);
1608         pr_debug("%s: stripe %llu\n", __func__,
1609                 (unsigned long long)sh->sector);
1610
1611         for (i = disks; i--; ) {
1612                 struct r5dev *dev = &sh->dev[i];
1613                 /* Only process blocks that are known to be uptodate */
1614                 if (test_bit(R5_InJournal, &dev->flags))
1615                         xor_srcs[count++] = dev->orig_page;
1616                 else if (test_bit(R5_Wantdrain, &dev->flags))
1617                         xor_srcs[count++] = dev->page;
1618         }
1619
1620         init_async_submit(&submit, ASYNC_TX_FENCE|ASYNC_TX_XOR_DROP_DST, tx,
1621                           ops_complete_prexor, sh, to_addr_conv(sh, percpu, 0));
1622         tx = async_xor(xor_dest, xor_srcs, 0, count, STRIPE_SIZE, &submit);
1623
1624         return tx;
1625 }
1626
1627 static struct dma_async_tx_descriptor *
1628 ops_run_prexor6(struct stripe_head *sh, struct raid5_percpu *percpu,
1629                 struct dma_async_tx_descriptor *tx)
1630 {
1631         struct page **blocks = to_addr_page(percpu, 0);
1632         int count;
1633         struct async_submit_ctl submit;
1634
1635         pr_debug("%s: stripe %llu\n", __func__,
1636                 (unsigned long long)sh->sector);
1637
1638         count = set_syndrome_sources(blocks, sh, SYNDROME_SRC_WANT_DRAIN);
1639
1640         init_async_submit(&submit, ASYNC_TX_FENCE|ASYNC_TX_PQ_XOR_DST, tx,
1641                           ops_complete_prexor, sh, to_addr_conv(sh, percpu, 0));
1642         tx = async_gen_syndrome(blocks, 0, count+2, STRIPE_SIZE,  &submit);
1643
1644         return tx;
1645 }
1646
1647 static struct dma_async_tx_descriptor *
1648 ops_run_biodrain(struct stripe_head *sh, struct dma_async_tx_descriptor *tx)
1649 {
1650         struct r5conf *conf = sh->raid_conf;
1651         int disks = sh->disks;
1652         int i;
1653         struct stripe_head *head_sh = sh;
1654
1655         pr_debug("%s: stripe %llu\n", __func__,
1656                 (unsigned long long)sh->sector);
1657
1658         for (i = disks; i--; ) {
1659                 struct r5dev *dev;
1660                 struct bio *chosen;
1661
1662                 sh = head_sh;
1663                 if (test_and_clear_bit(R5_Wantdrain, &head_sh->dev[i].flags)) {
1664                         struct bio *wbi;
1665
1666 again:
1667                         dev = &sh->dev[i];
1668                         /*
1669                          * clear R5_InJournal, so when rewriting a page in
1670                          * journal, it is not skipped by r5l_log_stripe()
1671                          */
1672                         clear_bit(R5_InJournal, &dev->flags);
1673                         spin_lock_irq(&sh->stripe_lock);
1674                         chosen = dev->towrite;
1675                         dev->towrite = NULL;
1676                         sh->overwrite_disks = 0;
1677                         BUG_ON(dev->written);
1678                         wbi = dev->written = chosen;
1679                         spin_unlock_irq(&sh->stripe_lock);
1680                         WARN_ON(dev->page != dev->orig_page);
1681
1682                         while (wbi && wbi->bi_iter.bi_sector <
1683                                 dev->sector + STRIPE_SECTORS) {
1684                                 if (wbi->bi_opf & REQ_FUA)
1685                                         set_bit(R5_WantFUA, &dev->flags);
1686                                 if (wbi->bi_opf & REQ_SYNC)
1687                                         set_bit(R5_SyncIO, &dev->flags);
1688                                 if (bio_op(wbi) == REQ_OP_DISCARD)
1689                                         set_bit(R5_Discard, &dev->flags);
1690                                 else {
1691                                         tx = async_copy_data(1, wbi, &dev->page,
1692                                                              dev->sector, tx, sh,
1693                                                              r5c_is_writeback(conf->log));
1694                                         if (dev->page != dev->orig_page &&
1695                                             !r5c_is_writeback(conf->log)) {
1696                                                 set_bit(R5_SkipCopy, &dev->flags);
1697                                                 clear_bit(R5_UPTODATE, &dev->flags);
1698                                                 clear_bit(R5_OVERWRITE, &dev->flags);
1699                                         }
1700                                 }
1701                                 wbi = r5_next_bio(wbi, dev->sector);
1702                         }
1703
1704                         if (head_sh->batch_head) {
1705                                 sh = list_first_entry(&sh->batch_list,
1706                                                       struct stripe_head,
1707                                                       batch_list);
1708                                 if (sh == head_sh)
1709                                         continue;
1710                                 goto again;
1711                         }
1712                 }
1713         }
1714
1715         return tx;
1716 }
1717
1718 static void ops_complete_reconstruct(void *stripe_head_ref)
1719 {
1720         struct stripe_head *sh = stripe_head_ref;
1721         int disks = sh->disks;
1722         int pd_idx = sh->pd_idx;
1723         int qd_idx = sh->qd_idx;
1724         int i;
1725         bool fua = false, sync = false, discard = false;
1726
1727         pr_debug("%s: stripe %llu\n", __func__,
1728                 (unsigned long long)sh->sector);
1729
1730         for (i = disks; i--; ) {
1731                 fua |= test_bit(R5_WantFUA, &sh->dev[i].flags);
1732                 sync |= test_bit(R5_SyncIO, &sh->dev[i].flags);
1733                 discard |= test_bit(R5_Discard, &sh->dev[i].flags);
1734         }
1735
1736         for (i = disks; i--; ) {
1737                 struct r5dev *dev = &sh->dev[i];
1738
1739                 if (dev->written || i == pd_idx || i == qd_idx) {
1740                         if (!discard && !test_bit(R5_SkipCopy, &dev->flags))
1741                                 set_bit(R5_UPTODATE, &dev->flags);
1742                         if (fua)
1743                                 set_bit(R5_WantFUA, &dev->flags);
1744                         if (sync)
1745                                 set_bit(R5_SyncIO, &dev->flags);
1746                 }
1747         }
1748
1749         if (sh->reconstruct_state == reconstruct_state_drain_run)
1750                 sh->reconstruct_state = reconstruct_state_drain_result;
1751         else if (sh->reconstruct_state == reconstruct_state_prexor_drain_run)
1752                 sh->reconstruct_state = reconstruct_state_prexor_drain_result;
1753         else {
1754                 BUG_ON(sh->reconstruct_state != reconstruct_state_run);
1755                 sh->reconstruct_state = reconstruct_state_result;
1756         }
1757
1758         set_bit(STRIPE_HANDLE, &sh->state);
1759         raid5_release_stripe(sh);
1760 }
1761
1762 static void
1763 ops_run_reconstruct5(struct stripe_head *sh, struct raid5_percpu *percpu,
1764                      struct dma_async_tx_descriptor *tx)
1765 {
1766         int disks = sh->disks;
1767         struct page **xor_srcs;
1768         struct async_submit_ctl submit;
1769         int count, pd_idx = sh->pd_idx, i;
1770         struct page *xor_dest;
1771         int prexor = 0;
1772         unsigned long flags;
1773         int j = 0;
1774         struct stripe_head *head_sh = sh;
1775         int last_stripe;
1776
1777         pr_debug("%s: stripe %llu\n", __func__,
1778                 (unsigned long long)sh->sector);
1779
1780         for (i = 0; i < sh->disks; i++) {
1781                 if (pd_idx == i)
1782                         continue;
1783                 if (!test_bit(R5_Discard, &sh->dev[i].flags))
1784                         break;
1785         }
1786         if (i >= sh->disks) {
1787                 atomic_inc(&sh->count);
1788                 set_bit(R5_Discard, &sh->dev[pd_idx].flags);
1789                 ops_complete_reconstruct(sh);
1790                 return;
1791         }
1792 again:
1793         count = 0;
1794         xor_srcs = to_addr_page(percpu, j);
1795         /* check if prexor is active which means only process blocks
1796          * that are part of a read-modify-write (written)
1797          */
1798         if (head_sh->reconstruct_state == reconstruct_state_prexor_drain_run) {
1799                 prexor = 1;
1800                 xor_dest = xor_srcs[count++] = sh->dev[pd_idx].page;
1801                 for (i = disks; i--; ) {
1802                         struct r5dev *dev = &sh->dev[i];
1803                         if (head_sh->dev[i].written ||
1804                             test_bit(R5_InJournal, &head_sh->dev[i].flags))
1805                                 xor_srcs[count++] = dev->page;
1806                 }
1807         } else {
1808                 xor_dest = sh->dev[pd_idx].page;
1809                 for (i = disks; i--; ) {
1810                         struct r5dev *dev = &sh->dev[i];
1811                         if (i != pd_idx)
1812                                 xor_srcs[count++] = dev->page;
1813                 }
1814         }
1815
1816         /* 1/ if we prexor'd then the dest is reused as a source
1817          * 2/ if we did not prexor then we are redoing the parity
1818          * set ASYNC_TX_XOR_DROP_DST and ASYNC_TX_XOR_ZERO_DST
1819          * for the synchronous xor case
1820          */
1821         last_stripe = !head_sh->batch_head ||
1822                 list_first_entry(&sh->batch_list,
1823                                  struct stripe_head, batch_list) == head_sh;
1824         if (last_stripe) {
1825                 flags = ASYNC_TX_ACK |
1826                         (prexor ? ASYNC_TX_XOR_DROP_DST : ASYNC_TX_XOR_ZERO_DST);
1827
1828                 atomic_inc(&head_sh->count);
1829                 init_async_submit(&submit, flags, tx, ops_complete_reconstruct, head_sh,
1830                                   to_addr_conv(sh, percpu, j));
1831         } else {
1832                 flags = prexor ? ASYNC_TX_XOR_DROP_DST : ASYNC_TX_XOR_ZERO_DST;
1833                 init_async_submit(&submit, flags, tx, NULL, NULL,
1834                                   to_addr_conv(sh, percpu, j));
1835         }
1836
1837         if (unlikely(count == 1))
1838                 tx = async_memcpy(xor_dest, xor_srcs[0], 0, 0, STRIPE_SIZE, &submit);
1839         else
1840                 tx = async_xor(xor_dest, xor_srcs, 0, count, STRIPE_SIZE, &submit);
1841         if (!last_stripe) {
1842                 j++;
1843                 sh = list_first_entry(&sh->batch_list, struct stripe_head,
1844                                       batch_list);
1845                 goto again;
1846         }
1847 }
1848
1849 static void
1850 ops_run_reconstruct6(struct stripe_head *sh, struct raid5_percpu *percpu,
1851                      struct dma_async_tx_descriptor *tx)
1852 {
1853         struct async_submit_ctl submit;
1854         struct page **blocks;
1855         int count, i, j = 0;
1856         struct stripe_head *head_sh = sh;
1857         int last_stripe;
1858         int synflags;
1859         unsigned long txflags;
1860
1861         pr_debug("%s: stripe %llu\n", __func__, (unsigned long long)sh->sector);
1862
1863         for (i = 0; i < sh->disks; i++) {
1864                 if (sh->pd_idx == i || sh->qd_idx == i)
1865                         continue;
1866                 if (!test_bit(R5_Discard, &sh->dev[i].flags))
1867                         break;
1868         }
1869         if (i >= sh->disks) {
1870                 atomic_inc(&sh->count);
1871                 set_bit(R5_Discard, &sh->dev[sh->pd_idx].flags);
1872                 set_bit(R5_Discard, &sh->dev[sh->qd_idx].flags);
1873                 ops_complete_reconstruct(sh);
1874                 return;
1875         }
1876
1877 again:
1878         blocks = to_addr_page(percpu, j);
1879
1880         if (sh->reconstruct_state == reconstruct_state_prexor_drain_run) {
1881                 synflags = SYNDROME_SRC_WRITTEN;
1882                 txflags = ASYNC_TX_ACK | ASYNC_TX_PQ_XOR_DST;
1883         } else {
1884                 synflags = SYNDROME_SRC_ALL;
1885                 txflags = ASYNC_TX_ACK;
1886         }
1887
1888         count = set_syndrome_sources(blocks, sh, synflags);
1889         last_stripe = !head_sh->batch_head ||
1890                 list_first_entry(&sh->batch_list,
1891                                  struct stripe_head, batch_list) == head_sh;
1892
1893         if (last_stripe) {
1894                 atomic_inc(&head_sh->count);
1895                 init_async_submit(&submit, txflags, tx, ops_complete_reconstruct,
1896                                   head_sh, to_addr_conv(sh, percpu, j));
1897         } else
1898                 init_async_submit(&submit, 0, tx, NULL, NULL,
1899                                   to_addr_conv(sh, percpu, j));
1900         tx = async_gen_syndrome(blocks, 0, count+2, STRIPE_SIZE,  &submit);
1901         if (!last_stripe) {
1902                 j++;
1903                 sh = list_first_entry(&sh->batch_list, struct stripe_head,
1904                                       batch_list);
1905                 goto again;
1906         }
1907 }
1908
1909 static void ops_complete_check(void *stripe_head_ref)
1910 {
1911         struct stripe_head *sh = stripe_head_ref;
1912
1913         pr_debug("%s: stripe %llu\n", __func__,
1914                 (unsigned long long)sh->sector);
1915
1916         sh->check_state = check_state_check_result;
1917         set_bit(STRIPE_HANDLE, &sh->state);
1918         raid5_release_stripe(sh);
1919 }
1920
1921 static void ops_run_check_p(struct stripe_head *sh, struct raid5_percpu *percpu)
1922 {
1923         int disks = sh->disks;
1924         int pd_idx = sh->pd_idx;
1925         int qd_idx = sh->qd_idx;
1926         struct page *xor_dest;
1927         struct page **xor_srcs = to_addr_page(percpu, 0);
1928         struct dma_async_tx_descriptor *tx;
1929         struct async_submit_ctl submit;
1930         int count;
1931         int i;
1932
1933         pr_debug("%s: stripe %llu\n", __func__,
1934                 (unsigned long long)sh->sector);
1935
1936         BUG_ON(sh->batch_head);
1937         count = 0;
1938         xor_dest = sh->dev[pd_idx].page;
1939         xor_srcs[count++] = xor_dest;
1940         for (i = disks; i--; ) {
1941                 if (i == pd_idx || i == qd_idx)
1942                         continue;
1943                 xor_srcs[count++] = sh->dev[i].page;
1944         }
1945
1946         init_async_submit(&submit, 0, NULL, NULL, NULL,
1947                           to_addr_conv(sh, percpu, 0));
1948         tx = async_xor_val(xor_dest, xor_srcs, 0, count, STRIPE_SIZE,
1949                            &sh->ops.zero_sum_result, &submit);
1950
1951         atomic_inc(&sh->count);
1952         init_async_submit(&submit, ASYNC_TX_ACK, tx, ops_complete_check, sh, NULL);
1953         tx = async_trigger_callback(&submit);
1954 }
1955
1956 static void ops_run_check_pq(struct stripe_head *sh, struct raid5_percpu *percpu, int checkp)
1957 {
1958         struct page **srcs = to_addr_page(percpu, 0);
1959         struct async_submit_ctl submit;
1960         int count;
1961
1962         pr_debug("%s: stripe %llu checkp: %d\n", __func__,
1963                 (unsigned long long)sh->sector, checkp);
1964
1965         BUG_ON(sh->batch_head);
1966         count = set_syndrome_sources(srcs, sh, SYNDROME_SRC_ALL);
1967         if (!checkp)
1968                 srcs[count] = NULL;
1969
1970         atomic_inc(&sh->count);
1971         init_async_submit(&submit, ASYNC_TX_ACK, NULL, ops_complete_check,
1972                           sh, to_addr_conv(sh, percpu, 0));
1973         async_syndrome_val(srcs, 0, count+2, STRIPE_SIZE,
1974                            &sh->ops.zero_sum_result, percpu->spare_page, &submit);
1975 }
1976
1977 static void raid_run_ops(struct stripe_head *sh, unsigned long ops_request)
1978 {
1979         int overlap_clear = 0, i, disks = sh->disks;
1980         struct dma_async_tx_descriptor *tx = NULL;
1981         struct r5conf *conf = sh->raid_conf;
1982         int level = conf->level;
1983         struct raid5_percpu *percpu;
1984         unsigned long cpu;
1985
1986         cpu = get_cpu();
1987         percpu = per_cpu_ptr(conf->percpu, cpu);
1988         if (test_bit(STRIPE_OP_BIOFILL, &ops_request)) {
1989                 ops_run_biofill(sh);
1990                 overlap_clear++;
1991         }
1992
1993         if (test_bit(STRIPE_OP_COMPUTE_BLK, &ops_request)) {
1994                 if (level < 6)
1995                         tx = ops_run_compute5(sh, percpu);
1996                 else {
1997                         if (sh->ops.target2 < 0 || sh->ops.target < 0)
1998                                 tx = ops_run_compute6_1(sh, percpu);
1999                         else
2000                                 tx = ops_run_compute6_2(sh, percpu);
2001                 }
2002                 /* terminate the chain if reconstruct is not set to be run */
2003                 if (tx && !test_bit(STRIPE_OP_RECONSTRUCT, &ops_request))
2004                         async_tx_ack(tx);
2005         }
2006
2007         if (test_bit(STRIPE_OP_PREXOR, &ops_request)) {
2008                 if (level < 6)
2009                         tx = ops_run_prexor5(sh, percpu, tx);
2010                 else
2011                         tx = ops_run_prexor6(sh, percpu, tx);
2012         }
2013
2014         if (test_bit(STRIPE_OP_BIODRAIN, &ops_request)) {
2015                 tx = ops_run_biodrain(sh, tx);
2016                 overlap_clear++;
2017         }
2018
2019         if (test_bit(STRIPE_OP_RECONSTRUCT, &ops_request)) {
2020                 if (level < 6)
2021                         ops_run_reconstruct5(sh, percpu, tx);
2022                 else
2023                         ops_run_reconstruct6(sh, percpu, tx);
2024         }
2025
2026         if (test_bit(STRIPE_OP_CHECK, &ops_request)) {
2027                 if (sh->check_state == check_state_run)
2028                         ops_run_check_p(sh, percpu);
2029                 else if (sh->check_state == check_state_run_q)
2030                         ops_run_check_pq(sh, percpu, 0);
2031                 else if (sh->check_state == check_state_run_pq)
2032                         ops_run_check_pq(sh, percpu, 1);
2033                 else
2034                         BUG();
2035         }
2036
2037         if (overlap_clear && !sh->batch_head)
2038                 for (i = disks; i--; ) {
2039                         struct r5dev *dev = &sh->dev[i];
2040                         if (test_and_clear_bit(R5_Overlap, &dev->flags))
2041                                 wake_up(&sh->raid_conf->wait_for_overlap);
2042                 }
2043         put_cpu();
2044 }
2045
2046 static struct stripe_head *alloc_stripe(struct kmem_cache *sc, gfp_t gfp,
2047         int disks)
2048 {
2049         struct stripe_head *sh;
2050         int i;
2051
2052         sh = kmem_cache_zalloc(sc, gfp);
2053         if (sh) {
2054                 spin_lock_init(&sh->stripe_lock);
2055                 spin_lock_init(&sh->batch_lock);
2056                 INIT_LIST_HEAD(&sh->batch_list);
2057                 INIT_LIST_HEAD(&sh->lru);
2058                 INIT_LIST_HEAD(&sh->r5c);
2059                 INIT_LIST_HEAD(&sh->log_list);
2060                 atomic_set(&sh->count, 1);
2061                 sh->log_start = MaxSector;
2062                 for (i = 0; i < disks; i++) {
2063                         struct r5dev *dev = &sh->dev[i];
2064
2065                         bio_init(&dev->req, &dev->vec, 1);
2066                         bio_init(&dev->rreq, &dev->rvec, 1);
2067                 }
2068         }
2069         return sh;
2070 }
2071 static int grow_one_stripe(struct r5conf *conf, gfp_t gfp)
2072 {
2073         struct stripe_head *sh;
2074
2075         sh = alloc_stripe(conf->slab_cache, gfp, conf->pool_size);
2076         if (!sh)
2077                 return 0;
2078
2079         sh->raid_conf = conf;
2080
2081         if (grow_buffers(sh, gfp)) {
2082                 shrink_buffers(sh);
2083                 kmem_cache_free(conf->slab_cache, sh);
2084                 return 0;
2085         }
2086         sh->hash_lock_index =
2087                 conf->max_nr_stripes % NR_STRIPE_HASH_LOCKS;
2088         /* we just created an active stripe so... */
2089         atomic_inc(&conf->active_stripes);
2090
2091         raid5_release_stripe(sh);
2092         conf->max_nr_stripes++;
2093         return 1;
2094 }
2095
2096 static int grow_stripes(struct r5conf *conf, int num)
2097 {
2098         struct kmem_cache *sc;
2099         int devs = max(conf->raid_disks, conf->previous_raid_disks);
2100
2101         if (conf->mddev->gendisk)
2102                 sprintf(conf->cache_name[0],
2103                         "raid%d-%s", conf->level, mdname(conf->mddev));
2104         else
2105                 sprintf(conf->cache_name[0],
2106                         "raid%d-%p", conf->level, conf->mddev);
2107         sprintf(conf->cache_name[1], "%s-alt", conf->cache_name[0]);
2108
2109         conf->active_name = 0;
2110         sc = kmem_cache_create(conf->cache_name[conf->active_name],
2111                                sizeof(struct stripe_head)+(devs-1)*sizeof(struct r5dev),
2112                                0, 0, NULL);
2113         if (!sc)
2114                 return 1;
2115         conf->slab_cache = sc;
2116         conf->pool_size = devs;
2117         while (num--)
2118                 if (!grow_one_stripe(conf, GFP_KERNEL))
2119                         return 1;
2120
2121         return 0;
2122 }
2123
2124 /**
2125  * scribble_len - return the required size of the scribble region
2126  * @num - total number of disks in the array
2127  *
2128  * The size must be enough to contain:
2129  * 1/ a struct page pointer for each device in the array +2
2130  * 2/ room to convert each entry in (1) to its corresponding dma
2131  *    (dma_map_page()) or page (page_address()) address.
2132  *
2133  * Note: the +2 is for the destination buffers of the ddf/raid6 case where we
2134  * calculate over all devices (not just the data blocks), using zeros in place
2135  * of the P and Q blocks.
2136  */
2137 static struct flex_array *scribble_alloc(int num, int cnt, gfp_t flags)
2138 {
2139         struct flex_array *ret;
2140         size_t len;
2141
2142         len = sizeof(struct page *) * (num+2) + sizeof(addr_conv_t) * (num+2);
2143         ret = flex_array_alloc(len, cnt, flags);
2144         if (!ret)
2145                 return NULL;
2146         /* always prealloc all elements, so no locking is required */
2147         if (flex_array_prealloc(ret, 0, cnt, flags)) {
2148                 flex_array_free(ret);
2149                 return NULL;
2150         }
2151         return ret;
2152 }
2153
2154 static int resize_chunks(struct r5conf *conf, int new_disks, int new_sectors)
2155 {
2156         unsigned long cpu;
2157         int err = 0;
2158
2159         /*
2160          * Never shrink. And mddev_suspend() could deadlock if this is called
2161          * from raid5d. In that case, scribble_disks and scribble_sectors
2162          * should equal to new_disks and new_sectors
2163          */
2164         if (conf->scribble_disks >= new_disks &&
2165             conf->scribble_sectors >= new_sectors)
2166                 return 0;
2167         mddev_suspend(conf->mddev);
2168         get_online_cpus();
2169         for_each_present_cpu(cpu) {
2170                 struct raid5_percpu *percpu;
2171                 struct flex_array *scribble;
2172
2173                 percpu = per_cpu_ptr(conf->percpu, cpu);
2174                 scribble = scribble_alloc(new_disks,
2175                                           new_sectors / STRIPE_SECTORS,
2176                                           GFP_NOIO);
2177
2178                 if (scribble) {
2179                         flex_array_free(percpu->scribble);
2180                         percpu->scribble = scribble;
2181                 } else {
2182                         err = -ENOMEM;
2183                         break;
2184                 }
2185         }
2186         put_online_cpus();
2187         mddev_resume(conf->mddev);
2188         if (!err) {
2189                 conf->scribble_disks = new_disks;
2190                 conf->scribble_sectors = new_sectors;
2191         }
2192         return err;
2193 }
2194
2195 static int resize_stripes(struct r5conf *conf, int newsize)
2196 {
2197         /* Make all the stripes able to hold 'newsize' devices.
2198          * New slots in each stripe get 'page' set to a new page.
2199          *
2200          * This happens in stages:
2201          * 1/ create a new kmem_cache and allocate the required number of
2202          *    stripe_heads.
2203          * 2/ gather all the old stripe_heads and transfer the pages across
2204          *    to the new stripe_heads.  This will have the side effect of
2205          *    freezing the array as once all stripe_heads have been collected,
2206          *    no IO will be possible.  Old stripe heads are freed once their
2207          *    pages have been transferred over, and the old kmem_cache is
2208          *    freed when all stripes are done.
2209          * 3/ reallocate conf->disks to be suitable bigger.  If this fails,
2210          *    we simple return a failre status - no need to clean anything up.
2211          * 4/ allocate new pages for the new slots in the new stripe_heads.
2212          *    If this fails, we don't bother trying the shrink the
2213          *    stripe_heads down again, we just leave them as they are.
2214          *    As each stripe_head is processed the new one is released into
2215          *    active service.
2216          *
2217          * Once step2 is started, we cannot afford to wait for a write,
2218          * so we use GFP_NOIO allocations.
2219          */
2220         struct stripe_head *osh, *nsh;
2221         LIST_HEAD(newstripes);
2222         struct disk_info *ndisks;
2223         int err;
2224         struct kmem_cache *sc;
2225         int i;
2226         int hash, cnt;
2227
2228         if (newsize <= conf->pool_size)
2229                 return 0; /* never bother to shrink */
2230
2231         err = md_allow_write(conf->mddev);
2232         if (err)
2233                 return err;
2234
2235         /* Step 1 */
2236         sc = kmem_cache_create(conf->cache_name[1-conf->active_name],
2237                                sizeof(struct stripe_head)+(newsize-1)*sizeof(struct r5dev),
2238                                0, 0, NULL);
2239         if (!sc)
2240                 return -ENOMEM;
2241
2242         /* Need to ensure auto-resizing doesn't interfere */
2243         mutex_lock(&conf->cache_size_mutex);
2244
2245         for (i = conf->max_nr_stripes; i; i--) {
2246                 nsh = alloc_stripe(sc, GFP_KERNEL, newsize);
2247                 if (!nsh)
2248                         break;
2249
2250                 nsh->raid_conf = conf;
2251                 list_add(&nsh->lru, &newstripes);
2252         }
2253         if (i) {
2254                 /* didn't get enough, give up */
2255                 while (!list_empty(&newstripes)) {
2256                         nsh = list_entry(newstripes.next, struct stripe_head, lru);
2257                         list_del(&nsh->lru);
2258                         kmem_cache_free(sc, nsh);
2259                 }
2260                 kmem_cache_destroy(sc);
2261                 mutex_unlock(&conf->cache_size_mutex);
2262                 return -ENOMEM;
2263         }
2264         /* Step 2 - Must use GFP_NOIO now.
2265          * OK, we have enough stripes, start collecting inactive
2266          * stripes and copying them over
2267          */
2268         hash = 0;
2269         cnt = 0;
2270         list_for_each_entry(nsh, &newstripes, lru) {
2271                 lock_device_hash_lock(conf, hash);
2272                 wait_event_cmd(conf->wait_for_stripe,
2273                                     !list_empty(conf->inactive_list + hash),
2274                                     unlock_device_hash_lock(conf, hash),
2275                                     lock_device_hash_lock(conf, hash));
2276                 osh = get_free_stripe(conf, hash);
2277                 unlock_device_hash_lock(conf, hash);
2278
2279                 for(i=0; i<conf->pool_size; i++) {
2280                         nsh->dev[i].page = osh->dev[i].page;
2281                         nsh->dev[i].orig_page = osh->dev[i].page;
2282                 }
2283                 nsh->hash_lock_index = hash;
2284                 kmem_cache_free(conf->slab_cache, osh);
2285                 cnt++;
2286                 if (cnt >= conf->max_nr_stripes / NR_STRIPE_HASH_LOCKS +
2287                     !!((conf->max_nr_stripes % NR_STRIPE_HASH_LOCKS) > hash)) {
2288                         hash++;
2289                         cnt = 0;
2290                 }
2291         }
2292         kmem_cache_destroy(conf->slab_cache);
2293
2294         /* Step 3.
2295          * At this point, we are holding all the stripes so the array
2296          * is completely stalled, so now is a good time to resize
2297          * conf->disks and the scribble region
2298          */
2299         ndisks = kzalloc(newsize * sizeof(struct disk_info), GFP_NOIO);
2300         if (ndisks) {
2301                 for (i = 0; i < conf->pool_size; i++)
2302                         ndisks[i] = conf->disks[i];
2303
2304                 for (i = conf->pool_size; i < newsize; i++) {
2305                         ndisks[i].extra_page = alloc_page(GFP_NOIO);
2306                         if (!ndisks[i].extra_page)
2307                                 err = -ENOMEM;
2308                 }
2309
2310                 if (err) {
2311                         for (i = conf->pool_size; i < newsize; i++)
2312                                 if (ndisks[i].extra_page)
2313                                         put_page(ndisks[i].extra_page);
2314                         kfree(ndisks);
2315                 } else {
2316                         kfree(conf->disks);
2317                         conf->disks = ndisks;
2318                 }
2319         } else
2320                 err = -ENOMEM;
2321
2322         mutex_unlock(&conf->cache_size_mutex);
2323         /* Step 4, return new stripes to service */
2324         while(!list_empty(&newstripes)) {
2325                 nsh = list_entry(newstripes.next, struct stripe_head, lru);
2326                 list_del_init(&nsh->lru);
2327
2328                 for (i=conf->raid_disks; i < newsize; i++)
2329                         if (nsh->dev[i].page == NULL) {
2330                                 struct page *p = alloc_page(GFP_NOIO);
2331                                 nsh->dev[i].page = p;
2332                                 nsh->dev[i].orig_page = p;
2333                                 if (!p)
2334                                         err = -ENOMEM;
2335                         }
2336                 raid5_release_stripe(nsh);
2337         }
2338         /* critical section pass, GFP_NOIO no longer needed */
2339
2340         conf->slab_cache = sc;
2341         conf->active_name = 1-conf->active_name;
2342         if (!err)
2343                 conf->pool_size = newsize;
2344         return err;
2345 }
2346
2347 static int drop_one_stripe(struct r5conf *conf)
2348 {
2349         struct stripe_head *sh;
2350         int hash = (conf->max_nr_stripes - 1) & STRIPE_HASH_LOCKS_MASK;
2351
2352         spin_lock_irq(conf->hash_locks + hash);
2353         sh = get_free_stripe(conf, hash);
2354         spin_unlock_irq(conf->hash_locks + hash);
2355         if (!sh)
2356                 return 0;
2357         BUG_ON(atomic_read(&sh->count));
2358         shrink_buffers(sh);
2359         kmem_cache_free(conf->slab_cache, sh);
2360         atomic_dec(&conf->active_stripes);
2361         conf->max_nr_stripes--;
2362         return 1;
2363 }
2364
2365 static void shrink_stripes(struct r5conf *conf)
2366 {
2367         while (conf->max_nr_stripes &&
2368                drop_one_stripe(conf))
2369                 ;
2370
2371         kmem_cache_destroy(conf->slab_cache);
2372         conf->slab_cache = NULL;
2373 }
2374
2375 static void raid5_end_read_request(struct bio * bi)
2376 {
2377         struct stripe_head *sh = bi->bi_private;
2378         struct r5conf *conf = sh->raid_conf;
2379         int disks = sh->disks, i;
2380         char b[BDEVNAME_SIZE];
2381         struct md_rdev *rdev = NULL;
2382         sector_t s;
2383
2384         for (i=0 ; i<disks; i++)
2385                 if (bi == &sh->dev[i].req)
2386                         break;
2387
2388         pr_debug("end_read_request %llu/%d, count: %d, error %d.\n",
2389                 (unsigned long long)sh->sector, i, atomic_read(&sh->count),
2390                 bi->bi_error);
2391         if (i == disks) {
2392                 bio_reset(bi);
2393                 BUG();
2394                 return;
2395         }
2396         if (test_bit(R5_ReadRepl, &sh->dev[i].flags))
2397                 /* If replacement finished while this request was outstanding,
2398                  * 'replacement' might be NULL already.
2399                  * In that case it moved down to 'rdev'.
2400                  * rdev is not removed until all requests are finished.
2401                  */
2402                 rdev = conf->disks[i].replacement;
2403         if (!rdev)
2404                 rdev = conf->disks[i].rdev;
2405
2406         if (use_new_offset(conf, sh))
2407                 s = sh->sector + rdev->new_data_offset;
2408         else
2409                 s = sh->sector + rdev->data_offset;
2410         if (!bi->bi_error) {
2411                 set_bit(R5_UPTODATE, &sh->dev[i].flags);
2412                 if (test_bit(R5_ReadError, &sh->dev[i].flags)) {
2413                         /* Note that this cannot happen on a
2414                          * replacement device.  We just fail those on
2415                          * any error
2416                          */
2417                         pr_info_ratelimited(
2418                                 "md/raid:%s: read error corrected (%lu sectors at %llu on %s)\n",
2419                                 mdname(conf->mddev), STRIPE_SECTORS,
2420                                 (unsigned long long)s,
2421                                 bdevname(rdev->bdev, b));
2422                         atomic_add(STRIPE_SECTORS, &rdev->corrected_errors);
2423                         clear_bit(R5_ReadError, &sh->dev[i].flags);
2424                         clear_bit(R5_ReWrite, &sh->dev[i].flags);
2425                 } else if (test_bit(R5_ReadNoMerge, &sh->dev[i].flags))
2426                         clear_bit(R5_ReadNoMerge, &sh->dev[i].flags);
2427
2428                 if (test_bit(R5_InJournal, &sh->dev[i].flags))
2429                         /*
2430                          * end read for a page in journal, this
2431                          * must be preparing for prexor in rmw
2432                          */
2433                         set_bit(R5_OrigPageUPTDODATE, &sh->dev[i].flags);
2434
2435                 if (atomic_read(&rdev->read_errors))
2436                         atomic_set(&rdev->read_errors, 0);
2437         } else {
2438                 const char *bdn = bdevname(rdev->bdev, b);
2439                 int retry = 0;
2440                 int set_bad = 0;
2441
2442                 clear_bit(R5_UPTODATE, &sh->dev[i].flags);
2443                 atomic_inc(&rdev->read_errors);
2444                 if (test_bit(R5_ReadRepl, &sh->dev[i].flags))
2445                         pr_warn_ratelimited(
2446                                 "md/raid:%s: read error on replacement device (sector %llu on %s).\n",
2447                                 mdname(conf->mddev),
2448                                 (unsigned long long)s,
2449                                 bdn);
2450                 else if (conf->mddev->degraded >= conf->max_degraded) {
2451                         set_bad = 1;
2452                         pr_warn_ratelimited(
2453                                 "md/raid:%s: read error not correctable (sector %llu on %s).\n",
2454                                 mdname(conf->mddev),
2455                                 (unsigned long long)s,
2456                                 bdn);
2457                 } else if (test_bit(R5_ReWrite, &sh->dev[i].flags)) {
2458                         /* Oh, no!!! */
2459                         set_bad = 1;
2460                         pr_warn_ratelimited(
2461                                 "md/raid:%s: read error NOT corrected!! (sector %llu on %s).\n",
2462                                 mdname(conf->mddev),
2463                                 (unsigned long long)s,
2464                                 bdn);
2465                 } else if (atomic_read(&rdev->read_errors)
2466                          > conf->max_nr_stripes)
2467                         pr_warn("md/raid:%s: Too many read errors, failing device %s.\n",
2468                                mdname(conf->mddev), bdn);
2469                 else
2470                         retry = 1;
2471                 if (set_bad && test_bit(In_sync, &rdev->flags)
2472                     && !test_bit(R5_ReadNoMerge, &sh->dev[i].flags))
2473                         retry = 1;
2474                 if (retry)
2475                         if (test_bit(R5_ReadNoMerge, &sh->dev[i].flags)) {
2476                                 set_bit(R5_ReadError, &sh->dev[i].flags);
2477                                 clear_bit(R5_ReadNoMerge, &sh->dev[i].flags);
2478                         } else
2479                                 set_bit(R5_ReadNoMerge, &sh->dev[i].flags);
2480                 else {
2481                         clear_bit(R5_ReadError, &sh->dev[i].flags);
2482                         clear_bit(R5_ReWrite, &sh->dev[i].flags);
2483                         if (!(set_bad
2484                               && test_bit(In_sync, &rdev->flags)
2485                               && rdev_set_badblocks(
2486                                       rdev, sh->sector, STRIPE_SECTORS, 0)))
2487                                 md_error(conf->mddev, rdev);
2488                 }
2489         }
2490         rdev_dec_pending(rdev, conf->mddev);
2491         bio_reset(bi);
2492         clear_bit(R5_LOCKED, &sh->dev[i].flags);
2493         set_bit(STRIPE_HANDLE, &sh->state);
2494         raid5_release_stripe(sh);
2495 }
2496
2497 static void raid5_end_write_request(struct bio *bi)
2498 {
2499         struct stripe_head *sh = bi->bi_private;
2500         struct r5conf *conf = sh->raid_conf;
2501         int disks = sh->disks, i;
2502         struct md_rdev *uninitialized_var(rdev);
2503         sector_t first_bad;
2504         int bad_sectors;
2505         int replacement = 0;
2506
2507         for (i = 0 ; i < disks; i++) {
2508                 if (bi == &sh->dev[i].req) {
2509                         rdev = conf->disks[i].rdev;
2510                         break;
2511                 }
2512                 if (bi == &sh->dev[i].rreq) {
2513                         rdev = conf->disks[i].replacement;
2514                         if (rdev)
2515                                 replacement = 1;
2516                         else
2517                                 /* rdev was removed and 'replacement'
2518                                  * replaced it.  rdev is not removed
2519                                  * until all requests are finished.
2520                                  */
2521                                 rdev = conf->disks[i].rdev;
2522                         break;
2523                 }
2524         }
2525         pr_debug("end_write_request %llu/%d, count %d, error: %d.\n",
2526                 (unsigned long long)sh->sector, i, atomic_read(&sh->count),
2527                 bi->bi_error);
2528         if (i == disks) {
2529                 bio_reset(bi);
2530                 BUG();
2531                 return;
2532         }
2533
2534         if (replacement) {
2535                 if (bi->bi_error)
2536                         md_error(conf->mddev, rdev);
2537                 else if (is_badblock(rdev, sh->sector,
2538                                      STRIPE_SECTORS,
2539                                      &first_bad, &bad_sectors))
2540                         set_bit(R5_MadeGoodRepl, &sh->dev[i].flags);
2541         } else {
2542                 if (bi->bi_error) {
2543                         set_bit(STRIPE_DEGRADED, &sh->state);
2544                         set_bit(WriteErrorSeen, &rdev->flags);
2545                         set_bit(R5_WriteError, &sh->dev[i].flags);
2546                         if (!test_and_set_bit(WantReplacement, &rdev->flags))
2547                                 set_bit(MD_RECOVERY_NEEDED,
2548                                         &rdev->mddev->recovery);
2549                 } else if (is_badblock(rdev, sh->sector,
2550                                        STRIPE_SECTORS,
2551                                        &first_bad, &bad_sectors)) {
2552                         set_bit(R5_MadeGood, &sh->dev[i].flags);
2553                         if (test_bit(R5_ReadError, &sh->dev[i].flags))
2554                                 /* That was a successful write so make
2555                                  * sure it looks like we already did
2556                                  * a re-write.
2557                                  */
2558                                 set_bit(R5_ReWrite, &sh->dev[i].flags);
2559                 }
2560         }
2561         rdev_dec_pending(rdev, conf->mddev);
2562
2563         if (sh->batch_head && bi->bi_error && !replacement)
2564                 set_bit(STRIPE_BATCH_ERR, &sh->batch_head->state);
2565
2566         bio_reset(bi);
2567         if (!test_and_clear_bit(R5_DOUBLE_LOCKED, &sh->dev[i].flags))
2568                 clear_bit(R5_LOCKED, &sh->dev[i].flags);
2569         set_bit(STRIPE_HANDLE, &sh->state);
2570         raid5_release_stripe(sh);
2571
2572         if (sh->batch_head && sh != sh->batch_head)
2573                 raid5_release_stripe(sh->batch_head);
2574 }
2575
2576 static void raid5_build_block(struct stripe_head *sh, int i, int previous)
2577 {
2578         struct r5dev *dev = &sh->dev[i];
2579
2580         dev->flags = 0;
2581         dev->sector = raid5_compute_blocknr(sh, i, previous);
2582 }
2583
2584 static void raid5_error(struct mddev *mddev, struct md_rdev *rdev)
2585 {
2586         char b[BDEVNAME_SIZE];
2587         struct r5conf *conf = mddev->private;
2588         unsigned long flags;
2589         pr_debug("raid456: error called\n");
2590
2591         spin_lock_irqsave(&conf->device_lock, flags);
2592         clear_bit(In_sync, &rdev->flags);
2593         mddev->degraded = raid5_calc_degraded(conf);
2594         spin_unlock_irqrestore(&conf->device_lock, flags);
2595         set_bit(MD_RECOVERY_INTR, &mddev->recovery);
2596
2597         set_bit(Blocked, &rdev->flags);
2598         set_bit(Faulty, &rdev->flags);
2599         set_mask_bits(&mddev->sb_flags, 0,
2600                       BIT(MD_SB_CHANGE_DEVS) | BIT(MD_SB_CHANGE_PENDING));
2601         pr_crit("md/raid:%s: Disk failure on %s, disabling device.\n"
2602                 "md/raid:%s: Operation continuing on %d devices.\n",
2603                 mdname(mddev),
2604                 bdevname(rdev->bdev, b),
2605                 mdname(mddev),
2606                 conf->raid_disks - mddev->degraded);
2607         r5c_update_on_rdev_error(mddev);
2608 }
2609
2610 /*
2611  * Input: a 'big' sector number,
2612  * Output: index of the data and parity disk, and the sector # in them.
2613  */
2614 sector_t raid5_compute_sector(struct r5conf *conf, sector_t r_sector,
2615                               int previous, int *dd_idx,
2616                               struct stripe_head *sh)
2617 {
2618         sector_t stripe, stripe2;
2619         sector_t chunk_number;
2620         unsigned int chunk_offset;
2621         int pd_idx, qd_idx;
2622         int ddf_layout = 0;
2623         sector_t new_sector;
2624         int algorithm = previous ? conf->prev_algo
2625                                  : conf->algorithm;
2626         int sectors_per_chunk = previous ? conf->prev_chunk_sectors
2627                                          : conf->chunk_sectors;
2628         int raid_disks = previous ? conf->previous_raid_disks
2629                                   : conf->raid_disks;
2630         int data_disks = raid_disks - conf->max_degraded;
2631
2632         /* First compute the information on this sector */
2633
2634         /*
2635          * Compute the chunk number and the sector offset inside the chunk
2636          */
2637         chunk_offset = sector_div(r_sector, sectors_per_chunk);
2638         chunk_number = r_sector;
2639
2640         /*
2641          * Compute the stripe number
2642          */
2643         stripe = chunk_number;
2644         *dd_idx = sector_div(stripe, data_disks);
2645         stripe2 = stripe;
2646         /*
2647          * Select the parity disk based on the user selected algorithm.
2648          */
2649         pd_idx = qd_idx = -1;
2650         switch(conf->level) {
2651         case 4:
2652                 pd_idx = data_disks;
2653                 break;
2654         case 5:
2655                 switch (algorithm) {
2656                 case ALGORITHM_LEFT_ASYMMETRIC:
2657                         pd_idx = data_disks - sector_div(stripe2, raid_disks);
2658                         if (*dd_idx >= pd_idx)
2659                                 (*dd_idx)++;
2660                         break;
2661                 case ALGORITHM_RIGHT_ASYMMETRIC:
2662                         pd_idx = sector_div(stripe2, raid_disks);
2663                         if (*dd_idx >= pd_idx)
2664                                 (*dd_idx)++;
2665                         break;
2666                 case ALGORITHM_LEFT_SYMMETRIC:
2667                         pd_idx = data_disks - sector_div(stripe2, raid_disks);
2668                         *dd_idx = (pd_idx + 1 + *dd_idx) % raid_disks;
2669                         break;
2670                 case ALGORITHM_RIGHT_SYMMETRIC:
2671                         pd_idx = sector_div(stripe2, raid_disks);
2672                         *dd_idx = (pd_idx + 1 + *dd_idx) % raid_disks;
2673                         break;
2674                 case ALGORITHM_PARITY_0:
2675                         pd_idx = 0;
2676                         (*dd_idx)++;
2677                         break;
2678                 case ALGORITHM_PARITY_N:
2679                         pd_idx = data_disks;
2680                         break;
2681                 default:
2682                         BUG();
2683                 }
2684                 break;
2685         case 6:
2686
2687                 switch (algorithm) {
2688                 case ALGORITHM_LEFT_ASYMMETRIC:
2689                         pd_idx = raid_disks - 1 - sector_div(stripe2, raid_disks);
2690                         qd_idx = pd_idx + 1;
2691                         if (pd_idx == raid_disks-1) {
2692                                 (*dd_idx)++;    /* Q D D D P */
2693                                 qd_idx = 0;
2694                         } else if (*dd_idx >= pd_idx)
2695                                 (*dd_idx) += 2; /* D D P Q D */
2696                         break;
2697                 case ALGORITHM_RIGHT_ASYMMETRIC:
2698                         pd_idx = sector_div(stripe2, raid_disks);
2699                         qd_idx = pd_idx + 1;
2700                         if (pd_idx == raid_disks-1) {
2701                                 (*dd_idx)++;    /* Q D D D P */
2702                                 qd_idx = 0;
2703                         } else if (*dd_idx >= pd_idx)
2704                                 (*dd_idx) += 2; /* D D P Q D */
2705                         break;
2706                 case ALGORITHM_LEFT_SYMMETRIC:
2707                         pd_idx = raid_disks - 1 - sector_div(stripe2, raid_disks);
2708                         qd_idx = (pd_idx + 1) % raid_disks;
2709                         *dd_idx = (pd_idx + 2 + *dd_idx) % raid_disks;
2710                         break;
2711                 case ALGORITHM_RIGHT_SYMMETRIC:
2712                         pd_idx = sector_div(stripe2, raid_disks);
2713                         qd_idx = (pd_idx + 1) % raid_disks;
2714                         *dd_idx = (pd_idx + 2 + *dd_idx) % raid_disks;
2715                         break;
2716
2717                 case ALGORITHM_PARITY_0:
2718                         pd_idx = 0;
2719                         qd_idx = 1;
2720                         (*dd_idx) += 2;
2721                         break;
2722                 case ALGORITHM_PARITY_N:
2723                         pd_idx = data_disks;
2724                         qd_idx = data_disks + 1;
2725                         break;
2726
2727                 case ALGORITHM_ROTATING_ZERO_RESTART:
2728                         /* Exactly the same as RIGHT_ASYMMETRIC, but or
2729                          * of blocks for computing Q is different.
2730                          */
2731                         pd_idx = sector_div(stripe2, raid_disks);
2732                         qd_idx = pd_idx + 1;
2733                         if (pd_idx == raid_disks-1) {
2734                                 (*dd_idx)++;    /* Q D D D P */
2735                                 qd_idx = 0;
2736                         } else if (*dd_idx >= pd_idx)
2737                                 (*dd_idx) += 2; /* D D P Q D */
2738                         ddf_layout = 1;
2739                         break;
2740
2741                 case ALGORITHM_ROTATING_N_RESTART:
2742                         /* Same a left_asymmetric, by first stripe is
2743                          * D D D P Q  rather than
2744                          * Q D D D P
2745                          */
2746                         stripe2 += 1;
2747                         pd_idx = raid_disks - 1 - sector_div(stripe2, raid_disks);
2748                         qd_idx = pd_idx + 1;
2749                         if (pd_idx == raid_disks-1) {
2750                                 (*dd_idx)++;    /* Q D D D P */
2751                                 qd_idx = 0;
2752                         } else if (*dd_idx >= pd_idx)
2753                                 (*dd_idx) += 2; /* D D P Q D */
2754                         ddf_layout = 1;
2755                         break;
2756
2757                 case ALGORITHM_ROTATING_N_CONTINUE:
2758                         /* Same as left_symmetric but Q is before P */
2759                         pd_idx = raid_disks - 1 - sector_div(stripe2, raid_disks);
2760                         qd_idx = (pd_idx + raid_disks - 1) % raid_disks;
2761                         *dd_idx = (pd_idx + 1 + *dd_idx) % raid_disks;
2762                         ddf_layout = 1;
2763                         break;
2764
2765                 case ALGORITHM_LEFT_ASYMMETRIC_6:
2766                         /* RAID5 left_asymmetric, with Q on last device */
2767                         pd_idx = data_disks - sector_div(stripe2, raid_disks-1);
2768                         if (*dd_idx >= pd_idx)
2769                                 (*dd_idx)++;
2770                         qd_idx = raid_disks - 1;
2771                         break;
2772
2773                 case ALGORITHM_RIGHT_ASYMMETRIC_6:
2774                         pd_idx = sector_div(stripe2, raid_disks-1);
2775                         if (*dd_idx >= pd_idx)
2776                                 (*dd_idx)++;
2777                         qd_idx = raid_disks - 1;
2778                         break;
2779
2780                 case ALGORITHM_LEFT_SYMMETRIC_6:
2781                         pd_idx = data_disks - sector_div(stripe2, raid_disks-1);
2782                         *dd_idx = (pd_idx + 1 + *dd_idx) % (raid_disks-1);
2783                         qd_idx = raid_disks - 1;
2784                         break;
2785
2786                 case ALGORITHM_RIGHT_SYMMETRIC_6:
2787                         pd_idx = sector_div(stripe2, raid_disks-1);
2788                         *dd_idx = (pd_idx + 1 + *dd_idx) % (raid_disks-1);
2789                         qd_idx = raid_disks - 1;
2790                         break;
2791
2792                 case ALGORITHM_PARITY_0_6:
2793                         pd_idx = 0;
2794                         (*dd_idx)++;
2795                         qd_idx = raid_disks - 1;
2796                         break;
2797
2798                 default:
2799                         BUG();
2800                 }
2801                 break;
2802         }
2803
2804         if (sh) {
2805                 sh->pd_idx = pd_idx;
2806                 sh->qd_idx = qd_idx;
2807                 sh->ddf_layout = ddf_layout;
2808         }
2809         /*
2810          * Finally, compute the new sector number
2811          */
2812         new_sector = (sector_t)stripe * sectors_per_chunk + chunk_offset;
2813         return new_sector;
2814 }
2815
2816 sector_t raid5_compute_blocknr(struct stripe_head *sh, int i, int previous)
2817 {
2818         struct r5conf *conf = sh->raid_conf;
2819         int raid_disks = sh->disks;
2820         int data_disks = raid_disks - conf->max_degraded;
2821         sector_t new_sector = sh->sector, check;
2822         int sectors_per_chunk = previous ? conf->prev_chunk_sectors
2823                                          : conf->chunk_sectors;
2824         int algorithm = previous ? conf->prev_algo
2825                                  : conf->algorithm;
2826         sector_t stripe;
2827         int chunk_offset;
2828         sector_t chunk_number;
2829         int dummy1, dd_idx = i;
2830         sector_t r_sector;
2831         struct stripe_head sh2;
2832
2833         chunk_offset = sector_div(new_sector, sectors_per_chunk);
2834         stripe = new_sector;
2835
2836         if (i == sh->pd_idx)
2837                 return 0;
2838         switch(conf->level) {
2839         case 4: break;
2840         case 5:
2841                 switch (algorithm) {
2842                 case ALGORITHM_LEFT_ASYMMETRIC:
2843                 case ALGORITHM_RIGHT_ASYMMETRIC:
2844                         if (i > sh->pd_idx)
2845                                 i--;
2846                         break;
2847                 case ALGORITHM_LEFT_SYMMETRIC:
2848                 case ALGORITHM_RIGHT_SYMMETRIC:
2849                         if (i < sh->pd_idx)
2850                                 i += raid_disks;
2851                         i -= (sh->pd_idx + 1);
2852                         break;
2853                 case ALGORITHM_PARITY_0:
2854                         i -= 1;
2855                         break;
2856                 case ALGORITHM_PARITY_N:
2857                         break;
2858                 default:
2859                         BUG();
2860                 }
2861                 break;
2862         case 6:
2863                 if (i == sh->qd_idx)
2864                         return 0; /* It is the Q disk */
2865                 switch (algorithm) {
2866                 case ALGORITHM_LEFT_ASYMMETRIC:
2867                 case ALGORITHM_RIGHT_ASYMMETRIC:
2868                 case ALGORITHM_ROTATING_ZERO_RESTART:
2869                 case ALGORITHM_ROTATING_N_RESTART:
2870                         if (sh->pd_idx == raid_disks-1)
2871                                 i--;    /* Q D D D P */
2872                         else if (i > sh->pd_idx)
2873                                 i -= 2; /* D D P Q D */
2874                         break;
2875                 case ALGORITHM_LEFT_SYMMETRIC:
2876                 case ALGORITHM_RIGHT_SYMMETRIC:
2877                         if (sh->pd_idx == raid_disks-1)
2878                                 i--; /* Q D D D P */
2879                         else {
2880                                 /* D D P Q D */
2881                                 if (i < sh->pd_idx)
2882                                         i += raid_disks;
2883                                 i -= (sh->pd_idx + 2);
2884                         }
2885                         break;
2886                 case ALGORITHM_PARITY_0:
2887                         i -= 2;
2888                         break;
2889                 case ALGORITHM_PARITY_N:
2890                         break;
2891                 case ALGORITHM_ROTATING_N_CONTINUE:
2892                         /* Like left_symmetric, but P is before Q */
2893                         if (sh->pd_idx == 0)
2894                                 i--;    /* P D D D Q */
2895                         else {
2896                                 /* D D Q P D */
2897                                 if (i < sh->pd_idx)
2898                                         i += raid_disks;
2899                                 i -= (sh->pd_idx + 1);
2900                         }
2901                         break;
2902                 case ALGORITHM_LEFT_ASYMMETRIC_6:
2903                 case ALGORITHM_RIGHT_ASYMMETRIC_6:
2904                         if (i > sh->pd_idx)
2905                                 i--;
2906                         break;
2907                 case ALGORITHM_LEFT_SYMMETRIC_6:
2908                 case ALGORITHM_RIGHT_SYMMETRIC_6:
2909                         if (i < sh->pd_idx)
2910                                 i += data_disks + 1;
2911                         i -= (sh->pd_idx + 1);
2912                         break;
2913                 case ALGORITHM_PARITY_0_6:
2914                         i -= 1;
2915                         break;
2916                 default:
2917                         BUG();
2918                 }
2919                 break;
2920         }
2921
2922         chunk_number = stripe * data_disks + i;
2923         r_sector = chunk_number * sectors_per_chunk + chunk_offset;
2924
2925         check = raid5_compute_sector(conf, r_sector,
2926                                      previous, &dummy1, &sh2);
2927         if (check != sh->sector || dummy1 != dd_idx || sh2.pd_idx != sh->pd_idx
2928                 || sh2.qd_idx != sh->qd_idx) {
2929                 pr_warn("md/raid:%s: compute_blocknr: map not correct\n",
2930                         mdname(conf->mddev));
2931                 return 0;
2932         }
2933         return r_sector;
2934 }
2935
2936 /*
2937  * There are cases where we want handle_stripe_dirtying() and
2938  * schedule_reconstruction() to delay towrite to some dev of a stripe.
2939  *
2940  * This function checks whether we want to delay the towrite. Specifically,
2941  * we delay the towrite when:
2942  *
2943  *   1. degraded stripe has a non-overwrite to the missing dev, AND this
2944  *      stripe has data in journal (for other devices).
2945  *
2946  *      In this case, when reading data for the non-overwrite dev, it is
2947  *      necessary to handle complex rmw of write back cache (prexor with
2948  *      orig_page, and xor with page). To keep read path simple, we would
2949  *      like to flush data in journal to RAID disks first, so complex rmw
2950  *      is handled in the write patch (handle_stripe_dirtying).
2951  *
2952  *   2. when journal space is critical (R5C_LOG_CRITICAL=1)
2953  *
2954  *      It is important to be able to flush all stripes in raid5-cache.
2955  *      Therefore, we need reserve some space on the journal device for
2956  *      these flushes. If flush operation includes pending writes to the
2957  *      stripe, we need to reserve (conf->raid_disk + 1) pages per stripe
2958  *      for the flush out. If we exclude these pending writes from flush
2959  *      operation, we only need (conf->max_degraded + 1) pages per stripe.
2960  *      Therefore, excluding pending writes in these cases enables more
2961  *      efficient use of the journal device.
2962  *
2963  *      Note: To make sure the stripe makes progress, we only delay
2964  *      towrite for stripes with data already in journal (injournal > 0).
2965  *      When LOG_CRITICAL, stripes with injournal == 0 will be sent to
2966  *      no_space_stripes list.
2967  *
2968  */
2969 static inline bool delay_towrite(struct r5conf *conf,
2970                                  struct r5dev *dev,
2971                                  struct stripe_head_state *s)
2972 {
2973         /* case 1 above */
2974         if (!test_bit(R5_OVERWRITE, &dev->flags) &&
2975             !test_bit(R5_Insync, &dev->flags) && s->injournal)
2976                 return true;
2977         /* case 2 above */
2978         if (test_bit(R5C_LOG_CRITICAL, &conf->cache_state) &&
2979             s->injournal > 0)
2980                 return true;
2981         return false;
2982 }
2983
2984 static void
2985 schedule_reconstruction(struct stripe_head *sh, struct stripe_head_state *s,
2986                          int rcw, int expand)
2987 {
2988         int i, pd_idx = sh->pd_idx, qd_idx = sh->qd_idx, disks = sh->disks;
2989         struct r5conf *conf = sh->raid_conf;
2990         int level = conf->level;
2991
2992         if (rcw) {
2993                 /*
2994                  * In some cases, handle_stripe_dirtying initially decided to
2995                  * run rmw and allocates extra page for prexor. However, rcw is
2996                  * cheaper later on. We need to free the extra page now,
2997                  * because we won't be able to do that in ops_complete_prexor().
2998                  */
2999                 r5c_release_extra_page(sh);
3000
3001                 for (i = disks; i--; ) {
3002                         struct r5dev *dev = &sh->dev[i];
3003
3004                         if (dev->towrite && !delay_towrite(conf, dev, s)) {
3005                                 set_bit(R5_LOCKED, &dev->flags);
3006                                 set_bit(R5_Wantdrain, &dev->flags);
3007                                 if (!expand)
3008                                         clear_bit(R5_UPTODATE, &dev->flags);
3009                                 s->locked++;
3010                         } else if (test_bit(R5_InJournal, &dev->flags)) {
3011                                 set_bit(R5_LOCKED, &dev->flags);
3012                                 s->locked++;
3013                         }
3014                 }
3015                 /* if we are not expanding this is a proper write request, and
3016                  * there will be bios with new data to be drained into the
3017                  * stripe cache
3018                  */
3019                 if (!expand) {
3020                         if (!s->locked)
3021                                 /* False alarm, nothing to do */
3022                                 return;
3023                         sh->reconstruct_state = reconstruct_state_drain_run;
3024                         set_bit(STRIPE_OP_BIODRAIN, &s->ops_request);
3025                 } else
3026                         sh->reconstruct_state = reconstruct_state_run;
3027
3028                 set_bit(STRIPE_OP_RECONSTRUCT, &s->ops_request);
3029
3030                 if (s->locked + conf->max_degraded == disks)
3031                         if (!test_and_set_bit(STRIPE_FULL_WRITE, &sh->state))
3032                                 atomic_inc(&conf->pending_full_writes);
3033         } else {
3034                 BUG_ON(!(test_bit(R5_UPTODATE, &sh->dev[pd_idx].flags) ||
3035                         test_bit(R5_Wantcompute, &sh->dev[pd_idx].flags)));
3036                 BUG_ON(level == 6 &&
3037                         (!(test_bit(R5_UPTODATE, &sh->dev[qd_idx].flags) ||
3038                            test_bit(R5_Wantcompute, &sh->dev[qd_idx].flags))));
3039
3040                 for (i = disks; i--; ) {
3041                         struct r5dev *dev = &sh->dev[i];
3042                         if (i == pd_idx || i == qd_idx)
3043                                 continue;
3044
3045                         if (dev->towrite &&
3046                             (test_bit(R5_UPTODATE, &dev->flags) ||
3047                              test_bit(R5_Wantcompute, &dev->flags))) {
3048                                 set_bit(R5_Wantdrain, &dev->flags);
3049                                 set_bit(R5_LOCKED, &dev->flags);
3050                                 clear_bit(R5_UPTODATE, &dev->flags);
3051                                 s->locked++;
3052                         } else if (test_bit(R5_InJournal, &dev->flags)) {
3053                                 set_bit(R5_LOCKED, &dev->flags);
3054                                 s->locked++;
3055                         }
3056                 }
3057                 if (!s->locked)
3058                         /* False alarm - nothing to do */
3059                         return;
3060                 sh->reconstruct_state = reconstruct_state_prexor_drain_run;
3061                 set_bit(STRIPE_OP_PREXOR, &s->ops_request);
3062                 set_bit(STRIPE_OP_BIODRAIN, &s->ops_request);
3063                 set_bit(STRIPE_OP_RECONSTRUCT, &s->ops_request);
3064         }
3065
3066         /* keep the parity disk(s) locked while asynchronous operations
3067          * are in flight
3068          */
3069         set_bit(R5_LOCKED, &sh->dev[pd_idx].flags);
3070         clear_bit(R5_UPTODATE, &sh->dev[pd_idx].flags);
3071         s->locked++;
3072
3073         if (level == 6) {
3074                 int qd_idx = sh->qd_idx;
3075                 struct r5dev *dev = &sh->dev[qd_idx];
3076
3077                 set_bit(R5_LOCKED, &dev->flags);
3078                 clear_bit(R5_UPTODATE, &dev->flags);
3079                 s->locked++;
3080         }
3081
3082         pr_debug("%s: stripe %llu locked: %d ops_request: %lx\n",
3083                 __func__, (unsigned long long)sh->sector,
3084                 s->locked, s->ops_request);
3085 }
3086
3087 /*
3088  * Each stripe/dev can have one or more bion attached.
3089  * toread/towrite point to the first in a chain.
3090  * The bi_next chain must be in order.
3091  */
3092 static int add_stripe_bio(struct stripe_head *sh, struct bio *bi, int dd_idx,
3093                           int forwrite, int previous)
3094 {
3095         struct bio **bip;
3096         struct r5conf *conf = sh->raid_conf;
3097         int firstwrite=0;
3098
3099         pr_debug("adding bi b#%llu to stripe s#%llu\n",
3100                 (unsigned long long)bi->bi_iter.bi_sector,
3101                 (unsigned long long)sh->sector);
3102
3103         /*
3104          * If several bio share a stripe. The bio bi_phys_segments acts as a
3105          * reference count to avoid race. The reference count should already be
3106          * increased before this function is called (for example, in
3107          * raid5_make_request()), so other bio sharing this stripe will not free the
3108          * stripe. If a stripe is owned by one stripe, the stripe lock will
3109          * protect it.
3110          */
3111         spin_lock_irq(&sh->stripe_lock);
3112         /* Don't allow new IO added to stripes in batch list */
3113         if (sh->batch_head)
3114                 goto overlap;
3115         if (forwrite) {
3116                 bip = &sh->dev[dd_idx].towrite;
3117                 if (*bip == NULL)
3118                         firstwrite = 1;
3119         } else
3120                 bip = &sh->dev[dd_idx].toread;
3121         while (*bip && (*bip)->bi_iter.bi_sector < bi->bi_iter.bi_sector) {
3122                 if (bio_end_sector(*bip) > bi->bi_iter.bi_sector)
3123                         goto overlap;
3124                 bip = & (*bip)->bi_next;
3125         }
3126         if (*bip && (*bip)->bi_iter.bi_sector < bio_end_sector(bi))
3127                 goto overlap;
3128
3129         if (!forwrite || previous)
3130                 clear_bit(STRIPE_BATCH_READY, &sh->state);
3131
3132         BUG_ON(*bip && bi->bi_next && (*bip) != bi->bi_next);
3133         if (*bip)
3134                 bi->bi_next = *bip;
3135         *bip = bi;
3136         raid5_inc_bi_active_stripes(bi);
3137
3138         if (forwrite) {
3139                 /* check if page is covered */
3140                 sector_t sector = sh->dev[dd_idx].sector;
3141                 for (bi=sh->dev[dd_idx].towrite;
3142                      sector < sh->dev[dd_idx].sector + STRIPE_SECTORS &&
3143                              bi && bi->bi_iter.bi_sector <= sector;
3144                      bi = r5_next_bio(bi, sh->dev[dd_idx].sector)) {
3145                         if (bio_end_sector(bi) >= sector)
3146                                 sector = bio_end_sector(bi);
3147                 }
3148                 if (sector >= sh->dev[dd_idx].sector + STRIPE_SECTORS)
3149                         if (!test_and_set_bit(R5_OVERWRITE, &sh->dev[dd_idx].flags))
3150                                 sh->overwrite_disks++;
3151         }
3152
3153         pr_debug("added bi b#%llu to stripe s#%llu, disk %d.\n",
3154                 (unsigned long long)(*bip)->bi_iter.bi_sector,
3155                 (unsigned long long)sh->sector, dd_idx);
3156
3157         if (conf->mddev->bitmap && firstwrite) {
3158                 /* Cannot hold spinlock over bitmap_startwrite,
3159                  * but must ensure this isn't added to a batch until
3160                  * we have added to the bitmap and set bm_seq.
3161                  * So set STRIPE_BITMAP_PENDING to prevent
3162                  * batching.
3163                  * If multiple add_stripe_bio() calls race here they
3164                  * much all set STRIPE_BITMAP_PENDING.  So only the first one
3165                  * to complete "bitmap_startwrite" gets to set
3166                  * STRIPE_BIT_DELAY.  This is important as once a stripe
3167                  * is added to a batch, STRIPE_BIT_DELAY cannot be changed
3168                  * any more.
3169                  */
3170                 set_bit(STRIPE_BITMAP_PENDING, &sh->state);
3171                 spin_unlock_irq(&sh->stripe_lock);
3172                 bitmap_startwrite(conf->mddev->bitmap, sh->sector,
3173                                   STRIPE_SECTORS, 0);
3174                 spin_lock_irq(&sh->stripe_lock);
3175                 clear_bit(STRIPE_BITMAP_PENDING, &sh->state);
3176                 if (!sh->batch_head) {
3177                         sh->bm_seq = conf->seq_flush+1;
3178                         set_bit(STRIPE_BIT_DELAY, &sh->state);
3179                 }
3180         }
3181         spin_unlock_irq(&sh->stripe_lock);
3182
3183         if (stripe_can_batch(sh))
3184                 stripe_add_to_batch_list(conf, sh);
3185         return 1;
3186
3187  overlap:
3188         set_bit(R5_Overlap, &sh->dev[dd_idx].flags);
3189         spin_unlock_irq(&sh->stripe_lock);
3190         return 0;
3191 }
3192
3193 static void end_reshape(struct r5conf *conf);
3194
3195 static void stripe_set_idx(sector_t stripe, struct r5conf *conf, int previous,
3196                             struct stripe_head *sh)
3197 {
3198         int sectors_per_chunk =
3199                 previous ? conf->prev_chunk_sectors : conf->chunk_sectors;
3200         int dd_idx;
3201         int chunk_offset = sector_div(stripe, sectors_per_chunk);
3202         int disks = previous ? conf->previous_raid_disks : conf->raid_disks;
3203
3204         raid5_compute_sector(conf,
3205                              stripe * (disks - conf->max_degraded)
3206                              *sectors_per_chunk + chunk_offset,
3207                              previous,
3208                              &dd_idx, sh);
3209 }
3210
3211 static void
3212 handle_failed_stripe(struct r5conf *conf, struct stripe_head *sh,
3213                                 struct stripe_head_state *s, int disks,
3214                                 struct bio_list *return_bi)
3215 {
3216         int i;
3217         BUG_ON(sh->batch_head);
3218         for (i = disks; i--; ) {
3219                 struct bio *bi;
3220                 int bitmap_end = 0;
3221
3222                 if (test_bit(R5_ReadError, &sh->dev[i].flags)) {
3223                         struct md_rdev *rdev;
3224                         rcu_read_lock();
3225                         rdev = rcu_dereference(conf->disks[i].rdev);
3226                         if (rdev && test_bit(In_sync, &rdev->flags) &&
3227                             !test_bit(Faulty, &rdev->flags))
3228                                 atomic_inc(&rdev->nr_pending);
3229                         else
3230                                 rdev = NULL;
3231                         rcu_read_unlock();
3232                         if (rdev) {
3233                                 if (!rdev_set_badblocks(
3234                                             rdev,
3235                                             sh->sector,
3236                                             STRIPE_SECTORS, 0))
3237                                         md_error(conf->mddev, rdev);
3238                                 rdev_dec_pending(rdev, conf->mddev);
3239                         }
3240                 }
3241                 spin_lock_irq(&sh->stripe_lock);
3242                 /* fail all writes first */
3243                 bi = sh->dev[i].towrite;
3244                 sh->dev[i].towrite = NULL;
3245                 sh->overwrite_disks = 0;
3246                 spin_unlock_irq(&sh->stripe_lock);
3247                 if (bi)
3248                         bitmap_end = 1;
3249
3250                 r5l_stripe_write_finished(sh);
3251
3252                 if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
3253                         wake_up(&conf->wait_for_overlap);
3254
3255                 while (bi && bi->bi_iter.bi_sector <
3256                         sh->dev[i].sector + STRIPE_SECTORS) {
3257                         struct bio *nextbi = r5_next_bio(bi, sh->dev[i].sector);
3258
3259                         bi->bi_error = -EIO;
3260                         if (!raid5_dec_bi_active_stripes(bi)) {
3261                                 md_write_end(conf->mddev);
3262                                 bio_list_add(return_bi, bi);
3263                         }
3264                         bi = nextbi;
3265                 }
3266                 if (bitmap_end)
3267                         bitmap_endwrite(conf->mddev->bitmap, sh->sector,
3268                                 STRIPE_SECTORS, 0, 0);
3269                 bitmap_end = 0;
3270                 /* and fail all 'written' */
3271                 bi = sh->dev[i].written;
3272                 sh->dev[i].written = NULL;
3273                 if (test_and_clear_bit(R5_SkipCopy, &sh->dev[i].flags)) {
3274                         WARN_ON(test_bit(R5_UPTODATE, &sh->dev[i].flags));
3275                         sh->dev[i].page = sh->dev[i].orig_page;
3276                 }
3277
3278                 if (bi) bitmap_end = 1;
3279                 while (bi && bi->bi_iter.bi_sector <
3280                        sh->dev[i].sector + STRIPE_SECTORS) {
3281                         struct bio *bi2 = r5_next_bio(bi, sh->dev[i].sector);
3282
3283                         bi->bi_error = -EIO;
3284                         if (!raid5_dec_bi_active_stripes(bi)) {
3285                                 md_write_end(conf->mddev);
3286                                 bio_list_add(return_bi, bi);
3287                         }
3288                         bi = bi2;
3289                 }
3290
3291                 /* fail any reads if this device is non-operational and
3292                  * the data has not reached the cache yet.
3293                  */
3294                 if (!test_bit(R5_Wantfill, &sh->dev[i].flags) &&
3295                     s->failed > conf->max_degraded &&
3296                     (!test_bit(R5_Insync, &sh->dev[i].flags) ||
3297                       test_bit(R5_ReadError, &sh->dev[i].flags))) {
3298                         spin_lock_irq(&sh->stripe_lock);
3299                         bi = sh->dev[i].toread;
3300                         sh->dev[i].toread = NULL;
3301                         spin_unlock_irq(&sh->stripe_lock);
3302                         if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
3303                                 wake_up(&conf->wait_for_overlap);
3304                         if (bi)
3305                                 s->to_read--;
3306                         while (bi && bi->bi_iter.bi_sector <
3307                                sh->dev[i].sector + STRIPE_SECTORS) {
3308                                 struct bio *nextbi =
3309                                         r5_next_bio(bi, sh->dev[i].sector);
3310
3311                                 bi->bi_error = -EIO;
3312                                 if (!raid5_dec_bi_active_stripes(bi))
3313                                         bio_list_add(return_bi, bi);
3314                                 bi = nextbi;
3315                         }
3316                 }
3317                 if (bitmap_end)
3318                         bitmap_endwrite(conf->mddev->bitmap, sh->sector,
3319                                         STRIPE_SECTORS, 0, 0);
3320                 /* If we were in the middle of a write the parity block might
3321                  * still be locked - so just clear all R5_LOCKED flags
3322                  */
3323                 clear_bit(R5_LOCKED, &sh->dev[i].flags);
3324         }
3325         s->to_write = 0;
3326         s->written = 0;
3327
3328         if (test_and_clear_bit(STRIPE_FULL_WRITE, &sh->state))
3329                 if (atomic_dec_and_test(&conf->pending_full_writes))
3330                         md_wakeup_thread(conf->mddev->thread);
3331 }
3332
3333 static void
3334 handle_failed_sync(struct r5conf *conf, struct stripe_head *sh,
3335                    struct stripe_head_state *s)
3336 {
3337         int abort = 0;
3338         int i;
3339
3340         BUG_ON(sh->batch_head);
3341         clear_bit(STRIPE_SYNCING, &sh->state);
3342         if (test_and_clear_bit(R5_Overlap, &sh->dev[sh->pd_idx].flags))
3343                 wake_up(&conf->wait_for_overlap);
3344         s->syncing = 0;
3345         s->replacing = 0;
3346         /* There is nothing more to do for sync/check/repair.
3347          * Don't even need to abort as that is handled elsewhere
3348          * if needed, and not always wanted e.g. if there is a known
3349          * bad block here.
3350          * For recover/replace we need to record a bad block on all
3351          * non-sync devices, or abort the recovery
3352          */
3353         if (test_bit(MD_RECOVERY_RECOVER, &conf->mddev->recovery)) {
3354                 /* During recovery devices cannot be removed, so
3355                  * locking and refcounting of rdevs is not needed
3356                  */
3357                 rcu_read_lock();
3358                 for (i = 0; i < conf->raid_disks; i++) {
3359                         struct md_rdev *rdev = rcu_dereference(conf->disks[i].rdev);
3360                         if (rdev
3361                             && !test_bit(Faulty, &rdev->flags)
3362                             && !test_bit(In_sync, &rdev->flags)
3363                             && !rdev_set_badblocks(rdev, sh->sector,
3364                                                    STRIPE_SECTORS, 0))
3365                                 abort = 1;
3366                         rdev = rcu_dereference(conf->disks[i].replacement);
3367                         if (rdev
3368                             && !test_bit(Faulty, &rdev->flags)
3369                             && !test_bit(In_sync, &rdev->flags)
3370                             && !rdev_set_badblocks(rdev, sh->sector,
3371                                                    STRIPE_SECTORS, 0))
3372                                 abort = 1;
3373                 }
3374                 rcu_read_unlock();
3375                 if (abort)
3376                         conf->recovery_disabled =
3377                                 conf->mddev->recovery_disabled;
3378         }
3379         md_done_sync(conf->mddev, STRIPE_SECTORS, !abort);
3380 }
3381
3382 static int want_replace(struct stripe_head *sh, int disk_idx)
3383 {
3384         struct md_rdev *rdev;
3385         int rv = 0;
3386
3387         rcu_read_lock();
3388         rdev = rcu_dereference(sh->raid_conf->disks[disk_idx].replacement);
3389         if (rdev
3390             && !test_bit(Faulty, &rdev->flags)
3391             && !test_bit(In_sync, &rdev->flags)
3392             && (rdev->recovery_offset <= sh->sector
3393                 || rdev->mddev->recovery_cp <= sh->sector))
3394                 rv = 1;
3395         rcu_read_unlock();
3396         return rv;
3397 }
3398
3399 static int need_this_block(struct stripe_head *sh, struct stripe_head_state *s,
3400                            int disk_idx, int disks)
3401 {
3402         struct r5dev *dev = &sh->dev[disk_idx];
3403         struct r5dev *fdev[2] = { &sh->dev[s->failed_num[0]],
3404                                   &sh->dev[s->failed_num[1]] };
3405         int i;
3406
3407
3408         if (test_bit(R5_LOCKED, &dev->flags) ||
3409             test_bit(R5_UPTODATE, &dev->flags))
3410                 /* No point reading this as we already have it or have
3411                  * decided to get it.
3412                  */
3413                 return 0;
3414
3415         if (dev->toread ||
3416             (dev->towrite && !test_bit(R5_OVERWRITE, &dev->flags)))
3417                 /* We need this block to directly satisfy a request */
3418                 return 1;
3419
3420         if (s->syncing || s->expanding ||
3421             (s->replacing && want_replace(sh, disk_idx)))
3422                 /* When syncing, or expanding we read everything.
3423                  * When replacing, we need the replaced block.
3424                  */
3425                 return 1;
3426
3427         if ((s->failed >= 1 && fdev[0]->toread) ||
3428             (s->failed >= 2 && fdev[1]->toread))
3429                 /* If we want to read from a failed device, then
3430                  * we need to actually read every other device.
3431                  */
3432                 return 1;
3433
3434         /* Sometimes neither read-modify-write nor reconstruct-write
3435          * cycles can work.  In those cases we read every block we
3436          * can.  Then the parity-update is certain to have enough to
3437          * work with.
3438          * This can only be a problem when we need to write something,
3439          * and some device has failed.  If either of those tests
3440          * fail we need look no further.
3441          */
3442         if (!s->failed || !s->to_write)
3443                 return 0;
3444
3445         if (test_bit(R5_Insync, &dev->flags) &&
3446             !test_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
3447                 /* Pre-reads at not permitted until after short delay
3448                  * to gather multiple requests.  However if this
3449                  * device is no Insync, the block could only be be computed
3450                  * and there is no need to delay that.
3451                  */
3452                 return 0;
3453
3454         for (i = 0; i < s->failed && i < 2; i++) {
3455                 if (fdev[i]->towrite &&
3456                     !test_bit(R5_UPTODATE, &fdev[i]->flags) &&
3457                     !test_bit(R5_OVERWRITE, &fdev[i]->flags))
3458                         /* If we have a partial write to a failed
3459                          * device, then we will need to reconstruct
3460                          * the content of that device, so all other
3461                          * devices must be read.
3462                          */
3463                         return 1;
3464         }
3465
3466         /* If we are forced to do a reconstruct-write, either because
3467          * the current RAID6 implementation only supports that, or
3468          * or because parity cannot be trusted and we are currently
3469          * recovering it, there is extra need to be careful.
3470          * If one of the devices that we would need to read, because
3471          * it is not being overwritten (and maybe not written at all)
3472          * is missing/faulty, then we need to read everything we can.
3473          */
3474         if (sh->raid_conf->level != 6 &&
3475             sh->sector < sh->raid_conf->mddev->recovery_cp)
3476                 /* reconstruct-write isn't being forced */
3477                 return 0;
3478         for (i = 0; i < s->failed && i < 2; i++) {
3479                 if (s->failed_num[i] != sh->pd_idx &&
3480                     s->failed_num[i] != sh->qd_idx &&
3481                     !test_bit(R5_UPTODATE, &fdev[i]->flags) &&
3482                     !test_bit(R5_OVERWRITE, &fdev[i]->flags))
3483                         return 1;
3484         }
3485
3486         return 0;
3487 }
3488
3489 /* fetch_block - checks the given member device to see if its data needs
3490  * to be read or computed to satisfy a request.
3491  *
3492  * Returns 1 when no more member devices need to be checked, otherwise returns
3493  * 0 to tell the loop in handle_stripe_fill to continue
3494  */
3495 static int fetch_block(struct stripe_head *sh, struct stripe_head_state *s,
3496                        int disk_idx, int disks)
3497 {
3498         struct r5dev *dev = &sh->dev[disk_idx];
3499
3500         /* is the data in this block needed, and can we get it? */
3501         if (need_this_block(sh, s, disk_idx, disks)) {
3502                 /* we would like to get this block, possibly by computing it,
3503                  * otherwise read it if the backing disk is insync
3504                  */
3505                 BUG_ON(test_bit(R5_Wantcompute, &dev->flags));
3506                 BUG_ON(test_bit(R5_Wantread, &dev->flags));
3507                 BUG_ON(sh->batch_head);
3508                 if ((s->uptodate == disks - 1) &&
3509                     (s->failed && (disk_idx == s->failed_num[0] ||
3510                                    disk_idx == s->failed_num[1]))) {
3511                         /* have disk failed, and we're requested to fetch it;
3512                          * do compute it
3513                          */
3514                         pr_debug("Computing stripe %llu block %d\n",
3515                                (unsigned long long)sh->sector, disk_idx);
3516                         set_bit(STRIPE_COMPUTE_RUN, &sh->state);
3517                         set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
3518                         set_bit(R5_Wantcompute, &dev->flags);
3519                         sh->ops.target = disk_idx;
3520                         sh->ops.target2 = -1; /* no 2nd target */
3521                         s->req_compute = 1;
3522                         /* Careful: from this point on 'uptodate' is in the eye
3523                          * of raid_run_ops which services 'compute' operations
3524                          * before writes. R5_Wantcompute flags a block that will
3525                          * be R5_UPTODATE by the time it is needed for a
3526                          * subsequent operation.
3527                          */
3528                         s->uptodate++;
3529                         return 1;
3530                 } else if (s->uptodate == disks-2 && s->failed >= 2) {
3531                         /* Computing 2-failure is *very* expensive; only
3532                          * do it if failed >= 2
3533                          */
3534                         int other;
3535                         for (other = disks; other--; ) {
3536                                 if (other == disk_idx)
3537                                         continue;
3538                                 if (!test_bit(R5_UPTODATE,
3539                                       &sh->dev[other].flags))
3540                                         break;
3541                         }
3542                         BUG_ON(other < 0);
3543                         pr_debug("Computing stripe %llu blocks %d,%d\n",
3544                                (unsigned long long)sh->sector,
3545                                disk_idx, other);
3546                         set_bit(STRIPE_COMPUTE_RUN, &sh->state);
3547                         set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
3548                         set_bit(R5_Wantcompute, &sh->dev[disk_idx].flags);
3549                         set_bit(R5_Wantcompute, &sh->dev[other].flags);
3550                         sh->ops.target = disk_idx;
3551                         sh->ops.target2 = other;
3552                         s->uptodate += 2;
3553                         s->req_compute = 1;
3554                         return 1;
3555                 } else if (test_bit(R5_Insync, &dev->flags)) {
3556                         set_bit(R5_LOCKED, &dev->flags);
3557                         set_bit(R5_Wantread, &dev->flags);
3558                         s->locked++;
3559                         pr_debug("Reading block %d (sync=%d)\n",
3560                                 disk_idx, s->syncing);
3561                 }
3562         }
3563
3564         return 0;
3565 }
3566
3567 /**
3568  * handle_stripe_fill - read or compute data to satisfy pending requests.
3569  */
3570 static void handle_stripe_fill(struct stripe_head *sh,
3571                                struct stripe_head_state *s,
3572                                int disks)
3573 {
3574         int i;
3575
3576         /* look for blocks to read/compute, skip this if a compute
3577          * is already in flight, or if the stripe contents are in the
3578          * midst of changing due to a write
3579          */
3580         if (!test_bit(STRIPE_COMPUTE_RUN, &sh->state) && !sh->check_state &&
3581             !sh->reconstruct_state) {
3582
3583                 /*
3584                  * For degraded stripe with data in journal, do not handle
3585                  * read requests yet, instead, flush the stripe to raid
3586                  * disks first, this avoids handling complex rmw of write
3587                  * back cache (prexor with orig_page, and then xor with
3588                  * page) in the read path
3589                  */
3590                 if (s->injournal && s->failed) {
3591                         if (test_bit(STRIPE_R5C_CACHING, &sh->state))
3592                                 r5c_make_stripe_write_out(sh);
3593                         goto out;
3594                 }
3595
3596                 for (i = disks; i--; )
3597                         if (fetch_block(sh, s, i, disks))
3598                                 break;
3599         }
3600 out:
3601         set_bit(STRIPE_HANDLE, &sh->state);
3602 }
3603
3604 static void break_stripe_batch_list(struct stripe_head *head_sh,
3605                                     unsigned long handle_flags);
3606 /* handle_stripe_clean_event
3607  * any written block on an uptodate or failed drive can be returned.
3608  * Note that if we 'wrote' to a failed drive, it will be UPTODATE, but
3609  * never LOCKED, so we don't need to test 'failed' directly.
3610  */
3611 static void handle_stripe_clean_event(struct r5conf *conf,
3612         struct stripe_head *sh, int disks, struct bio_list *return_bi)
3613 {
3614         int i;
3615         struct r5dev *dev;
3616         int discard_pending = 0;
3617         struct stripe_head *head_sh = sh;
3618         bool do_endio = false;
3619
3620         for (i = disks; i--; )
3621                 if (sh->dev[i].written) {
3622                         dev = &sh->dev[i];
3623                         if (!test_bit(R5_LOCKED, &dev->flags) &&
3624                             (test_bit(R5_UPTODATE, &dev->flags) ||
3625                              test_bit(R5_Discard, &dev->flags) ||
3626                              test_bit(R5_SkipCopy, &dev->flags))) {
3627                                 /* We can return any write requests */
3628                                 struct bio *wbi, *wbi2;
3629                                 pr_debug("Return write for disc %d\n", i);
3630                                 if (test_and_clear_bit(R5_Discard, &dev->flags))
3631                                         clear_bit(R5_UPTODATE, &dev->flags);
3632                                 if (test_and_clear_bit(R5_SkipCopy, &dev->flags)) {
3633                                         WARN_ON(test_bit(R5_UPTODATE, &dev->flags));
3634                                 }
3635                                 do_endio = true;
3636
3637 returnbi:
3638                                 dev->page = dev->orig_page;
3639                                 wbi = dev->written;
3640                                 dev->written = NULL;
3641                                 while (wbi && wbi->bi_iter.bi_sector <
3642                                         dev->sector + STRIPE_SECTORS) {
3643                                         wbi2 = r5_next_bio(wbi, dev->sector);
3644                                         if (!raid5_dec_bi_active_stripes(wbi)) {
3645                                                 md_write_end(conf->mddev);
3646                                                 bio_list_add(return_bi, wbi);
3647                                         }
3648                                         wbi = wbi2;
3649                                 }
3650                                 bitmap_endwrite(conf->mddev->bitmap, sh->sector,
3651                                                 STRIPE_SECTORS,
3652                                          !test_bit(STRIPE_DEGRADED, &sh->state),
3653                                                 0);
3654                                 if (head_sh->batch_head) {
3655                                         sh = list_first_entry(&sh->batch_list,
3656                                                               struct stripe_head,
3657                                                               batch_list);
3658                                         if (sh != head_sh) {
3659                                                 dev = &sh->dev[i];
3660                                                 goto returnbi;
3661                                         }
3662                                 }
3663                                 sh = head_sh;
3664                                 dev = &sh->dev[i];
3665                         } else if (test_bit(R5_Discard, &dev->flags))
3666                                 discard_pending = 1;
3667                 }
3668
3669         r5l_stripe_write_finished(sh);
3670
3671         if (!discard_pending &&
3672             test_bit(R5_Discard, &sh->dev[sh->pd_idx].flags)) {
3673                 int hash;
3674                 clear_bit(R5_Discard, &sh->dev[sh->pd_idx].flags);
3675                 clear_bit(R5_UPTODATE, &sh->dev[sh->pd_idx].flags);
3676                 if (sh->qd_idx >= 0) {
3677                         clear_bit(R5_Discard, &sh->dev[sh->qd_idx].flags);
3678                         clear_bit(R5_UPTODATE, &sh->dev[sh->qd_idx].flags);
3679                 }
3680                 /* now that discard is done we can proceed with any sync */
3681                 clear_bit(STRIPE_DISCARD, &sh->state);
3682                 /*
3683                  * SCSI discard will change some bio fields and the stripe has
3684                  * no updated data, so remove it from hash list and the stripe
3685                  * will be reinitialized
3686                  */
3687 unhash:
3688                 hash = sh->hash_lock_index;
3689                 spin_lock_irq(conf->hash_locks + hash);
3690                 remove_hash(sh);
3691                 spin_unlock_irq(conf->hash_locks + hash);
3692                 if (head_sh->batch_head) {
3693                         sh = list_first_entry(&sh->batch_list,
3694                                               struct stripe_head, batch_list);
3695                         if (sh != head_sh)
3696                                         goto unhash;
3697                 }
3698                 sh = head_sh;
3699
3700                 if (test_bit(STRIPE_SYNC_REQUESTED, &sh->state))
3701                         set_bit(STRIPE_HANDLE, &sh->state);
3702
3703         }
3704
3705         if (test_and_clear_bit(STRIPE_FULL_WRITE, &sh->state))
3706                 if (atomic_dec_and_test(&conf->pending_full_writes))
3707                         md_wakeup_thread(conf->mddev->thread);
3708
3709         if (head_sh->batch_head && do_endio)
3710                 break_stripe_batch_list(head_sh, STRIPE_EXPAND_SYNC_FLAGS);
3711 }
3712
3713 /*
3714  * For RMW in write back cache, we need extra page in prexor to store the
3715  * old data. This page is stored in dev->orig_page.
3716  *
3717  * This function checks whether we have data for prexor. The exact logic
3718  * is:
3719  *       R5_UPTODATE && (!R5_InJournal || R5_OrigPageUPTDODATE)
3720  */
3721 static inline bool uptodate_for_rmw(struct r5dev *dev)
3722 {
3723         return (test_bit(R5_UPTODATE, &dev->flags)) &&
3724                 (!test_bit(R5_InJournal, &dev->flags) ||
3725                  test_bit(R5_OrigPageUPTDODATE, &dev->flags));
3726 }
3727
3728 static int handle_stripe_dirtying(struct r5conf *conf,
3729                                   struct stripe_head *sh,
3730                                   struct stripe_head_state *s,
3731                                   int disks)
3732 {
3733         int rmw = 0, rcw = 0, i;
3734         sector_t recovery_cp = conf->mddev->recovery_cp;
3735
3736         /* Check whether resync is now happening or should start.
3737          * If yes, then the array is dirty (after unclean shutdown or
3738          * initial creation), so parity in some stripes might be inconsistent.
3739          * In this case, we need to always do reconstruct-write, to ensure
3740          * that in case of drive failure or read-error correction, we
3741          * generate correct data from the parity.
3742          */
3743         if (conf->rmw_level == PARITY_DISABLE_RMW ||
3744             (recovery_cp < MaxSector && sh->sector >= recovery_cp &&
3745              s->failed == 0)) {
3746                 /* Calculate the real rcw later - for now make it
3747                  * look like rcw is cheaper
3748                  */
3749                 rcw = 1; rmw = 2;
3750                 pr_debug("force RCW rmw_level=%u, recovery_cp=%llu sh->sector=%llu\n",
3751                          conf->rmw_level, (unsigned long long)recovery_cp,
3752                          (unsigned long long)sh->sector);
3753         } else for (i = disks; i--; ) {
3754                 /* would I have to read this buffer for read_modify_write */
3755                 struct r5dev *dev = &sh->dev[i];
3756                 if (((dev->towrite && !delay_towrite(conf, dev, s)) ||
3757                      i == sh->pd_idx || i == sh->qd_idx ||
3758                      test_bit(R5_InJournal, &dev->flags)) &&
3759                     !test_bit(R5_LOCKED, &dev->flags) &&
3760                     !(uptodate_for_rmw(dev) ||
3761                       test_bit(R5_Wantcompute, &dev->flags))) {
3762                         if (test_bit(R5_Insync, &dev->flags))
3763                                 rmw++;
3764                         else
3765                                 rmw += 2*disks;  /* cannot read it */
3766                 }
3767                 /* Would I have to read this buffer for reconstruct_write */
3768                 if (!test_bit(R5_OVERWRITE, &dev->flags) &&
3769                     i != sh->pd_idx && i != sh->qd_idx &&
3770                     !test_bit(R5_LOCKED, &dev->flags) &&
3771                     !(test_bit(R5_UPTODATE, &dev->flags) ||
3772                       test_bit(R5_Wantcompute, &dev->flags))) {
3773                         if (test_bit(R5_Insync, &dev->flags))
3774                                 rcw++;
3775                         else
3776                                 rcw += 2*disks;
3777                 }
3778         }
3779
3780         pr_debug("for sector %llu state 0x%lx, rmw=%d rcw=%d\n",
3781                  (unsigned long long)sh->sector, sh->state, rmw, rcw);
3782         set_bit(STRIPE_HANDLE, &sh->state);
3783         if ((rmw < rcw || (rmw == rcw && conf->rmw_level == PARITY_PREFER_RMW)) && rmw > 0) {
3784                 /* prefer read-modify-write, but need to get some data */
3785                 if (conf->mddev->queue)
3786                         blk_add_trace_msg(conf->mddev->queue,
3787                                           "raid5 rmw %llu %d",
3788                                           (unsigned long long)sh->sector, rmw);
3789                 for (i = disks; i--; ) {
3790                         struct r5dev *dev = &sh->dev[i];
3791                         if (test_bit(R5_InJournal, &dev->flags) &&
3792                             dev->page == dev->orig_page &&
3793                             !test_bit(R5_LOCKED, &sh->dev[sh->pd_idx].flags)) {
3794                                 /* alloc page for prexor */
3795                                 struct page *p = alloc_page(GFP_NOIO);
3796
3797                                 if (p) {
3798                                         dev->orig_page = p;
3799                                         continue;
3800                                 }
3801
3802                                 /*
3803                                  * alloc_page() failed, try use
3804                                  * disk_info->extra_page
3805                                  */
3806                                 if (!test_and_set_bit(R5C_EXTRA_PAGE_IN_USE,
3807                                                       &conf->cache_state)) {
3808                                         r5c_use_extra_page(sh);
3809                                         break;
3810                                 }
3811
3812                                 /* extra_page in use, add to delayed_list */
3813                                 set_bit(STRIPE_DELAYED, &sh->state);
3814                                 s->waiting_extra_page = 1;
3815                                 return -EAGAIN;
3816                         }
3817                 }
3818
3819                 for (i = disks; i--; ) {
3820                         struct r5dev *dev = &sh->dev[i];
3821                         if (((dev->towrite && !delay_towrite(conf, dev, s)) ||
3822                              i == sh->pd_idx || i == sh->qd_idx ||
3823                              test_bit(R5_InJournal, &dev->flags)) &&
3824                             !test_bit(R5_LOCKED, &dev->flags) &&
3825                             !(uptodate_for_rmw(dev) ||
3826                               test_bit(R5_Wantcompute, &dev->flags)) &&
3827                             test_bit(R5_Insync, &dev->flags)) {
3828                                 if (test_bit(STRIPE_PREREAD_ACTIVE,
3829                                              &sh->state)) {
3830                                         pr_debug("Read_old block %d for r-m-w\n",
3831                                                  i);
3832                                         set_bit(R5_LOCKED, &dev->flags);
3833                                         set_bit(R5_Wantread, &dev->flags);
3834                                         s->locked++;
3835                                 } else {
3836                                         set_bit(STRIPE_DELAYED, &sh->state);
3837                                         set_bit(STRIPE_HANDLE, &sh->state);
3838                                 }
3839                         }
3840                 }
3841         }
3842         if ((rcw < rmw || (rcw == rmw && conf->rmw_level != PARITY_PREFER_RMW)) && rcw > 0) {
3843                 /* want reconstruct write, but need to get some data */
3844                 int qread =0;
3845                 rcw = 0;
3846                 for (i = disks; i--; ) {
3847                         struct r5dev *dev = &sh->dev[i];
3848                         if (!test_bit(R5_OVERWRITE, &dev->flags) &&
3849                             i != sh->pd_idx && i != sh->qd_idx &&
3850                             !test_bit(R5_LOCKED, &dev->flags) &&
3851                             !(test_bit(R5_UPTODATE, &dev->flags) ||
3852                               test_bit(R5_Wantcompute, &dev->flags))) {
3853                                 rcw++;
3854                                 if (test_bit(R5_Insync, &dev->flags) &&
3855                                     test_bit(STRIPE_PREREAD_ACTIVE,
3856                                              &sh->state)) {
3857                                         pr_debug("Read_old block "
3858                                                 "%d for Reconstruct\n", i);
3859                                         set_bit(R5_LOCKED, &dev->flags);
3860                                         set_bit(R5_Wantread, &dev->flags);
3861                                         s->locked++;
3862                                         qread++;
3863                                 } else {
3864                                         set_bit(STRIPE_DELAYED, &sh->state);
3865                                         set_bit(STRIPE_HANDLE, &sh->state);
3866                                 }
3867                         }
3868                 }
3869                 if (rcw && conf->mddev->queue)
3870                         blk_add_trace_msg(conf->mddev->queue, "raid5 rcw %llu %d %d %d",
3871                                           (unsigned long long)sh->sector,
3872                                           rcw, qread, test_bit(STRIPE_DELAYED, &sh->state));
3873         }
3874
3875         if (rcw > disks && rmw > disks &&
3876             !test_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
3877                 set_bit(STRIPE_DELAYED, &sh->state);
3878
3879         /* now if nothing is locked, and if we have enough data,
3880          * we can start a write request
3881          */
3882         /* since handle_stripe can be called at any time we need to handle the
3883          * case where a compute block operation has been submitted and then a
3884          * subsequent call wants to start a write request.  raid_run_ops only
3885          * handles the case where compute block and reconstruct are requested
3886          * simultaneously.  If this is not the case then new writes need to be
3887          * held off until the compute completes.
3888          */
3889         if ((s->req_compute || !test_bit(STRIPE_COMPUTE_RUN, &sh->state)) &&
3890             (s->locked == 0 && (rcw == 0 || rmw == 0) &&
3891              !test_bit(STRIPE_BIT_DELAY, &sh->state)))
3892                 schedule_reconstruction(sh, s, rcw == 0, 0);
3893         return 0;
3894 }
3895
3896 static void handle_parity_checks5(struct r5conf *conf, struct stripe_head *sh,
3897                                 struct stripe_head_state *s, int disks)
3898 {
3899         struct r5dev *dev = NULL;
3900
3901         BUG_ON(sh->batch_head);
3902         set_bit(STRIPE_HANDLE, &sh->state);
3903
3904         switch (sh->check_state) {
3905         case check_state_idle:
3906                 /* start a new check operation if there are no failures */
3907                 if (s->failed == 0) {
3908                         BUG_ON(s->uptodate != disks);
3909                         sh->check_state = check_state_run;
3910                         set_bit(STRIPE_OP_CHECK, &s->ops_request);
3911                         clear_bit(R5_UPTODATE, &sh->dev[sh->pd_idx].flags);
3912                         s->uptodate--;
3913                         break;
3914                 }
3915                 dev = &sh->dev[s->failed_num[0]];
3916                 /* fall through */
3917         case check_state_compute_result:
3918                 sh->check_state = check_state_idle;
3919                 if (!dev)
3920                         dev = &sh->dev[sh->pd_idx];
3921
3922                 /* check that a write has not made the stripe insync */
3923                 if (test_bit(STRIPE_INSYNC, &sh->state))
3924                         break;
3925
3926                 /* either failed parity check, or recovery is happening */
3927                 BUG_ON(!test_bit(R5_UPTODATE, &dev->flags));
3928                 BUG_ON(s->uptodate != disks);
3929
3930                 set_bit(R5_LOCKED, &dev->flags);
3931                 s->locked++;
3932                 set_bit(R5_Wantwrite, &dev->flags);
3933
3934                 clear_bit(STRIPE_DEGRADED, &sh->state);
3935                 set_bit(STRIPE_INSYNC, &sh->state);
3936                 break;
3937         case check_state_run:
3938                 break; /* we will be called again upon completion */
3939         case check_state_check_result:
3940                 sh->check_state = check_state_idle;
3941
3942                 /* if a failure occurred during the check operation, leave
3943                  * STRIPE_INSYNC not set and let the stripe be handled again
3944                  */
3945                 if (s->failed)
3946                         break;
3947
3948                 /* handle a successful check operation, if parity is correct
3949                  * we are done.  Otherwise update the mismatch count and repair
3950                  * parity if !MD_RECOVERY_CHECK
3951                  */
3952                 if ((sh->ops.zero_sum_result & SUM_CHECK_P_RESULT) == 0)
3953                         /* parity is correct (on disc,
3954                          * not in buffer any more)
3955                          */
3956                         set_bit(STRIPE_INSYNC, &sh->state);
3957                 else {
3958                         atomic64_add(STRIPE_SECTORS, &conf->mddev->resync_mismatches);
3959                         if (test_bit(MD_RECOVERY_CHECK, &conf->mddev->recovery))
3960                                 /* don't try to repair!! */
3961                                 set_bit(STRIPE_INSYNC, &sh->state);
3962                         else {
3963                                 sh->check_state = check_state_compute_run;
3964                                 set_bit(STRIPE_COMPUTE_RUN, &sh->state);
3965                                 set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
3966                                 set_bit(R5_Wantcompute,
3967                                         &sh->dev[sh->pd_idx].flags);
3968                                 sh->ops.target = sh->pd_idx;
3969                                 sh->ops.target2 = -1;
3970                                 s->uptodate++;
3971                         }
3972                 }
3973                 break;
3974         case check_state_compute_run:
3975                 break;
3976         default:
3977                 pr_err("%s: unknown check_state: %d sector: %llu\n",
3978                        __func__, sh->check_state,
3979                        (unsigned long long) sh->sector);
3980                 BUG();
3981         }
3982 }
3983
3984 static void handle_parity_checks6(struct r5conf *conf, struct stripe_head *sh,
3985                                   struct stripe_head_state *s,
3986                                   int disks)
3987 {
3988         int pd_idx = sh->pd_idx;
3989         int qd_idx = sh->qd_idx;
3990         struct r5dev *dev;
3991
3992         BUG_ON(sh->batch_head);
3993         set_bit(STRIPE_HANDLE, &sh->state);
3994
3995         BUG_ON(s->failed > 2);
3996
3997         /* Want to check and possibly repair P and Q.
3998          * However there could be one 'failed' device, in which
3999          * case we can only check one of them, possibly using the
4000          * other to generate missing data
4001          */
4002
4003         switch (sh->check_state) {
4004         case check_state_idle:
4005                 /* start a new check operation if there are < 2 failures */
4006                 if (s->failed == s->q_failed) {
4007                         /* The only possible failed device holds Q, so it
4008                          * makes sense to check P (If anything else were failed,
4009                          * we would have used P to recreate it).
4010                          */
4011                         sh->check_state = check_state_run;
4012                 }
4013                 if (!s->q_failed && s->failed < 2) {
4014                         /* Q is not failed, and we didn't use it to generate
4015                          * anything, so it makes sense to check it
4016                          */
4017                         if (sh->check_state == check_state_run)
4018                                 sh->check_state = check_state_run_pq;
4019                         else
4020                                 sh->check_state = check_state_run_q;
4021                 }
4022
4023                 /* discard potentially stale zero_sum_result */
4024                 sh->ops.zero_sum_result = 0;
4025
4026                 if (sh->check_state == check_state_run) {
4027                         /* async_xor_zero_sum destroys the contents of P */
4028                         clear_bit(R5_UPTODATE, &sh->dev[pd_idx].flags);
4029                         s->uptodate--;
4030                 }
4031                 if (sh->check_state >= check_state_run &&
4032                     sh->check_state <= check_state_run_pq) {
4033                         /* async_syndrome_zero_sum preserves P and Q, so
4034                          * no need to mark them !uptodate here
4035                          */
4036                         set_bit(STRIPE_OP_CHECK, &s->ops_request);
4037                         break;
4038                 }
4039
4040                 /* we have 2-disk failure */
4041                 BUG_ON(s->failed != 2);
4042                 /* fall through */
4043         case check_state_compute_result:
4044                 sh->check_state = check_state_idle;
4045
4046                 /* check that a write has not made the stripe insync */
4047                 if (test_bit(STRIPE_INSYNC, &sh->state))
4048                         break;
4049
4050                 /* now write out any block on a failed drive,
4051                  * or P or Q if they were recomputed
4052                  */
4053                 BUG_ON(s->uptodate < disks - 1); /* We don't need Q to recover */
4054                 if (s->failed == 2) {
4055                         dev = &sh->dev[s->failed_num[1]];
4056                         s->locked++;
4057                         set_bit(R5_LOCKED, &dev->flags);
4058                         set_bit(R5_Wantwrite, &dev->flags);
4059                 }
4060                 if (s->failed >= 1) {
4061                         dev = &sh->dev[s->failed_num[0]];
4062                         s->locked++;
4063                         set_bit(R5_LOCKED, &dev->flags);
4064                         set_bit(R5_Wantwrite, &dev->flags);
4065                 }
4066                 if (sh->ops.zero_sum_result & SUM_CHECK_P_RESULT) {
4067                         dev = &sh->dev[pd_idx];
4068                         s->locked++;
4069                         set_bit(R5_LOCKED, &dev->flags);
4070                         set_bit(R5_Wantwrite, &dev->flags);
4071                 }
4072                 if (sh->ops.zero_sum_result & SUM_CHECK_Q_RESULT) {
4073                         dev = &sh->dev[qd_idx];
4074                         s->locked++;
4075                         set_bit(R5_LOCKED, &dev->flags);
4076                         set_bit(R5_Wantwrite, &dev->flags);
4077                 }
4078                 clear_bit(STRIPE_DEGRADED, &sh->state);
4079
4080                 set_bit(STRIPE_INSYNC, &sh->state);
4081                 break;
4082         case check_state_run:
4083         case check_state_run_q:
4084         case check_state_run_pq:
4085                 break; /* we will be called again upon completion */
4086         case check_state_check_result:
4087                 sh->check_state = check_state_idle;
4088
4089                 /* handle a successful check operation, if parity is correct
4090                  * we are done.  Otherwise update the mismatch count and repair
4091                  * parity if !MD_RECOVERY_CHECK
4092                  */
4093                 if (sh->ops.zero_sum_result == 0) {
4094                         /* both parities are correct */
4095                         if (!s->failed)
4096                                 set_bit(STRIPE_INSYNC, &sh->state);
4097                         else {
4098                                 /* in contrast to the raid5 case we can validate
4099                                  * parity, but still have a failure to write
4100                                  * back
4101                                  */
4102                                 sh->check_state = check_state_compute_result;
4103                                 /* Returning at this point means that we may go
4104                                  * off and bring p and/or q uptodate again so
4105                                  * we make sure to check zero_sum_result again
4106                                  * to verify if p or q need writeback
4107                                  */
4108                         }
4109                 } else {
4110                         atomic64_add(STRIPE_SECTORS, &conf->mddev->resync_mismatches);
4111                         if (test_bit(MD_RECOVERY_CHECK, &conf->mddev->recovery))
4112                                 /* don't try to repair!! */
4113                                 set_bit(STRIPE_INSYNC, &sh->state);
4114                         else {
4115                                 int *target = &sh->ops.target;
4116
4117                                 sh->ops.target = -1;
4118                                 sh->ops.target2 = -1;
4119                                 sh->check_state = check_state_compute_run;
4120                                 set_bit(STRIPE_COMPUTE_RUN, &sh->state);
4121                                 set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
4122                                 if (sh->ops.zero_sum_result & SUM_CHECK_P_RESULT) {
4123                                         set_bit(R5_Wantcompute,
4124                                                 &sh->dev[pd_idx].flags);
4125                                         *target = pd_idx;
4126                                         target = &sh->ops.target2;
4127                                         s->uptodate++;
4128                                 }
4129                                 if (sh->ops.zero_sum_result & SUM_CHECK_Q_RESULT) {
4130                                         set_bit(R5_Wantcompute,
4131                                                 &sh->dev[qd_idx].flags);
4132                                         *target = qd_idx;
4133                                         s->uptodate++;
4134                                 }
4135                         }
4136                 }
4137                 break;
4138         case check_state_compute_run:
4139                 break;
4140         default:
4141                 pr_warn("%s: unknown check_state: %d sector: %llu\n",
4142                         __func__, sh->check_state,
4143                         (unsigned long long) sh->sector);
4144                 BUG();
4145         }
4146 }
4147
4148 static void handle_stripe_expansion(struct r5conf *conf, struct stripe_head *sh)
4149 {
4150         int i;
4151
4152         /* We have read all the blocks in this stripe and now we need to
4153          * copy some of them into a target stripe for expand.
4154          */
4155         struct dma_async_tx_descriptor *tx = NULL;
4156         BUG_ON(sh->batch_head);
4157         clear_bit(STRIPE_EXPAND_SOURCE, &sh->state);
4158         for (i = 0; i < sh->disks; i++)
4159                 if (i != sh->pd_idx && i != sh->qd_idx) {
4160                         int dd_idx, j;
4161                         struct stripe_head *sh2;
4162                         struct async_submit_ctl submit;
4163
4164                         sector_t bn = raid5_compute_blocknr(sh, i, 1);
4165                         sector_t s = raid5_compute_sector(conf, bn, 0,
4166                                                           &dd_idx, NULL);
4167                         sh2 = raid5_get_active_stripe(conf, s, 0, 1, 1);
4168                         if (sh2 == NULL)
4169                                 /* so far only the early blocks of this stripe
4170                                  * have been requested.  When later blocks
4171                                  * get requested, we will try again
4172                                  */
4173                                 continue;
4174                         if (!test_bit(STRIPE_EXPANDING, &sh2->state) ||
4175                            test_bit(R5_Expanded, &sh2->dev[dd_idx].flags)) {
4176                                 /* must have already done this block */
4177                                 raid5_release_stripe(sh2);
4178                                 continue;
4179                         }
4180
4181                         /* place all the copies on one channel */
4182                         init_async_submit(&submit, 0, tx, NULL, NULL, NULL);
4183                         tx = async_memcpy(sh2->dev[dd_idx].page,
4184                                           sh->dev[i].page, 0, 0, STRIPE_SIZE,
4185                                           &submit);
4186
4187                         set_bit(R5_Expanded, &sh2->dev[dd_idx].flags);
4188                         set_bit(R5_UPTODATE, &sh2->dev[dd_idx].flags);
4189                         for (j = 0; j < conf->raid_disks; j++)
4190                                 if (j != sh2->pd_idx &&
4191                                     j != sh2->qd_idx &&
4192                                     !test_bit(R5_Expanded, &sh2->dev[j].flags))
4193                                         break;
4194                         if (j == conf->raid_disks) {
4195                                 set_bit(STRIPE_EXPAND_READY, &sh2->state);
4196                                 set_bit(STRIPE_HANDLE, &sh2->state);
4197                         }
4198                         raid5_release_stripe(sh2);
4199
4200                 }
4201         /* done submitting copies, wait for them to complete */
4202         async_tx_quiesce(&tx);
4203 }
4204
4205 /*
4206  * handle_stripe - do things to a stripe.
4207  *
4208  * We lock the stripe by setting STRIPE_ACTIVE and then examine the
4209  * state of various bits to see what needs to be done.
4210  * Possible results:
4211  *    return some read requests which now have data
4212  *    return some write requests which are safely on storage
4213  *    schedule a read on some buffers
4214  *    schedule a write of some buffers
4215  *    return confirmation of parity correctness
4216  *
4217  */
4218
4219 static void analyse_stripe(struct stripe_head *sh, struct stripe_head_state *s)
4220 {
4221         struct r5conf *conf = sh->raid_conf;
4222         int disks = sh->disks;
4223         struct r5dev *dev;
4224         int i;
4225         int do_recovery = 0;
4226
4227         memset(s, 0, sizeof(*s));
4228
4229         s->expanding = test_bit(STRIPE_EXPAND_SOURCE, &sh->state) && !sh->batch_head;
4230         s->expanded = test_bit(STRIPE_EXPAND_READY, &sh->state) && !sh->batch_head;
4231         s->failed_num[0] = -1;
4232         s->failed_num[1] = -1;
4233         s->log_failed = r5l_log_disk_error(conf);
4234
4235         /* Now to look around and see what can be done */
4236         rcu_read_lock();
4237         for (i=disks; i--; ) {
4238                 struct md_rdev *rdev;
4239                 sector_t first_bad;
4240                 int bad_sectors;
4241                 int is_bad = 0;
4242
4243                 dev = &sh->dev[i];
4244
4245                 pr_debug("check %d: state 0x%lx read %p write %p written %p\n",
4246                          i, dev->flags,
4247                          dev->toread, dev->towrite, dev->written);
4248                 /* maybe we can reply to a read
4249                  *
4250                  * new wantfill requests are only permitted while
4251                  * ops_complete_biofill is guaranteed to be inactive
4252                  */
4253                 if (test_bit(R5_UPTODATE, &dev->flags) && dev->toread &&
4254                     !test_bit(STRIPE_BIOFILL_RUN, &sh->state))
4255                         set_bit(R5_Wantfill, &dev->flags);
4256
4257                 /* now count some things */
4258                 if (test_bit(R5_LOCKED, &dev->flags))
4259                         s->locked++;
4260                 if (test_bit(R5_UPTODATE, &dev->flags))
4261                         s->uptodate++;
4262                 if (test_bit(R5_Wantcompute, &dev->flags)) {
4263                         s->compute++;
4264                         BUG_ON(s->compute > 2);
4265                 }
4266
4267                 if (test_bit(R5_Wantfill, &dev->flags))
4268                         s->to_fill++;
4269                 else if (dev->toread)
4270                         s->to_read++;
4271                 if (dev->towrite) {
4272                         s->to_write++;
4273                         if (!test_bit(R5_OVERWRITE, &dev->flags))
4274                                 s->non_overwrite++;
4275                 }
4276                 if (dev->written)
4277                         s->written++;
4278                 /* Prefer to use the replacement for reads, but only
4279                  * if it is recovered enough and has no bad blocks.
4280                  */
4281                 rdev = rcu_dereference(conf->disks[i].replacement);
4282                 if (rdev && !test_bit(Faulty, &rdev->flags) &&
4283                     rdev->recovery_offset >= sh->sector + STRIPE_SECTORS &&
4284                     !is_badblock(rdev, sh->sector, STRIPE_SECTORS,
4285                                  &first_bad, &bad_sectors))
4286                         set_bit(R5_ReadRepl, &dev->flags);
4287                 else {
4288                         if (rdev && !test_bit(Faulty, &rdev->flags))
4289                                 set_bit(R5_NeedReplace, &dev->flags);
4290                         else
4291                                 clear_bit(R5_NeedReplace, &dev->flags);
4292                         rdev = rcu_dereference(conf->disks[i].rdev);
4293                         clear_bit(R5_ReadRepl, &dev->flags);
4294                 }
4295                 if (rdev && test_bit(Faulty, &rdev->flags))
4296                         rdev = NULL;
4297                 if (rdev) {
4298                         is_bad = is_badblock(rdev, sh->sector, STRIPE_SECTORS,
4299                                              &first_bad, &bad_sectors);
4300                         if (s->blocked_rdev == NULL
4301                             && (test_bit(Blocked, &rdev->flags)
4302                                 || is_bad < 0)) {
4303                                 if (is_bad < 0)
4304                                         set_bit(BlockedBadBlocks,
4305                                                 &rdev->flags);
4306                                 s->blocked_rdev = rdev;
4307                                 atomic_inc(&rdev->nr_pending);
4308                         }
4309                 }
4310                 clear_bit(R5_Insync, &dev->flags);
4311                 if (!rdev)
4312                         /* Not in-sync */;
4313                 else if (is_bad) {
4314                         /* also not in-sync */
4315                         if (!test_bit(WriteErrorSeen, &rdev->flags) &&
4316                             test_bit(R5_UPTODATE, &dev->flags)) {
4317                                 /* treat as in-sync, but with a read error
4318                                  * which we can now try to correct
4319                                  */
4320                                 set_bit(R5_Insync, &dev->flags);
4321                                 set_bit(R5_ReadError, &dev->flags);
4322                         }
4323                 } else if (test_bit(In_sync, &rdev->flags))
4324                         set_bit(R5_Insync, &dev->flags);
4325                 else if (sh->sector + STRIPE_SECTORS <= rdev->recovery_offset)
4326                         /* in sync if before recovery_offset */
4327                         set_bit(R5_Insync, &dev->flags);
4328                 else if (test_bit(R5_UPTODATE, &dev->flags) &&
4329                          test_bit(R5_Expanded, &dev->flags))
4330                         /* If we've reshaped into here, we assume it is Insync.
4331                          * We will shortly update recovery_offset to make
4332                          * it official.
4333                          */
4334                         set_bit(R5_Insync, &dev->flags);
4335
4336                 if (test_bit(R5_WriteError, &dev->flags)) {
4337                         /* This flag does not apply to '.replacement'
4338                          * only to .rdev, so make sure to check that*/
4339                         struct md_rdev *rdev2 = rcu_dereference(
4340                                 conf->disks[i].rdev);
4341                         if (rdev2 == rdev)
4342                                 clear_bit(R5_Insync, &dev->flags);
4343                         if (rdev2 && !test_bit(Faulty, &rdev2->flags)) {
4344                                 s->handle_bad_blocks = 1;
4345                                 atomic_inc(&rdev2->nr_pending);
4346                         } else
4347                                 clear_bit(R5_WriteError, &dev->flags);
4348                 }
4349                 if (test_bit(R5_MadeGood, &dev->flags)) {
4350                         /* This flag does not apply to '.replacement'
4351                          * only to .rdev, so make sure to check that*/
4352                         struct md_rdev *rdev2 = rcu_dereference(
4353                                 conf->disks[i].rdev);
4354                         if (rdev2 && !test_bit(Faulty, &rdev2->flags)) {
4355                                 s->handle_bad_blocks = 1;
4356                                 atomic_inc(&rdev2->nr_pending);
4357                         } else
4358                                 clear_bit(R5_MadeGood, &dev->flags);
4359                 }
4360                 if (test_bit(R5_MadeGoodRepl, &dev->flags)) {
4361                         struct md_rdev *rdev2 = rcu_dereference(
4362                                 conf->disks[i].replacement);
4363                         if (rdev2 && !test_bit(Faulty, &rdev2->flags)) {
4364                                 s->handle_bad_blocks = 1;
4365                                 atomic_inc(&rdev2->nr_pending);
4366                         } else
4367                                 clear_bit(R5_MadeGoodRepl, &dev->flags);
4368                 }
4369                 if (!test_bit(R5_Insync, &dev->flags)) {
4370                         /* The ReadError flag will just be confusing now */
4371                         clear_bit(R5_ReadError, &dev->flags);
4372                         clear_bit(R5_ReWrite, &dev->flags);
4373                 }
4374                 if (test_bit(R5_ReadError, &dev->flags))
4375                         clear_bit(R5_Insync, &dev->flags);
4376                 if (!test_bit(R5_Insync, &dev->flags)) {
4377                         if (s->failed < 2)
4378                                 s->failed_num[s->failed] = i;
4379                         s->failed++;
4380                         if (rdev && !test_bit(Faulty, &rdev->flags))
4381                                 do_recovery = 1;
4382                 }
4383
4384                 if (test_bit(R5_InJournal, &dev->flags))
4385                         s->injournal++;
4386                 if (test_bit(R5_InJournal, &dev->flags) && dev->written)
4387                         s->just_cached++;
4388         }
4389         if (test_bit(STRIPE_SYNCING, &sh->state)) {
4390                 /* If there is a failed device being replaced,
4391                  *     we must be recovering.
4392                  * else if we are after recovery_cp, we must be syncing
4393                  * else if MD_RECOVERY_REQUESTED is set, we also are syncing.
4394                  * else we can only be replacing
4395                  * sync and recovery both need to read all devices, and so
4396                  * use the same flag.
4397                  */
4398                 if (do_recovery ||
4399                     sh->sector >= conf->mddev->recovery_cp ||
4400                     test_bit(MD_RECOVERY_REQUESTED, &(conf->mddev->recovery)))
4401                         s->syncing = 1;
4402                 else
4403                         s->replacing = 1;
4404         }
4405         rcu_read_unlock();
4406 }
4407
4408 static int clear_batch_ready(struct stripe_head *sh)
4409 {
4410         /* Return '1' if this is a member of batch, or
4411          * '0' if it is a lone stripe or a head which can now be
4412          * handled.
4413          */
4414         struct stripe_head *tmp;
4415         if (!test_and_clear_bit(STRIPE_BATCH_READY, &sh->state))
4416                 return (sh->batch_head && sh->batch_head != sh);
4417         spin_lock(&sh->stripe_lock);
4418         if (!sh->batch_head) {
4419                 spin_unlock(&sh->stripe_lock);
4420                 return 0;
4421         }
4422
4423         /*
4424          * this stripe could be added to a batch list before we check
4425          * BATCH_READY, skips it
4426          */
4427         if (sh->batch_head != sh) {
4428                 spin_unlock(&sh->stripe_lock);
4429                 return 1;
4430         }
4431         spin_lock(&sh->batch_lock);
4432         list_for_each_entry(tmp, &sh->batch_list, batch_list)
4433                 clear_bit(STRIPE_BATCH_READY, &tmp->state);
4434         spin_unlock(&sh->batch_lock);
4435         spin_unlock(&sh->stripe_lock);
4436
4437         /*
4438          * BATCH_READY is cleared, no new stripes can be added.
4439          * batch_list can be accessed without lock
4440          */
4441         return 0;
4442 }
4443
4444 static void break_stripe_batch_list(struct stripe_head *head_sh,
4445                                     unsigned long handle_flags)
4446 {
4447         struct stripe_head *sh, *next;
4448         int i;
4449         int do_wakeup = 0;
4450
4451         list_for_each_entry_safe(sh, next, &head_sh->batch_list, batch_list) {
4452
4453                 list_del_init(&sh->batch_list);
4454
4455                 WARN_ONCE(sh->state & ((1 << STRIPE_ACTIVE) |
4456                                           (1 << STRIPE_SYNCING) |
4457                                           (1 << STRIPE_REPLACED) |
4458                                           (1 << STRIPE_DELAYED) |
4459                                           (1 << STRIPE_BIT_DELAY) |
4460                                           (1 << STRIPE_FULL_WRITE) |
4461                                           (1 << STRIPE_BIOFILL_RUN) |
4462                                           (1 << STRIPE_COMPUTE_RUN)  |
4463                                           (1 << STRIPE_OPS_REQ_PENDING) |
4464                                           (1 << STRIPE_DISCARD) |
4465                                           (1 << STRIPE_BATCH_READY) |
4466                                           (1 << STRIPE_BATCH_ERR) |
4467                                           (1 << STRIPE_BITMAP_PENDING)),
4468                         "stripe state: %lx\n", sh->state);
4469                 WARN_ONCE(head_sh->state & ((1 << STRIPE_DISCARD) |
4470                                               (1 << STRIPE_REPLACED)),
4471                         "head stripe state: %lx\n", head_sh->state);
4472
4473                 set_mask_bits(&sh->state, ~(STRIPE_EXPAND_SYNC_FLAGS |
4474                                             (1 << STRIPE_PREREAD_ACTIVE) |
4475                                             (1 << STRIPE_DEGRADED)),
4476                               head_sh->state & (1 << STRIPE_INSYNC));
4477
4478                 sh->check_state = head_sh->check_state;
4479                 sh->reconstruct_state = head_sh->reconstruct_state;
4480                 for (i = 0; i < sh->disks; i++) {
4481                         if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
4482                                 do_wakeup = 1;
4483                         sh->dev[i].flags = head_sh->dev[i].flags &
4484                                 (~((1 << R5_WriteError) | (1 << R5_Overlap)));
4485                 }
4486                 spin_lock_irq(&sh->stripe_lock);
4487                 sh->batch_head = NULL;
4488                 spin_unlock_irq(&sh->stripe_lock);
4489                 if (handle_flags == 0 ||
4490                     sh->state & handle_flags)
4491                         set_bit(STRIPE_HANDLE, &sh->state);
4492                 raid5_release_stripe(sh);
4493         }
4494         spin_lock_irq(&head_sh->stripe_lock);
4495         head_sh->batch_head = NULL;
4496         spin_unlock_irq(&head_sh->stripe_lock);
4497         for (i = 0; i < head_sh->disks; i++)
4498                 if (test_and_clear_bit(R5_Overlap, &head_sh->dev[i].flags))
4499                         do_wakeup = 1;
4500         if (head_sh->state & handle_flags)
4501                 set_bit(STRIPE_HANDLE, &head_sh->state);
4502
4503         if (do_wakeup)
4504                 wake_up(&head_sh->raid_conf->wait_for_overlap);
4505 }
4506
4507 static void handle_stripe(struct stripe_head *sh)
4508 {
4509         struct stripe_head_state s;
4510         struct r5conf *conf = sh->raid_conf;
4511         int i;
4512         int prexor;
4513         int disks = sh->disks;
4514         struct r5dev *pdev, *qdev;
4515
4516         clear_bit(STRIPE_HANDLE, &sh->state);
4517         if (test_and_set_bit_lock(STRIPE_ACTIVE, &sh->state)) {
4518                 /* already being handled, ensure it gets handled
4519                  * again when current action finishes */
4520                 set_bit(STRIPE_HANDLE, &sh->state);
4521                 return;
4522         }
4523
4524         if (clear_batch_ready(sh) ) {
4525                 clear_bit_unlock(STRIPE_ACTIVE, &sh->state);
4526                 return;
4527         }
4528
4529         if (test_and_clear_bit(STRIPE_BATCH_ERR, &sh->state))
4530                 break_stripe_batch_list(sh, 0);
4531
4532         if (test_bit(STRIPE_SYNC_REQUESTED, &sh->state) && !sh->batch_head) {
4533                 spin_lock(&sh->stripe_lock);
4534                 /* Cannot process 'sync' concurrently with 'discard' */
4535                 if (!test_bit(STRIPE_DISCARD, &sh->state) &&
4536                     test_and_clear_bit(STRIPE_SYNC_REQUESTED, &sh->state)) {
4537                         set_bit(STRIPE_SYNCING, &sh->state);
4538                         clear_bit(STRIPE_INSYNC, &sh->state);
4539                         clear_bit(STRIPE_REPLACED, &sh->state);
4540                 }
4541                 spin_unlock(&sh->stripe_lock);
4542         }
4543         clear_bit(STRIPE_DELAYED, &sh->state);
4544
4545         pr_debug("handling stripe %llu, state=%#lx cnt=%d, "
4546                 "pd_idx=%d, qd_idx=%d\n, check:%d, reconstruct:%d\n",
4547                (unsigned long long)sh->sector, sh->state,
4548                atomic_read(&sh->count), sh->pd_idx, sh->qd_idx,
4549                sh->check_state, sh->reconstruct_state);
4550
4551         analyse_stripe(sh, &s);
4552
4553         if (test_bit(STRIPE_LOG_TRAPPED, &sh->state))
4554                 goto finish;
4555
4556         if (s.handle_bad_blocks) {
4557                 set_bit(STRIPE_HANDLE, &sh->state);
4558                 goto finish;
4559         }
4560
4561         if (unlikely(s.blocked_rdev)) {
4562                 if (s.syncing || s.expanding || s.expanded ||
4563                     s.replacing || s.to_write || s.written) {
4564                         set_bit(STRIPE_HANDLE, &sh->state);
4565                         goto finish;
4566                 }
4567                 /* There is nothing for the blocked_rdev to block */
4568                 rdev_dec_pending(s.blocked_rdev, conf->mddev);
4569                 s.blocked_rdev = NULL;
4570         }
4571
4572         if (s.to_fill && !test_bit(STRIPE_BIOFILL_RUN, &sh->state)) {
4573                 set_bit(STRIPE_OP_BIOFILL, &s.ops_request);
4574                 set_bit(STRIPE_BIOFILL_RUN, &sh->state);
4575         }
4576
4577         pr_debug("locked=%d uptodate=%d to_read=%d"
4578                " to_write=%d failed=%d failed_num=%d,%d\n",
4579                s.locked, s.uptodate, s.to_read, s.to_write, s.failed,
4580                s.failed_num[0], s.failed_num[1]);
4581         /* check if the array has lost more than max_degraded devices and,
4582          * if so, some requests might need to be failed.
4583          */
4584         if (s.failed > conf->max_degraded || s.log_failed) {
4585                 sh->check_state = 0;
4586                 sh->reconstruct_state = 0;
4587                 break_stripe_batch_list(sh, 0);
4588                 if (s.to_read+s.to_write+s.written)
4589                         handle_failed_stripe(conf, sh, &s, disks, &s.return_bi);
4590                 if (s.syncing + s.replacing)
4591                         handle_failed_sync(conf, sh, &s);
4592         }
4593
4594         /* Now we check to see if any write operations have recently
4595          * completed
4596          */
4597         prexor = 0;
4598         if (sh->reconstruct_state == reconstruct_state_prexor_drain_result)
4599                 prexor = 1;
4600         if (sh->reconstruct_state == reconstruct_state_drain_result ||
4601             sh->reconstruct_state == reconstruct_state_prexor_drain_result) {
4602                 sh->reconstruct_state = reconstruct_state_idle;
4603
4604                 /* All the 'written' buffers and the parity block are ready to
4605                  * be written back to disk
4606                  */
4607                 BUG_ON(!test_bit(R5_UPTODATE, &sh->dev[sh->pd_idx].flags) &&
4608                        !test_bit(R5_Discard, &sh->dev[sh->pd_idx].flags));
4609                 BUG_ON(sh->qd_idx >= 0 &&
4610                        !test_bit(R5_UPTODATE, &sh->dev[sh->qd_idx].flags) &&
4611                        !test_bit(R5_Discard, &sh->dev[sh->qd_idx].flags));
4612                 for (i = disks; i--; ) {
4613                         struct r5dev *dev = &sh->dev[i];
4614                         if (test_bit(R5_LOCKED, &dev->flags) &&
4615                                 (i == sh->pd_idx || i == sh->qd_idx ||
4616                                  dev->written || test_bit(R5_InJournal,
4617                                                           &dev->flags))) {
4618                                 pr_debug("Writing block %d\n", i);
4619                                 set_bit(R5_Wantwrite, &dev->flags);
4620                                 if (prexor)
4621                                         continue;
4622                                 if (s.failed > 1)
4623                                         continue;
4624                                 if (!test_bit(R5_Insync, &dev->flags) ||
4625                                     ((i == sh->pd_idx || i == sh->qd_idx)  &&
4626                                      s.failed == 0))
4627                                         set_bit(STRIPE_INSYNC, &sh->state);
4628                         }
4629                 }
4630                 if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
4631                         s.dec_preread_active = 1;
4632         }
4633
4634         /*
4635          * might be able to return some write requests if the parity blocks
4636          * are safe, or on a failed drive
4637          */
4638         pdev = &sh->dev[sh->pd_idx];
4639         s.p_failed = (s.failed >= 1 && s.failed_num[0] == sh->pd_idx)
4640                 || (s.failed >= 2 && s.failed_num[1] == sh->pd_idx);
4641         qdev = &sh->dev[sh->qd_idx];
4642         s.q_failed = (s.failed >= 1 && s.failed_num[0] == sh->qd_idx)
4643                 || (s.failed >= 2 && s.failed_num[1] == sh->qd_idx)
4644                 || conf->level < 6;
4645
4646         if (s.written &&
4647             (s.p_failed || ((test_bit(R5_Insync, &pdev->flags)
4648                              && !test_bit(R5_LOCKED, &pdev->flags)
4649                              && (test_bit(R5_UPTODATE, &pdev->flags) ||
4650                                  test_bit(R5_Discard, &pdev->flags))))) &&
4651             (s.q_failed || ((test_bit(R5_Insync, &qdev->flags)
4652                              && !test_bit(R5_LOCKED, &qdev->flags)
4653                              && (test_bit(R5_UPTODATE, &qdev->flags) ||
4654                                  test_bit(R5_Discard, &qdev->flags))))))
4655                 handle_stripe_clean_event(conf, sh, disks, &s.return_bi);
4656
4657         if (s.just_cached)
4658                 r5c_handle_cached_data_endio(conf, sh, disks, &s.return_bi);
4659         r5l_stripe_write_finished(sh);
4660
4661         /* Now we might consider reading some blocks, either to check/generate
4662          * parity, or to satisfy requests
4663          * or to load a block that is being partially written.
4664          */
4665         if (s.to_read || s.non_overwrite
4666             || (conf->level == 6 && s.to_write && s.failed)
4667             || (s.syncing && (s.uptodate + s.compute < disks))
4668             || s.replacing
4669             || s.expanding)
4670                 handle_stripe_fill(sh, &s, disks);
4671
4672         /*
4673          * When the stripe finishes full journal write cycle (write to journal
4674          * and raid disk), this is the clean up procedure so it is ready for
4675          * next operation.
4676          */
4677         r5c_finish_stripe_write_out(conf, sh, &s);
4678
4679         /*
4680          * Now to consider new write requests, cache write back and what else,
4681          * if anything should be read.  We do not handle new writes when:
4682          * 1/ A 'write' operation (copy+xor) is already in flight.
4683          * 2/ A 'check' operation is in flight, as it may clobber the parity
4684          *    block.
4685          * 3/ A r5c cache log write is in flight.
4686          */
4687
4688         if (!sh->reconstruct_state && !sh->check_state && !sh->log_io) {
4689                 if (!r5c_is_writeback(conf->log)) {
4690                         if (s.to_write)
4691                                 handle_stripe_dirtying(conf, sh, &s, disks);
4692                 } else { /* write back cache */
4693                         int ret = 0;
4694
4695                         /* First, try handle writes in caching phase */
4696                         if (s.to_write)
4697                                 ret = r5c_try_caching_write(conf, sh, &s,
4698                                                             disks);
4699                         /*
4700                          * If caching phase failed: ret == -EAGAIN
4701                          *    OR
4702                          * stripe under reclaim: !caching && injournal
4703                          *
4704                          * fall back to handle_stripe_dirtying()
4705                          */
4706                         if (ret == -EAGAIN ||
4707                             /* stripe under reclaim: !caching && injournal */
4708                             (!test_bit(STRIPE_R5C_CACHING, &sh->state) &&
4709                              s.injournal > 0)) {
4710                                 ret = handle_stripe_dirtying(conf, sh, &s,
4711                                                              disks);
4712                                 if (ret == -EAGAIN)
4713                                         goto finish;
4714                         }
4715                 }
4716         }
4717
4718         /* maybe we need to check and possibly fix the parity for this stripe
4719          * Any reads will already have been scheduled, so we just see if enough
4720          * data is available.  The parity check is held off while parity
4721          * dependent operations are in flight.
4722          */
4723         if (sh->check_state ||
4724             (s.syncing && s.locked == 0 &&
4725              !test_bit(STRIPE_COMPUTE_RUN, &sh->state) &&
4726              !test_bit(STRIPE_INSYNC, &sh->state))) {
4727                 if (conf->level == 6)
4728                         handle_parity_checks6(conf, sh, &s, disks);
4729                 else
4730                         handle_parity_checks5(conf, sh, &s, disks);
4731         }
4732
4733         if ((s.replacing || s.syncing) && s.locked == 0
4734             && !test_bit(STRIPE_COMPUTE_RUN, &sh->state)
4735             && !test_bit(STRIPE_REPLACED, &sh->state)) {
4736                 /* Write out to replacement devices where possible */
4737                 for (i = 0; i < conf->raid_disks; i++)
4738                         if (test_bit(R5_NeedReplace, &sh->dev[i].flags)) {
4739                                 WARN_ON(!test_bit(R5_UPTODATE, &sh->dev[i].flags));
4740                                 set_bit(R5_WantReplace, &sh->dev[i].flags);
4741                                 set_bit(R5_LOCKED, &sh->dev[i].flags);
4742                                 s.locked++;
4743                         }
4744                 if (s.replacing)
4745                         set_bit(STRIPE_INSYNC, &sh->state);
4746                 set_bit(STRIPE_REPLACED, &sh->state);
4747         }
4748         if ((s.syncing || s.replacing) && s.locked == 0 &&
4749             !test_bit(STRIPE_COMPUTE_RUN, &sh->state) &&
4750             test_bit(STRIPE_INSYNC, &sh->state)) {
4751                 md_done_sync(conf->mddev, STRIPE_SECTORS, 1);
4752                 clear_bit(STRIPE_SYNCING, &sh->state);
4753                 if (test_and_clear_bit(R5_Overlap, &sh->dev[sh->pd_idx].flags))
4754                         wake_up(&conf->wait_for_overlap);
4755         }
4756
4757         /* If the failed drives are just a ReadError, then we might need
4758          * to progress the repair/check process
4759          */
4760         if (s.failed <= conf->max_degraded && !conf->mddev->ro)
4761                 for (i = 0; i < s.failed; i++) {
4762                         struct r5dev *dev = &sh->dev[s.failed_num[i]];
4763                         if (test_bit(R5_ReadError, &dev->flags)
4764                             && !test_bit(R5_LOCKED, &dev->flags)
4765                             && test_bit(R5_UPTODATE, &dev->flags)
4766                                 ) {
4767                                 if (!test_bit(R5_ReWrite, &dev->flags)) {
4768                                         set_bit(R5_Wantwrite, &dev->flags);
4769                                         set_bit(R5_ReWrite, &dev->flags);
4770                                         set_bit(R5_LOCKED, &dev->flags);
4771                                         s.locked++;
4772                                 } else {
4773                                         /* let's read it back */
4774                                         set_bit(R5_Wantread, &dev->flags);
4775                                         set_bit(R5_LOCKED, &dev->flags);
4776                                         s.locked++;
4777                                 }
4778                         }
4779                 }
4780
4781         /* Finish reconstruct operations initiated by the expansion process */
4782         if (sh->reconstruct_state == reconstruct_state_result) {
4783                 struct stripe_head *sh_src
4784                         = raid5_get_active_stripe(conf, sh->sector, 1, 1, 1);
4785                 if (sh_src && test_bit(STRIPE_EXPAND_SOURCE, &sh_src->state)) {
4786                         /* sh cannot be written until sh_src has been read.
4787                          * so arrange for sh to be delayed a little
4788                          */
4789                         set_bit(STRIPE_DELAYED, &sh->state);
4790                         set_bit(STRIPE_HANDLE, &sh->state);
4791                         if (!test_and_set_bit(STRIPE_PREREAD_ACTIVE,
4792                                               &sh_src->state))
4793                                 atomic_inc(&conf->preread_active_stripes);
4794                         raid5_release_stripe(sh_src);
4795                         goto finish;
4796                 }
4797                 if (sh_src)
4798                         raid5_release_stripe(sh_src);
4799
4800                 sh->reconstruct_state = reconstruct_state_idle;
4801                 clear_bit(STRIPE_EXPANDING, &sh->state);
4802                 for (i = conf->raid_disks; i--; ) {
4803                         set_bit(R5_Wantwrite, &sh->dev[i].flags);
4804                         set_bit(R5_LOCKED, &sh->dev[i].flags);
4805                         s.locked++;
4806                 }
4807         }
4808
4809         if (s.expanded && test_bit(STRIPE_EXPANDING, &sh->state) &&
4810             !sh->reconstruct_state) {
4811                 /* Need to write out all blocks after computing parity */
4812                 sh->disks = conf->raid_disks;
4813                 stripe_set_idx(sh->sector, conf, 0, sh);
4814                 schedule_reconstruction(sh, &s, 1, 1);
4815         } else if (s.expanded && !sh->reconstruct_state && s.locked == 0) {
4816                 clear_bit(STRIPE_EXPAND_READY, &sh->state);
4817                 atomic_dec(&conf->reshape_stripes);
4818                 wake_up(&conf->wait_for_overlap);
4819                 md_done_sync(conf->mddev, STRIPE_SECTORS, 1);
4820         }
4821
4822         if (s.expanding && s.locked == 0 &&
4823             !test_bit(STRIPE_COMPUTE_RUN, &sh->state))
4824                 handle_stripe_expansion(conf, sh);
4825
4826 finish:
4827         /* wait for this device to become unblocked */
4828         if (unlikely(s.blocked_rdev)) {
4829                 if (conf->mddev->external)
4830                         md_wait_for_blocked_rdev(s.blocked_rdev,
4831                                                  conf->mddev);
4832                 else
4833                         /* Internal metadata will immediately
4834                          * be written by raid5d, so we don't
4835                          * need to wait here.
4836                          */
4837                         rdev_dec_pending(s.blocked_rdev,
4838                                          conf->mddev);
4839         }
4840
4841         if (s.handle_bad_blocks)
4842                 for (i = disks; i--; ) {
4843                         struct md_rdev *rdev;
4844                         struct r5dev *dev = &sh->dev[i];
4845                         if (test_and_clear_bit(R5_WriteError, &dev->flags)) {
4846                                 /* We own a safe reference to the rdev */
4847                                 rdev = conf->disks[i].rdev;
4848                                 if (!rdev_set_badblocks(rdev, sh->sector,
4849                                                         STRIPE_SECTORS, 0))
4850                                         md_error(conf->mddev, rdev);
4851                                 rdev_dec_pending(rdev, conf->mddev);
4852                         }
4853                         if (test_and_clear_bit(R5_MadeGood, &dev->flags)) {
4854                                 rdev = conf->disks[i].rdev;
4855                                 rdev_clear_badblocks(rdev, sh->sector,
4856                                                      STRIPE_SECTORS, 0);
4857                                 rdev_dec_pending(rdev, conf->mddev);
4858                         }
4859                         if (test_and_clear_bit(R5_MadeGoodRepl, &dev->flags)) {
4860                                 rdev = conf->disks[i].replacement;
4861                                 if (!rdev)
4862                                         /* rdev have been moved down */
4863                                         rdev = conf->disks[i].rdev;
4864                                 rdev_clear_badblocks(rdev, sh->sector,
4865                                                      STRIPE_SECTORS, 0);
4866                                 rdev_dec_pending(rdev, conf->mddev);
4867                         }
4868                 }
4869
4870         if (s.ops_request)
4871                 raid_run_ops(sh, s.ops_request);
4872
4873         ops_run_io(sh, &s);
4874
4875         if (s.dec_preread_active) {
4876                 /* We delay this until after ops_run_io so that if make_request
4877                  * is waiting on a flush, it won't continue until the writes
4878                  * have actually been submitted.
4879                  */
4880                 atomic_dec(&conf->preread_active_stripes);
4881                 if (atomic_read(&conf->preread_active_stripes) <
4882                     IO_THRESHOLD)
4883                         md_wakeup_thread(conf->mddev->thread);
4884         }
4885
4886         if (!bio_list_empty(&s.return_bi)) {
4887                 if (test_bit(MD_SB_CHANGE_PENDING, &conf->mddev->sb_flags)) {
4888                         spin_lock_irq(&conf->device_lock);
4889                         bio_list_merge(&conf->return_bi, &s.return_bi);
4890                         spin_unlock_irq(&conf->device_lock);
4891                         md_wakeup_thread(conf->mddev->thread);
4892                 } else
4893                         return_io(&s.return_bi);
4894         }
4895
4896         clear_bit_unlock(STRIPE_ACTIVE, &sh->state);
4897 }
4898
4899 static void raid5_activate_delayed(struct r5conf *conf)
4900 {
4901         if (atomic_read(&conf->preread_active_stripes) < IO_THRESHOLD) {
4902                 while (!list_empty(&conf->delayed_list)) {
4903                         struct list_head *l = conf->delayed_list.next;
4904                         struct stripe_head *sh;
4905                         sh = list_entry(l, struct stripe_head, lru);
4906                         list_del_init(l);
4907                         clear_bit(STRIPE_DELAYED, &sh->state);
4908                         if (!test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
4909                                 atomic_inc(&conf->preread_active_stripes);
4910                         list_add_tail(&sh->lru, &conf->hold_list);
4911                         raid5_wakeup_stripe_thread(sh);
4912                 }
4913         }
4914 }
4915
4916 static void activate_bit_delay(struct r5conf *conf,
4917         struct list_head *temp_inactive_list)
4918 {
4919         /* device_lock is held */
4920         struct list_head head;
4921         list_add(&head, &conf->bitmap_list);
4922         list_del_init(&conf->bitmap_list);
4923         while (!list_empty(&head)) {
4924                 struct stripe_head *sh = list_entry(head.next, struct stripe_head, lru);
4925                 int hash;
4926                 list_del_init(&sh->lru);
4927                 atomic_inc(&sh->count);
4928                 hash = sh->hash_lock_index;
4929                 __release_stripe(conf, sh, &temp_inactive_list[hash]);
4930         }
4931 }
4932
4933 static int raid5_congested(struct mddev *mddev, int bits)
4934 {
4935         struct r5conf *conf = mddev->private;
4936
4937         /* No difference between reads and writes.  Just check
4938          * how busy the stripe_cache is
4939          */
4940
4941         if (test_bit(R5_INACTIVE_BLOCKED, &conf->cache_state))
4942                 return 1;
4943
4944         /* Also checks whether there is pressure on r5cache log space */
4945         if (test_bit(R5C_LOG_TIGHT, &conf->cache_state))
4946                 return 1;
4947         if (conf->quiesce)
4948                 return 1;
4949         if (atomic_read(&conf->empty_inactive_list_nr))
4950                 return 1;
4951
4952         return 0;
4953 }
4954
4955 static int in_chunk_boundary(struct mddev *mddev, struct bio *bio)
4956 {
4957         struct r5conf *conf = mddev->private;
4958         sector_t sector = bio->bi_iter.bi_sector + get_start_sect(bio->bi_bdev);
4959         unsigned int chunk_sectors;
4960         unsigned int bio_sectors = bio_sectors(bio);
4961
4962         chunk_sectors = min(conf->chunk_sectors, conf->prev_chunk_sectors);
4963         return  chunk_sectors >=
4964                 ((sector & (chunk_sectors - 1)) + bio_sectors);
4965 }
4966
4967 /*
4968  *  add bio to the retry LIFO  ( in O(1) ... we are in interrupt )
4969  *  later sampled by raid5d.
4970  */
4971 static void add_bio_to_retry(struct bio *bi,struct r5conf *conf)
4972 {
4973         unsigned long flags;
4974
4975         spin_lock_irqsave(&conf->device_lock, flags);
4976
4977         bi->bi_next = conf->retry_read_aligned_list;
4978         conf->retry_read_aligned_list = bi;
4979
4980         spin_unlock_irqrestore(&conf->device_lock, flags);
4981         md_wakeup_thread(conf->mddev->thread);
4982 }
4983
4984 static struct bio *remove_bio_from_retry(struct r5conf *conf)
4985 {
4986         struct bio *bi;
4987
4988         bi = conf->retry_read_aligned;
4989         if (bi) {
4990                 conf->retry_read_aligned = NULL;
4991                 return bi;
4992         }
4993         bi = conf->retry_read_aligned_list;
4994         if(bi) {
4995                 conf->retry_read_aligned_list = bi->bi_next;
4996                 bi->bi_next = NULL;
4997                 /*
4998                  * this sets the active strip count to 1 and the processed
4999                  * strip count to zero (upper 8 bits)
5000                  */
5001                 raid5_set_bi_stripes(bi, 1); /* biased count of active stripes */
5002         }
5003
5004         return bi;
5005 }
5006
5007 /*
5008  *  The "raid5_align_endio" should check if the read succeeded and if it
5009  *  did, call bio_endio on the original bio (having bio_put the new bio
5010  *  first).
5011  *  If the read failed..
5012  */
5013 static void raid5_align_endio(struct bio *bi)
5014 {
5015         struct bio* raid_bi  = bi->bi_private;
5016         struct mddev *mddev;
5017         struct r5conf *conf;
5018         struct md_rdev *rdev;
5019         int error = bi->bi_error;
5020
5021         bio_put(bi);
5022
5023         rdev = (void*)raid_bi->bi_next;
5024         raid_bi->bi_next = NULL;
5025         mddev = rdev->mddev;
5026         conf = mddev->private;
5027
5028         rdev_dec_pending(rdev, conf->mddev);
5029
5030         if (!error) {
5031                 trace_block_bio_complete(bdev_get_queue(raid_bi->bi_bdev),
5032                                          raid_bi, 0);
5033                 bio_endio(raid_bi);
5034                 if (atomic_dec_and_test(&conf->active_aligned_reads))
5035                         wake_up(&conf->wait_for_quiescent);
5036                 return;
5037         }
5038
5039         pr_debug("raid5_align_endio : io error...handing IO for a retry\n");
5040
5041         add_bio_to_retry(raid_bi, conf);
5042 }
5043
5044 static int raid5_read_one_chunk(struct mddev *mddev, struct bio *raid_bio)
5045 {
5046         struct r5conf *conf = mddev->private;
5047         int dd_idx;
5048         struct bio* align_bi;
5049         struct md_rdev *rdev;
5050         sector_t end_sector;
5051
5052         if (!in_chunk_boundary(mddev, raid_bio)) {
5053                 pr_debug("%s: non aligned\n", __func__);
5054                 return 0;
5055         }
5056         /*
5057          * use bio_clone_fast to make a copy of the bio
5058          */
5059         align_bi = bio_clone_fast(raid_bio, GFP_NOIO, mddev->bio_set);
5060         if (!align_bi)
5061                 return 0;
5062         /*
5063          *   set bi_end_io to a new function, and set bi_private to the
5064          *     original bio.
5065          */
5066         align_bi->bi_end_io  = raid5_align_endio;
5067         align_bi->bi_private = raid_bio;
5068         /*
5069          *      compute position
5070          */
5071         align_bi->bi_iter.bi_sector =
5072                 raid5_compute_sector(conf, raid_bio->bi_iter.bi_sector,
5073                                      0, &dd_idx, NULL);
5074
5075         end_sector = bio_end_sector(align_bi);
5076         rcu_read_lock();
5077         rdev = rcu_dereference(conf->disks[dd_idx].replacement);
5078         if (!rdev || test_bit(Faulty, &rdev->flags) ||
5079             rdev->recovery_offset < end_sector) {
5080                 rdev = rcu_dereference(conf->disks[dd_idx].rdev);
5081                 if (rdev &&
5082                     (test_bit(Faulty, &rdev->flags) ||
5083                     !(test_bit(In_sync, &rdev->flags) ||
5084                       rdev->recovery_offset >= end_sector)))
5085                         rdev = NULL;
5086         }
5087
5088         if (r5c_big_stripe_cached(conf, align_bi->bi_iter.bi_sector)) {
5089                 rcu_read_unlock();
5090                 bio_put(align_bi);
5091                 return 0;
5092         }
5093
5094         if (rdev) {
5095                 sector_t first_bad;
5096                 int bad_sectors;
5097
5098                 atomic_inc(&rdev->nr_pending);
5099                 rcu_read_unlock();
5100                 raid_bio->bi_next = (void*)rdev;
5101                 align_bi->bi_bdev =  rdev->bdev;
5102                 bio_clear_flag(align_bi, BIO_SEG_VALID);
5103
5104                 if (is_badblock(rdev, align_bi->bi_iter.bi_sector,
5105                                 bio_sectors(align_bi),
5106                                 &first_bad, &bad_sectors)) {
5107                         bio_put(align_bi);
5108                         rdev_dec_pending(rdev, mddev);
5109                         return 0;
5110                 }
5111
5112                 /* No reshape active, so we can trust rdev->data_offset */
5113                 align_bi->bi_iter.bi_sector += rdev->data_offset;
5114
5115                 spin_lock_irq(&conf->device_lock);
5116                 wait_event_lock_irq(conf->wait_for_quiescent,
5117                                     conf->quiesce == 0,
5118                                     conf->device_lock);
5119                 atomic_inc(&conf->active_aligned_reads);
5120                 spin_unlock_irq(&conf->device_lock);
5121
5122                 if (mddev->gendisk)
5123                         trace_block_bio_remap(bdev_get_queue(align_bi->bi_bdev),
5124                                               align_bi, disk_devt(mddev->gendisk),
5125                                               raid_bio->bi_iter.bi_sector);
5126                 generic_make_request(align_bi);
5127                 return 1;
5128         } else {
5129                 rcu_read_unlock();
5130                 bio_put(align_bi);
5131                 return 0;
5132         }
5133 }
5134
5135 static struct bio *chunk_aligned_read(struct mddev *mddev, struct bio *raid_bio)
5136 {
5137         struct bio *split;
5138
5139         do {
5140                 sector_t sector = raid_bio->bi_iter.bi_sector;
5141                 unsigned chunk_sects = mddev->chunk_sectors;
5142                 unsigned sectors = chunk_sects - (sector & (chunk_sects-1));
5143
5144                 if (sectors < bio_sectors(raid_bio)) {
5145                         split = bio_split(raid_bio, sectors, GFP_NOIO, fs_bio_set);
5146                         bio_chain(split, raid_bio);
5147                 } else
5148                         split = raid_bio;
5149
5150                 if (!raid5_read_one_chunk(mddev, split)) {
5151                         if (split != raid_bio)
5152                                 generic_make_request(raid_bio);
5153                         return split;
5154                 }
5155         } while (split != raid_bio);
5156
5157         return NULL;
5158 }
5159
5160 /* __get_priority_stripe - get the next stripe to process
5161  *
5162  * Full stripe writes are allowed to pass preread active stripes up until
5163  * the bypass_threshold is exceeded.  In general the bypass_count
5164  * increments when the handle_list is handled before the hold_list; however, it
5165  * will not be incremented when STRIPE_IO_STARTED is sampled set signifying a
5166  * stripe with in flight i/o.  The bypass_count will be reset when the
5167  * head of the hold_list has changed, i.e. the head was promoted to the
5168  * handle_list.
5169  */
5170 static struct stripe_head *__get_priority_stripe(struct r5conf *conf, int group)
5171 {
5172         struct stripe_head *sh = NULL, *tmp;
5173         struct list_head *handle_list = NULL;
5174         struct r5worker_group *wg = NULL;
5175
5176         if (conf->worker_cnt_per_group == 0) {
5177                 handle_list = &conf->handle_list;
5178         } else if (group != ANY_GROUP) {
5179                 handle_list = &conf->worker_groups[group].handle_list;
5180                 wg = &conf->worker_groups[group];
5181         } else {
5182                 int i;
5183                 for (i = 0; i < conf->group_cnt; i++) {
5184                         handle_list = &conf->worker_groups[i].handle_list;
5185                         wg = &conf->worker_groups[i];
5186                         if (!list_empty(handle_list))
5187                                 break;
5188                 }
5189         }
5190
5191         pr_debug("%s: handle: %s hold: %s full_writes: %d bypass_count: %d\n",
5192                   __func__,
5193                   list_empty(handle_list) ? "empty" : "busy",
5194                   list_empty(&conf->hold_list) ? "empty" : "busy",
5195                   atomic_read(&conf->pending_full_writes), conf->bypass_count);
5196
5197         if (!list_empty(handle_list)) {
5198                 sh = list_entry(handle_list->next, typeof(*sh), lru);
5199
5200                 if (list_empty(&conf->hold_list))
5201                         conf->bypass_count = 0;
5202                 else if (!test_bit(STRIPE_IO_STARTED, &sh->state)) {
5203                         if (conf->hold_list.next == conf->last_hold)
5204                                 conf->bypass_count++;
5205                         else {
5206                                 conf->last_hold = conf->hold_list.next;
5207                                 conf->bypass_count -= conf->bypass_threshold;
5208                                 if (conf->bypass_count < 0)
5209                                         conf->bypass_count = 0;
5210                         }
5211                 }
5212         } else if (!list_empty(&conf->hold_list) &&
5213                    ((conf->bypass_threshold &&
5214                      conf->bypass_count > conf->bypass_threshold) ||
5215                     atomic_read(&conf->pending_full_writes) == 0)) {
5216
5217                 list_for_each_entry(tmp, &conf->hold_list,  lru) {
5218                         if (conf->worker_cnt_per_group == 0 ||
5219                             group == ANY_GROUP ||
5220                             !cpu_online(tmp->cpu) ||
5221                             cpu_to_group(tmp->cpu) == group) {
5222                                 sh = tmp;
5223                                 break;
5224                         }
5225                 }
5226
5227                 if (sh) {
5228                         conf->bypass_count -= conf->bypass_threshold;
5229                         if (conf->bypass_count < 0)
5230                                 conf->bypass_count = 0;
5231                 }
5232                 wg = NULL;
5233         }
5234
5235         if (!sh)
5236                 return NULL;
5237
5238         if (wg) {
5239                 wg->stripes_cnt--;
5240                 sh->group = NULL;
5241         }
5242         list_del_init(&sh->lru);
5243         BUG_ON(atomic_inc_return(&sh->count) != 1);
5244         return sh;
5245 }
5246
5247 struct raid5_plug_cb {
5248         struct blk_plug_cb      cb;
5249         struct list_head        list;
5250         struct list_head        temp_inactive_list[NR_STRIPE_HASH_LOCKS];
5251 };
5252
5253 static void raid5_unplug(struct blk_plug_cb *blk_cb, bool from_schedule)
5254 {
5255         struct raid5_plug_cb *cb = container_of(
5256                 blk_cb, struct raid5_plug_cb, cb);
5257         struct stripe_head *sh;
5258         struct mddev *mddev = cb->cb.data;
5259         struct r5conf *conf = mddev->private;
5260         int cnt = 0;
5261         int hash;
5262
5263         if (cb->list.next && !list_empty(&cb->list)) {
5264                 spin_lock_irq(&conf->device_lock);
5265                 while (!list_empty(&cb->list)) {
5266                         sh = list_first_entry(&cb->list, struct stripe_head, lru);
5267                         list_del_init(&sh->lru);
5268                         /*
5269                          * avoid race release_stripe_plug() sees
5270                          * STRIPE_ON_UNPLUG_LIST clear but the stripe
5271                          * is still in our list
5272                          */
5273                         smp_mb__before_atomic();
5274                         clear_bit(STRIPE_ON_UNPLUG_LIST, &sh->state);
5275                         /*
5276                          * STRIPE_ON_RELEASE_LIST could be set here. In that
5277                          * case, the count is always > 1 here
5278                          */
5279                         hash = sh->hash_lock_index;
5280                         __release_stripe(conf, sh, &cb->temp_inactive_list[hash]);
5281                         cnt++;
5282                 }
5283                 spin_unlock_irq(&conf->device_lock);
5284         }
5285         release_inactive_stripe_list(conf, cb->temp_inactive_list,
5286                                      NR_STRIPE_HASH_LOCKS);
5287         if (mddev->queue)
5288                 trace_block_unplug(mddev->queue, cnt, !from_schedule);
5289         kfree(cb);
5290 }
5291
5292 static void release_stripe_plug(struct mddev *mddev,
5293                                 struct stripe_head *sh)
5294 {
5295         struct blk_plug_cb *blk_cb = blk_check_plugged(
5296                 raid5_unplug, mddev,
5297                 sizeof(struct raid5_plug_cb));
5298         struct raid5_plug_cb *cb;
5299
5300         if (!blk_cb) {
5301                 raid5_release_stripe(sh);
5302                 return;
5303         }
5304
5305         cb = container_of(blk_cb, struct raid5_plug_cb, cb);
5306
5307         if (cb->list.next == NULL) {
5308                 int i;
5309                 INIT_LIST_HEAD(&cb->list);
5310                 for (i = 0; i < NR_STRIPE_HASH_LOCKS; i++)
5311                         INIT_LIST_HEAD(cb->temp_inactive_list + i);
5312         }
5313
5314         if (!test_and_set_bit(STRIPE_ON_UNPLUG_LIST, &sh->state))
5315                 list_add_tail(&sh->lru, &cb->list);
5316         else
5317                 raid5_release_stripe(sh);
5318 }
5319
5320 static void make_discard_request(struct mddev *mddev, struct bio *bi)
5321 {
5322         struct r5conf *conf = mddev->private;
5323         sector_t logical_sector, last_sector;
5324         struct stripe_head *sh;
5325         int remaining;
5326         int stripe_sectors;
5327
5328         if (mddev->reshape_position != MaxSector)
5329                 /* Skip discard while reshape is happening */
5330                 return;
5331
5332         logical_sector = bi->bi_iter.bi_sector & ~((sector_t)STRIPE_SECTORS-1);
5333         last_sector = bi->bi_iter.bi_sector + (bi->bi_iter.bi_size>>9);
5334
5335         bi->bi_next = NULL;
5336         bi->bi_phys_segments = 1; /* over-loaded to count active stripes */
5337
5338         stripe_sectors = conf->chunk_sectors *
5339                 (conf->raid_disks - conf->max_degraded);
5340         logical_sector = DIV_ROUND_UP_SECTOR_T(logical_sector,
5341                                                stripe_sectors);
5342         sector_div(last_sector, stripe_sectors);
5343
5344         logical_sector *= conf->chunk_sectors;
5345         last_sector *= conf->chunk_sectors;
5346
5347         for (; logical_sector < last_sector;
5348              logical_sector += STRIPE_SECTORS) {
5349                 DEFINE_WAIT(w);
5350                 int d;
5351         again:
5352                 sh = raid5_get_active_stripe(conf, logical_sector, 0, 0, 0);
5353                 prepare_to_wait(&conf->wait_for_overlap, &w,
5354                                 TASK_UNINTERRUPTIBLE);
5355                 set_bit(R5_Overlap, &sh->dev[sh->pd_idx].flags);
5356                 if (test_bit(STRIPE_SYNCING, &sh->state)) {
5357                         raid5_release_stripe(sh);
5358                         schedule();
5359                         goto again;
5360                 }
5361                 clear_bit(R5_Overlap, &sh->dev[sh->pd_idx].flags);
5362                 spin_lock_irq(&sh->stripe_lock);
5363                 for (d = 0; d < conf->raid_disks; d++) {
5364                         if (d == sh->pd_idx || d == sh->qd_idx)
5365                                 continue;
5366                         if (sh->dev[d].towrite || sh->dev[d].toread) {
5367                                 set_bit(R5_Overlap, &sh->dev[d].flags);
5368                                 spin_unlock_irq(&sh->stripe_lock);
5369                                 raid5_release_stripe(sh);
5370                                 schedule();
5371                                 goto again;
5372                         }
5373                 }
5374                 set_bit(STRIPE_DISCARD, &sh->state);
5375                 finish_wait(&conf->wait_for_overlap, &w);
5376                 sh->overwrite_disks = 0;
5377                 for (d = 0; d < conf->raid_disks; d++) {
5378                         if (d == sh->pd_idx || d == sh->qd_idx)
5379                                 continue;
5380                         sh->dev[d].towrite = bi;
5381                         set_bit(R5_OVERWRITE, &sh->dev[d].flags);
5382                         raid5_inc_bi_active_stripes(bi);
5383                         sh->overwrite_disks++;
5384                 }
5385                 spin_unlock_irq(&sh->stripe_lock);
5386                 if (conf->mddev->bitmap) {
5387                         for (d = 0;
5388                              d < conf->raid_disks - conf->max_degraded;
5389                              d++)
5390                                 bitmap_startwrite(mddev->bitmap,
5391                                                   sh->sector,
5392                                                   STRIPE_SECTORS,
5393                                                   0);
5394                         sh->bm_seq = conf->seq_flush + 1;
5395                         set_bit(STRIPE_BIT_DELAY, &sh->state);
5396                 }
5397
5398                 set_bit(STRIPE_HANDLE, &sh->state);
5399                 clear_bit(STRIPE_DELAYED, &sh->state);
5400                 if (!test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
5401                         atomic_inc(&conf->preread_active_stripes);
5402                 release_stripe_plug(mddev, sh);
5403         }
5404
5405         remaining = raid5_dec_bi_active_stripes(bi);
5406         if (remaining == 0) {
5407                 md_write_end(mddev);
5408                 bio_endio(bi);
5409         }
5410 }
5411
5412 static void raid5_make_request(struct mddev *mddev, struct bio * bi)
5413 {
5414         struct r5conf *conf = mddev->private;
5415         int dd_idx;
5416         sector_t new_sector;
5417         sector_t logical_sector, last_sector;
5418         struct stripe_head *sh;
5419         const int rw = bio_data_dir(bi);
5420         int remaining;
5421         DEFINE_WAIT(w);
5422         bool do_prepare;
5423         bool do_flush = false;
5424
5425         if (unlikely(bi->bi_opf & REQ_PREFLUSH)) {
5426                 int ret = r5l_handle_flush_request(conf->log, bi);
5427
5428                 if (ret == 0)
5429                         return;
5430                 if (ret == -ENODEV) {
5431                         md_flush_request(mddev, bi);
5432                         return;
5433                 }
5434                 /* ret == -EAGAIN, fallback */
5435                 /*
5436                  * if r5l_handle_flush_request() didn't clear REQ_PREFLUSH,
5437                  * we need to flush journal device
5438                  */
5439                 do_flush = bi->bi_opf & REQ_PREFLUSH;
5440         }
5441
5442         md_write_start(mddev, bi);
5443
5444         /*
5445          * If array is degraded, better not do chunk aligned read because
5446          * later we might have to read it again in order to reconstruct
5447          * data on failed drives.
5448          */
5449         if (rw == READ && mddev->degraded == 0 &&
5450             mddev->reshape_position == MaxSector) {
5451                 bi = chunk_aligned_read(mddev, bi);
5452                 if (!bi)
5453                         return;
5454         }
5455
5456         if (unlikely(bio_op(bi) == REQ_OP_DISCARD)) {
5457                 make_discard_request(mddev, bi);
5458                 return;
5459         }
5460
5461         logical_sector = bi->bi_iter.bi_sector & ~((sector_t)STRIPE_SECTORS-1);
5462         last_sector = bio_end_sector(bi);
5463         bi->bi_next = NULL;
5464         bi->bi_phys_segments = 1;       /* over-loaded to count active stripes */
5465
5466         prepare_to_wait(&conf->wait_for_overlap, &w, TASK_UNINTERRUPTIBLE);
5467         for (;logical_sector < last_sector; logical_sector += STRIPE_SECTORS) {
5468                 int previous;
5469                 int seq;
5470
5471                 do_prepare = false;
5472         retry:
5473                 seq = read_seqcount_begin(&conf->gen_lock);
5474                 previous = 0;
5475                 if (do_prepare)
5476                         prepare_to_wait(&conf->wait_for_overlap, &w,
5477                                 TASK_UNINTERRUPTIBLE);
5478                 if (unlikely(conf->reshape_progress != MaxSector)) {
5479                         /* spinlock is needed as reshape_progress may be
5480                          * 64bit on a 32bit platform, and so it might be
5481                          * possible to see a half-updated value
5482                          * Of course reshape_progress could change after
5483                          * the lock is dropped, so once we get a reference
5484                          * to the stripe that we think it is, we will have
5485                          * to check again.
5486                          */
5487                         spin_lock_irq(&conf->device_lock);
5488                         if (mddev->reshape_backwards
5489                             ? logical_sector < conf->reshape_progress
5490                             : logical_sector >= conf->reshape_progress) {
5491                                 previous = 1;
5492                         } else {
5493                                 if (mddev->reshape_backwards
5494                                     ? logical_sector < conf->reshape_safe
5495                                     : logical_sector >= conf->reshape_safe) {
5496                                         spin_unlock_irq(&conf->device_lock);
5497                                         schedule();
5498                                         do_prepare = true;
5499                                         goto retry;
5500                                 }
5501                         }
5502                         spin_unlock_irq(&conf->device_lock);
5503                 }
5504
5505                 new_sector = raid5_compute_sector(conf, logical_sector,
5506                                                   previous,
5507                                                   &dd_idx, NULL);
5508                 pr_debug("raid456: raid5_make_request, sector %llu logical %llu\n",
5509                         (unsigned long long)new_sector,
5510                         (unsigned long long)logical_sector);
5511
5512                 sh = raid5_get_active_stripe(conf, new_sector, previous,
5513                                        (bi->bi_opf & REQ_RAHEAD), 0);
5514                 if (sh) {
5515                         if (unlikely(previous)) {
5516                                 /* expansion might have moved on while waiting for a
5517                                  * stripe, so we must do the range check again.
5518                                  * Expansion could still move past after this
5519                                  * test, but as we are holding a reference to
5520                                  * 'sh', we know that if that happens,
5521                                  *  STRIPE_EXPANDING will get set and the expansion
5522                                  * won't proceed until we finish with the stripe.
5523                                  */
5524                                 int must_retry = 0;
5525                                 spin_lock_irq(&conf->device_lock);
5526                                 if (mddev->reshape_backwards
5527                                     ? logical_sector >= conf->reshape_progress
5528                                     : logical_sector < conf->reshape_progress)
5529                                         /* mismatch, need to try again */
5530                                         must_retry = 1;
5531                                 spin_unlock_irq(&conf->device_lock);
5532                                 if (must_retry) {
5533                                         raid5_release_stripe(sh);
5534                                         schedule();
5535                                         do_prepare = true;
5536                                         goto retry;
5537                                 }
5538                         }
5539                         if (read_seqcount_retry(&conf->gen_lock, seq)) {
5540                                 /* Might have got the wrong stripe_head
5541                                  * by accident
5542                                  */
5543                                 raid5_release_stripe(sh);
5544                                 goto retry;
5545                         }
5546
5547                         if (rw == WRITE &&
5548                             logical_sector >= mddev->suspend_lo &&
5549                             logical_sector < mddev->suspend_hi) {
5550                                 raid5_release_stripe(sh);
5551                                 /* As the suspend_* range is controlled by
5552                                  * userspace, we want an interruptible
5553                                  * wait.
5554                                  */
5555                                 flush_signals(current);
5556                                 prepare_to_wait(&conf->wait_for_overlap,
5557                                                 &w, TASK_INTERRUPTIBLE);
5558                                 if (logical_sector >= mddev->suspend_lo &&
5559                                     logical_sector < mddev->suspend_hi) {
5560                                         schedule();
5561                                         do_prepare = true;
5562                                 }
5563                                 goto retry;
5564                         }
5565
5566                         if (test_bit(STRIPE_EXPANDING, &sh->state) ||
5567                             !add_stripe_bio(sh, bi, dd_idx, rw, previous)) {
5568                                 /* Stripe is busy expanding or
5569                                  * add failed due to overlap.  Flush everything
5570                                  * and wait a while
5571                                  */
5572                                 md_wakeup_thread(mddev->thread);
5573                                 raid5_release_stripe(sh);
5574                                 schedule();
5575                                 do_prepare = true;
5576                                 goto retry;
5577                         }
5578                         if (do_flush) {
5579                                 set_bit(STRIPE_R5C_PREFLUSH, &sh->state);
5580                                 /* we only need flush for one stripe */
5581                                 do_flush = false;
5582                         }
5583
5584                         set_bit(STRIPE_HANDLE, &sh->state);
5585                         clear_bit(STRIPE_DELAYED, &sh->state);
5586                         if ((!sh->batch_head || sh == sh->batch_head) &&
5587                             (bi->bi_opf & REQ_SYNC) &&
5588                             !test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
5589                                 atomic_inc(&conf->preread_active_stripes);
5590                         release_stripe_plug(mddev, sh);
5591                 } else {
5592                         /* cannot get stripe for read-ahead, just give-up */
5593                         bi->bi_error = -EIO;
5594                         break;
5595                 }
5596         }
5597         finish_wait(&conf->wait_for_overlap, &w);
5598
5599         remaining = raid5_dec_bi_active_stripes(bi);
5600         if (remaining == 0) {
5601
5602                 if ( rw == WRITE )
5603                         md_write_end(mddev);
5604
5605                 trace_block_bio_complete(bdev_get_queue(bi->bi_bdev),
5606                                          bi, 0);
5607                 bio_endio(bi);
5608         }
5609 }
5610
5611 static sector_t raid5_size(struct mddev *mddev, sector_t sectors, int raid_disks);
5612
5613 static sector_t reshape_request(struct mddev *mddev, sector_t sector_nr, int *skipped)
5614 {
5615         /* reshaping is quite different to recovery/resync so it is
5616          * handled quite separately ... here.
5617          *
5618          * On each call to sync_request, we gather one chunk worth of
5619          * destination stripes and flag them as expanding.
5620          * Then we find all the source stripes and request reads.
5621          * As the reads complete, handle_stripe will copy the data
5622          * into the destination stripe and release that stripe.
5623          */
5624         struct r5conf *conf = mddev->private;
5625         struct stripe_head *sh;
5626         sector_t first_sector, last_sector;
5627         int raid_disks = conf->previous_raid_disks;
5628         int data_disks = raid_disks - conf->max_degraded;
5629         int new_data_disks = conf->raid_disks - conf->max_degraded;
5630         int i;
5631         int dd_idx;
5632         sector_t writepos, readpos, safepos;
5633         sector_t stripe_addr;
5634         int reshape_sectors;
5635         struct list_head stripes;
5636         sector_t retn;
5637
5638         if (sector_nr == 0) {
5639                 /* If restarting in the middle, skip the initial sectors */
5640                 if (mddev->reshape_backwards &&
5641                     conf->reshape_progress < raid5_size(mddev, 0, 0)) {
5642                         sector_nr = raid5_size(mddev, 0, 0)
5643                                 - conf->reshape_progress;
5644                 } else if (mddev->reshape_backwards &&
5645                            conf->reshape_progress == MaxSector) {
5646                         /* shouldn't happen, but just in case, finish up.*/
5647                         sector_nr = MaxSector;
5648                 } else if (!mddev->reshape_backwards &&
5649                            conf->reshape_progress > 0)
5650                         sector_nr = conf->reshape_progress;
5651                 sector_div(sector_nr, new_data_disks);
5652                 if (sector_nr) {
5653                         mddev->curr_resync_completed = sector_nr;
5654                         sysfs_notify(&mddev->kobj, NULL, "sync_completed");
5655                         *skipped = 1;
5656                         retn = sector_nr;
5657                         goto finish;
5658                 }
5659         }
5660
5661         /* We need to process a full chunk at a time.
5662          * If old and new chunk sizes differ, we need to process the
5663          * largest of these
5664          */
5665
5666         reshape_sectors = max(conf->chunk_sectors, conf->prev_chunk_sectors);
5667
5668         /* We update the metadata at least every 10 seconds, or when
5669          * the data about to be copied would over-write the source of
5670          * the data at the front of the range.  i.e. one new_stripe
5671          * along from reshape_progress new_maps to after where
5672          * reshape_safe old_maps to
5673          */
5674         writepos = conf->reshape_progress;
5675         sector_div(writepos, new_data_disks);
5676         readpos = conf->reshape_progress;
5677         sector_div(readpos, data_disks);
5678         safepos = conf->reshape_safe;
5679         sector_div(safepos, data_disks);
5680         if (mddev->reshape_backwards) {
5681                 BUG_ON(writepos < reshape_sectors);
5682                 writepos -= reshape_sectors;
5683                 readpos += reshape_sectors;
5684                 safepos += reshape_sectors;
5685         } else {
5686                 writepos += reshape_sectors;
5687                 /* readpos and safepos are worst-case calculations.
5688                  * A negative number is overly pessimistic, and causes
5689                  * obvious problems for unsigned storage.  So clip to 0.
5690                  */
5691                 readpos -= min_t(sector_t, reshape_sectors, readpos);
5692                 safepos -= min_t(sector_t, reshape_sectors, safepos);
5693         }
5694
5695         /* Having calculated the 'writepos' possibly use it
5696          * to set 'stripe_addr' which is where we will write to.
5697          */
5698         if (mddev->reshape_backwards) {
5699                 BUG_ON(conf->reshape_progress == 0);
5700                 stripe_addr = writepos;
5701                 BUG_ON((mddev->dev_sectors &
5702                         ~((sector_t)reshape_sectors - 1))
5703                        - reshape_sectors - stripe_addr
5704                        != sector_nr);
5705         } else {
5706                 BUG_ON(writepos != sector_nr + reshape_sectors);
5707                 stripe_addr = sector_nr;
5708         }
5709
5710         /* 'writepos' is the most advanced device address we might write.
5711          * 'readpos' is the least advanced device address we might read.
5712          * 'safepos' is the least address recorded in the metadata as having
5713          *     been reshaped.
5714          * If there is a min_offset_diff, these are adjusted either by
5715          * increasing the safepos/readpos if diff is negative, or
5716          * increasing writepos if diff is positive.
5717          * If 'readpos' is then behind 'writepos', there is no way that we can
5718          * ensure safety in the face of a crash - that must be done by userspace
5719          * making a backup of the data.  So in that case there is no particular
5720          * rush to update metadata.
5721          * Otherwise if 'safepos' is behind 'writepos', then we really need to
5722          * update the metadata to advance 'safepos' to match 'readpos' so that
5723          * we can be safe in the event of a crash.
5724          * So we insist on updating metadata if safepos is behind writepos and
5725          * readpos is beyond writepos.
5726          * In any case, update the metadata every 10 seconds.
5727          * Maybe that number should be configurable, but I'm not sure it is
5728          * worth it.... maybe it could be a multiple of safemode_delay???
5729          */
5730         if (conf->min_offset_diff < 0) {
5731                 safepos += -conf->min_offset_diff;
5732                 readpos += -conf->min_offset_diff;
5733         } else
5734                 writepos += conf->min_offset_diff;
5735
5736         if ((mddev->reshape_backwards
5737              ? (safepos > writepos && readpos < writepos)
5738              : (safepos < writepos && readpos > writepos)) ||
5739             time_after(jiffies, conf->reshape_checkpoint + 10*HZ)) {
5740                 /* Cannot proceed until we've updated the superblock... */
5741                 wait_event(conf->wait_for_overlap,
5742                            atomic_read(&conf->reshape_stripes)==0
5743                            || test_bit(MD_RECOVERY_INTR, &mddev->recovery));
5744                 if (atomic_read(&conf->reshape_stripes) != 0)
5745                         return 0;
5746                 mddev->reshape_position = conf->reshape_progress;
5747                 mddev->curr_resync_completed = sector_nr;
5748                 conf->reshape_checkpoint = jiffies;
5749                 set_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags);
5750                 md_wakeup_thread(mddev->thread);
5751                 wait_event(mddev->sb_wait, mddev->sb_flags == 0 ||
5752                            test_bit(MD_RECOVERY_INTR, &mddev->recovery));
5753                 if (test_bit(MD_RECOVERY_INTR, &mddev->recovery))
5754                         return 0;
5755                 spin_lock_irq(&conf->device_lock);
5756                 conf->reshape_safe = mddev->reshape_position;
5757                 spin_unlock_irq(&conf->device_lock);
5758                 wake_up(&conf->wait_for_overlap);
5759                 sysfs_notify(&mddev->kobj, NULL, "sync_completed");
5760         }
5761
5762         INIT_LIST_HEAD(&stripes);
5763         for (i = 0; i < reshape_sectors; i += STRIPE_SECTORS) {
5764                 int j;
5765                 int skipped_disk = 0;
5766                 sh = raid5_get_active_stripe(conf, stripe_addr+i, 0, 0, 1);
5767                 set_bit(STRIPE_EXPANDING, &sh->state);
5768                 atomic_inc(&conf->reshape_stripes);
5769                 /* If any of this stripe is beyond the end of the old
5770                  * array, then we need to zero those blocks
5771                  */
5772                 for (j=sh->disks; j--;) {
5773                         sector_t s;
5774                         if (j == sh->pd_idx)
5775                                 continue;
5776                         if (conf->level == 6 &&
5777                             j == sh->qd_idx)
5778                                 continue;
5779                         s = raid5_compute_blocknr(sh, j, 0);
5780                         if (s < raid5_size(mddev, 0, 0)) {
5781                                 skipped_disk = 1;
5782                                 continue;
5783                         }
5784                         memset(page_address(sh->dev[j].page), 0, STRIPE_SIZE);
5785                         set_bit(R5_Expanded, &sh->dev[j].flags);
5786                         set_bit(R5_UPTODATE, &sh->dev[j].flags);
5787                 }
5788                 if (!skipped_disk) {
5789                         set_bit(STRIPE_EXPAND_READY, &sh->state);
5790                         set_bit(STRIPE_HANDLE, &sh->state);
5791                 }
5792                 list_add(&sh->lru, &stripes);
5793         }
5794         spin_lock_irq(&conf->device_lock);
5795         if (mddev->reshape_backwards)
5796                 conf->reshape_progress -= reshape_sectors * new_data_disks;
5797         else
5798                 conf->reshape_progress += reshape_sectors * new_data_disks;
5799         spin_unlock_irq(&conf->device_lock);
5800         /* Ok, those stripe are ready. We can start scheduling
5801          * reads on the source stripes.
5802          * The source stripes are determined by mapping the first and last
5803          * block on the destination stripes.
5804          */
5805         first_sector =
5806                 raid5_compute_sector(conf, stripe_addr*(new_data_disks),
5807                                      1, &dd_idx, NULL);
5808         last_sector =
5809                 raid5_compute_sector(conf, ((stripe_addr+reshape_sectors)
5810                                             * new_data_disks - 1),
5811                                      1, &dd_idx, NULL);
5812         if (last_sector >= mddev->dev_sectors)
5813                 last_sector = mddev->dev_sectors - 1;
5814         while (first_sector <= last_sector) {
5815                 sh = raid5_get_active_stripe(conf, first_sector, 1, 0, 1);
5816                 set_bit(STRIPE_EXPAND_SOURCE, &sh->state);
5817                 set_bit(STRIPE_HANDLE, &sh->state);
5818                 raid5_release_stripe(sh);
5819                 first_sector += STRIPE_SECTORS;
5820         }
5821         /* Now that the sources are clearly marked, we can release
5822          * the destination stripes
5823          */
5824         while (!list_empty(&stripes)) {
5825                 sh = list_entry(stripes.next, struct stripe_head, lru);
5826                 list_del_init(&sh->lru);
5827                 raid5_release_stripe(sh);
5828         }
5829         /* If this takes us to the resync_max point where we have to pause,
5830          * then we need to write out the superblock.
5831          */
5832         sector_nr += reshape_sectors;
5833         retn = reshape_sectors;
5834 finish:
5835         if (mddev->curr_resync_completed > mddev->resync_max ||
5836             (sector_nr - mddev->curr_resync_completed) * 2
5837             >= mddev->resync_max - mddev->curr_resync_completed) {
5838                 /* Cannot proceed until we've updated the superblock... */
5839                 wait_event(conf->wait_for_overlap,
5840                            atomic_read(&conf->reshape_stripes) == 0
5841                            || test_bit(MD_RECOVERY_INTR, &mddev->recovery));
5842                 if (atomic_read(&conf->reshape_stripes) != 0)
5843                         goto ret;
5844                 mddev->reshape_position = conf->reshape_progress;
5845                 mddev->curr_resync_completed = sector_nr;
5846                 conf->reshape_checkpoint = jiffies;
5847                 set_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags);
5848                 md_wakeup_thread(mddev->thread);
5849                 wait_event(mddev->sb_wait,
5850                            !test_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags)
5851                            || test_bit(MD_RECOVERY_INTR, &mddev->recovery));
5852                 if (test_bit(MD_RECOVERY_INTR, &mddev->recovery))
5853                         goto ret;
5854                 spin_lock_irq(&conf->device_lock);
5855                 conf->reshape_safe = mddev->reshape_position;
5856                 spin_unlock_irq(&conf->device_lock);
5857                 wake_up(&conf->wait_for_overlap);
5858                 sysfs_notify(&mddev->kobj, NULL, "sync_completed");
5859         }
5860 ret:
5861         return retn;
5862 }
5863
5864 static inline sector_t raid5_sync_request(struct mddev *mddev, sector_t sector_nr,
5865                                           int *skipped)
5866 {
5867         struct r5conf *conf = mddev->private;
5868         struct stripe_head *sh;
5869         sector_t max_sector = mddev->dev_sectors;
5870         sector_t sync_blocks;
5871         int still_degraded = 0;
5872         int i;
5873
5874         if (sector_nr >= max_sector) {
5875                 /* just being told to finish up .. nothing much to do */
5876
5877                 if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery)) {
5878                         end_reshape(conf);
5879                         return 0;
5880                 }
5881
5882                 if (mddev->curr_resync < max_sector) /* aborted */
5883                         bitmap_end_sync(mddev->bitmap, mddev->curr_resync,
5884                                         &sync_blocks, 1);
5885                 else /* completed sync */
5886                         conf->fullsync = 0;
5887                 bitmap_close_sync(mddev->bitmap);
5888
5889                 return 0;
5890         }
5891
5892         /* Allow raid5_quiesce to complete */
5893         wait_event(conf->wait_for_overlap, conf->quiesce != 2);
5894
5895         if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery))
5896                 return reshape_request(mddev, sector_nr, skipped);
5897
5898         /* No need to check resync_max as we never do more than one
5899          * stripe, and as resync_max will always be on a chunk boundary,
5900          * if the check in md_do_sync didn't fire, there is no chance
5901          * of overstepping resync_max here
5902          */
5903
5904         /* if there is too many failed drives and we are trying
5905          * to resync, then assert that we are finished, because there is
5906          * nothing we can do.
5907          */
5908         if (mddev->degraded >= conf->max_degraded &&
5909             test_bit(MD_RECOVERY_SYNC, &mddev->recovery)) {
5910                 sector_t rv = mddev->dev_sectors - sector_nr;
5911                 *skipped = 1;
5912                 return rv;
5913         }
5914         if (!test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery) &&
5915             !conf->fullsync &&
5916             !bitmap_start_sync(mddev->bitmap, sector_nr, &sync_blocks, 1) &&
5917             sync_blocks >= STRIPE_SECTORS) {
5918                 /* we can skip this block, and probably more */
5919                 sync_blocks /= STRIPE_SECTORS;
5920                 *skipped = 1;
5921                 return sync_blocks * STRIPE_SECTORS; /* keep things rounded to whole stripes */
5922         }
5923
5924         bitmap_cond_end_sync(mddev->bitmap, sector_nr, false);
5925
5926         sh = raid5_get_active_stripe(conf, sector_nr, 0, 1, 0);
5927         if (sh == NULL) {
5928                 sh = raid5_get_active_stripe(conf, sector_nr, 0, 0, 0);
5929                 /* make sure we don't swamp the stripe cache if someone else
5930                  * is trying to get access
5931                  */
5932                 schedule_timeout_uninterruptible(1);
5933         }
5934         /* Need to check if array will still be degraded after recovery/resync
5935          * Note in case of > 1 drive failures it's possible we're rebuilding
5936          * one drive while leaving another faulty drive in array.
5937          */
5938         rcu_read_lock();
5939         for (i = 0; i < conf->raid_disks; i++) {
5940                 struct md_rdev *rdev = ACCESS_ONCE(conf->disks[i].rdev);
5941
5942                 if (rdev == NULL || test_bit(Faulty, &rdev->flags))
5943                         still_degraded = 1;
5944         }
5945         rcu_read_unlock();
5946
5947         bitmap_start_sync(mddev->bitmap, sector_nr, &sync_blocks, still_degraded);
5948
5949         set_bit(STRIPE_SYNC_REQUESTED, &sh->state);
5950         set_bit(STRIPE_HANDLE, &sh->state);
5951
5952         raid5_release_stripe(sh);
5953
5954         return STRIPE_SECTORS;
5955 }
5956
5957 static int  retry_aligned_read(struct r5conf *conf, struct bio *raid_bio)
5958 {
5959         /* We may not be able to submit a whole bio at once as there
5960          * may not be enough stripe_heads available.
5961          * We cannot pre-allocate enough stripe_heads as we may need
5962          * more than exist in the cache (if we allow ever large chunks).
5963          * So we do one stripe head at a time and record in
5964          * ->bi_hw_segments how many have been done.
5965          *
5966          * We *know* that this entire raid_bio is in one chunk, so
5967          * it will be only one 'dd_idx' and only need one call to raid5_compute_sector.
5968          */
5969         struct stripe_head *sh;
5970         int dd_idx;
5971         sector_t sector, logical_sector, last_sector;
5972         int scnt = 0;
5973         int remaining;
5974         int handled = 0;
5975
5976         logical_sector = raid_bio->bi_iter.bi_sector &
5977                 ~((sector_t)STRIPE_SECTORS-1);
5978         sector = raid5_compute_sector(conf, logical_sector,
5979                                       0, &dd_idx, NULL);
5980         last_sector = bio_end_sector(raid_bio);
5981
5982         for (; logical_sector < last_sector;
5983              logical_sector += STRIPE_SECTORS,
5984                      sector += STRIPE_SECTORS,
5985                      scnt++) {
5986
5987                 if (scnt < raid5_bi_processed_stripes(raid_bio))
5988                         /* already done this stripe */
5989                         continue;
5990
5991                 sh = raid5_get_active_stripe(conf, sector, 0, 1, 1);
5992
5993                 if (!sh) {
5994                         /* failed to get a stripe - must wait */
5995                         raid5_set_bi_processed_stripes(raid_bio, scnt);
5996                         conf->retry_read_aligned = raid_bio;
5997                         return handled;
5998                 }
5999
6000                 if (!add_stripe_bio(sh, raid_bio, dd_idx, 0, 0)) {
6001                         raid5_release_stripe(sh);
6002                         raid5_set_bi_processed_stripes(raid_bio, scnt);
6003                         conf->retry_read_aligned = raid_bio;
6004                         return handled;
6005                 }
6006
6007                 set_bit(R5_ReadNoMerge, &sh->dev[dd_idx].flags);
6008                 handle_stripe(sh);
6009                 raid5_release_stripe(sh);
6010                 handled++;
6011         }
6012         remaining = raid5_dec_bi_active_stripes(raid_bio);
6013         if (remaining == 0) {
6014                 trace_block_bio_complete(bdev_get_queue(raid_bio->bi_bdev),
6015                                          raid_bio, 0);
6016                 bio_endio(raid_bio);
6017         }
6018         if (atomic_dec_and_test(&conf->active_aligned_reads))
6019                 wake_up(&conf->wait_for_quiescent);
6020         return handled;
6021 }
6022
6023 static int handle_active_stripes(struct r5conf *conf, int group,
6024                                  struct r5worker *worker,
6025                                  struct list_head *temp_inactive_list)
6026 {
6027         struct stripe_head *batch[MAX_STRIPE_BATCH], *sh;
6028         int i, batch_size = 0, hash;
6029         bool release_inactive = false;
6030
6031         while (batch_size < MAX_STRIPE_BATCH &&
6032                         (sh = __get_priority_stripe(conf, group)) != NULL)
6033                 batch[batch_size++] = sh;
6034
6035         if (batch_size == 0) {
6036                 for (i = 0; i < NR_STRIPE_HASH_LOCKS; i++)
6037                         if (!list_empty(temp_inactive_list + i))
6038                                 break;
6039                 if (i == NR_STRIPE_HASH_LOCKS) {
6040                         spin_unlock_irq(&conf->device_lock);
6041                         r5l_flush_stripe_to_raid(conf->log);
6042                         spin_lock_irq(&conf->device_lock);
6043                         return batch_size;
6044                 }
6045                 release_inactive = true;
6046         }
6047         spin_unlock_irq(&conf->device_lock);
6048
6049         release_inactive_stripe_list(conf, temp_inactive_list,
6050                                      NR_STRIPE_HASH_LOCKS);
6051
6052         r5l_flush_stripe_to_raid(conf->log);
6053         if (release_inactive) {
6054                 spin_lock_irq(&conf->device_lock);
6055                 return 0;
6056         }
6057
6058         for (i = 0; i < batch_size; i++)
6059                 handle_stripe(batch[i]);
6060         r5l_write_stripe_run(conf->log);
6061
6062         cond_resched();
6063
6064         spin_lock_irq(&conf->device_lock);
6065         for (i = 0; i < batch_size; i++) {
6066                 hash = batch[i]->hash_lock_index;
6067                 __release_stripe(conf, batch[i], &temp_inactive_list[hash]);
6068         }
6069         return batch_size;
6070 }
6071
6072 static void raid5_do_work(struct work_struct *work)
6073 {
6074         struct r5worker *worker = container_of(work, struct r5worker, work);
6075         struct r5worker_group *group = worker->group;
6076         struct r5conf *conf = group->conf;
6077         int group_id = group - conf->worker_groups;
6078         int handled;
6079         struct blk_plug plug;
6080
6081         pr_debug("+++ raid5worker active\n");
6082
6083         blk_start_plug(&plug);
6084         handled = 0;
6085         spin_lock_irq(&conf->device_lock);
6086         while (1) {
6087                 int batch_size, released;
6088
6089                 released = release_stripe_list(conf, worker->temp_inactive_list);
6090
6091                 batch_size = handle_active_stripes(conf, group_id, worker,
6092                                                    worker->temp_inactive_list);
6093                 worker->working = false;
6094                 if (!batch_size && !released)
6095                         break;
6096                 handled += batch_size;
6097         }
6098         pr_debug("%d stripes handled\n", handled);
6099
6100         spin_unlock_irq(&conf->device_lock);
6101         blk_finish_plug(&plug);
6102
6103         pr_debug("--- raid5worker inactive\n");
6104 }
6105
6106 /*
6107  * This is our raid5 kernel thread.
6108  *
6109  * We scan the hash table for stripes which can be handled now.
6110  * During the scan, completed stripes are saved for us by the interrupt
6111  * handler, so that they will not have to wait for our next wakeup.
6112  */
6113 static void raid5d(struct md_thread *thread)
6114 {
6115         struct mddev *mddev = thread->mddev;
6116         struct r5conf *conf = mddev->private;
6117         int handled;
6118         struct blk_plug plug;
6119
6120         pr_debug("+++ raid5d active\n");
6121
6122         md_check_recovery(mddev);
6123
6124         if (!bio_list_empty(&conf->return_bi) &&
6125             !test_bit(MD_SB_CHANGE_PENDING, &mddev->sb_flags)) {
6126                 struct bio_list tmp = BIO_EMPTY_LIST;
6127                 spin_lock_irq(&conf->device_lock);
6128                 if (!test_bit(MD_SB_CHANGE_PENDING, &mddev->sb_flags)) {
6129                         bio_list_merge(&tmp, &conf->return_bi);
6130                         bio_list_init(&conf->return_bi);
6131                 }
6132                 spin_unlock_irq(&conf->device_lock);
6133                 return_io(&tmp);
6134         }
6135
6136         blk_start_plug(&plug);
6137         handled = 0;
6138         spin_lock_irq(&conf->device_lock);
6139         while (1) {
6140                 struct bio *bio;
6141                 int batch_size, released;
6142
6143                 released = release_stripe_list(conf, conf->temp_inactive_list);
6144                 if (released)
6145                         clear_bit(R5_DID_ALLOC, &conf->cache_state);
6146
6147                 if (
6148                     !list_empty(&conf->bitmap_list)) {
6149                         /* Now is a good time to flush some bitmap updates */
6150                         conf->seq_flush++;
6151                         spin_unlock_irq(&conf->device_lock);
6152                         bitmap_unplug(mddev->bitmap);
6153                         spin_lock_irq(&conf->device_lock);
6154                         conf->seq_write = conf->seq_flush;
6155                         activate_bit_delay(conf, conf->temp_inactive_list);
6156                 }
6157                 raid5_activate_delayed(conf);
6158
6159                 while ((bio = remove_bio_from_retry(conf))) {
6160                         int ok;
6161                         spin_unlock_irq(&conf->device_lock);
6162                         ok = retry_aligned_read(conf, bio);
6163                         spin_lock_irq(&conf->device_lock);
6164                         if (!ok)
6165                                 break;
6166                         handled++;
6167                 }
6168
6169                 batch_size = handle_active_stripes(conf, ANY_GROUP, NULL,
6170                                                    conf->temp_inactive_list);
6171                 if (!batch_size && !released)
6172                         break;
6173                 handled += batch_size;
6174
6175                 if (mddev->sb_flags & ~(1 << MD_SB_CHANGE_PENDING)) {
6176                         spin_unlock_irq(&conf->device_lock);
6177                         md_check_recovery(mddev);
6178                         spin_lock_irq(&conf->device_lock);
6179                 }
6180         }
6181         pr_debug("%d stripes handled\n", handled);
6182
6183         spin_unlock_irq(&conf->device_lock);
6184         if (test_and_clear_bit(R5_ALLOC_MORE, &conf->cache_state) &&
6185             mutex_trylock(&conf->cache_size_mutex)) {
6186                 grow_one_stripe(conf, __GFP_NOWARN);
6187                 /* Set flag even if allocation failed.  This helps
6188                  * slow down allocation requests when mem is short
6189                  */
6190                 set_bit(R5_DID_ALLOC, &conf->cache_state);
6191                 mutex_unlock(&conf->cache_size_mutex);
6192         }
6193
6194         flush_deferred_bios(conf);
6195
6196         r5l_flush_stripe_to_raid(conf->log);
6197
6198         async_tx_issue_pending_all();
6199         blk_finish_plug(&plug);
6200
6201         pr_debug("--- raid5d inactive\n");
6202 }
6203
6204 static ssize_t
6205 raid5_show_stripe_cache_size(struct mddev *mddev, char *page)
6206 {
6207         struct r5conf *conf;
6208         int ret = 0;
6209         spin_lock(&mddev->lock);
6210         conf = mddev->private;
6211         if (conf)
6212                 ret = sprintf(page, "%d\n", conf->min_nr_stripes);
6213         spin_unlock(&mddev->lock);
6214         return ret;
6215 }
6216
6217 int
6218 raid5_set_cache_size(struct mddev *mddev, int size)
6219 {
6220         struct r5conf *conf = mddev->private;
6221         int err;
6222
6223         if (size <= 16 || size > 32768)
6224                 return -EINVAL;
6225
6226         conf->min_nr_stripes = size;
6227         mutex_lock(&conf->cache_size_mutex);
6228         while (size < conf->max_nr_stripes &&
6229                drop_one_stripe(conf))
6230                 ;
6231         mutex_unlock(&conf->cache_size_mutex);
6232
6233
6234         err = md_allow_write(mddev);
6235         if (err)
6236                 return err;
6237
6238         mutex_lock(&conf->cache_size_mutex);
6239         while (size > conf->max_nr_stripes)
6240                 if (!grow_one_stripe(conf, GFP_KERNEL))
6241                         break;
6242         mutex_unlock(&conf->cache_size_mutex);
6243
6244         return 0;
6245 }
6246 EXPORT_SYMBOL(raid5_set_cache_size);
6247
6248 static ssize_t
6249 raid5_store_stripe_cache_size(struct mddev *mddev, const char *page, size_t len)
6250 {
6251         struct r5conf *conf;
6252         unsigned long new;
6253         int err;
6254
6255         if (len >= PAGE_SIZE)
6256                 return -EINVAL;
6257         if (kstrtoul(page, 10, &new))
6258                 return -EINVAL;
6259         err = mddev_lock(mddev);
6260         if (err)
6261                 return err;
6262         conf = mddev->private;
6263         if (!conf)
6264                 err = -ENODEV;
6265         else
6266                 err = raid5_set_cache_size(mddev, new);
6267         mddev_unlock(mddev);
6268
6269         return err ?: len;
6270 }
6271
6272 static struct md_sysfs_entry
6273 raid5_stripecache_size = __ATTR(stripe_cache_size, S_IRUGO | S_IWUSR,
6274                                 raid5_show_stripe_cache_size,
6275                                 raid5_store_stripe_cache_size);
6276
6277 static ssize_t
6278 raid5_show_rmw_level(struct mddev  *mddev, char *page)
6279 {
6280         struct r5conf *conf = mddev->private;
6281         if (conf)
6282                 return sprintf(page, "%d\n", conf->rmw_level);
6283         else
6284                 return 0;
6285 }
6286
6287 static ssize_t
6288 raid5_store_rmw_level(struct mddev  *mddev, const char *page, size_t len)
6289 {
6290         struct r5conf *conf = mddev->private;
6291         unsigned long new;
6292
6293         if (!conf)
6294                 return -ENODEV;
6295
6296         if (len >= PAGE_SIZE)
6297                 return -EINVAL;
6298
6299         if (kstrtoul(page, 10, &new))
6300                 return -EINVAL;
6301
6302         if (new != PARITY_DISABLE_RMW && !raid6_call.xor_syndrome)
6303                 return -EINVAL;
6304
6305         if (new != PARITY_DISABLE_RMW &&
6306             new != PARITY_ENABLE_RMW &&
6307             new != PARITY_PREFER_RMW)
6308                 return -EINVAL;
6309
6310         conf->rmw_level = new;
6311         return len;
6312 }
6313
6314 static struct md_sysfs_entry
6315 raid5_rmw_level = __ATTR(rmw_level, S_IRUGO | S_IWUSR,
6316                          raid5_show_rmw_level,
6317                          raid5_store_rmw_level);
6318
6319
6320 static ssize_t
6321 raid5_show_preread_threshold(struct mddev *mddev, char *page)
6322 {
6323         struct r5conf *conf;
6324         int ret = 0;
6325         spin_lock(&mddev->lock);
6326         conf = mddev->private;
6327         if (conf)
6328                 ret = sprintf(page, "%d\n", conf->bypass_threshold);
6329         spin_unlock(&mddev->lock);
6330         return ret;
6331 }
6332
6333 static ssize_t
6334 raid5_store_preread_threshold(struct mddev *mddev, const char *page, size_t len)
6335 {
6336         struct r5conf *conf;
6337         unsigned long new;
6338         int err;
6339
6340         if (len >= PAGE_SIZE)
6341                 return -EINVAL;
6342         if (kstrtoul(page, 10, &new))
6343                 return -EINVAL;
6344
6345         err = mddev_lock(mddev);
6346         if (err)
6347                 return err;
6348         conf = mddev->private;
6349         if (!conf)
6350                 err = -ENODEV;
6351         else if (new > conf->min_nr_stripes)
6352                 err = -EINVAL;
6353         else
6354                 conf->bypass_threshold = new;
6355         mddev_unlock(mddev);
6356         return err ?: len;
6357 }
6358
6359 static struct md_sysfs_entry
6360 raid5_preread_bypass_threshold = __ATTR(preread_bypass_threshold,
6361                                         S_IRUGO | S_IWUSR,
6362                                         raid5_show_preread_threshold,
6363                                         raid5_store_preread_threshold);
6364
6365 static ssize_t
6366 raid5_show_skip_copy(struct mddev *mddev, char *page)
6367 {
6368         struct r5conf *conf;
6369         int ret = 0;
6370         spin_lock(&mddev->lock);
6371         conf = mddev->private;
6372         if (conf)
6373                 ret = sprintf(page, "%d\n", conf->skip_copy);
6374         spin_unlock(&mddev->lock);
6375         return ret;
6376 }
6377
6378 static ssize_t
6379 raid5_store_skip_copy(struct mddev *mddev, const char *page, size_t len)
6380 {
6381         struct r5conf *conf;
6382         unsigned long new;
6383         int err;
6384
6385         if (len >= PAGE_SIZE)
6386                 return -EINVAL;
6387         if (kstrtoul(page, 10, &new))
6388                 return -EINVAL;
6389         new = !!new;
6390
6391         err = mddev_lock(mddev);
6392         if (err)
6393                 return err;
6394         conf = mddev->private;
6395         if (!conf)
6396                 err = -ENODEV;
6397         else if (new != conf->skip_copy) {
6398                 mddev_suspend(mddev);
6399                 conf->skip_copy = new;
6400                 if (new)
6401                         mddev->queue->backing_dev_info->capabilities |=
6402                                 BDI_CAP_STABLE_WRITES;
6403                 else
6404                         mddev->queue->backing_dev_info->capabilities &=
6405                                 ~BDI_CAP_STABLE_WRITES;
6406                 mddev_resume(mddev);
6407         }
6408         mddev_unlock(mddev);
6409         return err ?: len;
6410 }
6411
6412 static struct md_sysfs_entry
6413 raid5_skip_copy = __ATTR(skip_copy, S_IRUGO | S_IWUSR,
6414                                         raid5_show_skip_copy,
6415                                         raid5_store_skip_copy);
6416
6417 static ssize_t
6418 stripe_cache_active_show(struct mddev *mddev, char *page)
6419 {
6420         struct r5conf *conf = mddev->private;
6421         if (conf)
6422                 return sprintf(page, "%d\n", atomic_read(&conf->active_stripes));
6423         else
6424                 return 0;
6425 }
6426
6427 static struct md_sysfs_entry
6428 raid5_stripecache_active = __ATTR_RO(stripe_cache_active);
6429
6430 static ssize_t
6431 raid5_show_group_thread_cnt(struct mddev *mddev, char *page)
6432 {
6433         struct r5conf *conf;
6434         int ret = 0;
6435         spin_lock(&mddev->lock);
6436         conf = mddev->private;
6437         if (conf)
6438                 ret = sprintf(page, "%d\n", conf->worker_cnt_per_group);
6439         spin_unlock(&mddev->lock);
6440         return ret;
6441 }
6442
6443 static int alloc_thread_groups(struct r5conf *conf, int cnt,
6444                                int *group_cnt,
6445                                int *worker_cnt_per_group,
6446                                struct r5worker_group **worker_groups);
6447 static ssize_t
6448 raid5_store_group_thread_cnt(struct mddev *mddev, const char *page, size_t len)
6449 {
6450         struct r5conf *conf;
6451         unsigned long new;
6452         int err;
6453         struct r5worker_group *new_groups, *old_groups;
6454         int group_cnt, worker_cnt_per_group;
6455
6456         if (len >= PAGE_SIZE)
6457                 return -EINVAL;
6458         if (kstrtoul(page, 10, &new))
6459                 return -EINVAL;
6460
6461         err = mddev_lock(mddev);
6462         if (err)
6463                 return err;
6464         conf = mddev->private;
6465         if (!conf)
6466                 err = -ENODEV;
6467         else if (new != conf->worker_cnt_per_group) {
6468                 mddev_suspend(mddev);
6469
6470                 old_groups = conf->worker_groups;
6471                 if (old_groups)
6472                         flush_workqueue(raid5_wq);
6473
6474                 err = alloc_thread_groups(conf, new,
6475                                           &group_cnt, &worker_cnt_per_group,
6476                                           &new_groups);
6477                 if (!err) {
6478                         spin_lock_irq(&conf->device_lock);
6479                         conf->group_cnt = group_cnt;
6480                         conf->worker_cnt_per_group = worker_cnt_per_group;
6481                         conf->worker_groups = new_groups;
6482                         spin_unlock_irq(&conf->device_lock);
6483
6484                         if (old_groups)
6485                                 kfree(old_groups[0].workers);
6486                         kfree(old_groups);
6487                 }
6488                 mddev_resume(mddev);
6489         }
6490         mddev_unlock(mddev);
6491
6492         return err ?: len;
6493 }
6494
6495 static struct md_sysfs_entry
6496 raid5_group_thread_cnt = __ATTR(group_thread_cnt, S_IRUGO | S_IWUSR,
6497                                 raid5_show_group_thread_cnt,
6498                                 raid5_store_group_thread_cnt);
6499
6500 static struct attribute *raid5_attrs[] =  {
6501         &raid5_stripecache_size.attr,
6502         &raid5_stripecache_active.attr,
6503         &raid5_preread_bypass_threshold.attr,
6504         &raid5_group_thread_cnt.attr,
6505         &raid5_skip_copy.attr,
6506         &raid5_rmw_level.attr,
6507         &r5c_journal_mode.attr,
6508         NULL,
6509 };
6510 static struct attribute_group raid5_attrs_group = {
6511         .name = NULL,
6512         .attrs = raid5_attrs,
6513 };
6514
6515 static int alloc_thread_groups(struct r5conf *conf, int cnt,
6516                                int *group_cnt,
6517                                int *worker_cnt_per_group,
6518                                struct r5worker_group **worker_groups)
6519 {
6520         int i, j, k;
6521         ssize_t size;
6522         struct r5worker *workers;
6523
6524         *worker_cnt_per_group = cnt;
6525         if (cnt == 0) {
6526                 *group_cnt = 0;
6527                 *worker_groups = NULL;
6528                 return 0;
6529         }
6530         *group_cnt = num_possible_nodes();
6531         size = sizeof(struct r5worker) * cnt;
6532         workers = kzalloc(size * *group_cnt, GFP_NOIO);
6533         *worker_groups = kzalloc(sizeof(struct r5worker_group) *
6534                                 *group_cnt, GFP_NOIO);
6535         if (!*worker_groups || !workers) {
6536                 kfree(workers);
6537                 kfree(*worker_groups);
6538                 return -ENOMEM;
6539         }
6540
6541         for (i = 0; i < *group_cnt; i++) {
6542                 struct r5worker_group *group;
6543
6544                 group = &(*worker_groups)[i];
6545                 INIT_LIST_HEAD(&group->handle_list);
6546                 group->conf = conf;
6547                 group->workers = workers + i * cnt;
6548
6549                 for (j = 0; j < cnt; j++) {
6550                         struct r5worker *worker = group->workers + j;
6551                         worker->group = group;
6552                         INIT_WORK(&worker->work, raid5_do_work);
6553
6554                         for (k = 0; k < NR_STRIPE_HASH_LOCKS; k++)
6555                                 INIT_LIST_HEAD(worker->temp_inactive_list + k);
6556                 }
6557         }
6558
6559         return 0;
6560 }
6561
6562 static void free_thread_groups(struct r5conf *conf)
6563 {
6564         if (conf->worker_groups)
6565                 kfree(conf->worker_groups[0].workers);
6566         kfree(conf->worker_groups);
6567         conf->worker_groups = NULL;
6568 }
6569
6570 static sector_t
6571 raid5_size(struct mddev *mddev, sector_t sectors, int raid_disks)
6572 {
6573         struct r5conf *conf = mddev->private;
6574
6575         if (!sectors)
6576                 sectors = mddev->dev_sectors;
6577         if (!raid_disks)
6578                 /* size is defined by the smallest of previous and new size */
6579                 raid_disks = min(conf->raid_disks, conf->previous_raid_disks);
6580
6581         sectors &= ~((sector_t)conf->chunk_sectors - 1);
6582         sectors &= ~((sector_t)conf->prev_chunk_sectors - 1);
6583         return sectors * (raid_disks - conf->max_degraded);
6584 }
6585
6586 static void free_scratch_buffer(struct r5conf *conf, struct raid5_percpu *percpu)
6587 {
6588         safe_put_page(percpu->spare_page);
6589         if (percpu->scribble)
6590                 flex_array_free(percpu->scribble);
6591         percpu->spare_page = NULL;
6592         percpu->scribble = NULL;
6593 }
6594
6595 static int alloc_scratch_buffer(struct r5conf *conf, struct raid5_percpu *percpu)
6596 {
6597         if (conf->level == 6 && !percpu->spare_page)
6598                 percpu->spare_page = alloc_page(GFP_KERNEL);
6599         if (!percpu->scribble)
6600                 percpu->scribble = scribble_alloc(max(conf->raid_disks,
6601                                                       conf->previous_raid_disks),
6602                                                   max(conf->chunk_sectors,
6603                                                       conf->prev_chunk_sectors)
6604                                                    / STRIPE_SECTORS,
6605                                                   GFP_KERNEL);
6606
6607         if (!percpu->scribble || (conf->level == 6 && !percpu->spare_page)) {
6608                 free_scratch_buffer(conf, percpu);
6609                 return -ENOMEM;
6610         }
6611
6612         return 0;
6613 }
6614
6615 static int raid456_cpu_dead(unsigned int cpu, struct hlist_node *node)
6616 {
6617         struct r5conf *conf = hlist_entry_safe(node, struct r5conf, node);
6618
6619         free_scratch_buffer(conf, per_cpu_ptr(conf->percpu, cpu));
6620         return 0;
6621 }
6622
6623 static void raid5_free_percpu(struct r5conf *conf)
6624 {
6625         if (!conf->percpu)
6626                 return;
6627
6628         cpuhp_state_remove_instance(CPUHP_MD_RAID5_PREPARE, &conf->node);
6629         free_percpu(conf->percpu);
6630 }
6631
6632 static void free_conf(struct r5conf *conf)
6633 {
6634         int i;
6635
6636         if (conf->log)
6637                 r5l_exit_log(conf->log);
6638         if (conf->shrinker.nr_deferred)
6639                 unregister_shrinker(&conf->shrinker);
6640
6641         free_thread_groups(conf);
6642         shrink_stripes(conf);
6643         raid5_free_percpu(conf);
6644         for (i = 0; i < conf->pool_size; i++)
6645                 if (conf->disks[i].extra_page)
6646                         put_page(conf->disks[i].extra_page);
6647         kfree(conf->disks);
6648         kfree(conf->stripe_hashtbl);
6649         kfree(conf);
6650 }
6651
6652 static int raid456_cpu_up_prepare(unsigned int cpu, struct hlist_node *node)
6653 {
6654         struct r5conf *conf = hlist_entry_safe(node, struct r5conf, node);
6655         struct raid5_percpu *percpu = per_cpu_ptr(conf->percpu, cpu);
6656
6657         if (alloc_scratch_buffer(conf, percpu)) {
6658                 pr_warn("%s: failed memory allocation for cpu%u\n",
6659                         __func__, cpu);
6660                 return -ENOMEM;
6661         }
6662         return 0;
6663 }
6664
6665 static int raid5_alloc_percpu(struct r5conf *conf)
6666 {
6667         int err = 0;
6668
6669         conf->percpu = alloc_percpu(struct raid5_percpu);
6670         if (!conf->percpu)
6671                 return -ENOMEM;
6672
6673         err = cpuhp_state_add_instance(CPUHP_MD_RAID5_PREPARE, &conf->node);
6674         if (!err) {
6675                 conf->scribble_disks = max(conf->raid_disks,
6676                         conf->previous_raid_disks);
6677                 conf->scribble_sectors = max(conf->chunk_sectors,
6678                         conf->prev_chunk_sectors);
6679         }
6680         return err;
6681 }
6682
6683 static unsigned long raid5_cache_scan(struct shrinker *shrink,
6684                                       struct shrink_control *sc)
6685 {
6686         struct r5conf *conf = container_of(shrink, struct r5conf, shrinker);
6687         unsigned long ret = SHRINK_STOP;
6688
6689         if (mutex_trylock(&conf->cache_size_mutex)) {
6690                 ret= 0;
6691                 while (ret < sc->nr_to_scan &&
6692                        conf->max_nr_stripes > conf->min_nr_stripes) {
6693                         if (drop_one_stripe(conf) == 0) {
6694                                 ret = SHRINK_STOP;
6695                                 break;
6696                         }
6697                         ret++;
6698                 }
6699                 mutex_unlock(&conf->cache_size_mutex);
6700         }
6701         return ret;
6702 }
6703
6704 static unsigned long raid5_cache_count(struct shrinker *shrink,
6705                                        struct shrink_control *sc)
6706 {
6707         struct r5conf *conf = container_of(shrink, struct r5conf, shrinker);
6708
6709         if (conf->max_nr_stripes < conf->min_nr_stripes)
6710                 /* unlikely, but not impossible */
6711                 return 0;
6712         return conf->max_nr_stripes - conf->min_nr_stripes;
6713 }
6714
6715 static struct r5conf *setup_conf(struct mddev *mddev)
6716 {
6717         struct r5conf *conf;
6718         int raid_disk, memory, max_disks;
6719         struct md_rdev *rdev;
6720         struct disk_info *disk;
6721         char pers_name[6];
6722         int i;
6723         int group_cnt, worker_cnt_per_group;
6724         struct r5worker_group *new_group;
6725
6726         if (mddev->new_level != 5
6727             && mddev->new_level != 4
6728             && mddev->new_level != 6) {
6729                 pr_warn("md/raid:%s: raid level not set to 4/5/6 (%d)\n",
6730                         mdname(mddev), mddev->new_level);
6731                 return ERR_PTR(-EIO);
6732         }
6733         if ((mddev->new_level == 5
6734              && !algorithm_valid_raid5(mddev->new_layout)) ||
6735             (mddev->new_level == 6
6736              && !algorithm_valid_raid6(mddev->new_layout))) {
6737                 pr_warn("md/raid:%s: layout %d not supported\n",
6738                         mdname(mddev), mddev->new_layout);
6739                 return ERR_PTR(-EIO);
6740         }
6741         if (mddev->new_level == 6 && mddev->raid_disks < 4) {
6742                 pr_warn("md/raid:%s: not enough configured devices (%d, minimum 4)\n",
6743                         mdname(mddev), mddev->raid_disks);
6744                 return ERR_PTR(-EINVAL);
6745         }
6746
6747         if (!mddev->new_chunk_sectors ||
6748             (mddev->new_chunk_sectors << 9) % PAGE_SIZE ||
6749             !is_power_of_2(mddev->new_chunk_sectors)) {
6750                 pr_warn("md/raid:%s: invalid chunk size %d\n",
6751                         mdname(mddev), mddev->new_chunk_sectors << 9);
6752                 return ERR_PTR(-EINVAL);
6753         }
6754
6755         conf = kzalloc(sizeof(struct r5conf), GFP_KERNEL);
6756         if (conf == NULL)
6757                 goto abort;
6758         /* Don't enable multi-threading by default*/
6759         if (!alloc_thread_groups(conf, 0, &group_cnt, &worker_cnt_per_group,
6760                                  &new_group)) {
6761                 conf->group_cnt = group_cnt;
6762                 conf->worker_cnt_per_group = worker_cnt_per_group;
6763                 conf->worker_groups = new_group;
6764         } else
6765                 goto abort;
6766         spin_lock_init(&conf->device_lock);
6767         seqcount_init(&conf->gen_lock);
6768         mutex_init(&conf->cache_size_mutex);
6769         init_waitqueue_head(&conf->wait_for_quiescent);
6770         init_waitqueue_head(&conf->wait_for_stripe);
6771         init_waitqueue_head(&conf->wait_for_overlap);
6772         INIT_LIST_HEAD(&conf->handle_list);
6773         INIT_LIST_HEAD(&conf->hold_list);
6774         INIT_LIST_HEAD(&conf->delayed_list);
6775         INIT_LIST_HEAD(&conf->bitmap_list);
6776         bio_list_init(&conf->return_bi);
6777         init_llist_head(&conf->released_stripes);
6778         atomic_set(&conf->active_stripes, 0);
6779         atomic_set(&conf->preread_active_stripes, 0);
6780         atomic_set(&conf->active_aligned_reads, 0);
6781         bio_list_init(&conf->pending_bios);
6782         spin_lock_init(&conf->pending_bios_lock);
6783         conf->batch_bio_dispatch = true;
6784         rdev_for_each(rdev, mddev) {
6785                 if (test_bit(Journal, &rdev->flags))
6786                         continue;
6787                 if (blk_queue_nonrot(bdev_get_queue(rdev->bdev))) {
6788                         conf->batch_bio_dispatch = false;
6789                         break;
6790                 }
6791         }
6792
6793         conf->bypass_threshold = BYPASS_THRESHOLD;
6794         conf->recovery_disabled = mddev->recovery_disabled - 1;
6795
6796         conf->raid_disks = mddev->raid_disks;
6797         if (mddev->reshape_position == MaxSector)
6798                 conf->previous_raid_disks = mddev->raid_disks;
6799         else
6800                 conf->previous_raid_disks = mddev->raid_disks - mddev->delta_disks;
6801         max_disks = max(conf->raid_disks, conf->previous_raid_disks);
6802
6803         conf->disks = kzalloc(max_disks * sizeof(struct disk_info),
6804                               GFP_KERNEL);
6805
6806         if (!conf->disks)
6807                 goto abort;
6808
6809         for (i = 0; i < max_disks; i++) {
6810                 conf->disks[i].extra_page = alloc_page(GFP_KERNEL);
6811                 if (!conf->disks[i].extra_page)
6812                         goto abort;
6813         }
6814
6815         conf->mddev = mddev;
6816
6817         if ((conf->stripe_hashtbl = kzalloc(PAGE_SIZE, GFP_KERNEL)) == NULL)
6818                 goto abort;
6819
6820         /* We init hash_locks[0] separately to that it can be used
6821          * as the reference lock in the spin_lock_nest_lock() call
6822          * in lock_all_device_hash_locks_irq in order to convince
6823          * lockdep that we know what we are doing.
6824          */
6825         spin_lock_init(conf->hash_locks);
6826         for (i = 1; i < NR_STRIPE_HASH_LOCKS; i++)
6827                 spin_lock_init(conf->hash_locks + i);
6828
6829         for (i = 0; i < NR_STRIPE_HASH_LOCKS; i++)
6830                 INIT_LIST_HEAD(conf->inactive_list + i);
6831
6832         for (i = 0; i < NR_STRIPE_HASH_LOCKS; i++)
6833                 INIT_LIST_HEAD(conf->temp_inactive_list + i);
6834
6835         atomic_set(&conf->r5c_cached_full_stripes, 0);
6836         INIT_LIST_HEAD(&conf->r5c_full_stripe_list);
6837         atomic_set(&conf->r5c_cached_partial_stripes, 0);
6838         INIT_LIST_HEAD(&conf->r5c_partial_stripe_list);
6839         atomic_set(&conf->r5c_flushing_full_stripes, 0);
6840         atomic_set(&conf->r5c_flushing_partial_stripes, 0);
6841
6842         conf->level = mddev->new_level;
6843         conf->chunk_sectors = mddev->new_chunk_sectors;
6844         if (raid5_alloc_percpu(conf) != 0)
6845                 goto abort;
6846
6847         pr_debug("raid456: run(%s) called.\n", mdname(mddev));
6848
6849         rdev_for_each(rdev, mddev) {
6850                 raid_disk = rdev->raid_disk;
6851                 if (raid_disk >= max_disks
6852                     || raid_disk < 0 || test_bit(Journal, &rdev->flags))
6853                         continue;
6854                 disk = conf->disks + raid_disk;
6855
6856                 if (test_bit(Replacement, &rdev->flags)) {
6857                         if (disk->replacement)
6858                                 goto abort;
6859                         disk->replacement = rdev;
6860                 } else {
6861                         if (disk->rdev)
6862                                 goto abort;
6863                         disk->rdev = rdev;
6864                 }
6865
6866                 if (test_bit(In_sync, &rdev->flags)) {
6867                         char b[BDEVNAME_SIZE];
6868                         pr_info("md/raid:%s: device %s operational as raid disk %d\n",
6869                                 mdname(mddev), bdevname(rdev->bdev, b), raid_disk);
6870                 } else if (rdev->saved_raid_disk != raid_disk)
6871                         /* Cannot rely on bitmap to complete recovery */
6872                         conf->fullsync = 1;
6873         }
6874
6875         conf->level = mddev->new_level;
6876         if (conf->level == 6) {
6877                 conf->max_degraded = 2;
6878                 if (raid6_call.xor_syndrome)
6879                         conf->rmw_level = PARITY_ENABLE_RMW;
6880                 else
6881                         conf->rmw_level = PARITY_DISABLE_RMW;
6882         } else {
6883                 conf->max_degraded = 1;
6884                 conf->rmw_level = PARITY_ENABLE_RMW;
6885         }
6886         conf->algorithm = mddev->new_layout;
6887         conf->reshape_progress = mddev->reshape_position;
6888         if (conf->reshape_progress != MaxSector) {
6889                 conf->prev_chunk_sectors = mddev->chunk_sectors;
6890                 conf->prev_algo = mddev->layout;
6891         } else {
6892                 conf->prev_chunk_sectors = conf->chunk_sectors;
6893                 conf->prev_algo = conf->algorithm;
6894         }
6895
6896         conf->min_nr_stripes = NR_STRIPES;
6897         if (mddev->reshape_position != MaxSector) {
6898                 int stripes = max_t(int,
6899                         ((mddev->chunk_sectors << 9) / STRIPE_SIZE) * 4,
6900                         ((mddev->new_chunk_sectors << 9) / STRIPE_SIZE) * 4);
6901                 conf->min_nr_stripes = max(NR_STRIPES, stripes);
6902                 if (conf->min_nr_stripes != NR_STRIPES)
6903                         pr_info("md/raid:%s: force stripe size %d for reshape\n",
6904                                 mdname(mddev), conf->min_nr_stripes);
6905         }
6906         memory = conf->min_nr_stripes * (sizeof(struct stripe_head) +
6907                  max_disks * ((sizeof(struct bio) + PAGE_SIZE))) / 1024;
6908         atomic_set(&conf->empty_inactive_list_nr, NR_STRIPE_HASH_LOCKS);
6909         if (grow_stripes(conf, conf->min_nr_stripes)) {
6910                 pr_warn("md/raid:%s: couldn't allocate %dkB for buffers\n",
6911                         mdname(mddev), memory);
6912                 goto abort;
6913         } else
6914                 pr_debug("md/raid:%s: allocated %dkB\n", mdname(mddev), memory);
6915         /*
6916          * Losing a stripe head costs more than the time to refill it,
6917          * it reduces the queue depth and so can hurt throughput.
6918          * So set it rather large, scaled by number of devices.
6919          */
6920         conf->shrinker.seeks = DEFAULT_SEEKS * conf->raid_disks * 4;
6921         conf->shrinker.scan_objects = raid5_cache_scan;
6922         conf->shrinker.count_objects = raid5_cache_count;
6923         conf->shrinker.batch = 128;
6924         conf->shrinker.flags = 0;
6925         if (register_shrinker(&conf->shrinker)) {
6926                 pr_warn("md/raid:%s: couldn't register shrinker.\n",
6927                         mdname(mddev));
6928                 goto abort;
6929         }
6930
6931         sprintf(pers_name, "raid%d", mddev->new_level);
6932         conf->thread = md_register_thread(raid5d, mddev, pers_name);
6933         if (!conf->thread) {
6934                 pr_warn("md/raid:%s: couldn't allocate thread.\n",
6935                         mdname(mddev));
6936                 goto abort;
6937         }
6938
6939         return conf;
6940
6941  abort:
6942         if (conf) {
6943                 free_conf(conf);
6944                 return ERR_PTR(-EIO);
6945         } else
6946                 return ERR_PTR(-ENOMEM);
6947 }
6948
6949 static int only_parity(int raid_disk, int algo, int raid_disks, int max_degraded)
6950 {
6951         switch (algo) {
6952         case ALGORITHM_PARITY_0:
6953                 if (raid_disk < max_degraded)
6954                         return 1;
6955                 break;
6956         case ALGORITHM_PARITY_N:
6957                 if (raid_disk >= raid_disks - max_degraded)
6958                         return 1;
6959                 break;
6960         case ALGORITHM_PARITY_0_6:
6961                 if (raid_disk == 0 ||
6962                     raid_disk == raid_disks - 1)
6963                         return 1;
6964                 break;
6965         case ALGORITHM_LEFT_ASYMMETRIC_6:
6966         case ALGORITHM_RIGHT_ASYMMETRIC_6:
6967         case ALGORITHM_LEFT_SYMMETRIC_6:
6968         case ALGORITHM_RIGHT_SYMMETRIC_6:
6969                 if (raid_disk == raid_disks - 1)
6970                         return 1;
6971         }
6972         return 0;
6973 }
6974
6975 static int raid5_run(struct mddev *mddev)
6976 {
6977         struct r5conf *conf;
6978         int working_disks = 0;
6979         int dirty_parity_disks = 0;
6980         struct md_rdev *rdev;
6981         struct md_rdev *journal_dev = NULL;
6982         sector_t reshape_offset = 0;
6983         int i;
6984         long long min_offset_diff = 0;
6985         int first = 1;
6986
6987         if (mddev->recovery_cp != MaxSector)
6988                 pr_notice("md/raid:%s: not clean -- starting background reconstruction\n",
6989                           mdname(mddev));
6990
6991         rdev_for_each(rdev, mddev) {
6992                 long long diff;
6993
6994                 if (test_bit(Journal, &rdev->flags)) {
6995                         journal_dev = rdev;
6996                         continue;
6997                 }
6998                 if (rdev->raid_disk < 0)
6999                         continue;
7000                 diff = (rdev->new_data_offset - rdev->data_offset);
7001                 if (first) {
7002                         min_offset_diff = diff;
7003                         first = 0;
7004                 } else if (mddev->reshape_backwards &&
7005                          diff < min_offset_diff)
7006                         min_offset_diff = diff;
7007                 else if (!mddev->reshape_backwards &&
7008                          diff > min_offset_diff)
7009                         min_offset_diff = diff;
7010         }
7011
7012         if (mddev->reshape_position != MaxSector) {
7013                 /* Check that we can continue the reshape.
7014                  * Difficulties arise if the stripe we would write to
7015                  * next is at or after the stripe we would read from next.
7016                  * For a reshape that changes the number of devices, this
7017                  * is only possible for a very short time, and mdadm makes
7018                  * sure that time appears to have past before assembling
7019                  * the array.  So we fail if that time hasn't passed.
7020                  * For a reshape that keeps the number of devices the same
7021                  * mdadm must be monitoring the reshape can keeping the
7022                  * critical areas read-only and backed up.  It will start
7023                  * the array in read-only mode, so we check for that.
7024                  */
7025                 sector_t here_new, here_old;
7026                 int old_disks;
7027                 int max_degraded = (mddev->level == 6 ? 2 : 1);
7028                 int chunk_sectors;
7029                 int new_data_disks;
7030
7031                 if (journal_dev) {
7032                         pr_warn("md/raid:%s: don't support reshape with journal - aborting.\n",
7033                                 mdname(mddev));
7034                         return -EINVAL;
7035                 }
7036
7037                 if (mddev->new_level != mddev->level) {
7038                         pr_warn("md/raid:%s: unsupported reshape required - aborting.\n",
7039                                 mdname(mddev));
7040                         return -EINVAL;
7041                 }
7042                 old_disks = mddev->raid_disks - mddev->delta_disks;
7043                 /* reshape_position must be on a new-stripe boundary, and one
7044                  * further up in new geometry must map after here in old
7045                  * geometry.
7046                  * If the chunk sizes are different, then as we perform reshape
7047                  * in units of the largest of the two, reshape_position needs
7048                  * be a multiple of the largest chunk size times new data disks.
7049                  */
7050                 here_new = mddev->reshape_position;
7051                 chunk_sectors = max(mddev->chunk_sectors, mddev->new_chunk_sectors);
7052                 new_data_disks = mddev->raid_disks - max_degraded;
7053                 if (sector_div(here_new, chunk_sectors * new_data_disks)) {
7054                         pr_warn("md/raid:%s: reshape_position not on a stripe boundary\n",
7055                                 mdname(mddev));
7056                         return -EINVAL;
7057                 }
7058                 reshape_offset = here_new * chunk_sectors;
7059                 /* here_new is the stripe we will write to */
7060                 here_old = mddev->reshape_position;
7061                 sector_div(here_old, chunk_sectors * (old_disks-max_degraded));
7062                 /* here_old is the first stripe that we might need to read
7063                  * from */
7064                 if (mddev->delta_disks == 0) {
7065                         /* We cannot be sure it is safe to start an in-place
7066                          * reshape.  It is only safe if user-space is monitoring
7067                          * and taking constant backups.
7068                          * mdadm always starts a situation like this in
7069                          * readonly mode so it can take control before
7070                          * allowing any writes.  So just check for that.
7071                          */
7072                         if (abs(min_offset_diff) >= mddev->chunk_sectors &&
7073                             abs(min_offset_diff) >= mddev->new_chunk_sectors)
7074                                 /* not really in-place - so OK */;
7075                         else if (mddev->ro == 0) {
7076                                 pr_warn("md/raid:%s: in-place reshape must be started in read-only mode - aborting\n",
7077                                         mdname(mddev));
7078                                 return -EINVAL;
7079                         }
7080                 } else if (mddev->reshape_backwards
7081                     ? (here_new * chunk_sectors + min_offset_diff <=
7082                        here_old * chunk_sectors)
7083                     : (here_new * chunk_sectors >=
7084                        here_old * chunk_sectors + (-min_offset_diff))) {
7085                         /* Reading from the same stripe as writing to - bad */
7086                         pr_warn("md/raid:%s: reshape_position too early for auto-recovery - aborting.\n",
7087                                 mdname(mddev));
7088                         return -EINVAL;
7089                 }
7090                 pr_debug("md/raid:%s: reshape will continue\n", mdname(mddev));
7091                 /* OK, we should be able to continue; */
7092         } else {
7093                 BUG_ON(mddev->level != mddev->new_level);
7094                 BUG_ON(mddev->layout != mddev->new_layout);
7095                 BUG_ON(mddev->chunk_sectors != mddev->new_chunk_sectors);
7096                 BUG_ON(mddev->delta_disks != 0);
7097         }
7098
7099         if (mddev->private == NULL)
7100                 conf = setup_conf(mddev);
7101         else
7102                 conf = mddev->private;
7103
7104         if (IS_ERR(conf))
7105                 return PTR_ERR(conf);
7106
7107         if (test_bit(MD_HAS_JOURNAL, &mddev->flags)) {
7108                 if (!journal_dev) {
7109                         pr_warn("md/raid:%s: journal disk is missing, force array readonly\n",
7110                                 mdname(mddev));
7111                         mddev->ro = 1;
7112                         set_disk_ro(mddev->gendisk, 1);
7113                 } else if (mddev->recovery_cp == MaxSector)
7114                         set_bit(MD_JOURNAL_CLEAN, &mddev->flags);
7115         }
7116
7117         conf->min_offset_diff = min_offset_diff;
7118         mddev->thread = conf->thread;
7119         conf->thread = NULL;
7120         mddev->private = conf;
7121
7122         for (i = 0; i < conf->raid_disks && conf->previous_raid_disks;
7123              i++) {
7124                 rdev = conf->disks[i].rdev;
7125                 if (!rdev && conf->disks[i].replacement) {
7126                         /* The replacement is all we have yet */
7127                         rdev = conf->disks[i].replacement;
7128                         conf->disks[i].replacement = NULL;
7129                         clear_bit(Replacement, &rdev->flags);
7130                         conf->disks[i].rdev = rdev;
7131                 }
7132                 if (!rdev)
7133                         continue;
7134                 if (conf->disks[i].replacement &&
7135                     conf->reshape_progress != MaxSector) {
7136                         /* replacements and reshape simply do not mix. */
7137                         pr_warn("md: cannot handle concurrent replacement and reshape.\n");
7138                         goto abort;
7139                 }
7140                 if (test_bit(In_sync, &rdev->flags)) {
7141                         working_disks++;
7142                         continue;
7143                 }
7144                 /* This disc is not fully in-sync.  However if it
7145                  * just stored parity (beyond the recovery_offset),
7146                  * when we don't need to be concerned about the
7147                  * array being dirty.
7148                  * When reshape goes 'backwards', we never have
7149                  * partially completed devices, so we only need
7150                  * to worry about reshape going forwards.
7151                  */
7152                 /* Hack because v0.91 doesn't store recovery_offset properly. */
7153                 if (mddev->major_version == 0 &&
7154                     mddev->minor_version > 90)
7155                         rdev->recovery_offset = reshape_offset;
7156
7157                 if (rdev->recovery_offset < reshape_offset) {
7158                         /* We need to check old and new layout */
7159                         if (!only_parity(rdev->raid_disk,
7160                                          conf->algorithm,
7161                                          conf->raid_disks,
7162                                          conf->max_degraded))
7163                                 continue;
7164                 }
7165                 if (!only_parity(rdev->raid_disk,
7166                                  conf->prev_algo,
7167                                  conf->previous_raid_disks,
7168                                  conf->max_degraded))
7169                         continue;
7170                 dirty_parity_disks++;
7171         }
7172
7173         /*
7174          * 0 for a fully functional array, 1 or 2 for a degraded array.
7175          */
7176         mddev->degraded = raid5_calc_degraded(conf);
7177
7178         if (has_failed(conf)) {
7179                 pr_crit("md/raid:%s: not enough operational devices (%d/%d failed)\n",
7180                         mdname(mddev), mddev->degraded, conf->raid_disks);
7181                 goto abort;
7182         }
7183
7184         /* device size must be a multiple of chunk size */
7185         mddev->dev_sectors &= ~(mddev->chunk_sectors - 1);
7186         mddev->resync_max_sectors = mddev->dev_sectors;
7187
7188         if (mddev->degraded > dirty_parity_disks &&
7189             mddev->recovery_cp != MaxSector) {
7190                 if (mddev->ok_start_degraded)
7191                         pr_crit("md/raid:%s: starting dirty degraded array - data corruption possible.\n",
7192                                 mdname(mddev));
7193                 else {
7194                         pr_crit("md/raid:%s: cannot start dirty degraded array.\n",
7195                                 mdname(mddev));
7196                         goto abort;
7197                 }
7198         }
7199
7200         pr_info("md/raid:%s: raid level %d active with %d out of %d devices, algorithm %d\n",
7201                 mdname(mddev), conf->level,
7202                 mddev->raid_disks-mddev->degraded, mddev->raid_disks,
7203                 mddev->new_layout);
7204
7205         print_raid5_conf(conf);
7206
7207         if (conf->reshape_progress != MaxSector) {
7208                 conf->reshape_safe = conf->reshape_progress;
7209                 atomic_set(&conf->reshape_stripes, 0);
7210                 clear_bit(MD_RECOVERY_SYNC, &mddev->recovery);
7211                 clear_bit(MD_RECOVERY_CHECK, &mddev->recovery);
7212                 set_bit(MD_RECOVERY_RESHAPE, &mddev->recovery);
7213                 set_bit(MD_RECOVERY_RUNNING, &mddev->recovery);
7214                 mddev->sync_thread = md_register_thread(md_do_sync, mddev,
7215                                                         "reshape");
7216         }
7217
7218         /* Ok, everything is just fine now */
7219         if (mddev->to_remove == &raid5_attrs_group)
7220                 mddev->to_remove = NULL;
7221         else if (mddev->kobj.sd &&
7222             sysfs_create_group(&mddev->kobj, &raid5_attrs_group))
7223                 pr_warn("raid5: failed to create sysfs attributes for %s\n",
7224                         mdname(mddev));
7225         md_set_array_sectors(mddev, raid5_size(mddev, 0, 0));
7226
7227         if (mddev->queue) {
7228                 int chunk_size;
7229                 bool discard_supported = true;
7230                 /* read-ahead size must cover two whole stripes, which
7231                  * is 2 * (datadisks) * chunksize where 'n' is the
7232                  * number of raid devices
7233                  */
7234                 int data_disks = conf->previous_raid_disks - conf->max_degraded;
7235                 int stripe = data_disks *
7236                         ((mddev->chunk_sectors << 9) / PAGE_SIZE);
7237                 if (mddev->queue->backing_dev_info->ra_pages < 2 * stripe)
7238                         mddev->queue->backing_dev_info->ra_pages = 2 * stripe;
7239
7240                 chunk_size = mddev->chunk_sectors << 9;
7241                 blk_queue_io_min(mddev->queue, chunk_size);
7242                 blk_queue_io_opt(mddev->queue, chunk_size *
7243                                  (conf->raid_disks - conf->max_degraded));
7244                 mddev->queue->limits.raid_partial_stripes_expensive = 1;
7245                 /*
7246                  * We can only discard a whole stripe. It doesn't make sense to
7247                  * discard data disk but write parity disk
7248                  */
7249                 stripe = stripe * PAGE_SIZE;
7250                 /* Round up to power of 2, as discard handling
7251                  * currently assumes that */
7252                 while ((stripe-1) & stripe)
7253                         stripe = (stripe | (stripe-1)) + 1;
7254                 mddev->queue->limits.discard_alignment = stripe;
7255                 mddev->queue->limits.discard_granularity = stripe;
7256
7257                 /*
7258                  * We use 16-bit counter of active stripes in bi_phys_segments
7259                  * (minus one for over-loaded initialization)
7260                  */
7261                 blk_queue_max_hw_sectors(mddev->queue, 0xfffe * STRIPE_SECTORS);
7262                 blk_queue_max_discard_sectors(mddev->queue,
7263                                               0xfffe * STRIPE_SECTORS);
7264
7265                 /*
7266                  * unaligned part of discard request will be ignored, so can't
7267                  * guarantee discard_zeroes_data
7268                  */
7269                 mddev->queue->limits.discard_zeroes_data = 0;
7270
7271                 blk_queue_max_write_same_sectors(mddev->queue, 0);
7272
7273                 rdev_for_each(rdev, mddev) {
7274                         disk_stack_limits(mddev->gendisk, rdev->bdev,
7275                                           rdev->data_offset << 9);
7276                         disk_stack_limits(mddev->gendisk, rdev->bdev,
7277                                           rdev->new_data_offset << 9);
7278                         /*
7279                          * discard_zeroes_data is required, otherwise data
7280                          * could be lost. Consider a scenario: discard a stripe
7281                          * (the stripe could be inconsistent if
7282                          * discard_zeroes_data is 0); write one disk of the
7283                          * stripe (the stripe could be inconsistent again
7284                          * depending on which disks are used to calculate
7285                          * parity); the disk is broken; The stripe data of this
7286                          * disk is lost.
7287                          */
7288                         if (!blk_queue_discard(bdev_get_queue(rdev->bdev)) ||
7289                             !bdev_get_queue(rdev->bdev)->
7290                                                 limits.discard_zeroes_data)
7291                                 discard_supported = false;
7292                         /* Unfortunately, discard_zeroes_data is not currently
7293                          * a guarantee - just a hint.  So we only allow DISCARD
7294                          * if the sysadmin has confirmed that only safe devices
7295                          * are in use by setting a module parameter.
7296                          */
7297                         if (!devices_handle_discard_safely) {
7298                                 if (discard_supported) {
7299                                         pr_info("md/raid456: discard support disabled due to uncertainty.\n");
7300                                         pr_info("Set raid456.devices_handle_discard_safely=Y to override.\n");
7301                                 }
7302                                 discard_supported = false;
7303                         }
7304                 }
7305
7306                 if (discard_supported &&
7307                     mddev->queue->limits.max_discard_sectors >= (stripe >> 9) &&
7308                     mddev->queue->limits.discard_granularity >= stripe)
7309                         queue_flag_set_unlocked(QUEUE_FLAG_DISCARD,
7310                                                 mddev->queue);
7311                 else
7312                         queue_flag_clear_unlocked(QUEUE_FLAG_DISCARD,
7313                                                 mddev->queue);
7314
7315                 blk_queue_max_hw_sectors(mddev->queue, UINT_MAX);
7316         }
7317
7318         if (journal_dev) {
7319                 char b[BDEVNAME_SIZE];
7320
7321                 pr_debug("md/raid:%s: using device %s as journal\n",
7322                          mdname(mddev), bdevname(journal_dev->bdev, b));
7323                 if (r5l_init_log(conf, journal_dev))
7324                         goto abort;
7325         }
7326
7327         return 0;
7328 abort:
7329         md_unregister_thread(&mddev->thread);
7330         print_raid5_conf(conf);
7331         free_conf(conf);
7332         mddev->private = NULL;
7333         pr_warn("md/raid:%s: failed to run raid set.\n", mdname(mddev));
7334         return -EIO;
7335 }
7336
7337 static void raid5_free(struct mddev *mddev, void *priv)
7338 {
7339         struct r5conf *conf = priv;
7340
7341         free_conf(conf);
7342         mddev->to_remove = &raid5_attrs_group;
7343 }
7344
7345 static void raid5_status(struct seq_file *seq, struct mddev *mddev)
7346 {
7347         struct r5conf *conf = mddev->private;
7348         int i;
7349
7350         seq_printf(seq, " level %d, %dk chunk, algorithm %d", mddev->level,
7351                 conf->chunk_sectors / 2, mddev->layout);
7352         seq_printf (seq, " [%d/%d] [", conf->raid_disks, conf->raid_disks - mddev->degraded);
7353         rcu_read_lock();
7354         for (i = 0; i < conf->raid_disks; i++) {
7355                 struct md_rdev *rdev = rcu_dereference(conf->disks[i].rdev);
7356                 seq_printf (seq, "%s", rdev && test_bit(In_sync, &rdev->flags) ? "U" : "_");
7357         }
7358         rcu_read_unlock();
7359         seq_printf (seq, "]");
7360 }
7361
7362 static void print_raid5_conf (struct r5conf *conf)
7363 {
7364         int i;
7365         struct disk_info *tmp;
7366
7367         pr_debug("RAID conf printout:\n");
7368         if (!conf) {
7369                 pr_debug("(conf==NULL)\n");
7370                 return;
7371         }
7372         pr_debug(" --- level:%d rd:%d wd:%d\n", conf->level,
7373                conf->raid_disks,
7374                conf->raid_disks - conf->mddev->degraded);
7375
7376         for (i = 0; i < conf->raid_disks; i++) {
7377                 char b[BDEVNAME_SIZE];
7378                 tmp = conf->disks + i;
7379                 if (tmp->rdev)
7380                         pr_debug(" disk %d, o:%d, dev:%s\n",
7381                                i, !test_bit(Faulty, &tmp->rdev->flags),
7382                                bdevname(tmp->rdev->bdev, b));
7383         }
7384 }
7385
7386 static int raid5_spare_active(struct mddev *mddev)
7387 {
7388         int i;
7389         struct r5conf *conf = mddev->private;
7390         struct disk_info *tmp;
7391         int count = 0;
7392         unsigned long flags;
7393
7394         for (i = 0; i < conf->raid_disks; i++) {
7395                 tmp = conf->disks + i;
7396                 if (tmp->replacement
7397                     && tmp->replacement->recovery_offset == MaxSector
7398                     && !test_bit(Faulty, &tmp->replacement->flags)
7399                     && !test_and_set_bit(In_sync, &tmp->replacement->flags)) {
7400                         /* Replacement has just become active. */
7401                         if (!tmp->rdev
7402                             || !test_and_clear_bit(In_sync, &tmp->rdev->flags))
7403                                 count++;
7404                         if (tmp->rdev) {
7405                                 /* Replaced device not technically faulty,
7406                                  * but we need to be sure it gets removed
7407                                  * and never re-added.
7408                                  */
7409                                 set_bit(Faulty, &tmp->rdev->flags);
7410                                 sysfs_notify_dirent_safe(
7411                                         tmp->rdev->sysfs_state);
7412                         }
7413                         sysfs_notify_dirent_safe(tmp->replacement->sysfs_state);
7414                 } else if (tmp->rdev
7415                     && tmp->rdev->recovery_offset == MaxSector
7416                     && !test_bit(Faulty, &tmp->rdev->flags)
7417                     && !test_and_set_bit(In_sync, &tmp->rdev->flags)) {
7418                         count++;
7419                         sysfs_notify_dirent_safe(tmp->rdev->sysfs_state);
7420                 }
7421         }
7422         spin_lock_irqsave(&conf->device_lock, flags);
7423         mddev->degraded = raid5_calc_degraded(conf);
7424         spin_unlock_irqrestore(&conf->device_lock, flags);
7425         print_raid5_conf(conf);
7426         return count;
7427 }
7428
7429 static int raid5_remove_disk(struct mddev *mddev, struct md_rdev *rdev)
7430 {
7431         struct r5conf *conf = mddev->private;
7432         int err = 0;
7433         int number = rdev->raid_disk;
7434         struct md_rdev **rdevp;
7435         struct disk_info *p = conf->disks + number;
7436
7437         print_raid5_conf(conf);
7438         if (test_bit(Journal, &rdev->flags) && conf->log) {
7439                 struct r5l_log *log;
7440                 /*
7441                  * we can't wait pending write here, as this is called in
7442                  * raid5d, wait will deadlock.
7443                  */
7444                 if (atomic_read(&mddev->writes_pending))
7445                         return -EBUSY;
7446                 log = conf->log;
7447                 conf->log = NULL;
7448                 synchronize_rcu();
7449                 r5l_exit_log(log);
7450                 return 0;
7451         }
7452         if (rdev == p->rdev)
7453                 rdevp = &p->rdev;
7454         else if (rdev == p->replacement)
7455                 rdevp = &p->replacement;
7456         else
7457                 return 0;
7458
7459         if (number >= conf->raid_disks &&
7460             conf->reshape_progress == MaxSector)
7461                 clear_bit(In_sync, &rdev->flags);
7462
7463         if (test_bit(In_sync, &rdev->flags) ||
7464             atomic_read(&rdev->nr_pending)) {
7465                 err = -EBUSY;
7466                 goto abort;
7467         }
7468         /* Only remove non-faulty devices if recovery
7469          * isn't possible.
7470          */
7471         if (!test_bit(Faulty, &rdev->flags) &&
7472             mddev->recovery_disabled != conf->recovery_disabled &&
7473             !has_failed(conf) &&
7474             (!p->replacement || p->replacement == rdev) &&
7475             number < conf->raid_disks) {
7476                 err = -EBUSY;
7477                 goto abort;
7478         }
7479         *rdevp = NULL;
7480         if (!test_bit(RemoveSynchronized, &rdev->flags)) {
7481                 synchronize_rcu();
7482                 if (atomic_read(&rdev->nr_pending)) {
7483                         /* lost the race, try later */
7484                         err = -EBUSY;
7485                         *rdevp = rdev;
7486                 }
7487         }
7488         if (p->replacement) {
7489                 /* We must have just cleared 'rdev' */
7490                 p->rdev = p->replacement;
7491                 clear_bit(Replacement, &p->replacement->flags);
7492                 smp_mb(); /* Make sure other CPUs may see both as identical
7493                            * but will never see neither - if they are careful
7494                            */
7495                 p->replacement = NULL;
7496                 clear_bit(WantReplacement, &rdev->flags);
7497         } else
7498                 /* We might have just removed the Replacement as faulty-
7499                  * clear the bit just in case
7500                  */
7501                 clear_bit(WantReplacement, &rdev->flags);
7502 abort:
7503
7504         print_raid5_conf(conf);
7505         return err;
7506 }
7507
7508 static int raid5_add_disk(struct mddev *mddev, struct md_rdev *rdev)
7509 {
7510         struct r5conf *conf = mddev->private;
7511         int err = -EEXIST;
7512         int disk;
7513         struct disk_info *p;
7514         int first = 0;
7515         int last = conf->raid_disks - 1;
7516
7517         if (test_bit(Journal, &rdev->flags)) {
7518                 char b[BDEVNAME_SIZE];
7519                 if (conf->log)
7520                         return -EBUSY;
7521
7522                 rdev->raid_disk = 0;
7523                 /*
7524                  * The array is in readonly mode if journal is missing, so no
7525                  * write requests running. We should be safe
7526                  */
7527                 r5l_init_log(conf, rdev);
7528                 pr_debug("md/raid:%s: using device %s as journal\n",
7529                          mdname(mddev), bdevname(rdev->bdev, b));
7530                 return 0;
7531         }
7532         if (mddev->recovery_disabled == conf->recovery_disabled)
7533                 return -EBUSY;
7534
7535         if (rdev->saved_raid_disk < 0 && has_failed(conf))
7536                 /* no point adding a device */
7537                 return -EINVAL;
7538
7539         if (rdev->raid_disk >= 0)
7540                 first = last = rdev->raid_disk;
7541
7542         /*
7543          * find the disk ... but prefer rdev->saved_raid_disk
7544          * if possible.
7545          */
7546         if (rdev->saved_raid_disk >= 0 &&
7547             rdev->saved_raid_disk >= first &&
7548             conf->disks[rdev->saved_raid_disk].rdev == NULL)
7549                 first = rdev->saved_raid_disk;
7550
7551         for (disk = first; disk <= last; disk++) {
7552                 p = conf->disks + disk;
7553                 if (p->rdev == NULL) {
7554                         clear_bit(In_sync, &rdev->flags);
7555                         rdev->raid_disk = disk;
7556                         err = 0;
7557                         if (rdev->saved_raid_disk != disk)
7558                                 conf->fullsync = 1;
7559                         rcu_assign_pointer(p->rdev, rdev);
7560                         goto out;
7561                 }
7562         }
7563         for (disk = first; disk <= last; disk++) {
7564                 p = conf->disks + disk;
7565                 if (test_bit(WantReplacement, &p->rdev->flags) &&
7566                     p->replacement == NULL) {
7567                         clear_bit(In_sync, &rdev->flags);
7568                         set_bit(Replacement, &rdev->flags);
7569                         rdev->raid_disk = disk;
7570                         err = 0;
7571                         conf->fullsync = 1;
7572                         rcu_assign_pointer(p->replacement, rdev);
7573                         break;
7574                 }
7575         }
7576 out:
7577         print_raid5_conf(conf);
7578         return err;
7579 }
7580
7581 static int raid5_resize(struct mddev *mddev, sector_t sectors)
7582 {
7583         /* no resync is happening, and there is enough space
7584          * on all devices, so we can resize.
7585          * We need to make sure resync covers any new space.
7586          * If the array is shrinking we should possibly wait until
7587          * any io in the removed space completes, but it hardly seems
7588          * worth it.
7589          */
7590         sector_t newsize;
7591         struct r5conf *conf = mddev->private;
7592
7593         if (conf->log)
7594                 return -EINVAL;
7595         sectors &= ~((sector_t)conf->chunk_sectors - 1);
7596         newsize = raid5_size(mddev, sectors, mddev->raid_disks);
7597         if (mddev->external_size &&
7598             mddev->array_sectors > newsize)
7599                 return -EINVAL;
7600         if (mddev->bitmap) {
7601                 int ret = bitmap_resize(mddev->bitmap, sectors, 0, 0);
7602                 if (ret)
7603                         return ret;
7604         }
7605         md_set_array_sectors(mddev, newsize);
7606         set_capacity(mddev->gendisk, mddev->array_sectors);
7607         revalidate_disk(mddev->gendisk);
7608         if (sectors > mddev->dev_sectors &&
7609             mddev->recovery_cp > mddev->dev_sectors) {
7610                 mddev->recovery_cp = mddev->dev_sectors;
7611                 set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
7612         }
7613         mddev->dev_sectors = sectors;
7614         mddev->resync_max_sectors = sectors;
7615         return 0;
7616 }
7617
7618 static int check_stripe_cache(struct mddev *mddev)
7619 {
7620         /* Can only proceed if there are plenty of stripe_heads.
7621          * We need a minimum of one full stripe,, and for sensible progress
7622          * it is best to have about 4 times that.
7623          * If we require 4 times, then the default 256 4K stripe_heads will
7624          * allow for chunk sizes up to 256K, which is probably OK.
7625          * If the chunk size is greater, user-space should request more
7626          * stripe_heads first.
7627          */
7628         struct r5conf *conf = mddev->private;
7629         if (((mddev->chunk_sectors << 9) / STRIPE_SIZE) * 4
7630             > conf->min_nr_stripes ||
7631             ((mddev->new_chunk_sectors << 9) / STRIPE_SIZE) * 4
7632             > conf->min_nr_stripes) {
7633                 pr_warn("md/raid:%s: reshape: not enough stripes.  Needed %lu\n",
7634                         mdname(mddev),
7635                         ((max(mddev->chunk_sectors, mddev->new_chunk_sectors) << 9)
7636                          / STRIPE_SIZE)*4);
7637                 return 0;
7638         }
7639         return 1;
7640 }
7641
7642 static int check_reshape(struct mddev *mddev)
7643 {
7644         struct r5conf *conf = mddev->private;
7645
7646         if (conf->log)
7647                 return -EINVAL;
7648         if (mddev->delta_disks == 0 &&
7649             mddev->new_layout == mddev->layout &&
7650             mddev->new_chunk_sectors == mddev->chunk_sectors)
7651                 return 0; /* nothing to do */
7652         if (has_failed(conf))
7653                 return -EINVAL;
7654         if (mddev->delta_disks < 0 && mddev->reshape_position == MaxSector) {
7655                 /* We might be able to shrink, but the devices must
7656                  * be made bigger first.
7657                  * For raid6, 4 is the minimum size.
7658                  * Otherwise 2 is the minimum
7659                  */
7660                 int min = 2;
7661                 if (mddev->level == 6)
7662                         min = 4;
7663                 if (mddev->raid_disks + mddev->delta_disks < min)
7664                         return -EINVAL;
7665         }
7666
7667         if (!check_stripe_cache(mddev))
7668                 return -ENOSPC;
7669
7670         if (mddev->new_chunk_sectors > mddev->chunk_sectors ||
7671             mddev->delta_disks > 0)
7672                 if (resize_chunks(conf,
7673                                   conf->previous_raid_disks
7674                                   + max(0, mddev->delta_disks),
7675                                   max(mddev->new_chunk_sectors,
7676                                       mddev->chunk_sectors)
7677                             ) < 0)
7678                         return -ENOMEM;
7679         return resize_stripes(conf, (conf->previous_raid_disks
7680                                      + mddev->delta_disks));
7681 }
7682
7683 static int raid5_start_reshape(struct mddev *mddev)
7684 {
7685         struct r5conf *conf = mddev->private;
7686         struct md_rdev *rdev;
7687         int spares = 0;
7688         unsigned long flags;
7689
7690         if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery))
7691                 return -EBUSY;
7692
7693         if (!check_stripe_cache(mddev))
7694                 return -ENOSPC;
7695
7696         if (has_failed(conf))
7697                 return -EINVAL;
7698
7699         rdev_for_each(rdev, mddev) {
7700                 if (!test_bit(In_sync, &rdev->flags)
7701                     && !test_bit(Faulty, &rdev->flags))
7702                         spares++;
7703         }
7704
7705         if (spares - mddev->degraded < mddev->delta_disks - conf->max_degraded)
7706                 /* Not enough devices even to make a degraded array
7707                  * of that size
7708                  */
7709                 return -EINVAL;
7710
7711         /* Refuse to reduce size of the array.  Any reductions in
7712          * array size must be through explicit setting of array_size
7713          * attribute.
7714          */
7715         if (raid5_size(mddev, 0, conf->raid_disks + mddev->delta_disks)
7716             < mddev->array_sectors) {
7717                 pr_warn("md/raid:%s: array size must be reduced before number of disks\n",
7718                         mdname(mddev));
7719                 return -EINVAL;
7720         }
7721
7722         atomic_set(&conf->reshape_stripes, 0);
7723         spin_lock_irq(&conf->device_lock);
7724         write_seqcount_begin(&conf->gen_lock);
7725         conf->previous_raid_disks = conf->raid_disks;
7726         conf->raid_disks += mddev->delta_disks;
7727         conf->prev_chunk_sectors = conf->chunk_sectors;
7728         conf->chunk_sectors = mddev->new_chunk_sectors;
7729         conf->prev_algo = conf->algorithm;
7730         conf->algorithm = mddev->new_layout;
7731         conf->generation++;
7732         /* Code that selects data_offset needs to see the generation update
7733          * if reshape_progress has been set - so a memory barrier needed.
7734          */
7735         smp_mb();
7736         if (mddev->reshape_backwards)
7737                 conf->reshape_progress = raid5_size(mddev, 0, 0);
7738         else
7739                 conf->reshape_progress = 0;
7740         conf->reshape_safe = conf->reshape_progress;
7741         write_seqcount_end(&conf->gen_lock);
7742         spin_unlock_irq(&conf->device_lock);
7743
7744         /* Now make sure any requests that proceeded on the assumption
7745          * the reshape wasn't running - like Discard or Read - have
7746          * completed.
7747          */
7748         mddev_suspend(mddev);
7749         mddev_resume(mddev);
7750
7751         /* Add some new drives, as many as will fit.
7752          * We know there are enough to make the newly sized array work.
7753          * Don't add devices if we are reducing the number of
7754          * devices in the array.  This is because it is not possible
7755          * to correctly record the "partially reconstructed" state of
7756          * such devices during the reshape and confusion could result.
7757          */
7758         if (mddev->delta_disks >= 0) {
7759                 rdev_for_each(rdev, mddev)
7760                         if (rdev->raid_disk < 0 &&
7761                             !test_bit(Faulty, &rdev->flags)) {
7762                                 if (raid5_add_disk(mddev, rdev) == 0) {
7763                                         if (rdev->raid_disk
7764                                             >= conf->previous_raid_disks)
7765                                                 set_bit(In_sync, &rdev->flags);
7766                                         else
7767                                                 rdev->recovery_offset = 0;
7768
7769                                         if (sysfs_link_rdev(mddev, rdev))
7770                                                 /* Failure here is OK */;
7771                                 }
7772                         } else if (rdev->raid_disk >= conf->previous_raid_disks
7773                                    && !test_bit(Faulty, &rdev->flags)) {
7774                                 /* This is a spare that was manually added */
7775                                 set_bit(In_sync, &rdev->flags);
7776                         }
7777
7778                 /* When a reshape changes the number of devices,
7779                  * ->degraded is measured against the larger of the
7780                  * pre and post number of devices.
7781                  */
7782                 spin_lock_irqsave(&conf->device_lock, flags);
7783                 mddev->degraded = raid5_calc_degraded(conf);
7784                 spin_unlock_irqrestore(&conf->device_lock, flags);
7785         }
7786         mddev->raid_disks = conf->raid_disks;
7787         mddev->reshape_position = conf->reshape_progress;
7788         set_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags);
7789
7790         clear_bit(MD_RECOVERY_SYNC, &mddev->recovery);
7791         clear_bit(MD_RECOVERY_CHECK, &mddev->recovery);
7792         clear_bit(MD_RECOVERY_DONE, &mddev->recovery);
7793         set_bit(MD_RECOVERY_RESHAPE, &mddev->recovery);
7794         set_bit(MD_RECOVERY_RUNNING, &mddev->recovery);
7795         mddev->sync_thread = md_register_thread(md_do_sync, mddev,
7796                                                 "reshape");
7797         if (!mddev->sync_thread) {
7798                 mddev->recovery = 0;
7799                 spin_lock_irq(&conf->device_lock);
7800                 write_seqcount_begin(&conf->gen_lock);
7801                 mddev->raid_disks = conf->raid_disks = conf->previous_raid_disks;
7802                 mddev->new_chunk_sectors =
7803                         conf->chunk_sectors = conf->prev_chunk_sectors;
7804                 mddev->new_layout = conf->algorithm = conf->prev_algo;
7805                 rdev_for_each(rdev, mddev)
7806                         rdev->new_data_offset = rdev->data_offset;
7807                 smp_wmb();
7808                 conf->generation --;
7809                 conf->reshape_progress = MaxSector;
7810                 mddev->reshape_position = MaxSector;
7811                 write_seqcount_end(&conf->gen_lock);
7812                 spin_unlock_irq(&conf->device_lock);
7813                 return -EAGAIN;
7814         }
7815         conf->reshape_checkpoint = jiffies;
7816         md_wakeup_thread(mddev->sync_thread);
7817         md_new_event(mddev);
7818         return 0;
7819 }
7820
7821 /* This is called from the reshape thread and should make any
7822  * changes needed in 'conf'
7823  */
7824 static void end_reshape(struct r5conf *conf)
7825 {
7826
7827         if (!test_bit(MD_RECOVERY_INTR, &conf->mddev->recovery)) {
7828                 struct md_rdev *rdev;
7829
7830                 spin_lock_irq(&conf->device_lock);
7831                 conf->previous_raid_disks = conf->raid_disks;
7832                 rdev_for_each(rdev, conf->mddev)
7833                         rdev->data_offset = rdev->new_data_offset;
7834                 smp_wmb();
7835                 conf->reshape_progress = MaxSector;
7836                 conf->mddev->reshape_position = MaxSector;
7837                 spin_unlock_irq(&conf->device_lock);
7838                 wake_up(&conf->wait_for_overlap);
7839
7840                 /* read-ahead size must cover two whole stripes, which is
7841                  * 2 * (datadisks) * chunksize where 'n' is the number of raid devices
7842                  */
7843                 if (conf->mddev->queue) {
7844                         int data_disks = conf->raid_disks - conf->max_degraded;
7845                         int stripe = data_disks * ((conf->chunk_sectors << 9)
7846                                                    / PAGE_SIZE);
7847                         if (conf->mddev->queue->backing_dev_info->ra_pages < 2 * stripe)
7848                                 conf->mddev->queue->backing_dev_info->ra_pages = 2 * stripe;
7849                 }
7850         }
7851 }
7852
7853 /* This is called from the raid5d thread with mddev_lock held.
7854  * It makes config changes to the device.
7855  */
7856 static void raid5_finish_reshape(struct mddev *mddev)
7857 {
7858         struct r5conf *conf = mddev->private;
7859
7860         if (!test_bit(MD_RECOVERY_INTR, &mddev->recovery)) {
7861
7862                 if (mddev->delta_disks > 0) {
7863                         md_set_array_sectors(mddev, raid5_size(mddev, 0, 0));
7864                         if (mddev->queue) {
7865                                 set_capacity(mddev->gendisk, mddev->array_sectors);
7866                                 revalidate_disk(mddev->gendisk);
7867                         }
7868                 } else {
7869                         int d;
7870                         spin_lock_irq(&conf->device_lock);
7871                         mddev->degraded = raid5_calc_degraded(conf);
7872                         spin_unlock_irq(&conf->device_lock);
7873                         for (d = conf->raid_disks ;
7874                              d < conf->raid_disks - mddev->delta_disks;
7875                              d++) {
7876                                 struct md_rdev *rdev = conf->disks[d].rdev;
7877                                 if (rdev)
7878                                         clear_bit(In_sync, &rdev->flags);
7879                                 rdev = conf->disks[d].replacement;
7880                                 if (rdev)
7881                                         clear_bit(In_sync, &rdev->flags);
7882                         }
7883                 }
7884                 mddev->layout = conf->algorithm;
7885                 mddev->chunk_sectors = conf->chunk_sectors;
7886                 mddev->reshape_position = MaxSector;
7887                 mddev->delta_disks = 0;
7888                 mddev->reshape_backwards = 0;
7889         }
7890 }
7891
7892 static void raid5_quiesce(struct mddev *mddev, int state)
7893 {
7894         struct r5conf *conf = mddev->private;
7895
7896         switch(state) {
7897         case 2: /* resume for a suspend */
7898                 wake_up(&conf->wait_for_overlap);
7899                 break;
7900
7901         case 1: /* stop all writes */
7902                 lock_all_device_hash_locks_irq(conf);
7903                 /* '2' tells resync/reshape to pause so that all
7904                  * active stripes can drain
7905                  */
7906                 r5c_flush_cache(conf, INT_MAX);
7907                 conf->quiesce = 2;
7908                 wait_event_cmd(conf->wait_for_quiescent,
7909                                     atomic_read(&conf->active_stripes) == 0 &&
7910                                     atomic_read(&conf->active_aligned_reads) == 0,
7911                                     unlock_all_device_hash_locks_irq(conf),
7912                                     lock_all_device_hash_locks_irq(conf));
7913                 conf->quiesce = 1;
7914                 unlock_all_device_hash_locks_irq(conf);
7915                 /* allow reshape to continue */
7916                 wake_up(&conf->wait_for_overlap);
7917                 break;
7918
7919         case 0: /* re-enable writes */
7920                 lock_all_device_hash_locks_irq(conf);
7921                 conf->quiesce = 0;
7922                 wake_up(&conf->wait_for_quiescent);
7923                 wake_up(&conf->wait_for_overlap);
7924                 unlock_all_device_hash_locks_irq(conf);
7925                 break;
7926         }
7927         r5l_quiesce(conf->log, state);
7928 }
7929
7930 static void *raid45_takeover_raid0(struct mddev *mddev, int level)
7931 {
7932         struct r0conf *raid0_conf = mddev->private;
7933         sector_t sectors;
7934
7935         /* for raid0 takeover only one zone is supported */
7936         if (raid0_conf->nr_strip_zones > 1) {
7937                 pr_warn("md/raid:%s: cannot takeover raid0 with more than one zone.\n",
7938                         mdname(mddev));
7939                 return ERR_PTR(-EINVAL);
7940         }
7941
7942         sectors = raid0_conf->strip_zone[0].zone_end;
7943         sector_div(sectors, raid0_conf->strip_zone[0].nb_dev);
7944         mddev->dev_sectors = sectors;
7945         mddev->new_level = level;
7946         mddev->new_layout = ALGORITHM_PARITY_N;
7947         mddev->new_chunk_sectors = mddev->chunk_sectors;
7948         mddev->raid_disks += 1;
7949         mddev->delta_disks = 1;
7950         /* make sure it will be not marked as dirty */
7951         mddev->recovery_cp = MaxSector;
7952
7953         return setup_conf(mddev);
7954 }
7955
7956 static void *raid5_takeover_raid1(struct mddev *mddev)
7957 {
7958         int chunksect;
7959         void *ret;
7960
7961         if (mddev->raid_disks != 2 ||
7962             mddev->degraded > 1)
7963                 return ERR_PTR(-EINVAL);
7964
7965         /* Should check if there are write-behind devices? */
7966
7967         chunksect = 64*2; /* 64K by default */
7968
7969         /* The array must be an exact multiple of chunksize */
7970         while (chunksect && (mddev->array_sectors & (chunksect-1)))
7971                 chunksect >>= 1;
7972
7973         if ((chunksect<<9) < STRIPE_SIZE)
7974                 /* array size does not allow a suitable chunk size */
7975                 return ERR_PTR(-EINVAL);
7976
7977         mddev->new_level = 5;
7978         mddev->new_layout = ALGORITHM_LEFT_SYMMETRIC;
7979         mddev->new_chunk_sectors = chunksect;
7980
7981         ret = setup_conf(mddev);
7982         if (!IS_ERR(ret))
7983                 mddev_clear_unsupported_flags(mddev,
7984                         UNSUPPORTED_MDDEV_FLAGS);
7985         return ret;
7986 }
7987
7988 static void *raid5_takeover_raid6(struct mddev *mddev)
7989 {
7990         int new_layout;
7991
7992         switch (mddev->layout) {
7993         case ALGORITHM_LEFT_ASYMMETRIC_6:
7994                 new_layout = ALGORITHM_LEFT_ASYMMETRIC;
7995                 break;
7996         case ALGORITHM_RIGHT_ASYMMETRIC_6:
7997                 new_layout = ALGORITHM_RIGHT_ASYMMETRIC;
7998                 break;
7999         case ALGORITHM_LEFT_SYMMETRIC_6:
8000                 new_layout = ALGORITHM_LEFT_SYMMETRIC;
8001                 break;
8002         case ALGORITHM_RIGHT_SYMMETRIC_6:
8003                 new_layout = ALGORITHM_RIGHT_SYMMETRIC;
8004                 break;
8005         case ALGORITHM_PARITY_0_6:
8006                 new_layout = ALGORITHM_PARITY_0;
8007                 break;
8008         case ALGORITHM_PARITY_N:
8009                 new_layout = ALGORITHM_PARITY_N;
8010                 break;
8011         default:
8012                 return ERR_PTR(-EINVAL);
8013         }
8014         mddev->new_level = 5;
8015         mddev->new_layout = new_layout;
8016         mddev->delta_disks = -1;
8017         mddev->raid_disks -= 1;
8018         return setup_conf(mddev);
8019 }
8020
8021 static int raid5_check_reshape(struct mddev *mddev)
8022 {
8023         /* For a 2-drive array, the layout and chunk size can be changed
8024          * immediately as not restriping is needed.
8025          * For larger arrays we record the new value - after validation
8026          * to be used by a reshape pass.
8027          */
8028         struct r5conf *conf = mddev->private;
8029         int new_chunk = mddev->new_chunk_sectors;
8030
8031         if (mddev->new_layout >= 0 && !algorithm_valid_raid5(mddev->new_layout))
8032                 return -EINVAL;
8033         if (new_chunk > 0) {
8034                 if (!is_power_of_2(new_chunk))
8035                         return -EINVAL;
8036                 if (new_chunk < (PAGE_SIZE>>9))
8037                         return -EINVAL;
8038                 if (mddev->array_sectors & (new_chunk-1))
8039                         /* not factor of array size */
8040                         return -EINVAL;
8041         }
8042
8043         /* They look valid */
8044
8045         if (mddev->raid_disks == 2) {
8046                 /* can make the change immediately */
8047                 if (mddev->new_layout >= 0) {
8048                         conf->algorithm = mddev->new_layout;
8049                         mddev->layout = mddev->new_layout;
8050                 }
8051                 if (new_chunk > 0) {
8052                         conf->chunk_sectors = new_chunk ;
8053                         mddev->chunk_sectors = new_chunk;
8054                 }
8055                 set_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags);
8056                 md_wakeup_thread(mddev->thread);
8057         }
8058         return check_reshape(mddev);
8059 }
8060
8061 static int raid6_check_reshape(struct mddev *mddev)
8062 {
8063         int new_chunk = mddev->new_chunk_sectors;
8064
8065         if (mddev->new_layout >= 0 && !algorithm_valid_raid6(mddev->new_layout))
8066                 return -EINVAL;
8067         if (new_chunk > 0) {
8068                 if (!is_power_of_2(new_chunk))
8069                         return -EINVAL;
8070                 if (new_chunk < (PAGE_SIZE >> 9))
8071                         return -EINVAL;
8072                 if (mddev->array_sectors & (new_chunk-1))
8073                         /* not factor of array size */
8074                         return -EINVAL;
8075         }
8076
8077         /* They look valid */
8078         return check_reshape(mddev);
8079 }
8080
8081 static void *raid5_takeover(struct mddev *mddev)
8082 {
8083         /* raid5 can take over:
8084          *  raid0 - if there is only one strip zone - make it a raid4 layout
8085          *  raid1 - if there are two drives.  We need to know the chunk size
8086          *  raid4 - trivial - just use a raid4 layout.
8087          *  raid6 - Providing it is a *_6 layout
8088          */
8089         if (mddev->level == 0)
8090                 return raid45_takeover_raid0(mddev, 5);
8091         if (mddev->level == 1)
8092                 return raid5_takeover_raid1(mddev);
8093         if (mddev->level == 4) {
8094                 mddev->new_layout = ALGORITHM_PARITY_N;
8095                 mddev->new_level = 5;
8096                 return setup_conf(mddev);
8097         }
8098         if (mddev->level == 6)
8099                 return raid5_takeover_raid6(mddev);
8100
8101         return ERR_PTR(-EINVAL);
8102 }
8103
8104 static void *raid4_takeover(struct mddev *mddev)
8105 {
8106         /* raid4 can take over:
8107          *  raid0 - if there is only one strip zone
8108          *  raid5 - if layout is right
8109          */
8110         if (mddev->level == 0)
8111                 return raid45_takeover_raid0(mddev, 4);
8112         if (mddev->level == 5 &&
8113             mddev->layout == ALGORITHM_PARITY_N) {
8114                 mddev->new_layout = 0;
8115                 mddev->new_level = 4;
8116                 return setup_conf(mddev);
8117         }
8118         return ERR_PTR(-EINVAL);
8119 }
8120
8121 static struct md_personality raid5_personality;
8122
8123 static void *raid6_takeover(struct mddev *mddev)
8124 {
8125         /* Currently can only take over a raid5.  We map the
8126          * personality to an equivalent raid6 personality
8127          * with the Q block at the end.
8128          */
8129         int new_layout;
8130
8131         if (mddev->pers != &raid5_personality)
8132                 return ERR_PTR(-EINVAL);
8133         if (mddev->degraded > 1)
8134                 return ERR_PTR(-EINVAL);
8135         if (mddev->raid_disks > 253)
8136                 return ERR_PTR(-EINVAL);
8137         if (mddev->raid_disks < 3)
8138                 return ERR_PTR(-EINVAL);
8139
8140         switch (mddev->layout) {
8141         case ALGORITHM_LEFT_ASYMMETRIC:
8142                 new_layout = ALGORITHM_LEFT_ASYMMETRIC_6;
8143                 break;
8144         case ALGORITHM_RIGHT_ASYMMETRIC:
8145                 new_layout = ALGORITHM_RIGHT_ASYMMETRIC_6;
8146                 break;
8147         case ALGORITHM_LEFT_SYMMETRIC:
8148                 new_layout = ALGORITHM_LEFT_SYMMETRIC_6;
8149                 break;
8150         case ALGORITHM_RIGHT_SYMMETRIC:
8151                 new_layout = ALGORITHM_RIGHT_SYMMETRIC_6;
8152                 break;
8153         case ALGORITHM_PARITY_0:
8154                 new_layout = ALGORITHM_PARITY_0_6;
8155                 break;
8156         case ALGORITHM_PARITY_N:
8157                 new_layout = ALGORITHM_PARITY_N;
8158                 break;
8159         default:
8160                 return ERR_PTR(-EINVAL);
8161         }
8162         mddev->new_level = 6;
8163         mddev->new_layout = new_layout;
8164         mddev->delta_disks = 1;
8165         mddev->raid_disks += 1;
8166         return setup_conf(mddev);
8167 }
8168
8169 static struct md_personality raid6_personality =
8170 {
8171         .name           = "raid6",
8172         .level          = 6,
8173         .owner          = THIS_MODULE,
8174         .make_request   = raid5_make_request,
8175         .run            = raid5_run,
8176         .free           = raid5_free,
8177         .status         = raid5_status,
8178         .error_handler  = raid5_error,
8179         .hot_add_disk   = raid5_add_disk,
8180         .hot_remove_disk= raid5_remove_disk,
8181         .spare_active   = raid5_spare_active,
8182         .sync_request   = raid5_sync_request,
8183         .resize         = raid5_resize,
8184         .size           = raid5_size,
8185         .check_reshape  = raid6_check_reshape,
8186         .start_reshape  = raid5_start_reshape,
8187         .finish_reshape = raid5_finish_reshape,
8188         .quiesce        = raid5_quiesce,
8189         .takeover       = raid6_takeover,
8190         .congested      = raid5_congested,
8191 };
8192 static struct md_personality raid5_personality =
8193 {
8194         .name           = "raid5",
8195         .level          = 5,
8196         .owner          = THIS_MODULE,
8197         .make_request   = raid5_make_request,
8198         .run            = raid5_run,
8199         .free           = raid5_free,
8200         .status         = raid5_status,
8201         .error_handler  = raid5_error,
8202         .hot_add_disk   = raid5_add_disk,
8203         .hot_remove_disk= raid5_remove_disk,
8204         .spare_active   = raid5_spare_active,
8205         .sync_request   = raid5_sync_request,
8206         .resize         = raid5_resize,
8207         .size           = raid5_size,
8208         .check_reshape  = raid5_check_reshape,
8209         .start_reshape  = raid5_start_reshape,
8210         .finish_reshape = raid5_finish_reshape,
8211         .quiesce        = raid5_quiesce,
8212         .takeover       = raid5_takeover,
8213         .congested      = raid5_congested,
8214 };
8215
8216 static struct md_personality raid4_personality =
8217 {
8218         .name           = "raid4",
8219         .level          = 4,
8220         .owner          = THIS_MODULE,
8221         .make_request   = raid5_make_request,
8222         .run            = raid5_run,
8223         .free           = raid5_free,
8224         .status         = raid5_status,
8225         .error_handler  = raid5_error,
8226         .hot_add_disk   = raid5_add_disk,
8227         .hot_remove_disk= raid5_remove_disk,
8228         .spare_active   = raid5_spare_active,
8229         .sync_request   = raid5_sync_request,
8230         .resize         = raid5_resize,
8231         .size           = raid5_size,
8232         .check_reshape  = raid5_check_reshape,
8233         .start_reshape  = raid5_start_reshape,
8234         .finish_reshape = raid5_finish_reshape,
8235         .quiesce        = raid5_quiesce,
8236         .takeover       = raid4_takeover,
8237         .congested      = raid5_congested,
8238 };
8239
8240 static int __init raid5_init(void)
8241 {
8242         int ret;
8243
8244         raid5_wq = alloc_workqueue("raid5wq",
8245                 WQ_UNBOUND|WQ_MEM_RECLAIM|WQ_CPU_INTENSIVE|WQ_SYSFS, 0);
8246         if (!raid5_wq)
8247                 return -ENOMEM;
8248
8249         ret = cpuhp_setup_state_multi(CPUHP_MD_RAID5_PREPARE,
8250                                       "md/raid5:prepare",
8251                                       raid456_cpu_up_prepare,
8252                                       raid456_cpu_dead);
8253         if (ret) {
8254                 destroy_workqueue(raid5_wq);
8255                 return ret;
8256         }
8257         register_md_personality(&raid6_personality);
8258         register_md_personality(&raid5_personality);
8259         register_md_personality(&raid4_personality);
8260         return 0;
8261 }
8262
8263 static void raid5_exit(void)
8264 {
8265         unregister_md_personality(&raid6_personality);
8266         unregister_md_personality(&raid5_personality);
8267         unregister_md_personality(&raid4_personality);
8268         cpuhp_remove_multi_state(CPUHP_MD_RAID5_PREPARE);
8269         destroy_workqueue(raid5_wq);
8270 }
8271
8272 module_init(raid5_init);
8273 module_exit(raid5_exit);
8274 MODULE_LICENSE("GPL");
8275 MODULE_DESCRIPTION("RAID4/5/6 (striping with parity) personality for MD");
8276 MODULE_ALIAS("md-personality-4"); /* RAID5 */
8277 MODULE_ALIAS("md-raid5");
8278 MODULE_ALIAS("md-raid4");
8279 MODULE_ALIAS("md-level-5");
8280 MODULE_ALIAS("md-level-4");
8281 MODULE_ALIAS("md-personality-8"); /* RAID6 */
8282 MODULE_ALIAS("md-raid6");
8283 MODULE_ALIAS("md-level-6");
8284
8285 /* This used to be two separate modules, they were: */
8286 MODULE_ALIAS("raid5");
8287 MODULE_ALIAS("raid6");