block/blk-mq.c

   1 /*
   2  * Block multiqueue core code
   3  *
   4  * Copyright (C) 2013-2014 Jens Axboe
   5  * Copyright (C) 2013-2014 Christoph Hellwig
   6  */
   7 #include <linux/kernel.h>
   8 #include <linux/module.h>
   9 #include <linux/backing-dev.h>
  10 #include <linux/bio.h>
  11 #include <linux/blkdev.h>
  12 #include <linux/kmemleak.h>
  13 #include <linux/mm.h>
  14 #include <linux/init.h>
  15 #include <linux/slab.h>
  16 #include <linux/workqueue.h>
  17 #include <linux/smp.h>
  18 #include <linux/llist.h>
  19 #include <linux/list_sort.h>
  20 #include <linux/cpu.h>
  21 #include <linux/cache.h>
  22 #include <linux/sched/sysctl.h>
  23 #include <linux/sched/topology.h>
  24 #include <linux/sched/signal.h>
  25 #include <linux/delay.h>
  26 #include <linux/crash_dump.h>
  27 #include <linux/prefetch.h>
  28
  29 #include <trace/events/block.h>
  30
  31 #include <linux/blk-mq.h>
  32 #include "blk.h"
  33 #include "blk-mq.h"
  34 #include "blk-mq-debugfs.h"
  35 #include "blk-mq-tag.h"
  36 #include "blk-stat.h"
  37 #include "blk-wbt.h"
  38 #include "blk-mq-sched.h"
  39
  40 static bool blk_mq_poll(struct request_queue *q, blk_qc_t cookie);
  41 static void blk_mq_poll_stats_start(struct request_queue *q);
  42 static void blk_mq_poll_stats_fn(struct blk_stat_callback *cb);
  43
  44 static int blk_mq_poll_stats_bkt(const struct request *rq)
  45 {
  46         int ddir, bytes, bucket;
  47
  48         ddir = rq_data_dir(rq);
  49         bytes = blk_rq_bytes(rq);
  50
  51         bucket = ddir + 2*(ilog2(bytes) - 9);
  52
  53         if (bucket < 0)
  54                 return -1;
  55         else if (bucket >= BLK_MQ_POLL_STATS_BKTS)
  56                 return ddir + BLK_MQ_POLL_STATS_BKTS - 2;
  57
  58         return bucket;
  59 }
  60
  61 /*
  62  * Check if any of the ctx's have pending work in this hardware queue
  63  */
  64 static bool blk_mq_hctx_has_pending(struct blk_mq_hw_ctx *hctx)
  65 {
  66         return !list_empty_careful(&hctx->dispatch) ||
  67                 sbitmap_any_bit_set(&hctx->ctx_map) ||
  68                         blk_mq_sched_has_work(hctx);
  69 }
  70
  71 /*
  72  * Mark this ctx as having pending work in this hardware queue
  73  */
  74 static void blk_mq_hctx_mark_pending(struct blk_mq_hw_ctx *hctx,
  75                                      struct blk_mq_ctx *ctx)
  76 {
  77         if (!sbitmap_test_bit(&hctx->ctx_map, ctx->index_hw))
  78                 sbitmap_set_bit(&hctx->ctx_map, ctx->index_hw);
  79 }
  80
  81 static void blk_mq_hctx_clear_pending(struct blk_mq_hw_ctx *hctx,
  82                                       struct blk_mq_ctx *ctx)
  83 {
  84         sbitmap_clear_bit(&hctx->ctx_map, ctx->index_hw);
  85 }
  86
  87 struct mq_inflight {
  88         struct hd_struct *part;
  89         unsigned int *inflight;
  90 };
  91
  92 static void blk_mq_check_inflight(struct blk_mq_hw_ctx *hctx,
  93                                   struct request *rq, void *priv,
  94                                   bool reserved)
  95 {
  96         struct mq_inflight *mi = priv;
  97
  98         /*
  99          * index[0] counts the specific partition that was asked for. index[1]
 100          * counts the ones that are active on the whole device, so increment
 101          * that if mi->part is indeed a partition, and not a whole device.
 102          */
 103         if (rq->part == mi->part)
 104                 mi->inflight[0]++;
 105         if (mi->part->partno)
 106                 mi->inflight[1]++;
 107 }
 108
 109 void blk_mq_in_flight(struct request_queue *q, struct hd_struct *part,
 110                       unsigned int inflight[2])
 111 {
 112         struct mq_inflight mi = { .part = part, .inflight = inflight, };
 113
 114         inflight[0] = inflight[1] = 0;
 115         blk_mq_queue_tag_busy_iter(q, blk_mq_check_inflight, &mi);
 116 }
 117
 118 static void blk_mq_check_inflight_rw(struct blk_mq_hw_ctx *hctx,
 119                                      struct request *rq, void *priv,
 120                                      bool reserved)
 121 {
 122         struct mq_inflight *mi = priv;
 123
 124         if (rq->part == mi->part)
 125                 mi->inflight[rq_data_dir(rq)]++;
 126 }
 127
 128 void blk_mq_in_flight_rw(struct request_queue *q, struct hd_struct *part,
 129                          unsigned int inflight[2])
 130 {
 131         struct mq_inflight mi = { .part = part, .inflight = inflight, };
 132
 133         inflight[0] = inflight[1] = 0;
 134         blk_mq_queue_tag_busy_iter(q, blk_mq_check_inflight_rw, &mi);
 135 }
 136
 137 void blk_freeze_queue_start(struct request_queue *q)
 138 {
 139         int freeze_depth;
 140
 141         freeze_depth = atomic_inc_return(&q->mq_freeze_depth);
 142         if (freeze_depth == 1) {
 143                 percpu_ref_kill(&q->q_usage_counter);
 144                 if (q->mq_ops)
 145                         blk_mq_run_hw_queues(q, false);
 146         }
 147 }
 148 EXPORT_SYMBOL_GPL(blk_freeze_queue_start);
 149
 150 void blk_mq_freeze_queue_wait(struct request_queue *q)
 151 {
 152         wait_event(q->mq_freeze_wq, percpu_ref_is_zero(&q->q_usage_counter));
 153 }
 154 EXPORT_SYMBOL_GPL(blk_mq_freeze_queue_wait);
 155
 156 int blk_mq_freeze_queue_wait_timeout(struct request_queue *q,
 157                                      unsigned long timeout)
 158 {
 159         return wait_event_timeout(q->mq_freeze_wq,
 160                                         percpu_ref_is_zero(&q->q_usage_counter),
 161                                         timeout);
 162 }
 163 EXPORT_SYMBOL_GPL(blk_mq_freeze_queue_wait_timeout);
 164
 165 /*
 166  * Guarantee no request is in use, so we can change any data structure of
 167  * the queue afterward.
 168  */
 169 void blk_freeze_queue(struct request_queue *q)
 170 {
 171         /*
 172          * In the !blk_mq case we are only calling this to kill the
 173          * q_usage_counter, otherwise this increases the freeze depth
 174          * and waits for it to return to zero.  For this reason there is
 175          * no blk_unfreeze_queue(), and blk_freeze_queue() is not
 176          * exported to drivers as the only user for unfreeze is blk_mq.
 177          */
 178         blk_freeze_queue_start(q);
 179         if (!q->mq_ops)
 180                 blk_drain_queue(q);
 181         blk_mq_freeze_queue_wait(q);
 182 }
 183
 184 void blk_mq_freeze_queue(struct request_queue *q)
 185 {
 186         /*
 187          * ...just an alias to keep freeze and unfreeze actions balanced
 188          * in the blk_mq_* namespace
 189          */
 190         blk_freeze_queue(q);
 191 }
 192 EXPORT_SYMBOL_GPL(blk_mq_freeze_queue);
 193
 194 void blk_mq_unfreeze_queue(struct request_queue *q)
 195 {
 196         int freeze_depth;
 197
 198         freeze_depth = atomic_dec_return(&q->mq_freeze_depth);
 199         WARN_ON_ONCE(freeze_depth < 0);
 200         if (!freeze_depth) {
 201                 percpu_ref_reinit(&q->q_usage_counter);
 202                 wake_up_all(&q->mq_freeze_wq);
 203         }
 204 }
 205 EXPORT_SYMBOL_GPL(blk_mq_unfreeze_queue);
 206
 207 /*
 208  * FIXME: replace the scsi_internal_device_*block_nowait() calls in the
 209  * mpt3sas driver such that this function can be removed.
 210  */
 211 void blk_mq_quiesce_queue_nowait(struct request_queue *q)
 212 {
 213         blk_queue_flag_set(QUEUE_FLAG_QUIESCED, q);
 214 }
 215 EXPORT_SYMBOL_GPL(blk_mq_quiesce_queue_nowait);
 216
 217 /**
 218  * blk_mq_quiesce_queue() - wait until all ongoing dispatches have finished
 219  * @q: request queue.
 220  *
 221  * Note: this function does not prevent that the struct request end_io()
 222  * callback function is invoked. Once this function is returned, we make
 223  * sure no dispatch can happen until the queue is unquiesced via
 224  * blk_mq_unquiesce_queue().
 225  */
 226 void blk_mq_quiesce_queue(struct request_queue *q)
 227 {
 228         struct blk_mq_hw_ctx *hctx;
 229         unsigned int i;
 230         bool rcu = false;
 231
 232         blk_mq_quiesce_queue_nowait(q);
 233
 234         queue_for_each_hw_ctx(q, hctx, i) {
 235                 if (hctx->flags & BLK_MQ_F_BLOCKING)
 236                         synchronize_srcu(hctx->srcu);
 237                 else
 238                         rcu = true;
 239         }
 240         if (rcu)
 241                 synchronize_rcu();
 242 }
 243 EXPORT_SYMBOL_GPL(blk_mq_quiesce_queue);
 244
 245 /*
 246  * blk_mq_unquiesce_queue() - counterpart of blk_mq_quiesce_queue()
 247  * @q: request queue.
 248  *
 249  * This function recovers queue into the state before quiescing
 250  * which is done by blk_mq_quiesce_queue.
 251  */
 252 void blk_mq_unquiesce_queue(struct request_queue *q)
 253 {
 254         blk_queue_flag_clear(QUEUE_FLAG_QUIESCED, q);
 255
 256         /* dispatch requests which are inserted during quiescing */
 257         blk_mq_run_hw_queues(q, true);
 258 }
 259 EXPORT_SYMBOL_GPL(blk_mq_unquiesce_queue);
 260
 261 void blk_mq_wake_waiters(struct request_queue *q)
 262 {
 263         struct blk_mq_hw_ctx *hctx;
 264         unsigned int i;
 265
 266         queue_for_each_hw_ctx(q, hctx, i)
 267                 if (blk_mq_hw_queue_mapped(hctx))
 268                         blk_mq_tag_wakeup_all(hctx->tags, true);
 269 }
 270
 271 bool blk_mq_can_queue(struct blk_mq_hw_ctx *hctx)
 272 {
 273         return blk_mq_has_free_tags(hctx->tags);
 274 }
 275 EXPORT_SYMBOL(blk_mq_can_queue);
 276
 277 static struct request *blk_mq_rq_ctx_init(struct blk_mq_alloc_data *data,
 278                 unsigned int tag, unsigned int op)
 279 {
 280         struct blk_mq_tags *tags = blk_mq_tags_from_data(data);
 281         struct request *rq = tags->static_rqs[tag];
 282         req_flags_t rq_flags = 0;
 283
 284         if (data->flags & BLK_MQ_REQ_INTERNAL) {
 285                 rq->tag = -1;
 286                 rq->internal_tag = tag;
 287         } else {
 288                 if (blk_mq_tag_busy(data->hctx)) {
 289                         rq_flags = RQF_MQ_INFLIGHT;
 290                         atomic_inc(&data->hctx->nr_active);
 291                 }
 292                 rq->tag = tag;
 293                 rq->internal_tag = -1;
 294                 data->hctx->tags->rqs[rq->tag] = rq;
 295         }
 296
 297         /* csd/requeue_work/fifo_time is initialized before use */
 298         rq->q = data->q;
 299         rq->mq_ctx = data->ctx;
 300         rq->rq_flags = rq_flags;
 301         rq->cpu = -1;
 302         rq->cmd_flags = op;
 303         if (data->flags & BLK_MQ_REQ_PREEMPT)
 304                 rq->rq_flags |= RQF_PREEMPT;
 305         if (blk_queue_io_stat(data->q))
 306                 rq->rq_flags |= RQF_IO_STAT;
 307         INIT_LIST_HEAD(&rq->queuelist);
 308         INIT_HLIST_NODE(&rq->hash);
 309         RB_CLEAR_NODE(&rq->rb_node);
 310         rq->rq_disk = NULL;
 311         rq->part = NULL;
 312         rq->start_time_ns = ktime_get_ns();
 313         rq->io_start_time_ns = 0;
 314         rq->nr_phys_segments = 0;
 315 #if defined(CONFIG_BLK_DEV_INTEGRITY)
 316         rq->nr_integrity_segments = 0;
 317 #endif
 318         rq->special = NULL;
 319         /* tag was already set */
 320         rq->extra_len = 0;
 321         rq->__deadline = 0;
 322
 323         INIT_LIST_HEAD(&rq->timeout_list);
 324         rq->timeout = 0;
 325
 326         rq->end_io = NULL;
 327         rq->end_io_data = NULL;
 328         rq->next_rq = NULL;
 329
 330 #ifdef CONFIG_BLK_CGROUP
 331         rq->rl = NULL;
 332 #endif
 333
 334         data->ctx->rq_dispatched[op_is_sync(op)]++;
 335         refcount_set(&rq->ref, 1);
 336         return rq;
 337 }
 338
 339 static struct request *blk_mq_get_request(struct request_queue *q,
 340                 struct bio *bio, unsigned int op,
 341                 struct blk_mq_alloc_data *data)
 342 {
 343         struct elevator_queue *e = q->elevator;
 344         struct request *rq;
 345         unsigned int tag;
 346         bool put_ctx_on_error = false;
 347
 348         blk_queue_enter_live(q);
 349         data->q = q;
 350         if (likely(!data->ctx)) {
 351                 data->ctx = blk_mq_get_ctx(q);
 352                 put_ctx_on_error = true;
 353         }
 354         if (likely(!data->hctx))
 355                 data->hctx = blk_mq_map_queue(q, data->ctx->cpu);
 356         if (op & REQ_NOWAIT)
 357                 data->flags |= BLK_MQ_REQ_NOWAIT;
 358
 359         if (e) {
 360                 data->flags |= BLK_MQ_REQ_INTERNAL;
 361
 362                 /*
 363                  * Flush requests are special and go directly to the
 364                  * dispatch list. Don't include reserved tags in the
 365                  * limiting, as it isn't useful.
 366                  */
 367                 if (!op_is_flush(op) && e->type->ops.mq.limit_depth &&
 368                     !(data->flags & BLK_MQ_REQ_RESERVED))
 369                         e->type->ops.mq.limit_depth(op, data);
 370         }
 371
 372         tag = blk_mq_get_tag(data);
 373         if (tag == BLK_MQ_TAG_FAIL) {
 374                 if (put_ctx_on_error) {
 375                         blk_mq_put_ctx(data->ctx);
 376                         data->ctx = NULL;
 377                 }
 378                 blk_queue_exit(q);
 379                 return NULL;
 380         }
 381
 382         rq = blk_mq_rq_ctx_init(data, tag, op);
 383         if (!op_is_flush(op)) {
 384                 rq->elv.icq = NULL;
 385                 if (e && e->type->ops.mq.prepare_request) {
 386                         if (e->type->icq_cache && rq_ioc(bio))
 387                                 blk_mq_sched_assign_ioc(rq, bio);
 388
 389                         e->type->ops.mq.prepare_request(rq, bio);
 390                         rq->rq_flags |= RQF_ELVPRIV;
 391                 }
 392         }
 393         data->hctx->queued++;
 394         return rq;
 395 }
 396
 397 struct request *blk_mq_alloc_request(struct request_queue *q, unsigned int op,
 398                 blk_mq_req_flags_t flags)
 399 {
 400         struct blk_mq_alloc_data alloc_data = { .flags = flags };
 401         struct request *rq;
 402         int ret;
 403
 404         ret = blk_queue_enter(q, flags);
 405         if (ret)
 406                 return ERR_PTR(ret);
 407
 408         rq = blk_mq_get_request(q, NULL, op, &alloc_data);
 409         blk_queue_exit(q);
 410
 411         if (!rq)
 412                 return ERR_PTR(-EWOULDBLOCK);
 413
 414         blk_mq_put_ctx(alloc_data.ctx);
 415
 416         rq->__data_len = 0;
 417         rq->__sector = (sector_t) -1;
 418         rq->bio = rq->biotail = NULL;
 419         return rq;
 420 }
 421 EXPORT_SYMBOL(blk_mq_alloc_request);
 422
 423 struct request *blk_mq_alloc_request_hctx(struct request_queue *q,
 424         unsigned int op, blk_mq_req_flags_t flags, unsigned int hctx_idx)
 425 {
 426         struct blk_mq_alloc_data alloc_data = { .flags = flags };
 427         struct request *rq;
 428         unsigned int cpu;
 429         int ret;
 430
 431         /*
 432          * If the tag allocator sleeps we could get an allocation for a
 433          * different hardware context.  No need to complicate the low level
 434          * allocator for this for the rare use case of a command tied to
 435          * a specific queue.
 436          */
 437         if (WARN_ON_ONCE(!(flags & BLK_MQ_REQ_NOWAIT)))
 438                 return ERR_PTR(-EINVAL);
 439
 440         if (hctx_idx >= q->nr_hw_queues)
 441                 return ERR_PTR(-EIO);
 442
 443         ret = blk_queue_enter(q, flags);
 444         if (ret)
 445                 return ERR_PTR(ret);
 446
 447         /*
 448          * Check if the hardware context is actually mapped to anything.
 449          * If not tell the caller that it should skip this queue.
 450          */
 451         alloc_data.hctx = q->queue_hw_ctx[hctx_idx];
 452         if (!blk_mq_hw_queue_mapped(alloc_data.hctx)) {
 453                 blk_queue_exit(q);
 454                 return ERR_PTR(-EXDEV);
 455         }
 456         cpu = cpumask_first_and(alloc_data.hctx->cpumask, cpu_online_mask);
 457         alloc_data.ctx = __blk_mq_get_ctx(q, cpu);
 458
 459         rq = blk_mq_get_request(q, NULL, op, &alloc_data);
 460         blk_queue_exit(q);
 461
 462         if (!rq)
 463                 return ERR_PTR(-EWOULDBLOCK);
 464
 465         return rq;
 466 }
 467 EXPORT_SYMBOL_GPL(blk_mq_alloc_request_hctx);
 468
 469 static void __blk_mq_free_request(struct request *rq)
 470 {
 471         struct request_queue *q = rq->q;
 472         struct blk_mq_ctx *ctx = rq->mq_ctx;
 473         struct blk_mq_hw_ctx *hctx = blk_mq_map_queue(q, ctx->cpu);
 474         const int sched_tag = rq->internal_tag;
 475
 476         if (rq->tag != -1)
 477                 blk_mq_put_tag(hctx, hctx->tags, ctx, rq->tag);
 478         if (sched_tag != -1)
 479                 blk_mq_put_tag(hctx, hctx->sched_tags, ctx, sched_tag);
 480         blk_mq_sched_restart(hctx);
 481         blk_queue_exit(q);
 482 }
 483
 484 void blk_mq_free_request(struct request *rq)
 485 {
 486         struct request_queue *q = rq->q;
 487         struct elevator_queue *e = q->elevator;
 488         struct blk_mq_ctx *ctx = rq->mq_ctx;
 489         struct blk_mq_hw_ctx *hctx = blk_mq_map_queue(q, ctx->cpu);
 490
 491         if (rq->rq_flags & RQF_ELVPRIV) {
 492                 if (e && e->type->ops.mq.finish_request)
 493                         e->type->ops.mq.finish_request(rq);
 494                 if (rq->elv.icq) {
 495                         put_io_context(rq->elv.icq->ioc);
 496                         rq->elv.icq = NULL;
 497                 }
 498         }
 499
 500         ctx->rq_completed[rq_is_sync(rq)]++;
 501         if (rq->rq_flags & RQF_MQ_INFLIGHT)
 502                 atomic_dec(&hctx->nr_active);
 503
 504         if (unlikely(laptop_mode && !blk_rq_is_passthrough(rq)))
 505                 laptop_io_completion(q->backing_dev_info);
 506
 507         wbt_done(q->rq_wb, rq);
 508
 509         if (blk_rq_rl(rq))
 510                 blk_put_rl(blk_rq_rl(rq));
 511
 512         WRITE_ONCE(rq->state, MQ_RQ_IDLE);
 513         if (refcount_dec_and_test(&rq->ref))
 514                 __blk_mq_free_request(rq);
 515 }
 516 EXPORT_SYMBOL_GPL(blk_mq_free_request);
 517
 518 inline void __blk_mq_end_request(struct request *rq, blk_status_t error)
 519 {
 520         u64 now = ktime_get_ns();
 521
 522         if (rq->rq_flags & RQF_STATS) {
 523                 blk_mq_poll_stats_start(rq->q);
 524                 blk_stat_add(rq, now);
 525         }
 526
 527         blk_account_io_done(rq, now);
 528
 529         if (rq->end_io) {
 530                 wbt_done(rq->q->rq_wb, rq);
 531                 rq->end_io(rq, error);
 532         } else {
 533                 if (unlikely(blk_bidi_rq(rq)))
 534                         blk_mq_free_request(rq->next_rq);
 535                 blk_mq_free_request(rq);
 536         }
 537 }
 538 EXPORT_SYMBOL(__blk_mq_end_request);
 539
 540 void blk_mq_end_request(struct request *rq, blk_status_t error)
 541 {
 542         if (blk_update_request(rq, error, blk_rq_bytes(rq)))
 543                 BUG();
 544         __blk_mq_end_request(rq, error);
 545 }
 546 EXPORT_SYMBOL(blk_mq_end_request);
 547
 548 static void __blk_mq_complete_request_remote(void *data)
 549 {
 550         struct request *rq = data;
 551
 552         rq->q->softirq_done_fn(rq);
 553 }
 554
 555 static void __blk_mq_complete_request(struct request *rq)
 556 {
 557         struct blk_mq_ctx *ctx = rq->mq_ctx;
 558         bool shared = false;
 559         int cpu;
 560
 561         if (cmpxchg(&rq->state, MQ_RQ_IN_FLIGHT, MQ_RQ_COMPLETE) !=
 562                         MQ_RQ_IN_FLIGHT)
 563                 return;
 564
 565         if (rq->internal_tag != -1)
 566                 blk_mq_sched_completed_request(rq);
 567
 568         if (!test_bit(QUEUE_FLAG_SAME_COMP, &rq->q->queue_flags)) {
 569                 rq->q->softirq_done_fn(rq);
 570                 return;
 571         }
 572
 573         cpu = get_cpu();
 574         if (!test_bit(QUEUE_FLAG_SAME_FORCE, &rq->q->queue_flags))
 575                 shared = cpus_share_cache(cpu, ctx->cpu);
 576
 577         if (cpu != ctx->cpu && !shared && cpu_online(ctx->cpu)) {
 578                 rq->csd.func = __blk_mq_complete_request_remote;
 579                 rq->csd.info = rq;
 580                 rq->csd.flags = 0;
 581                 smp_call_function_single_async(ctx->cpu, &rq->csd);
 582         } else {
 583                 rq->q->softirq_done_fn(rq);
 584         }
 585         put_cpu();
 586 }
 587
 588 static void hctx_unlock(struct blk_mq_hw_ctx *hctx, int srcu_idx)
 589         __releases(hctx->srcu)
 590 {
 591         if (!(hctx->flags & BLK_MQ_F_BLOCKING))
 592                 rcu_read_unlock();
 593         else
 594                 srcu_read_unlock(hctx->srcu, srcu_idx);
 595 }
 596
 597 static void hctx_lock(struct blk_mq_hw_ctx *hctx, int *srcu_idx)
 598         __acquires(hctx->srcu)
 599 {
 600         if (!(hctx->flags & BLK_MQ_F_BLOCKING)) {
 601                 /* shut up gcc false positive */
 602                 *srcu_idx = 0;
 603                 rcu_read_lock();
 604         } else
 605                 *srcu_idx = srcu_read_lock(hctx->srcu);
 606 }
 607
 608 /**
 609  * blk_mq_complete_request - end I/O on a request
 610  * @rq:         the request being processed
 611  *
 612  * Description:
 613  *      Ends all I/O on a request. It does not handle partial completions.
 614  *      The actual completion happens out-of-order, through a IPI handler.
 615  **/
 616 void blk_mq_complete_request(struct request *rq)
 617 {
 618         if (unlikely(blk_should_fake_timeout(rq->q)))
 619                 return;
 620         __blk_mq_complete_request(rq);
 621 }
 622 EXPORT_SYMBOL(blk_mq_complete_request);
 623
 624 int blk_mq_request_started(struct request *rq)
 625 {
 626         return blk_mq_rq_state(rq) != MQ_RQ_IDLE;
 627 }
 628 EXPORT_SYMBOL_GPL(blk_mq_request_started);
 629
 630 void blk_mq_start_request(struct request *rq)
 631 {
 632         struct request_queue *q = rq->q;
 633
 634         blk_mq_sched_started_request(rq);
 635
 636         trace_block_rq_issue(q, rq);
 637
 638         if (test_bit(QUEUE_FLAG_STATS, &q->queue_flags)) {
 639                 rq->io_start_time_ns = ktime_get_ns();
 640 #ifdef CONFIG_BLK_DEV_THROTTLING_LOW
 641                 rq->throtl_size = blk_rq_sectors(rq);
 642 #endif
 643                 rq->rq_flags |= RQF_STATS;
 644                 wbt_issue(q->rq_wb, rq);
 645         }
 646
 647         WARN_ON_ONCE(blk_mq_rq_state(rq) != MQ_RQ_IDLE);
 648
 649         blk_add_timer(rq);
 650         WRITE_ONCE(rq->state, MQ_RQ_IN_FLIGHT);
 651
 652         if (q->dma_drain_size && blk_rq_bytes(rq)) {
 653                 /*
 654                  * Make sure space for the drain appears.  We know we can do
 655                  * this because max_hw_segments has been adjusted to be one
 656                  * fewer than the device can handle.
 657                  */
 658                 rq->nr_phys_segments++;
 659         }
 660 }
 661 EXPORT_SYMBOL(blk_mq_start_request);
 662
 663 static void __blk_mq_requeue_request(struct request *rq)
 664 {
 665         struct request_queue *q = rq->q;
 666
 667         blk_mq_put_driver_tag(rq);
 668
 669         trace_block_rq_requeue(q, rq);
 670         wbt_requeue(q->rq_wb, rq);
 671
 672         if (blk_mq_request_started(rq)) {
 673                 WRITE_ONCE(rq->state, MQ_RQ_IDLE);
 674                 rq->rq_flags &= ~RQF_TIMED_OUT;
 675                 if (q->dma_drain_size && blk_rq_bytes(rq))
 676                         rq->nr_phys_segments--;
 677         }
 678 }
 679
 680 void blk_mq_requeue_request(struct request *rq, bool kick_requeue_list)
 681 {
 682         __blk_mq_requeue_request(rq);
 683
 684         /* this request will be re-inserted to io scheduler queue */
 685         blk_mq_sched_requeue_request(rq);
 686
 687         BUG_ON(blk_queued_rq(rq));
 688         blk_mq_add_to_requeue_list(rq, true, kick_requeue_list);
 689 }
 690 EXPORT_SYMBOL(blk_mq_requeue_request);
 691
 692 static void blk_mq_requeue_work(struct work_struct *work)
 693 {
 694         struct request_queue *q =
 695                 container_of(work, struct request_queue, requeue_work.work);
 696         LIST_HEAD(rq_list);
 697         struct request *rq, *next;
 698
 699         spin_lock_irq(&q->requeue_lock);
 700         list_splice_init(&q->requeue_list, &rq_list);
 701         spin_unlock_irq(&q->requeue_lock);
 702
 703         list_for_each_entry_safe(rq, next, &rq_list, queuelist) {
 704                 if (!(rq->rq_flags & RQF_SOFTBARRIER))
 705                         continue;
 706
 707                 rq->rq_flags &= ~RQF_SOFTBARRIER;
 708                 list_del_init(&rq->queuelist);
 709                 blk_mq_sched_insert_request(rq, true, false, false);
 710         }
 711
 712         while (!list_empty(&rq_list)) {
 713                 rq = list_entry(rq_list.next, struct request, queuelist);
 714                 list_del_init(&rq->queuelist);
 715                 blk_mq_sched_insert_request(rq, false, false, false);
 716         }
 717
 718         blk_mq_run_hw_queues(q, false);
 719 }
 720
 721 void blk_mq_add_to_requeue_list(struct request *rq, bool at_head,
 722                                 bool kick_requeue_list)
 723 {
 724         struct request_queue *q = rq->q;
 725         unsigned long flags;
 726
 727         /*
 728          * We abuse this flag that is otherwise used by the I/O scheduler to
 729          * request head insertion from the workqueue.
 730          */
 731         BUG_ON(rq->rq_flags & RQF_SOFTBARRIER);
 732
 733         spin_lock_irqsave(&q->requeue_lock, flags);
 734         if (at_head) {
 735                 rq->rq_flags |= RQF_SOFTBARRIER;
 736                 list_add(&rq->queuelist, &q->requeue_list);
 737         } else {
 738                 list_add_tail(&rq->queuelist, &q->requeue_list);
 739         }
 740         spin_unlock_irqrestore(&q->requeue_lock, flags);
 741
 742         if (kick_requeue_list)
 743                 blk_mq_kick_requeue_list(q);
 744 }
 745 EXPORT_SYMBOL(blk_mq_add_to_requeue_list);
 746
 747 void blk_mq_kick_requeue_list(struct request_queue *q)
 748 {
 749         kblockd_mod_delayed_work_on(WORK_CPU_UNBOUND, &q->requeue_work, 0);
 750 }
 751 EXPORT_SYMBOL(blk_mq_kick_requeue_list);
 752
 753 void blk_mq_delay_kick_requeue_list(struct request_queue *q,
 754                                     unsigned long msecs)
 755 {
 756         kblockd_mod_delayed_work_on(WORK_CPU_UNBOUND, &q->requeue_work,
 757                                     msecs_to_jiffies(msecs));
 758 }
 759 EXPORT_SYMBOL(blk_mq_delay_kick_requeue_list);
 760
 761 struct request *blk_mq_tag_to_rq(struct blk_mq_tags *tags, unsigned int tag)
 762 {
 763         if (tag < tags->nr_tags) {
 764                 prefetch(tags->rqs[tag]);
 765                 return tags->rqs[tag];
 766         }
 767
 768         return NULL;
 769 }
 770 EXPORT_SYMBOL(blk_mq_tag_to_rq);
 771
 772 static void blk_mq_rq_timed_out(struct request *req, bool reserved)
 773 {
 774         req->rq_flags |= RQF_TIMED_OUT;
 775         if (req->q->mq_ops->timeout) {
 776                 enum blk_eh_timer_return ret;
 777
 778                 ret = req->q->mq_ops->timeout(req, reserved);
 779                 if (ret == BLK_EH_DONE)
 780                         return;
 781                 WARN_ON_ONCE(ret != BLK_EH_RESET_TIMER);
 782         }
 783
 784         blk_add_timer(req);
 785 }
 786
 787 static bool blk_mq_req_expired(struct request *rq, unsigned long *next)
 788 {
 789         unsigned long deadline;
 790
 791         if (blk_mq_rq_state(rq) != MQ_RQ_IN_FLIGHT)
 792                 return false;
 793         if (rq->rq_flags & RQF_TIMED_OUT)
 794                 return false;
 795
 796         deadline = blk_rq_deadline(rq);
 797         if (time_after_eq(jiffies, deadline))
 798                 return true;
 799
 800         if (*next == 0)
 801                 *next = deadline;
 802         else if (time_after(*next, deadline))
 803                 *next = deadline;
 804         return false;
 805 }
 806
 807 static void blk_mq_check_expired(struct blk_mq_hw_ctx *hctx,
 808                 struct request *rq, void *priv, bool reserved)
 809 {
 810         unsigned long *next = priv;
 811
 812         /*
 813          * Just do a quick check if it is expired before locking the request in
 814          * so we're not unnecessarilly synchronizing across CPUs.
 815          */
 816         if (!blk_mq_req_expired(rq, next))
 817                 return;
 818
 819         /*
 820          * We have reason to believe the request may be expired. Take a
 821          * reference on the request to lock this request lifetime into its
 822          * currently allocated context to prevent it from being reallocated in
 823          * the event the completion by-passes this timeout handler.
 824          *
 825          * If the reference was already released, then the driver beat the
 826          * timeout handler to posting a natural completion.
 827          */
 828         if (!refcount_inc_not_zero(&rq->ref))
 829                 return;
 830
 831         /*
 832          * The request is now locked and cannot be reallocated underneath the
 833          * timeout handler's processing. Re-verify this exact request is truly
 834          * expired; if it is not expired, then the request was completed and
 835          * reallocated as a new request.
 836          */
 837         if (blk_mq_req_expired(rq, next))
 838                 blk_mq_rq_timed_out(rq, reserved);
 839         if (refcount_dec_and_test(&rq->ref))
 840                 __blk_mq_free_request(rq);
 841 }
 842
 843 static void blk_mq_timeout_work(struct work_struct *work)
 844 {
 845         struct request_queue *q =
 846                 container_of(work, struct request_queue, timeout_work);
 847         unsigned long next = 0;
 848         struct blk_mq_hw_ctx *hctx;
 849         int i;
 850
 851         /* A deadlock might occur if a request is stuck requiring a
 852          * timeout at the same time a queue freeze is waiting
 853          * completion, since the timeout code would not be able to
 854          * acquire the queue reference here.
 855          *
 856          * That's why we don't use blk_queue_enter here; instead, we use
 857          * percpu_ref_tryget directly, because we need to be able to
 858          * obtain a reference even in the short window between the queue
 859          * starting to freeze, by dropping the first reference in
 860          * blk_freeze_queue_start, and the moment the last request is
 861          * consumed, marked by the instant q_usage_counter reaches
 862          * zero.
 863          */
 864         if (!percpu_ref_tryget(&q->q_usage_counter))
 865                 return;
 866
 867         blk_mq_queue_tag_busy_iter(q, blk_mq_check_expired, &next);
 868
 869         if (next != 0) {
 870                 mod_timer(&q->timeout, next);
 871         } else {
 872                 /*
 873                  * Request timeouts are handled as a forward rolling timer. If
 874                  * we end up here it means that no requests are pending and
 875                  * also that no request has been pending for a while. Mark
 876                  * each hctx as idle.
 877                  */
 878                 queue_for_each_hw_ctx(q, hctx, i) {
 879                         /* the hctx may be unmapped, so check it here */
 880                         if (blk_mq_hw_queue_mapped(hctx))
 881                                 blk_mq_tag_idle(hctx);
 882                 }
 883         }
 884         blk_queue_exit(q);
 885 }
 886
 887 struct flush_busy_ctx_data {
 888         struct blk_mq_hw_ctx *hctx;
 889         struct list_head *list;
 890 };
 891
 892 static bool flush_busy_ctx(struct sbitmap *sb, unsigned int bitnr, void *data)
 893 {
 894         struct flush_busy_ctx_data *flush_data = data;
 895         struct blk_mq_hw_ctx *hctx = flush_data->hctx;
 896         struct blk_mq_ctx *ctx = hctx->ctxs[bitnr];
 897
 898         spin_lock(&ctx->lock);
 899         list_splice_tail_init(&ctx->rq_list, flush_data->list);
 900         sbitmap_clear_bit(sb, bitnr);
 901         spin_unlock(&ctx->lock);
 902         return true;
 903 }
 904
 905 /*
 906  * Process software queues that have been marked busy, splicing them
 907  * to the for-dispatch
 908  */
 909 void blk_mq_flush_busy_ctxs(struct blk_mq_hw_ctx *hctx, struct list_head *list)
 910 {
 911         struct flush_busy_ctx_data data = {
 912                 .hctx = hctx,
 913                 .list = list,
 914         };
 915
 916         sbitmap_for_each_set(&hctx->ctx_map, flush_busy_ctx, &data);
 917 }
 918 EXPORT_SYMBOL_GPL(blk_mq_flush_busy_ctxs);
 919
 920 struct dispatch_rq_data {
 921         struct blk_mq_hw_ctx *hctx;
 922         struct request *rq;
 923 };
 924
 925 static bool dispatch_rq_from_ctx(struct sbitmap *sb, unsigned int bitnr,
 926                 void *data)
 927 {
 928         struct dispatch_rq_data *dispatch_data = data;
 929         struct blk_mq_hw_ctx *hctx = dispatch_data->hctx;
 930         struct blk_mq_ctx *ctx = hctx->ctxs[bitnr];
 931
 932         spin_lock(&ctx->lock);
 933         if (!list_empty(&ctx->rq_list)) {
 934                 dispatch_data->rq = list_entry_rq(ctx->rq_list.next);
 935                 list_del_init(&dispatch_data->rq->queuelist);
 936                 if (list_empty(&ctx->rq_list))
 937                         sbitmap_clear_bit(sb, bitnr);
 938         }
 939         spin_unlock(&ctx->lock);
 940
 941         return !dispatch_data->rq;
 942 }
 943
 944 struct request *blk_mq_dequeue_from_ctx(struct blk_mq_hw_ctx *hctx,
 945                                         struct blk_mq_ctx *start)
 946 {
 947         unsigned off = start ? start->index_hw : 0;
 948         struct dispatch_rq_data data = {
 949                 .hctx = hctx,
 950                 .rq   = NULL,
 951         };
 952
 953         __sbitmap_for_each_set(&hctx->ctx_map, off,
 954                                dispatch_rq_from_ctx, &data);
 955
 956         return data.rq;
 957 }
 958
 959 static inline unsigned int queued_to_index(unsigned int queued)
 960 {
 961         if (!queued)
 962                 return 0;
 963
 964         return min(BLK_MQ_MAX_DISPATCH_ORDER - 1, ilog2(queued) + 1);
 965 }
 966
 967 bool blk_mq_get_driver_tag(struct request *rq, struct blk_mq_hw_ctx **hctx,
 968                            bool wait)
 969 {
 970         struct blk_mq_alloc_data data = {
 971                 .q = rq->q,
 972                 .hctx = blk_mq_map_queue(rq->q, rq->mq_ctx->cpu),
 973                 .flags = wait ? 0 : BLK_MQ_REQ_NOWAIT,
 974         };
 975
 976         might_sleep_if(wait);
 977
 978         if (rq->tag != -1)
 979                 goto done;
 980
 981         if (blk_mq_tag_is_reserved(data.hctx->sched_tags, rq->internal_tag))
 982                 data.flags |= BLK_MQ_REQ_RESERVED;
 983
 984         rq->tag = blk_mq_get_tag(&data);
 985         if (rq->tag >= 0) {
 986                 if (blk_mq_tag_busy(data.hctx)) {
 987                         rq->rq_flags |= RQF_MQ_INFLIGHT;
 988                         atomic_inc(&data.hctx->nr_active);
 989                 }
 990                 data.hctx->tags->rqs[rq->tag] = rq;
 991         }
 992
 993 done:
 994         if (hctx)
 995                 *hctx = data.hctx;
 996         return rq->tag != -1;
 997 }
 998
 999 static int blk_mq_dispatch_wake(wait_queue_entry_t *wait, unsigned mode,
1000                                 int flags, void *key)
1001 {
1002         struct blk_mq_hw_ctx *hctx;
1003
1004         hctx = container_of(wait, struct blk_mq_hw_ctx, dispatch_wait);
1005
1006         list_del_init(&wait->entry);
1007         blk_mq_run_hw_queue(hctx, true);
1008         return 1;
1009 }
1010
1011 /*
1012  * Mark us waiting for a tag. For shared tags, this involves hooking us into
1013  * the tag wakeups. For non-shared tags, we can simply mark us needing a
1014  * restart. For both cases, take care to check the condition again after
1015  * marking us as waiting.
1016  */
1017 static bool blk_mq_mark_tag_wait(struct blk_mq_hw_ctx **hctx,
1018                                  struct request *rq)
1019 {
1020         struct blk_mq_hw_ctx *this_hctx = *hctx;
1021         struct sbq_wait_state *ws;
1022         wait_queue_entry_t *wait;
1023         bool ret;
1024
1025         if (!(this_hctx->flags & BLK_MQ_F_TAG_SHARED)) {
1026                 if (!test_bit(BLK_MQ_S_SCHED_RESTART, &this_hctx->state))
1027                         set_bit(BLK_MQ_S_SCHED_RESTART, &this_hctx->state);
1028
1029                 /*
1030                  * It's possible that a tag was freed in the window between the
1031                  * allocation failure and adding the hardware queue to the wait
1032                  * queue.
1033                  *
1034                  * Don't clear RESTART here, someone else could have set it.
1035                  * At most this will cost an extra queue run.
1036                  */
1037                 return blk_mq_get_driver_tag(rq, hctx, false);
1038         }
1039
1040         wait = &this_hctx->dispatch_wait;
1041         if (!list_empty_careful(&wait->entry))
1042                 return false;
1043
1044         spin_lock(&this_hctx->lock);
1045         if (!list_empty(&wait->entry)) {
1046                 spin_unlock(&this_hctx->lock);
1047                 return false;
1048         }
1049
1050         ws = bt_wait_ptr(&this_hctx->tags->bitmap_tags, this_hctx);
1051         add_wait_queue(&ws->wait, wait);
1052
1053         /*
1054          * It's possible that a tag was freed in the window between the
1055          * allocation failure and adding the hardware queue to the wait
1056          * queue.
1057          */
1058         ret = blk_mq_get_driver_tag(rq, hctx, false);
1059         if (!ret) {
1060                 spin_unlock(&this_hctx->lock);
1061                 return false;
1062         }
1063
1064         /*
1065          * We got a tag, remove ourselves from the wait queue to ensure
1066          * someone else gets the wakeup.
1067          */
1068         spin_lock_irq(&ws->wait.lock);
1069         list_del_init(&wait->entry);
1070         spin_unlock_irq(&ws->wait.lock);
1071         spin_unlock(&this_hctx->lock);
1072
1073         return true;
1074 }
1075
1076 #define BLK_MQ_RESOURCE_DELAY   3               /* ms units */
1077
1078 bool blk_mq_dispatch_rq_list(struct request_queue *q, struct list_head *list,
1079                              bool got_budget)
1080 {
1081         struct blk_mq_hw_ctx *hctx;
1082         struct request *rq, *nxt;
1083         bool no_tag = false;
1084         int errors, queued;
1085         blk_status_t ret = BLK_STS_OK;
1086
1087         if (list_empty(list))
1088                 return false;
1089
1090         WARN_ON(!list_is_singular(list) && got_budget);
1091
1092         /*
1093          * Now process all the entries, sending them to the driver.
1094          */
1095         errors = queued = 0;
1096         do {
1097                 struct blk_mq_queue_data bd;
1098
1099                 rq = list_first_entry(list, struct request, queuelist);
1100
1101                 hctx = blk_mq_map_queue(rq->q, rq->mq_ctx->cpu);
1102                 if (!got_budget && !blk_mq_get_dispatch_budget(hctx))
1103                         break;
1104
1105                 if (!blk_mq_get_driver_tag(rq, NULL, false)) {
1106                         /*
1107                          * The initial allocation attempt failed, so we need to
1108                          * rerun the hardware queue when a tag is freed. The
1109                          * waitqueue takes care of that. If the queue is run
1110                          * before we add this entry back on the dispatch list,
1111                          * we'll re-run it below.
1112                          */
1113                         if (!blk_mq_mark_tag_wait(&hctx, rq)) {
1114                                 blk_mq_put_dispatch_budget(hctx);
1115                                 /*
1116                                  * For non-shared tags, the RESTART check
1117                                  * will suffice.
1118                                  */
1119                                 if (hctx->flags & BLK_MQ_F_TAG_SHARED)
1120                                         no_tag = true;
1121                                 break;
1122                         }
1123                 }
1124
1125                 list_del_init(&rq->queuelist);
1126
1127                 bd.rq = rq;
1128
1129                 /*
1130                  * Flag last if we have no more requests, or if we have more
1131                  * but can't assign a driver tag to it.
1132                  */
1133                 if (list_empty(list))
1134                         bd.last = true;
1135                 else {
1136                         nxt = list_first_entry(list, struct request, queuelist);
1137                         bd.last = !blk_mq_get_driver_tag(nxt, NULL, false);
1138                 }
1139
1140                 ret = q->mq_ops->queue_rq(hctx, &bd);
1141                 if (ret == BLK_STS_RESOURCE || ret == BLK_STS_DEV_RESOURCE) {
1142                         /*
1143                          * If an I/O scheduler has been configured and we got a
1144                          * driver tag for the next request already, free it
1145                          * again.
1146                          */
1147                         if (!list_empty(list)) {
1148                                 nxt = list_first_entry(list, struct request, queuelist);
1149                                 blk_mq_put_driver_tag(nxt);
1150                         }
1151                         list_add(&rq->queuelist, list);
1152                         __blk_mq_requeue_request(rq);
1153                         break;
1154                 }
1155
1156                 if (unlikely(ret != BLK_STS_OK)) {
1157                         errors++;
1158                         blk_mq_end_request(rq, BLK_STS_IOERR);
1159                         continue;
1160                 }
1161
1162                 queued++;
1163         } while (!list_empty(list));
1164
1165         hctx->dispatched[queued_to_index(queued)]++;
1166
1167         /*
1168          * Any items that need requeuing? Stuff them into hctx->dispatch,
1169          * that is where we will continue on next queue run.
1170          */
1171         if (!list_empty(list)) {
1172                 bool needs_restart;
1173
1174                 spin_lock(&hctx->lock);
1175                 list_splice_init(list, &hctx->dispatch);
1176                 spin_unlock(&hctx->lock);
1177
1178                 /*
1179                  * If SCHED_RESTART was set by the caller of this function and
1180                  * it is no longer set that means that it was cleared by another
1181                  * thread and hence that a queue rerun is needed.
1182                  *
1183                  * If 'no_tag' is set, that means that we failed getting
1184                  * a driver tag with an I/O scheduler attached. If our dispatch
1185                  * waitqueue is no longer active, ensure that we run the queue
1186                  * AFTER adding our entries back to the list.
1187                  *
1188                  * If no I/O scheduler has been configured it is possible that
1189                  * the hardware queue got stopped and restarted before requests
1190                  * were pushed back onto the dispatch list. Rerun the queue to
1191                  * avoid starvation. Notes:
1192                  * - blk_mq_run_hw_queue() checks whether or not a queue has
1193                  *   been stopped before rerunning a queue.
1194                  * - Some but not all block drivers stop a queue before
1195                  *   returning BLK_STS_RESOURCE. Two exceptions are scsi-mq
1196                  *   and dm-rq.
1197                  *
1198                  * If driver returns BLK_STS_RESOURCE and SCHED_RESTART
1199                  * bit is set, run queue after a delay to avoid IO stalls
1200                  * that could otherwise occur if the queue is idle.
1201                  */
1202                 needs_restart = blk_mq_sched_needs_restart(hctx);
1203                 if (!needs_restart ||
1204                     (no_tag && list_empty_careful(&hctx->dispatch_wait.entry)))
1205                         blk_mq_run_hw_queue(hctx, true);
1206                 else if (needs_restart && (ret == BLK_STS_RESOURCE))
1207                         blk_mq_delay_run_hw_queue(hctx, BLK_MQ_RESOURCE_DELAY);
1208         }
1209
1210         return (queued + errors) != 0;
1211 }
1212
1213 static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx)
1214 {
1215         int srcu_idx;
1216
1217         /*
1218          * We should be running this queue from one of the CPUs that
1219          * are mapped to it.
1220          *
1221          * There are at least two related races now between setting
1222          * hctx->next_cpu from blk_mq_hctx_next_cpu() and running
1223          * __blk_mq_run_hw_queue():
1224          *
1225          * - hctx->next_cpu is found offline in blk_mq_hctx_next_cpu(),
1226          *   but later it becomes online, then this warning is harmless
1227          *   at all
1228          *
1229          * - hctx->next_cpu is found online in blk_mq_hctx_next_cpu(),
1230          *   but later it becomes offline, then the warning can't be
1231          *   triggered, and we depend on blk-mq timeout handler to
1232          *   handle dispatched requests to this hctx
1233          */
1234         if (!cpumask_test_cpu(raw_smp_processor_id(), hctx->cpumask) &&
1235                 cpu_online(hctx->next_cpu)) {
1236                 printk(KERN_WARNING "run queue from wrong CPU %d, hctx %s\n",
1237                         raw_smp_processor_id(),
1238                         cpumask_empty(hctx->cpumask) ? "inactive": "active");
1239                 dump_stack();
1240         }
1241
1242         /*
1243          * We can't run the queue inline with ints disabled. Ensure that
1244          * we catch bad users of this early.
1245          */
1246         WARN_ON_ONCE(in_interrupt());
1247
1248         might_sleep_if(hctx->flags & BLK_MQ_F_BLOCKING);
1249
1250         hctx_lock(hctx, &srcu_idx);
1251         blk_mq_sched_dispatch_requests(hctx);
1252         hctx_unlock(hctx, srcu_idx);
1253 }
1254
1255 static inline int blk_mq_first_mapped_cpu(struct blk_mq_hw_ctx *hctx)
1256 {
1257         int cpu = cpumask_first_and(hctx->cpumask, cpu_online_mask);
1258
1259         if (cpu >= nr_cpu_ids)
1260                 cpu = cpumask_first(hctx->cpumask);
1261         return cpu;
1262 }
1263
1264 /*
1265  * It'd be great if the workqueue API had a way to pass
1266  * in a mask and had some smarts for more clever placement.
1267  * For now we just round-robin here, switching for every
1268  * BLK_MQ_CPU_WORK_BATCH queued items.
1269  */
1270 static int blk_mq_hctx_next_cpu(struct blk_mq_hw_ctx *hctx)
1271 {
1272         bool tried = false;
1273         int next_cpu = hctx->next_cpu;
1274
1275         if (hctx->queue->nr_hw_queues == 1)
1276                 return WORK_CPU_UNBOUND;
1277
1278         if (--hctx->next_cpu_batch <= 0) {
1279 select_cpu:
1280                 next_cpu = cpumask_next_and(next_cpu, hctx->cpumask,
1281                                 cpu_online_mask);
1282                 if (next_cpu >= nr_cpu_ids)
1283                         next_cpu = blk_mq_first_mapped_cpu(hctx);
1284                 hctx->next_cpu_batch = BLK_MQ_CPU_WORK_BATCH;
1285         }
1286
1287         /*
1288          * Do unbound schedule if we can't find a online CPU for this hctx,
1289          * and it should only happen in the path of handling CPU DEAD.
1290          */
1291         if (!cpu_online(next_cpu)) {
1292                 if (!tried) {
1293                         tried = true;
1294                         goto select_cpu;
1295                 }
1296
1297                 /*
1298                  * Make sure to re-select CPU next time once after CPUs
1299                  * in hctx->cpumask become online again.
1300                  */
1301                 hctx->next_cpu = next_cpu;
1302                 hctx->next_cpu_batch = 1;
1303                 return WORK_CPU_UNBOUND;
1304         }
1305
1306         hctx->next_cpu = next_cpu;
1307         return next_cpu;
1308 }
1309
1310 static void __blk_mq_delay_run_hw_queue(struct blk_mq_hw_ctx *hctx, bool async,
1311                                         unsigned long msecs)
1312 {
1313         if (unlikely(blk_mq_hctx_stopped(hctx)))
1314                 return;
1315
1316         if (!async && !(hctx->flags & BLK_MQ_F_BLOCKING)) {
1317                 int cpu = get_cpu();
1318                 if (cpumask_test_cpu(cpu, hctx->cpumask)) {
1319                         __blk_mq_run_hw_queue(hctx);
1320                         put_cpu();
1321                         return;
1322                 }
1323
1324                 put_cpu();
1325         }
1326
1327         kblockd_mod_delayed_work_on(blk_mq_hctx_next_cpu(hctx), &hctx->run_work,
1328                                     msecs_to_jiffies(msecs));
1329 }
1330
1331 void blk_mq_delay_run_hw_queue(struct blk_mq_hw_ctx *hctx, unsigned long msecs)
1332 {
1333         __blk_mq_delay_run_hw_queue(hctx, true, msecs);
1334 }
1335 EXPORT_SYMBOL(blk_mq_delay_run_hw_queue);
1336
1337 bool blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx, bool async)
1338 {
1339         int srcu_idx;
1340         bool need_run;
1341
1342         /*
1343          * When queue is quiesced, we may be switching io scheduler, or
1344          * updating nr_hw_queues, or other things, and we can't run queue
1345          * any more, even __blk_mq_hctx_has_pending() can't be called safely.
1346          *
1347          * And queue will be rerun in blk_mq_unquiesce_queue() if it is
1348          * quiesced.
1349          */
1350         hctx_lock(hctx, &srcu_idx);
1351         need_run = !blk_queue_quiesced(hctx->queue) &&
1352                 blk_mq_hctx_has_pending(hctx);
1353         hctx_unlock(hctx, srcu_idx);
1354
1355         if (need_run) {
1356                 __blk_mq_delay_run_hw_queue(hctx, async, 0);
1357                 return true;
1358         }
1359
1360         return false;
1361 }
1362 EXPORT_SYMBOL(blk_mq_run_hw_queue);
1363
1364 void blk_mq_run_hw_queues(struct request_queue *q, bool async)
1365 {
1366         struct blk_mq_hw_ctx *hctx;
1367         int i;
1368
1369         queue_for_each_hw_ctx(q, hctx, i) {
1370                 if (blk_mq_hctx_stopped(hctx))
1371                         continue;
1372
1373                 blk_mq_run_hw_queue(hctx, async);
1374         }
1375 }
1376 EXPORT_SYMBOL(blk_mq_run_hw_queues);
1377
1378 /**
1379  * blk_mq_queue_stopped() - check whether one or more hctxs have been stopped
1380  * @q: request queue.
1381  *
1382  * The caller is responsible for serializing this function against
1383  * blk_mq_{start,stop}_hw_queue().
1384  */
1385 bool blk_mq_queue_stopped(struct request_queue *q)
1386 {
1387         struct blk_mq_hw_ctx *hctx;
1388         int i;
1389
1390         queue_for_each_hw_ctx(q, hctx, i)
1391                 if (blk_mq_hctx_stopped(hctx))
1392                         return true;
1393
1394         return false;
1395 }
1396 EXPORT_SYMBOL(blk_mq_queue_stopped);
1397
1398 /*
1399  * This function is often used for pausing .queue_rq() by driver when
1400  * there isn't enough resource or some conditions aren't satisfied, and
1401  * BLK_STS_RESOURCE is usually returned.
1402  *
1403  * We do not guarantee that dispatch can be drained or blocked
1404  * after blk_mq_stop_hw_queue() returns. Please use
1405  * blk_mq_quiesce_queue() for that requirement.
1406  */
1407 void blk_mq_stop_hw_queue(struct blk_mq_hw_ctx *hctx)
1408 {
1409         cancel_delayed_work(&hctx->run_work);
1410
1411         set_bit(BLK_MQ_S_STOPPED, &hctx->state);
1412 }
1413 EXPORT_SYMBOL(blk_mq_stop_hw_queue);
1414
1415 /*
1416  * This function is often used for pausing .queue_rq() by driver when
1417  * there isn't enough resource or some conditions aren't satisfied, and
1418  * BLK_STS_RESOURCE is usually returned.
1419  *
1420  * We do not guarantee that dispatch can be drained or blocked
1421  * after blk_mq_stop_hw_queues() returns. Please use
1422  * blk_mq_quiesce_queue() for that requirement.
1423  */
1424 void blk_mq_stop_hw_queues(struct request_queue *q)
1425 {
1426         struct blk_mq_hw_ctx *hctx;
1427         int i;
1428
1429         queue_for_each_hw_ctx(q, hctx, i)
1430                 blk_mq_stop_hw_queue(hctx);
1431 }
1432 EXPORT_SYMBOL(blk_mq_stop_hw_queues);
1433
1434 void blk_mq_start_hw_queue(struct blk_mq_hw_ctx *hctx)
1435 {
1436         clear_bit(BLK_MQ_S_STOPPED, &hctx->state);
1437
1438         blk_mq_run_hw_queue(hctx, false);
1439 }
1440 EXPORT_SYMBOL(blk_mq_start_hw_queue);
1441
1442 void blk_mq_start_hw_queues(struct request_queue *q)
1443 {
1444         struct blk_mq_hw_ctx *hctx;
1445         int i;
1446
1447         queue_for_each_hw_ctx(q, hctx, i)
1448                 blk_mq_start_hw_queue(hctx);
1449 }
1450 EXPORT_SYMBOL(blk_mq_start_hw_queues);
1451
1452 void blk_mq_start_stopped_hw_queue(struct blk_mq_hw_ctx *hctx, bool async)
1453 {
1454         if (!blk_mq_hctx_stopped(hctx))
1455                 return;
1456
1457         clear_bit(BLK_MQ_S_STOPPED, &hctx->state);
1458         blk_mq_run_hw_queue(hctx, async);
1459 }
1460 EXPORT_SYMBOL_GPL(blk_mq_start_stopped_hw_queue);
1461
1462 void blk_mq_start_stopped_hw_queues(struct request_queue *q, bool async)
1463 {
1464         struct blk_mq_hw_ctx *hctx;
1465         int i;
1466
1467         queue_for_each_hw_ctx(q, hctx, i)
1468                 blk_mq_start_stopped_hw_queue(hctx, async);
1469 }
1470 EXPORT_SYMBOL(blk_mq_start_stopped_hw_queues);
1471
1472 static void blk_mq_run_work_fn(struct work_struct *work)
1473 {
1474         struct blk_mq_hw_ctx *hctx;
1475
1476         hctx = container_of(work, struct blk_mq_hw_ctx, run_work.work);
1477
1478         /*
1479          * If we are stopped, don't run the queue.
1480          */
1481         if (test_bit(BLK_MQ_S_STOPPED, &hctx->state))
1482                 return;
1483
1484         __blk_mq_run_hw_queue(hctx);
1485 }
1486
1487 static inline void __blk_mq_insert_req_list(struct blk_mq_hw_ctx *hctx,
1488                                             struct request *rq,
1489                                             bool at_head)
1490 {
1491         struct blk_mq_ctx *ctx = rq->mq_ctx;
1492
1493         lockdep_assert_held(&ctx->lock);
1494
1495         trace_block_rq_insert(hctx->queue, rq);
1496
1497         if (at_head)
1498                 list_add(&rq->queuelist, &ctx->rq_list);
1499         else
1500                 list_add_tail(&rq->queuelist, &ctx->rq_list);
1501 }
1502
1503 void __blk_mq_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq,
1504                              bool at_head)
1505 {
1506         struct blk_mq_ctx *ctx = rq->mq_ctx;
1507
1508         lockdep_assert_held(&ctx->lock);
1509
1510         __blk_mq_insert_req_list(hctx, rq, at_head);
1511         blk_mq_hctx_mark_pending(hctx, ctx);
1512 }
1513
1514 /*
1515  * Should only be used carefully, when the caller knows we want to
1516  * bypass a potential IO scheduler on the target device.
1517  */
1518 void blk_mq_request_bypass_insert(struct request *rq, bool run_queue)
1519 {
1520         struct blk_mq_ctx *ctx = rq->mq_ctx;
1521         struct blk_mq_hw_ctx *hctx = blk_mq_map_queue(rq->q, ctx->cpu);
1522
1523         spin_lock(&hctx->lock);
1524         list_add_tail(&rq->queuelist, &hctx->dispatch);
1525         spin_unlock(&hctx->lock);
1526
1527         if (run_queue)
1528                 blk_mq_run_hw_queue(hctx, false);
1529 }
1530
1531 void blk_mq_insert_requests(struct blk_mq_hw_ctx *hctx, struct blk_mq_ctx *ctx,
1532                             struct list_head *list)
1533
1534 {
1535         /*
1536          * preemption doesn't flush plug list, so it's possible ctx->cpu is
1537          * offline now
1538          */
1539         spin_lock(&ctx->lock);
1540         while (!list_empty(list)) {
1541                 struct request *rq;
1542
1543                 rq = list_first_entry(list, struct request, queuelist);
1544                 BUG_ON(rq->mq_ctx != ctx);
1545                 list_del_init(&rq->queuelist);
1546                 __blk_mq_insert_req_list(hctx, rq, false);
1547         }
1548         blk_mq_hctx_mark_pending(hctx, ctx);
1549         spin_unlock(&ctx->lock);
1550 }
1551
1552 static int plug_ctx_cmp(void *priv, struct list_head *a, struct list_head *b)
1553 {
1554         struct request *rqa = container_of(a, struct request, queuelist);
1555         struct request *rqb = container_of(b, struct request, queuelist);
1556
1557         return !(rqa->mq_ctx < rqb->mq_ctx ||
1558                  (rqa->mq_ctx == rqb->mq_ctx &&
1559                   blk_rq_pos(rqa) < blk_rq_pos(rqb)));
1560 }
1561
1562 void blk_mq_flush_plug_list(struct blk_plug *plug, bool from_schedule)
1563 {
1564         struct blk_mq_ctx *this_ctx;
1565         struct request_queue *this_q;
1566         struct request *rq;
1567         LIST_HEAD(list);
1568         LIST_HEAD(ctx_list);
1569         unsigned int depth;
1570
1571         list_splice_init(&plug->mq_list, &list);
1572
1573         list_sort(NULL, &list, plug_ctx_cmp);
1574
1575         this_q = NULL;
1576         this_ctx = NULL;
1577         depth = 0;
1578
1579         while (!list_empty(&list)) {
1580                 rq = list_entry_rq(list.next);
1581                 list_del_init(&rq->queuelist);
1582                 BUG_ON(!rq->q);
1583                 if (rq->mq_ctx != this_ctx) {
1584                         if (this_ctx) {
1585                                 trace_block_unplug(this_q, depth, from_schedule);
1586                                 blk_mq_sched_insert_requests(this_q, this_ctx,
1587                                                                 &ctx_list,
1588                                                                 from_schedule);
1589                         }
1590
1591                         this_ctx = rq->mq_ctx;
1592                         this_q = rq->q;
1593                         depth = 0;
1594                 }
1595
1596                 depth++;
1597                 list_add_tail(&rq->queuelist, &ctx_list);
1598         }
1599
1600         /*
1601          * If 'this_ctx' is set, we know we have entries to complete
1602          * on 'ctx_list'. Do those.
1603          */
1604         if (this_ctx) {
1605                 trace_block_unplug(this_q, depth, from_schedule);
1606                 blk_mq_sched_insert_requests(this_q, this_ctx, &ctx_list,
1607                                                 from_schedule);
1608         }
1609 }
1610
1611 static void blk_mq_bio_to_request(struct request *rq, struct bio *bio)
1612 {
1613         blk_init_request_from_bio(rq, bio);
1614
1615         blk_rq_set_rl(rq, blk_get_rl(rq->q, bio));
1616
1617         blk_account_io_start(rq, true);
1618 }
1619
1620 static blk_qc_t request_to_qc_t(struct blk_mq_hw_ctx *hctx, struct request *rq)
1621 {
1622         if (rq->tag != -1)
1623                 return blk_tag_to_qc_t(rq->tag, hctx->queue_num, false);
1624
1625         return blk_tag_to_qc_t(rq->internal_tag, hctx->queue_num, true);
1626 }
1627
1628 static blk_status_t __blk_mq_issue_directly(struct blk_mq_hw_ctx *hctx,
1629                                             struct request *rq,
1630                                             blk_qc_t *cookie)
1631 {
1632         struct request_queue *q = rq->q;
1633         struct blk_mq_queue_data bd = {
1634                 .rq = rq,
1635                 .last = true,
1636         };
1637         blk_qc_t new_cookie;
1638         blk_status_t ret;
1639
1640         new_cookie = request_to_qc_t(hctx, rq);
1641
1642         /*
1643          * For OK queue, we are done. For error, caller may kill it.
1644          * Any other error (busy), just add it to our list as we
1645          * previously would have done.
1646          */
1647         ret = q->mq_ops->queue_rq(hctx, &bd);
1648         switch (ret) {
1649         case BLK_STS_OK:
1650                 *cookie = new_cookie;
1651                 break;
1652         case BLK_STS_RESOURCE:
1653         case BLK_STS_DEV_RESOURCE:
1654                 __blk_mq_requeue_request(rq);
1655                 break;
1656         default:
1657                 *cookie = BLK_QC_T_NONE;
1658                 break;
1659         }
1660
1661         return ret;
1662 }
1663
1664 static blk_status_t __blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx,
1665                                                 struct request *rq,
1666                                                 blk_qc_t *cookie,
1667                                                 bool bypass_insert)
1668 {
1669         struct request_queue *q = rq->q;
1670         bool run_queue = true;
1671
1672         /*
1673          * RCU or SRCU read lock is needed before checking quiesced flag.
1674          *
1675          * When queue is stopped or quiesced, ignore 'bypass_insert' from
1676          * blk_mq_request_issue_directly(), and return BLK_STS_OK to caller,
1677          * and avoid driver to try to dispatch again.
1678          */
1679         if (blk_mq_hctx_stopped(hctx) || blk_queue_quiesced(q)) {
1680                 run_queue = false;
1681                 bypass_insert = false;
1682                 goto insert;
1683         }
1684
1685         if (q->elevator && !bypass_insert)
1686                 goto insert;
1687
1688         if (!blk_mq_get_dispatch_budget(hctx))
1689                 goto insert;
1690
1691         if (!blk_mq_get_driver_tag(rq, NULL, false)) {
1692                 blk_mq_put_dispatch_budget(hctx);
1693                 goto insert;
1694         }
1695
1696         return __blk_mq_issue_directly(hctx, rq, cookie);
1697 insert:
1698         if (bypass_insert)
1699                 return BLK_STS_RESOURCE;
1700
1701         blk_mq_sched_insert_request(rq, false, run_queue, false);
1702         return BLK_STS_OK;
1703 }
1704
1705 static void blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx,
1706                 struct request *rq, blk_qc_t *cookie)
1707 {
1708         blk_status_t ret;
1709         int srcu_idx;
1710
1711         might_sleep_if(hctx->flags & BLK_MQ_F_BLOCKING);
1712
1713         hctx_lock(hctx, &srcu_idx);
1714
1715         ret = __blk_mq_try_issue_directly(hctx, rq, cookie, false);
1716         if (ret == BLK_STS_RESOURCE || ret == BLK_STS_DEV_RESOURCE)
1717                 blk_mq_sched_insert_request(rq, false, true, false);
1718         else if (ret != BLK_STS_OK)
1719                 blk_mq_end_request(rq, ret);
1720
1721         hctx_unlock(hctx, srcu_idx);
1722 }
1723
1724 blk_status_t blk_mq_request_issue_directly(struct request *rq)
1725 {
1726         blk_status_t ret;
1727         int srcu_idx;
1728         blk_qc_t unused_cookie;
1729         struct blk_mq_ctx *ctx = rq->mq_ctx;
1730         struct blk_mq_hw_ctx *hctx = blk_mq_map_queue(rq->q, ctx->cpu);
1731
1732         hctx_lock(hctx, &srcu_idx);
1733         ret = __blk_mq_try_issue_directly(hctx, rq, &unused_cookie, true);
1734         hctx_unlock(hctx, srcu_idx);
1735
1736         return ret;
1737 }
1738
1739 static blk_qc_t blk_mq_make_request(struct request_queue *q, struct bio *bio)
1740 {
1741         const int is_sync = op_is_sync(bio->bi_opf);
1742         const int is_flush_fua = op_is_flush(bio->bi_opf);
1743         struct blk_mq_alloc_data data = { .flags = 0 };
1744         struct request *rq;
1745         unsigned int request_count = 0;
1746         struct blk_plug *plug;
1747         struct request *same_queue_rq = NULL;
1748         blk_qc_t cookie;
1749         unsigned int wb_acct;
1750
1751         blk_queue_bounce(q, &bio);
1752
1753         blk_queue_split(q, &bio);
1754
1755         if (!bio_integrity_prep(bio))
1756                 return BLK_QC_T_NONE;
1757
1758         if (!is_flush_fua && !blk_queue_nomerges(q) &&
1759             blk_attempt_plug_merge(q, bio, &request_count, &same_queue_rq))
1760                 return BLK_QC_T_NONE;
1761
1762         if (blk_mq_sched_bio_merge(q, bio))
1763                 return BLK_QC_T_NONE;
1764
1765         wb_acct = wbt_wait(q->rq_wb, bio, NULL);
1766
1767         trace_block_getrq(q, bio, bio->bi_opf);
1768
1769         rq = blk_mq_get_request(q, bio, bio->bi_opf, &data);
1770         if (unlikely(!rq)) {
1771                 __wbt_done(q->rq_wb, wb_acct);
1772                 if (bio->bi_opf & REQ_NOWAIT)
1773                         bio_wouldblock_error(bio);
1774                 return BLK_QC_T_NONE;
1775         }
1776
1777         wbt_track(rq, wb_acct);
1778
1779         cookie = request_to_qc_t(data.hctx, rq);
1780
1781         plug = current->plug;
1782         if (unlikely(is_flush_fua)) {
1783                 blk_mq_put_ctx(data.ctx);
1784                 blk_mq_bio_to_request(rq, bio);
1785
1786                 /* bypass scheduler for flush rq */
1787                 blk_insert_flush(rq);
1788                 blk_mq_run_hw_queue(data.hctx, true);
1789         } else if (plug && q->nr_hw_queues == 1) {
1790                 struct request *last = NULL;
1791
1792                 blk_mq_put_ctx(data.ctx);
1793                 blk_mq_bio_to_request(rq, bio);
1794
1795                 /*
1796                  * @request_count may become stale because of schedule
1797                  * out, so check the list again.
1798                  */
1799                 if (list_empty(&plug->mq_list))
1800                         request_count = 0;
1801                 else if (blk_queue_nomerges(q))
1802                         request_count = blk_plug_queued_count(q);
1803
1804                 if (!request_count)
1805                         trace_block_plug(q);
1806                 else
1807                         last = list_entry_rq(plug->mq_list.prev);
1808
1809                 if (request_count >= BLK_MAX_REQUEST_COUNT || (last &&
1810                     blk_rq_bytes(last) >= BLK_PLUG_FLUSH_SIZE)) {
1811                         blk_flush_plug_list(plug, false);
1812                         trace_block_plug(q);
1813                 }
1814
1815                 list_add_tail(&rq->queuelist, &plug->mq_list);
1816         } else if (plug && !blk_queue_nomerges(q)) {
1817                 blk_mq_bio_to_request(rq, bio);
1818
1819                 /*
1820                  * We do limited plugging. If the bio can be merged, do that.
1821                  * Otherwise the existing request in the plug list will be
1822                  * issued. So the plug list will have one request at most
1823                  * The plug list might get flushed before this. If that happens,
1824                  * the plug list is empty, and same_queue_rq is invalid.
1825                  */
1826                 if (list_empty(&plug->mq_list))
1827                         same_queue_rq = NULL;
1828                 if (same_queue_rq)
1829                         list_del_init(&same_queue_rq->queuelist);
1830                 list_add_tail(&rq->queuelist, &plug->mq_list);
1831
1832                 blk_mq_put_ctx(data.ctx);
1833
1834                 if (same_queue_rq) {
1835                         data.hctx = blk_mq_map_queue(q,
1836                                         same_queue_rq->mq_ctx->cpu);
1837                         blk_mq_try_issue_directly(data.hctx, same_queue_rq,
1838                                         &cookie);
1839                 }
1840         } else if (q->nr_hw_queues > 1 && is_sync) {
1841                 blk_mq_put_ctx(data.ctx);
1842                 blk_mq_bio_to_request(rq, bio);
1843                 blk_mq_try_issue_directly(data.hctx, rq, &cookie);
1844         } else {
1845                 blk_mq_put_ctx(data.ctx);
1846                 blk_mq_bio_to_request(rq, bio);
1847                 blk_mq_sched_insert_request(rq, false, true, true);
1848         }
1849
1850         return cookie;
1851 }
1852
1853 void blk_mq_free_rqs(struct blk_mq_tag_set *set, struct blk_mq_tags *tags,
1854                      unsigned int hctx_idx)
1855 {
1856         struct page *page;
1857
1858         if (tags->rqs && set->ops->exit_request) {
1859                 int i;
1860
1861                 for (i = 0; i < tags->nr_tags; i++) {
1862                         struct request *rq = tags->static_rqs[i];
1863
1864                         if (!rq)
1865                                 continue;
1866                         set->ops->exit_request(set, rq, hctx_idx);
1867                         tags->static_rqs[i] = NULL;
1868                 }
1869         }
1870
1871         while (!list_empty(&tags->page_list)) {
1872                 page = list_first_entry(&tags->page_list, struct page, lru);
1873                 list_del_init(&page->lru);
1874                 /*
1875                  * Remove kmemleak object previously allocated in
1876                  * blk_mq_init_rq_map().
1877                  */
1878                 kmemleak_free(page_address(page));
1879                 __free_pages(page, page->private);
1880         }
1881 }
1882
1883 void blk_mq_free_rq_map(struct blk_mq_tags *tags)
1884 {
1885         kfree(tags->rqs);
1886         tags->rqs = NULL;
1887         kfree(tags->static_rqs);
1888         tags->static_rqs = NULL;
1889
1890         blk_mq_free_tags(tags);
1891 }
1892
1893 struct blk_mq_tags *blk_mq_alloc_rq_map(struct blk_mq_tag_set *set,
1894                                         unsigned int hctx_idx,
1895                                         unsigned int nr_tags,
1896                                         unsigned int reserved_tags)
1897 {
1898         struct blk_mq_tags *tags;
1899         int node;
1900
1901         node = blk_mq_hw_queue_to_node(set->mq_map, hctx_idx);
1902         if (node == NUMA_NO_NODE)
1903                 node = set->numa_node;
1904
1905         tags = blk_mq_init_tags(nr_tags, reserved_tags, node,
1906                                 BLK_MQ_FLAG_TO_ALLOC_POLICY(set->flags));
1907         if (!tags)
1908                 return NULL;
1909
1910         tags->rqs = kcalloc_node(nr_tags, sizeof(struct request *),
1911                                  GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY,
1912                                  node);
1913         if (!tags->rqs) {
1914                 blk_mq_free_tags(tags);
1915                 return NULL;
1916         }
1917
1918         tags->static_rqs = kcalloc_node(nr_tags, sizeof(struct request *),
1919                                         GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY,
1920                                         node);
1921         if (!tags->static_rqs) {
1922                 kfree(tags->rqs);
1923                 blk_mq_free_tags(tags);
1924                 return NULL;
1925         }
1926
1927         return tags;
1928 }
1929
1930 static size_t order_to_size(unsigned int order)
1931 {
1932         return (size_t)PAGE_SIZE << order;
1933 }
1934
1935 static int blk_mq_init_request(struct blk_mq_tag_set *set, struct request *rq,
1936                                unsigned int hctx_idx, int node)
1937 {
1938         int ret;
1939
1940         if (set->ops->init_request) {
1941                 ret = set->ops->init_request(set, rq, hctx_idx, node);
1942                 if (ret)
1943                         return ret;
1944         }
1945
1946         WRITE_ONCE(rq->state, MQ_RQ_IDLE);
1947         return 0;
1948 }
1949
1950 int blk_mq_alloc_rqs(struct blk_mq_tag_set *set, struct blk_mq_tags *tags,
1951                      unsigned int hctx_idx, unsigned int depth)
1952 {
1953         unsigned int i, j, entries_per_page, max_order = 4;
1954         size_t rq_size, left;
1955         int node;
1956
1957         node = blk_mq_hw_queue_to_node(set->mq_map, hctx_idx);
1958         if (node == NUMA_NO_NODE)
1959                 node = set->numa_node;
1960
1961         INIT_LIST_HEAD(&tags->page_list);
1962
1963         /*
1964          * rq_size is the size of the request plus driver payload, rounded
1965          * to the cacheline size
1966          */
1967         rq_size = round_up(sizeof(struct request) + set->cmd_size,
1968                                 cache_line_size());
1969         left = rq_size * depth;
1970
1971         for (i = 0; i < depth; ) {
1972                 int this_order = max_order;
1973                 struct page *page;
1974                 int to_do;
1975                 void *p;
1976
1977                 while (this_order && left < order_to_size(this_order - 1))
1978                         this_order--;
1979
1980                 do {
1981                         page = alloc_pages_node(node,
1982                                 GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY | __GFP_ZERO,
1983                                 this_order);
1984                         if (page)
1985                                 break;
1986                         if (!this_order--)
1987                                 break;
1988                         if (order_to_size(this_order) < rq_size)
1989                                 break;
1990                 } while (1);
1991
1992                 if (!page)
1993                         goto fail;
1994
1995                 page->private = this_order;
1996                 list_add_tail(&page->lru, &tags->page_list);
1997
1998                 p = page_address(page);
1999                 /*
2000                  * Allow kmemleak to scan these pages as they contain pointers
2001                  * to additional allocations like via ops->init_request().
2002                  */
2003                 kmemleak_alloc(p, order_to_size(this_order), 1, GFP_NOIO);
2004                 entries_per_page = order_to_size(this_order) / rq_size;
2005                 to_do = min(entries_per_page, depth - i);
2006                 left -= to_do * rq_size;
2007                 for (j = 0; j < to_do; j++) {
2008                         struct request *rq = p;
2009
2010                         tags->static_rqs[i] = rq;
2011                         if (blk_mq_init_request(set, rq, hctx_idx, node)) {
2012                                 tags->static_rqs[i] = NULL;
2013                                 goto fail;
2014                         }
2015
2016                         p += rq_size;
2017                         i++;
2018                 }
2019         }
2020         return 0;
2021
2022 fail:
2023         blk_mq_free_rqs(set, tags, hctx_idx);
2024         return -ENOMEM;
2025 }
2026
2027 /*
2028  * 'cpu' is going away. splice any existing rq_list entries from this
2029  * software queue to the hw queue dispatch list, and ensure that it
2030  * gets run.
2031  */
2032 static int blk_mq_hctx_notify_dead(unsigned int cpu, struct hlist_node *node)
2033 {
2034         struct blk_mq_hw_ctx *hctx;
2035         struct blk_mq_ctx *ctx;
2036         LIST_HEAD(tmp);
2037
2038         hctx = hlist_entry_safe(node, struct blk_mq_hw_ctx, cpuhp_dead);
2039         ctx = __blk_mq_get_ctx(hctx->queue, cpu);
2040
2041         spin_lock(&ctx->lock);
2042         if (!list_empty(&ctx->rq_list)) {
2043                 list_splice_init(&ctx->rq_list, &tmp);
2044                 blk_mq_hctx_clear_pending(hctx, ctx);
2045         }
2046         spin_unlock(&ctx->lock);
2047
2048         if (list_empty(&tmp))
2049                 return 0;
2050
2051         spin_lock(&hctx->lock);
2052         list_splice_tail_init(&tmp, &hctx->dispatch);
2053         spin_unlock(&hctx->lock);
2054
2055         blk_mq_run_hw_queue(hctx, true);
2056         return 0;
2057 }
2058
2059 static void blk_mq_remove_cpuhp(struct blk_mq_hw_ctx *hctx)
2060 {
2061         cpuhp_state_remove_instance_nocalls(CPUHP_BLK_MQ_DEAD,
2062                                             &hctx->cpuhp_dead);
2063 }
2064
2065 /* hctx->ctxs will be freed in queue's release handler */
2066 static void blk_mq_exit_hctx(struct request_queue *q,
2067                 struct blk_mq_tag_set *set,
2068                 struct blk_mq_hw_ctx *hctx, unsigned int hctx_idx)
2069 {
2070         blk_mq_debugfs_unregister_hctx(hctx);
2071
2072         if (blk_mq_hw_queue_mapped(hctx))
2073                 blk_mq_tag_idle(hctx);
2074
2075         if (set->ops->exit_request)
2076                 set->ops->exit_request(set, hctx->fq->flush_rq, hctx_idx);
2077
2078         blk_mq_sched_exit_hctx(q, hctx, hctx_idx);
2079
2080         if (set->ops->exit_hctx)
2081                 set->ops->exit_hctx(hctx, hctx_idx);
2082
2083         if (hctx->flags & BLK_MQ_F_BLOCKING)
2084                 cleanup_srcu_struct(hctx->srcu);
2085
2086         blk_mq_remove_cpuhp(hctx);
2087         blk_free_flush_queue(hctx->fq);
2088         sbitmap_free(&hctx->ctx_map);
2089 }
2090
2091 static void blk_mq_exit_hw_queues(struct request_queue *q,
2092                 struct blk_mq_tag_set *set, int nr_queue)
2093 {
2094         struct blk_mq_hw_ctx *hctx;
2095         unsigned int i;
2096
2097         queue_for_each_hw_ctx(q, hctx, i) {
2098                 if (i == nr_queue)
2099                         break;
2100                 blk_mq_exit_hctx(q, set, hctx, i);
2101         }
2102 }
2103
2104 static int blk_mq_init_hctx(struct request_queue *q,
2105                 struct blk_mq_tag_set *set,
2106                 struct blk_mq_hw_ctx *hctx, unsigned hctx_idx)
2107 {
2108         int node;
2109
2110         node = hctx->numa_node;
2111         if (node == NUMA_NO_NODE)
2112                 node = hctx->numa_node = set->numa_node;
2113
2114         INIT_DELAYED_WORK(&hctx->run_work, blk_mq_run_work_fn);
2115         spin_lock_init(&hctx->lock);
2116         INIT_LIST_HEAD(&hctx->dispatch);
2117         hctx->queue = q;
2118         hctx->flags = set->flags & ~BLK_MQ_F_TAG_SHARED;
2119
2120         cpuhp_state_add_instance_nocalls(CPUHP_BLK_MQ_DEAD, &hctx->cpuhp_dead);
2121
2122         hctx->tags = set->tags[hctx_idx];
2123
2124         /*
2125          * Allocate space for all possible cpus to avoid allocation at
2126          * runtime
2127          */
2128         hctx->ctxs = kmalloc_array_node(nr_cpu_ids, sizeof(void *),
2129                                         GFP_KERNEL, node);
2130         if (!hctx->ctxs)
2131                 goto unregister_cpu_notifier;
2132
2133         if (sbitmap_init_node(&hctx->ctx_map, nr_cpu_ids, ilog2(8), GFP_KERNEL,
2134                               node))
2135                 goto free_ctxs;
2136
2137         hctx->nr_ctx = 0;
2138
2139         init_waitqueue_func_entry(&hctx->dispatch_wait, blk_mq_dispatch_wake);
2140         INIT_LIST_HEAD(&hctx->dispatch_wait.entry);
2141
2142         if (set->ops->init_hctx &&
2143             set->ops->init_hctx(hctx, set->driver_data, hctx_idx))
2144                 goto free_bitmap;
2145
2146         if (blk_mq_sched_init_hctx(q, hctx, hctx_idx))
2147                 goto exit_hctx;
2148
2149         hctx->fq = blk_alloc_flush_queue(q, hctx->numa_node, set->cmd_size);
2150         if (!hctx->fq)
2151                 goto sched_exit_hctx;
2152
2153         if (blk_mq_init_request(set, hctx->fq->flush_rq, hctx_idx, node))
2154                 goto free_fq;
2155
2156         if (hctx->flags & BLK_MQ_F_BLOCKING)
2157                 init_srcu_struct(hctx->srcu);
2158
2159         blk_mq_debugfs_register_hctx(q, hctx);
2160
2161         return 0;
2162
2163  free_fq:
2164         kfree(hctx->fq);
2165  sched_exit_hctx:
2166         blk_mq_sched_exit_hctx(q, hctx, hctx_idx);
2167  exit_hctx:
2168         if (set->ops->exit_hctx)
2169                 set->ops->exit_hctx(hctx, hctx_idx);
2170  free_bitmap:
2171         sbitmap_free(&hctx->ctx_map);
2172  free_ctxs:
2173         kfree(hctx->ctxs);
2174  unregister_cpu_notifier:
2175         blk_mq_remove_cpuhp(hctx);
2176         return -1;
2177 }
2178
2179 static void blk_mq_init_cpu_queues(struct request_queue *q,
2180                                    unsigned int nr_hw_queues)
2181 {
2182         unsigned int i;
2183
2184         for_each_possible_cpu(i) {
2185                 struct blk_mq_ctx *__ctx = per_cpu_ptr(q->queue_ctx, i);
2186                 struct blk_mq_hw_ctx *hctx;
2187
2188                 __ctx->cpu = i;
2189                 spin_lock_init(&__ctx->lock);
2190                 INIT_LIST_HEAD(&__ctx->rq_list);
2191                 __ctx->queue = q;
2192
2193                 /*
2194                  * Set local node, IFF we have more than one hw queue. If
2195                  * not, we remain on the home node of the device
2196                  */
2197                 hctx = blk_mq_map_queue(q, i);
2198                 if (nr_hw_queues > 1 && hctx->numa_node == NUMA_NO_NODE)
2199                         hctx->numa_node = local_memory_node(cpu_to_node(i));
2200         }
2201 }
2202
2203 static bool __blk_mq_alloc_rq_map(struct blk_mq_tag_set *set, int hctx_idx)
2204 {
2205         int ret = 0;
2206
2207         set->tags[hctx_idx] = blk_mq_alloc_rq_map(set, hctx_idx,
2208                                         set->queue_depth, set->reserved_tags);
2209         if (!set->tags[hctx_idx])
2210                 return false;
2211
2212         ret = blk_mq_alloc_rqs(set, set->tags[hctx_idx], hctx_idx,
2213                                 set->queue_depth);
2214         if (!ret)
2215                 return true;
2216
2217         blk_mq_free_rq_map(set->tags[hctx_idx]);
2218         set->tags[hctx_idx] = NULL;
2219         return false;
2220 }
2221
2222 static void blk_mq_free_map_and_requests(struct blk_mq_tag_set *set,
2223                                          unsigned int hctx_idx)
2224 {
2225         if (set->tags[hctx_idx]) {
2226                 blk_mq_free_rqs(set, set->tags[hctx_idx], hctx_idx);
2227                 blk_mq_free_rq_map(set->tags[hctx_idx]);
2228                 set->tags[hctx_idx] = NULL;
2229         }
2230 }
2231
2232 static void blk_mq_map_swqueue(struct request_queue *q)
2233 {
2234         unsigned int i, hctx_idx;
2235         struct blk_mq_hw_ctx *hctx;
2236         struct blk_mq_ctx *ctx;
2237         struct blk_mq_tag_set *set = q->tag_set;
2238
2239         /*
2240          * Avoid others reading imcomplete hctx->cpumask through sysfs
2241          */
2242         mutex_lock(&q->sysfs_lock);
2243
2244         queue_for_each_hw_ctx(q, hctx, i) {
2245                 cpumask_clear(hctx->cpumask);
2246                 hctx->nr_ctx = 0;
2247                 hctx->dispatch_from = NULL;
2248         }
2249
2250         /*
2251          * Map software to hardware queues.
2252          *
2253          * If the cpu isn't present, the cpu is mapped to first hctx.
2254          */
2255         for_each_possible_cpu(i) {
2256                 hctx_idx = q->mq_map[i];
2257                 /* unmapped hw queue can be remapped after CPU topo changed */
2258                 if (!set->tags[hctx_idx] &&
2259                     !__blk_mq_alloc_rq_map(set, hctx_idx)) {
2260                         /*
2261                          * If tags initialization fail for some hctx,
2262                          * that hctx won't be brought online.  In this
2263                          * case, remap the current ctx to hctx[0] which
2264                          * is guaranteed to always have tags allocated
2265                          */
2266                         q->mq_map[i] = 0;
2267                 }
2268
2269                 ctx = per_cpu_ptr(q->queue_ctx, i);
2270                 hctx = blk_mq_map_queue(q, i);
2271
2272                 cpumask_set_cpu(i, hctx->cpumask);
2273                 ctx->index_hw = hctx->nr_ctx;
2274                 hctx->ctxs[hctx->nr_ctx++] = ctx;
2275         }
2276
2277         mutex_unlock(&q->sysfs_lock);
2278
2279         queue_for_each_hw_ctx(q, hctx, i) {
2280                 /*
2281                  * If no software queues are mapped to this hardware queue,
2282                  * disable it and free the request entries.
2283                  */
2284                 if (!hctx->nr_ctx) {
2285                         /* Never unmap queue 0.  We need it as a
2286                          * fallback in case of a new remap fails
2287                          * allocation
2288                          */
2289                         if (i && set->tags[i])
2290                                 blk_mq_free_map_and_requests(set, i);
2291
2292                         hctx->tags = NULL;
2293                         continue;
2294                 }
2295
2296                 hctx->tags = set->tags[i];
2297                 WARN_ON(!hctx->tags);
2298
2299                 /*
2300                  * Set the map size to the number of mapped software queues.
2301                  * This is more accurate and more efficient than looping
2302                  * over all possibly mapped software queues.
2303                  */
2304                 sbitmap_resize(&hctx->ctx_map, hctx->nr_ctx);
2305
2306                 /*
2307                  * Initialize batch roundrobin counts
2308                  */
2309                 hctx->next_cpu = blk_mq_first_mapped_cpu(hctx);
2310                 hctx->next_cpu_batch = BLK_MQ_CPU_WORK_BATCH;
2311         }
2312 }
2313
2314 /*
2315  * Caller needs to ensure that we're either frozen/quiesced, or that
2316  * the queue isn't live yet.
2317  */
2318 static void queue_set_hctx_shared(struct request_queue *q, bool shared)
2319 {
2320         struct blk_mq_hw_ctx *hctx;
2321         int i;
2322
2323         queue_for_each_hw_ctx(q, hctx, i) {
2324                 if (shared) {
2325                         if (test_bit(BLK_MQ_S_SCHED_RESTART, &hctx->state))
2326                                 atomic_inc(&q->shared_hctx_restart);
2327                         hctx->flags |= BLK_MQ_F_TAG_SHARED;
2328                 } else {
2329                         if (test_bit(BLK_MQ_S_SCHED_RESTART, &hctx->state))
2330                                 atomic_dec(&q->shared_hctx_restart);
2331                         hctx->flags &= ~BLK_MQ_F_TAG_SHARED;
2332                 }
2333         }
2334 }
2335
2336 static void blk_mq_update_tag_set_depth(struct blk_mq_tag_set *set,
2337                                         bool shared)
2338 {
2339         struct request_queue *q;
2340
2341         lockdep_assert_held(&set->tag_list_lock);
2342
2343         list_for_each_entry(q, &set->tag_list, tag_set_list) {
2344                 blk_mq_freeze_queue(q);
2345                 queue_set_hctx_shared(q, shared);
2346                 blk_mq_unfreeze_queue(q);
2347         }
2348 }
2349
2350 static void blk_mq_del_queue_tag_set(struct request_queue *q)
2351 {
2352         struct blk_mq_tag_set *set = q->tag_set;
2353
2354         mutex_lock(&set->tag_list_lock);
2355         list_del_rcu(&q->tag_set_list);
2356         if (list_is_singular(&set->tag_list)) {
2357                 /* just transitioned to unshared */
2358                 set->flags &= ~BLK_MQ_F_TAG_SHARED;
2359                 /* update existing queue */
2360                 blk_mq_update_tag_set_depth(set, false);
2361         }
2362         mutex_unlock(&set->tag_list_lock);
2363         synchronize_rcu();
2364         INIT_LIST_HEAD(&q->tag_set_list);
2365 }
2366
2367 static void blk_mq_add_queue_tag_set(struct blk_mq_tag_set *set,
2368                                      struct request_queue *q)
2369 {
2370         q->tag_set = set;
2371
2372         mutex_lock(&set->tag_list_lock);
2373
2374         /*
2375          * Check to see if we're transitioning to shared (from 1 to 2 queues).
2376          */
2377         if (!list_empty(&set->tag_list) &&
2378             !(set->flags & BLK_MQ_F_TAG_SHARED)) {
2379                 set->flags |= BLK_MQ_F_TAG_SHARED;
2380                 /* update existing queue */
2381                 blk_mq_update_tag_set_depth(set, true);
2382         }
2383         if (set->flags & BLK_MQ_F_TAG_SHARED)
2384                 queue_set_hctx_shared(q, true);
2385         list_add_tail_rcu(&q->tag_set_list, &set->tag_list);
2386
2387         mutex_unlock(&set->tag_list_lock);
2388 }
2389
2390 /*
2391  * It is the actual release handler for mq, but we do it from
2392  * request queue's release handler for avoiding use-after-free
2393  * and headache because q->mq_kobj shouldn't have been introduced,
2394  * but we can't group ctx/kctx kobj without it.
2395  */
2396 void blk_mq_release(struct request_queue *q)
2397 {
2398         struct blk_mq_hw_ctx *hctx;
2399         unsigned int i;
2400
2401         /* hctx kobj stays in hctx */
2402         queue_for_each_hw_ctx(q, hctx, i) {
2403                 if (!hctx)
2404                         continue;
2405                 kobject_put(&hctx->kobj);
2406         }
2407
2408         q->mq_map = NULL;
2409
2410         kfree(q->queue_hw_ctx);
2411
2412         /*
2413          * release .mq_kobj and sw queue's kobject now because
2414          * both share lifetime with request queue.
2415          */
2416         blk_mq_sysfs_deinit(q);
2417
2418         free_percpu(q->queue_ctx);
2419 }
2420
2421 struct request_queue *blk_mq_init_queue(struct blk_mq_tag_set *set)
2422 {
2423         struct request_queue *uninit_q, *q;
2424
2425         uninit_q = blk_alloc_queue_node(GFP_KERNEL, set->numa_node, NULL);
2426         if (!uninit_q)
2427                 return ERR_PTR(-ENOMEM);
2428
2429         q = blk_mq_init_allocated_queue(set, uninit_q);
2430         if (IS_ERR(q))
2431                 blk_cleanup_queue(uninit_q);
2432
2433         return q;
2434 }
2435 EXPORT_SYMBOL(blk_mq_init_queue);
2436
2437 static int blk_mq_hw_ctx_size(struct blk_mq_tag_set *tag_set)
2438 {
2439         int hw_ctx_size = sizeof(struct blk_mq_hw_ctx);
2440
2441         BUILD_BUG_ON(ALIGN(offsetof(struct blk_mq_hw_ctx, srcu),
2442                            __alignof__(struct blk_mq_hw_ctx)) !=
2443                      sizeof(struct blk_mq_hw_ctx));
2444
2445         if (tag_set->flags & BLK_MQ_F_BLOCKING)
2446                 hw_ctx_size += sizeof(struct srcu_struct);
2447
2448         return hw_ctx_size;
2449 }
2450
2451 static void blk_mq_realloc_hw_ctxs(struct blk_mq_tag_set *set,
2452                                                 struct request_queue *q)
2453 {
2454         int i, j;
2455         struct blk_mq_hw_ctx **hctxs = q->queue_hw_ctx;
2456
2457         blk_mq_sysfs_unregister(q);
2458
2459         /* protect against switching io scheduler  */
2460         mutex_lock(&q->sysfs_lock);
2461         for (i = 0; i < set->nr_hw_queues; i++) {
2462                 int node;
2463
2464                 if (hctxs[i])
2465                         continue;
2466
2467                 node = blk_mq_hw_queue_to_node(q->mq_map, i);
2468                 hctxs[i] = kzalloc_node(blk_mq_hw_ctx_size(set),
2469                                         GFP_KERNEL, node);
2470                 if (!hctxs[i])
2471                         break;
2472
2473                 if (!zalloc_cpumask_var_node(&hctxs[i]->cpumask, GFP_KERNEL,
2474                                                 node)) {
2475                         kfree(hctxs[i]);
2476                         hctxs[i] = NULL;
2477                         break;
2478                 }
2479
2480                 atomic_set(&hctxs[i]->nr_active, 0);
2481                 hctxs[i]->numa_node = node;
2482                 hctxs[i]->queue_num = i;
2483
2484                 if (blk_mq_init_hctx(q, set, hctxs[i], i)) {
2485                         free_cpumask_var(hctxs[i]->cpumask);
2486                         kfree(hctxs[i]);
2487                         hctxs[i] = NULL;
2488                         break;
2489                 }
2490                 blk_mq_hctx_kobj_init(hctxs[i]);
2491         }
2492         for (j = i; j < q->nr_hw_queues; j++) {
2493                 struct blk_mq_hw_ctx *hctx = hctxs[j];
2494
2495                 if (hctx) {
2496                         if (hctx->tags)
2497                                 blk_mq_free_map_and_requests(set, j);
2498                         blk_mq_exit_hctx(q, set, hctx, j);
2499                         kobject_put(&hctx->kobj);
2500                         hctxs[j] = NULL;
2501
2502                 }
2503         }
2504         q->nr_hw_queues = i;
2505         mutex_unlock(&q->sysfs_lock);
2506         blk_mq_sysfs_register(q);
2507 }
2508
2509 struct request_queue *blk_mq_init_allocated_queue(struct blk_mq_tag_set *set,
2510                                                   struct request_queue *q)
2511 {
2512         /* mark the queue as mq asap */
2513         q->mq_ops = set->ops;
2514
2515         q->poll_cb = blk_stat_alloc_callback(blk_mq_poll_stats_fn,
2516                                              blk_mq_poll_stats_bkt,
2517                                              BLK_MQ_POLL_STATS_BKTS, q);
2518         if (!q->poll_cb)
2519                 goto err_exit;
2520
2521         q->queue_ctx = alloc_percpu(struct blk_mq_ctx);
2522         if (!q->queue_ctx)
2523                 goto err_exit;
2524
2525         /* init q->mq_kobj and sw queues' kobjects */
2526         blk_mq_sysfs_init(q);
2527
2528         q->queue_hw_ctx = kcalloc_node(nr_cpu_ids, sizeof(*(q->queue_hw_ctx)),
2529                                                 GFP_KERNEL, set->numa_node);
2530         if (!q->queue_hw_ctx)
2531                 goto err_percpu;
2532
2533         q->mq_map = set->mq_map;
2534
2535         blk_mq_realloc_hw_ctxs(set, q);
2536         if (!q->nr_hw_queues)
2537                 goto err_hctxs;
2538
2539         INIT_WORK(&q->timeout_work, blk_mq_timeout_work);
2540         blk_queue_rq_timeout(q, set->timeout ? set->timeout : 30 * HZ);
2541
2542         q->nr_queues = nr_cpu_ids;
2543
2544         q->queue_flags |= QUEUE_FLAG_MQ_DEFAULT;
2545
2546         if (!(set->flags & BLK_MQ_F_SG_MERGE))
2547                 queue_flag_set_unlocked(QUEUE_FLAG_NO_SG_MERGE, q);
2548
2549         q->sg_reserved_size = INT_MAX;
2550
2551         INIT_DELAYED_WORK(&q->requeue_work, blk_mq_requeue_work);
2552         INIT_LIST_HEAD(&q->requeue_list);
2553         spin_lock_init(&q->requeue_lock);
2554
2555         blk_queue_make_request(q, blk_mq_make_request);
2556         if (q->mq_ops->poll)
2557                 q->poll_fn = blk_mq_poll;
2558
2559         /*
2560          * Do this after blk_queue_make_request() overrides it...
2561          */
2562         q->nr_requests = set->queue_depth;
2563
2564         /*
2565          * Default to classic polling
2566          */
2567         q->poll_nsec = -1;
2568
2569         if (set->ops->complete)
2570                 blk_queue_softirq_done(q, set->ops->complete);
2571
2572         blk_mq_init_cpu_queues(q, set->nr_hw_queues);
2573         blk_mq_add_queue_tag_set(set, q);
2574         blk_mq_map_swqueue(q);
2575
2576         if (!(set->flags & BLK_MQ_F_NO_SCHED)) {
2577                 int ret;
2578
2579                 ret = elevator_init_mq(q);
2580                 if (ret)
2581                         return ERR_PTR(ret);
2582         }
2583
2584         return q;
2585
2586 err_hctxs:
2587         kfree(q->queue_hw_ctx);
2588 err_percpu:
2589         free_percpu(q->queue_ctx);
2590 err_exit:
2591         q->mq_ops = NULL;
2592         return ERR_PTR(-ENOMEM);
2593 }
2594 EXPORT_SYMBOL(blk_mq_init_allocated_queue);
2595
2596 void blk_mq_free_queue(struct request_queue *q)
2597 {
2598         struct blk_mq_tag_set   *set = q->tag_set;
2599
2600         blk_mq_del_queue_tag_set(q);
2601         blk_mq_exit_hw_queues(q, set, set->nr_hw_queues);
2602 }
2603
2604 /* Basically redo blk_mq_init_queue with queue frozen */
2605 static void blk_mq_queue_reinit(struct request_queue *q)
2606 {
2607         WARN_ON_ONCE(!atomic_read(&q->mq_freeze_depth));
2608
2609         blk_mq_debugfs_unregister_hctxs(q);
2610         blk_mq_sysfs_unregister(q);
2611
2612         /*
2613          * redo blk_mq_init_cpu_queues and blk_mq_init_hw_queues. FIXME: maybe
2614          * we should change hctx numa_node according to the new topology (this
2615          * involves freeing and re-allocating memory, worth doing?)
2616          */
2617         blk_mq_map_swqueue(q);
2618
2619         blk_mq_sysfs_register(q);
2620         blk_mq_debugfs_register_hctxs(q);
2621 }
2622
2623 static int __blk_mq_alloc_rq_maps(struct blk_mq_tag_set *set)
2624 {
2625         int i;
2626
2627         for (i = 0; i < set->nr_hw_queues; i++)
2628                 if (!__blk_mq_alloc_rq_map(set, i))
2629                         goto out_unwind;
2630
2631         return 0;
2632
2633 out_unwind:
2634         while (--i >= 0)
2635                 blk_mq_free_rq_map(set->tags[i]);
2636
2637         return -ENOMEM;
2638 }
2639
2640 /*
2641  * Allocate the request maps associated with this tag_set. Note that this
2642  * may reduce the depth asked for, if memory is tight. set->queue_depth
2643  * will be updated to reflect the allocated depth.
2644  */
2645 static int blk_mq_alloc_rq_maps(struct blk_mq_tag_set *set)
2646 {
2647         unsigned int depth;
2648         int err;
2649
2650         depth = set->queue_depth;
2651         do {
2652                 err = __blk_mq_alloc_rq_maps(set);
2653                 if (!err)
2654                         break;
2655
2656                 set->queue_depth >>= 1;
2657                 if (set->queue_depth < set->reserved_tags + BLK_MQ_TAG_MIN) {
2658                         err = -ENOMEM;
2659                         break;
2660                 }
2661         } while (set->queue_depth);
2662
2663         if (!set->queue_depth || err) {
2664                 pr_err("blk-mq: failed to allocate request map\n");
2665                 return -ENOMEM;
2666         }
2667
2668         if (depth != set->queue_depth)
2669                 pr_info("blk-mq: reduced tag depth (%u -> %u)\n",
2670                                                 depth, set->queue_depth);
2671
2672         return 0;
2673 }
2674
2675 static int blk_mq_update_queue_map(struct blk_mq_tag_set *set)
2676 {
2677         if (set->ops->map_queues) {
2678                 int cpu;
2679                 /*
2680                  * transport .map_queues is usually done in the following
2681                  * way:
2682                  *
2683                  * for (queue = 0; queue < set->nr_hw_queues; queue++) {
2684                  *      mask = get_cpu_mask(queue)
2685                  *      for_each_cpu(cpu, mask)
2686                  *              set->mq_map[cpu] = queue;
2687                  * }
2688                  *
2689                  * When we need to remap, the table has to be cleared for
2690                  * killing stale mapping since one CPU may not be mapped
2691                  * to any hw queue.
2692                  */
2693                 for_each_possible_cpu(cpu)
2694                         set->mq_map[cpu] = 0;
2695
2696                 return set->ops->map_queues(set);
2697         } else
2698                 return blk_mq_map_queues(set);
2699 }
2700
2701 /*
2702  * Alloc a tag set to be associated with one or more request queues.
2703  * May fail with EINVAL for various error conditions. May adjust the
2704  * requested depth down, if if it too large. In that case, the set
2705  * value will be stored in set->queue_depth.
2706  */
2707 int blk_mq_alloc_tag_set(struct blk_mq_tag_set *set)
2708 {
2709         int ret;
2710
2711         BUILD_BUG_ON(BLK_MQ_MAX_DEPTH > 1 << BLK_MQ_UNIQUE_TAG_BITS);
2712
2713         if (!set->nr_hw_queues)
2714                 return -EINVAL;
2715         if (!set->queue_depth)
2716                 return -EINVAL;
2717         if (set->queue_depth < set->reserved_tags + BLK_MQ_TAG_MIN)
2718                 return -EINVAL;
2719
2720         if (!set->ops->queue_rq)
2721                 return -EINVAL;
2722
2723         if (!set->ops->get_budget ^ !set->ops->put_budget)
2724                 return -EINVAL;
2725
2726         if (set->queue_depth > BLK_MQ_MAX_DEPTH) {
2727                 pr_info("blk-mq: reduced tag depth to %u\n",
2728                         BLK_MQ_MAX_DEPTH);
2729                 set->queue_depth = BLK_MQ_MAX_DEPTH;
2730         }
2731
2732         /*
2733          * If a crashdump is active, then we are potentially in a very
2734          * memory constrained environment. Limit us to 1 queue and
2735          * 64 tags to prevent using too much memory.
2736          */
2737         if (is_kdump_kernel()) {
2738                 set->nr_hw_queues = 1;
2739                 set->queue_depth = min(64U, set->queue_depth);
2740         }
2741         /*
2742          * There is no use for more h/w queues than cpus.
2743          */
2744         if (set->nr_hw_queues > nr_cpu_ids)
2745                 set->nr_hw_queues = nr_cpu_ids;
2746
2747         set->tags = kcalloc_node(nr_cpu_ids, sizeof(struct blk_mq_tags *),
2748                                  GFP_KERNEL, set->numa_node);
2749         if (!set->tags)
2750                 return -ENOMEM;
2751
2752         ret = -ENOMEM;
2753         set->mq_map = kcalloc_node(nr_cpu_ids, sizeof(*set->mq_map),
2754                                    GFP_KERNEL, set->numa_node);
2755         if (!set->mq_map)
2756                 goto out_free_tags;
2757
2758         ret = blk_mq_update_queue_map(set);
2759         if (ret)
2760                 goto out_free_mq_map;
2761
2762         ret = blk_mq_alloc_rq_maps(set);
2763         if (ret)
2764                 goto out_free_mq_map;
2765
2766         mutex_init(&set->tag_list_lock);
2767         INIT_LIST_HEAD(&set->tag_list);
2768
2769         return 0;
2770
2771 out_free_mq_map:
2772         kfree(set->mq_map);
2773         set->mq_map = NULL;
2774 out_free_tags:
2775         kfree(set->tags);
2776         set->tags = NULL;
2777         return ret;
2778 }
2779 EXPORT_SYMBOL(blk_mq_alloc_tag_set);
2780
2781 void blk_mq_free_tag_set(struct blk_mq_tag_set *set)
2782 {
2783         int i;
2784
2785         for (i = 0; i < nr_cpu_ids; i++)
2786                 blk_mq_free_map_and_requests(set, i);
2787
2788         kfree(set->mq_map);
2789         set->mq_map = NULL;
2790
2791         kfree(set->tags);
2792         set->tags = NULL;
2793 }
2794 EXPORT_SYMBOL(blk_mq_free_tag_set);
2795
2796 int blk_mq_update_nr_requests(struct request_queue *q, unsigned int nr)
2797 {
2798         struct blk_mq_tag_set *set = q->tag_set;
2799         struct blk_mq_hw_ctx *hctx;
2800         int i, ret;
2801
2802         if (!set)
2803                 return -EINVAL;
2804
2805         blk_mq_freeze_queue(q);
2806         blk_mq_quiesce_queue(q);
2807
2808         ret = 0;
2809         queue_for_each_hw_ctx(q, hctx, i) {
2810                 if (!hctx->tags)
2811                         continue;
2812                 /*
2813                  * If we're using an MQ scheduler, just update the scheduler
2814                  * queue depth. This is similar to what the old code would do.
2815                  */
2816                 if (!hctx->sched_tags) {
2817                         ret = blk_mq_tag_update_depth(hctx, &hctx->tags, nr,
2818                                                         false);
2819                 } else {
2820                         ret = blk_mq_tag_update_depth(hctx, &hctx->sched_tags,
2821                                                         nr, true);
2822                 }
2823                 if (ret)
2824                         break;
2825         }
2826
2827         if (!ret)
2828                 q->nr_requests = nr;
2829
2830         blk_mq_unquiesce_queue(q);
2831         blk_mq_unfreeze_queue(q);
2832
2833         return ret;
2834 }
2835
2836 static void __blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set,
2837                                                         int nr_hw_queues)
2838 {
2839         struct request_queue *q;
2840
2841         lockdep_assert_held(&set->tag_list_lock);
2842
2843         if (nr_hw_queues > nr_cpu_ids)
2844                 nr_hw_queues = nr_cpu_ids;
2845         if (nr_hw_queues < 1 || nr_hw_queues == set->nr_hw_queues)
2846                 return;
2847
2848         list_for_each_entry(q, &set->tag_list, tag_set_list)
2849                 blk_mq_freeze_queue(q);
2850
2851         set->nr_hw_queues = nr_hw_queues;
2852         blk_mq_update_queue_map(set);
2853         list_for_each_entry(q, &set->tag_list, tag_set_list) {
2854                 blk_mq_realloc_hw_ctxs(set, q);
2855                 blk_mq_queue_reinit(q);
2856         }
2857
2858         list_for_each_entry(q, &set->tag_list, tag_set_list)
2859                 blk_mq_unfreeze_queue(q);
2860 }
2861
2862 void blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set, int nr_hw_queues)
2863 {
2864         mutex_lock(&set->tag_list_lock);
2865         __blk_mq_update_nr_hw_queues(set, nr_hw_queues);
2866         mutex_unlock(&set->tag_list_lock);
2867 }
2868 EXPORT_SYMBOL_GPL(blk_mq_update_nr_hw_queues);
2869
2870 /* Enable polling stats and return whether they were already enabled. */
2871 static bool blk_poll_stats_enable(struct request_queue *q)
2872 {
2873         if (test_bit(QUEUE_FLAG_POLL_STATS, &q->queue_flags) ||
2874             blk_queue_flag_test_and_set(QUEUE_FLAG_POLL_STATS, q))
2875                 return true;
2876         blk_stat_add_callback(q, q->poll_cb);
2877         return false;
2878 }
2879
2880 static void blk_mq_poll_stats_start(struct request_queue *q)
2881 {
2882         /*
2883          * We don't arm the callback if polling stats are not enabled or the
2884          * callback is already active.
2885          */
2886         if (!test_bit(QUEUE_FLAG_POLL_STATS, &q->queue_flags) ||
2887             blk_stat_is_active(q->poll_cb))
2888                 return;
2889
2890         blk_stat_activate_msecs(q->poll_cb, 100);
2891 }
2892
2893 static void blk_mq_poll_stats_fn(struct blk_stat_callback *cb)
2894 {
2895         struct request_queue *q = cb->data;
2896         int bucket;
2897
2898         for (bucket = 0; bucket < BLK_MQ_POLL_STATS_BKTS; bucket++) {
2899                 if (cb->stat[bucket].nr_samples)
2900                         q->poll_stat[bucket] = cb->stat[bucket];
2901         }
2902 }
2903
2904 static unsigned long blk_mq_poll_nsecs(struct request_queue *q,
2905                                        struct blk_mq_hw_ctx *hctx,
2906                                        struct request *rq)
2907 {
2908         unsigned long ret = 0;
2909         int bucket;
2910
2911         /*
2912          * If stats collection isn't on, don't sleep but turn it on for
2913          * future users
2914          */
2915         if (!blk_poll_stats_enable(q))
2916                 return 0;
2917
2918         /*
2919          * As an optimistic guess, use half of the mean service time
2920          * for this type of request. We can (and should) make this smarter.
2921          * For instance, if the completion latencies are tight, we can
2922          * get closer than just half the mean. This is especially
2923          * important on devices where the completion latencies are longer
2924          * than ~10 usec. We do use the stats for the relevant IO size
2925          * if available which does lead to better estimates.
2926          */
2927         bucket = blk_mq_poll_stats_bkt(rq);
2928         if (bucket < 0)
2929                 return ret;
2930
2931         if (q->poll_stat[bucket].nr_samples)
2932                 ret = (q->poll_stat[bucket].mean + 1) / 2;
2933
2934         return ret;
2935 }
2936
2937 static bool blk_mq_poll_hybrid_sleep(struct request_queue *q,
2938                                      struct blk_mq_hw_ctx *hctx,
2939                                      struct request *rq)
2940 {
2941         struct hrtimer_sleeper hs;
2942         enum hrtimer_mode mode;
2943         unsigned int nsecs;
2944         ktime_t kt;
2945
2946         if (rq->rq_flags & RQF_MQ_POLL_SLEPT)
2947                 return false;
2948
2949         /*
2950          * poll_nsec can be:
2951          *
2952          * -1:  don't ever hybrid sleep
2953          *  0:  use half of prev avg
2954          * >0:  use this specific value
2955          */
2956         if (q->poll_nsec == -1)
2957                 return false;
2958         else if (q->poll_nsec > 0)
2959                 nsecs = q->poll_nsec;
2960         else
2961                 nsecs = blk_mq_poll_nsecs(q, hctx, rq);
2962
2963         if (!nsecs)
2964                 return false;
2965
2966         rq->rq_flags |= RQF_MQ_POLL_SLEPT;
2967
2968         /*
2969          * This will be replaced with the stats tracking code, using
2970          * 'avg_completion_time / 2' as the pre-sleep target.
2971          */
2972         kt = nsecs;
2973
2974         mode = HRTIMER_MODE_REL;
2975         hrtimer_init_on_stack(&hs.timer, CLOCK_MONOTONIC, mode);
2976         hrtimer_set_expires(&hs.timer, kt);
2977
2978         hrtimer_init_sleeper(&hs, current);
2979         do {
2980                 if (blk_mq_rq_state(rq) == MQ_RQ_COMPLETE)
2981                         break;
2982                 set_current_state(TASK_UNINTERRUPTIBLE);
2983                 hrtimer_start_expires(&hs.timer, mode);
2984                 if (hs.task)
2985                         io_schedule();
2986                 hrtimer_cancel(&hs.timer);
2987                 mode = HRTIMER_MODE_ABS;
2988         } while (hs.task && !signal_pending(current));
2989
2990         __set_current_state(TASK_RUNNING);
2991         destroy_hrtimer_on_stack(&hs.timer);
2992         return true;
2993 }
2994
2995 static bool __blk_mq_poll(struct blk_mq_hw_ctx *hctx, struct request *rq)
2996 {
2997         struct request_queue *q = hctx->queue;
2998         long state;
2999
3000         /*
3001          * If we sleep, have the caller restart the poll loop to reset
3002          * the state. Like for the other success return cases, the
3003          * caller is responsible for checking if the IO completed. If
3004          * the IO isn't complete, we'll get called again and will go
3005          * straight to the busy poll loop.
3006          */
3007         if (blk_mq_poll_hybrid_sleep(q, hctx, rq))
3008                 return true;
3009
3010         hctx->poll_considered++;
3011
3012         state = current->state;
3013         while (!need_resched()) {
3014                 int ret;
3015
3016                 hctx->poll_invoked++;
3017
3018                 ret = q->mq_ops->poll(hctx, rq->tag);
3019                 if (ret > 0) {
3020                         hctx->poll_success++;
3021                         set_current_state(TASK_RUNNING);
3022                         return true;
3023                 }
3024
3025                 if (signal_pending_state(state, current))
3026                         set_current_state(TASK_RUNNING);
3027
3028                 if (current->state == TASK_RUNNING)
3029                         return true;
3030                 if (ret < 0)
3031                         break;
3032                 cpu_relax();
3033         }
3034
3035         __set_current_state(TASK_RUNNING);
3036         return false;
3037 }
3038
3039 static bool blk_mq_poll(struct request_queue *q, blk_qc_t cookie)
3040 {
3041         struct blk_mq_hw_ctx *hctx;
3042         struct request *rq;
3043
3044         if (!test_bit(QUEUE_FLAG_POLL, &q->queue_flags))
3045                 return false;
3046
3047         hctx = q->queue_hw_ctx[blk_qc_t_to_queue_num(cookie)];
3048         if (!blk_qc_t_is_internal(cookie))
3049                 rq = blk_mq_tag_to_rq(hctx->tags, blk_qc_t_to_tag(cookie));
3050         else {
3051                 rq = blk_mq_tag_to_rq(hctx->sched_tags, blk_qc_t_to_tag(cookie));
3052                 /*
3053                  * With scheduling, if the request has completed, we'll
3054                  * get a NULL return here, as we clear the sched tag when
3055                  * that happens. The request still remains valid, like always,
3056                  * so we should be safe with just the NULL check.
3057                  */
3058                 if (!rq)
3059                         return false;
3060         }
3061
3062         return __blk_mq_poll(hctx, rq);
3063 }
3064
3065 static int __init blk_mq_init(void)
3066 {
3067         cpuhp_setup_state_multi(CPUHP_BLK_MQ_DEAD, "block/mq:dead", NULL,
3068                                 blk_mq_hctx_notify_dead);
3069         return 0;
3070 }
3071 subsys_initcall(blk_mq_init);