drivers/block/nbd.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Network block device - make block devices work over TCP
   4  *
   5  * Note that you can not swap over this thing, yet. Seems to work but
   6  * deadlocks sometimes - you can not swap over TCP in general.
   7  *
   8  * Copyright 1997-2000, 2008 Pavel Machek <pavel@ucw.cz>
   9  * Parts copyright 2001 Steven Whitehouse <steve@chygwyn.com>
  10  *
  11  * (part of code stolen from loop.c)
  12  */
  13
  14 #include <linux/major.h>
  15
  16 #include <linux/blkdev.h>
  17 #include <linux/module.h>
  18 #include <linux/init.h>
  19 #include <linux/sched.h>
  20 #include <linux/sched/mm.h>
  21 #include <linux/fs.h>
  22 #include <linux/bio.h>
  23 #include <linux/stat.h>
  24 #include <linux/errno.h>
  25 #include <linux/file.h>
  26 #include <linux/ioctl.h>
  27 #include <linux/mutex.h>
  28 #include <linux/compiler.h>
  29 #include <linux/err.h>
  30 #include <linux/kernel.h>
  31 #include <linux/slab.h>
  32 #include <net/sock.h>
  33 #include <linux/net.h>
  34 #include <linux/kthread.h>
  35 #include <linux/types.h>
  36 #include <linux/debugfs.h>
  37 #include <linux/blk-mq.h>
  38
  39 #include <linux/uaccess.h>
  40 #include <asm/types.h>
  41
  42 #include <linux/nbd.h>
  43 #include <linux/nbd-netlink.h>
  44 #include <net/genetlink.h>
  45
  46 #define CREATE_TRACE_POINTS
  47 #include <trace/events/nbd.h>
  48
  49 static DEFINE_IDR(nbd_index_idr);
  50 static DEFINE_MUTEX(nbd_index_mutex);
  51 static int nbd_total_devices = 0;
  52
  53 struct nbd_sock {
  54         struct socket *sock;
  55         struct mutex tx_lock;
  56         struct request *pending;
  57         int sent;
  58         bool dead;
  59         int fallback_index;
  60         int cookie;
  61 };
  62
  63 struct recv_thread_args {
  64         struct work_struct work;
  65         struct nbd_device *nbd;
  66         int index;
  67 };
  68
  69 struct link_dead_args {
  70         struct work_struct work;
  71         int index;
  72 };
  73
  74 #define NBD_TIMEDOUT                    0
  75 #define NBD_DISCONNECT_REQUESTED        1
  76 #define NBD_DISCONNECTED                2
  77 #define NBD_HAS_PID_FILE                3
  78 #define NBD_HAS_CONFIG_REF              4
  79 #define NBD_BOUND                       5
  80 #define NBD_DESTROY_ON_DISCONNECT       6
  81 #define NBD_DISCONNECT_ON_CLOSE         7
  82
  83 struct nbd_config {
  84         u32 flags;
  85         unsigned long runtime_flags;
  86         u64 dead_conn_timeout;
  87
  88         struct nbd_sock **socks;
  89         int num_connections;
  90         atomic_t live_connections;
  91         wait_queue_head_t conn_wait;
  92
  93         atomic_t recv_threads;
  94         wait_queue_head_t recv_wq;
  95         loff_t blksize;
  96         loff_t bytesize;
  97 #if IS_ENABLED(CONFIG_DEBUG_FS)
  98         struct dentry *dbg_dir;
  99 #endif
 100 };
 101
 102 struct nbd_device {
 103         struct blk_mq_tag_set tag_set;
 104
 105         int index;
 106         refcount_t config_refs;
 107         refcount_t refs;
 108         struct nbd_config *config;
 109         struct mutex config_lock;
 110         struct gendisk *disk;
 111         struct workqueue_struct *recv_workq;
 112
 113         struct list_head list;
 114         struct task_struct *task_recv;
 115         struct task_struct *task_setup;
 116 };
 117
 118 #define NBD_CMD_REQUEUED        1
 119
 120 struct nbd_cmd {
 121         struct nbd_device *nbd;
 122         struct mutex lock;
 123         int index;
 124         int cookie;
 125         int retries;
 126         blk_status_t status;
 127         unsigned long flags;
 128         u32 cmd_cookie;
 129 };
 130
 131 #if IS_ENABLED(CONFIG_DEBUG_FS)
 132 static struct dentry *nbd_dbg_dir;
 133 #endif
 134
 135 #define nbd_name(nbd) ((nbd)->disk->disk_name)
 136
 137 #define NBD_MAGIC 0x68797548
 138
 139 #define NBD_DEF_BLKSIZE 1024
 140
 141 static unsigned int nbds_max = 16;
 142 static int max_part = 16;
 143 static int part_shift;
 144
 145 static int nbd_dev_dbg_init(struct nbd_device *nbd);
 146 static void nbd_dev_dbg_close(struct nbd_device *nbd);
 147 static void nbd_config_put(struct nbd_device *nbd);
 148 static void nbd_connect_reply(struct genl_info *info, int index);
 149 static int nbd_genl_status(struct sk_buff *skb, struct genl_info *info);
 150 static void nbd_dead_link_work(struct work_struct *work);
 151 static void nbd_disconnect_and_put(struct nbd_device *nbd);
 152
 153 static inline struct device *nbd_to_dev(struct nbd_device *nbd)
 154 {
 155         return disk_to_dev(nbd->disk);
 156 }
 157
 158 static void nbd_requeue_cmd(struct nbd_cmd *cmd)
 159 {
 160         struct request *req = blk_mq_rq_from_pdu(cmd);
 161
 162         if (!test_and_set_bit(NBD_CMD_REQUEUED, &cmd->flags))
 163                 blk_mq_requeue_request(req, true);
 164 }
 165
 166 #define NBD_COOKIE_BITS 32
 167
 168 static u64 nbd_cmd_handle(struct nbd_cmd *cmd)
 169 {
 170         struct request *req = blk_mq_rq_from_pdu(cmd);
 171         u32 tag = blk_mq_unique_tag(req);
 172         u64 cookie = cmd->cmd_cookie;
 173
 174         return (cookie << NBD_COOKIE_BITS) | tag;
 175 }
 176
 177 static u32 nbd_handle_to_tag(u64 handle)
 178 {
 179         return (u32)handle;
 180 }
 181
 182 static u32 nbd_handle_to_cookie(u64 handle)
 183 {
 184         return (u32)(handle >> NBD_COOKIE_BITS);
 185 }
 186
 187 static const char *nbdcmd_to_ascii(int cmd)
 188 {
 189         switch (cmd) {
 190         case  NBD_CMD_READ: return "read";
 191         case NBD_CMD_WRITE: return "write";
 192         case  NBD_CMD_DISC: return "disconnect";
 193         case NBD_CMD_FLUSH: return "flush";
 194         case  NBD_CMD_TRIM: return "trim/discard";
 195         }
 196         return "invalid";
 197 }
 198
 199 static ssize_t pid_show(struct device *dev,
 200                         struct device_attribute *attr, char *buf)
 201 {
 202         struct gendisk *disk = dev_to_disk(dev);
 203         struct nbd_device *nbd = (struct nbd_device *)disk->private_data;
 204
 205         return sprintf(buf, "%d\n", task_pid_nr(nbd->task_recv));
 206 }
 207
 208 static const struct device_attribute pid_attr = {
 209         .attr = { .name = "pid", .mode = 0444},
 210         .show = pid_show,
 211 };
 212
 213 static void nbd_dev_remove(struct nbd_device *nbd)
 214 {
 215         struct gendisk *disk = nbd->disk;
 216         struct request_queue *q;
 217
 218         if (disk) {
 219                 q = disk->queue;
 220                 del_gendisk(disk);
 221                 blk_cleanup_queue(q);
 222                 blk_mq_free_tag_set(&nbd->tag_set);
 223                 disk->private_data = NULL;
 224                 put_disk(disk);
 225         }
 226         kfree(nbd);
 227 }
 228
 229 static void nbd_put(struct nbd_device *nbd)
 230 {
 231         if (refcount_dec_and_mutex_lock(&nbd->refs,
 232                                         &nbd_index_mutex)) {
 233                 idr_remove(&nbd_index_idr, nbd->index);
 234                 mutex_unlock(&nbd_index_mutex);
 235                 nbd_dev_remove(nbd);
 236         }
 237 }
 238
 239 static int nbd_disconnected(struct nbd_config *config)
 240 {
 241         return test_bit(NBD_DISCONNECTED, &config->runtime_flags) ||
 242                 test_bit(NBD_DISCONNECT_REQUESTED, &config->runtime_flags);
 243 }
 244
 245 static void nbd_mark_nsock_dead(struct nbd_device *nbd, struct nbd_sock *nsock,
 246                                 int notify)
 247 {
 248         if (!nsock->dead && notify && !nbd_disconnected(nbd->config)) {
 249                 struct link_dead_args *args;
 250                 args = kmalloc(sizeof(struct link_dead_args), GFP_NOIO);
 251                 if (args) {
 252                         INIT_WORK(&args->work, nbd_dead_link_work);
 253                         args->index = nbd->index;
 254                         queue_work(system_wq, &args->work);
 255                 }
 256         }
 257         if (!nsock->dead) {
 258                 kernel_sock_shutdown(nsock->sock, SHUT_RDWR);
 259                 if (atomic_dec_return(&nbd->config->live_connections) == 0) {
 260                         if (test_and_clear_bit(NBD_DISCONNECT_REQUESTED,
 261                                                &nbd->config->runtime_flags)) {
 262                                 set_bit(NBD_DISCONNECTED,
 263                                         &nbd->config->runtime_flags);
 264                                 dev_info(nbd_to_dev(nbd),
 265                                         "Disconnected due to user request.\n");
 266                         }
 267                 }
 268         }
 269         nsock->dead = true;
 270         nsock->pending = NULL;
 271         nsock->sent = 0;
 272 }
 273
 274 static void nbd_size_clear(struct nbd_device *nbd)
 275 {
 276         if (nbd->config->bytesize) {
 277                 set_capacity(nbd->disk, 0);
 278                 kobject_uevent(&nbd_to_dev(nbd)->kobj, KOBJ_CHANGE);
 279         }
 280 }
 281
 282 static void nbd_size_update(struct nbd_device *nbd)
 283 {
 284         struct nbd_config *config = nbd->config;
 285         struct block_device *bdev = bdget_disk(nbd->disk, 0);
 286
 287         if (config->flags & NBD_FLAG_SEND_TRIM) {
 288                 nbd->disk->queue->limits.discard_granularity = config->blksize;
 289                 nbd->disk->queue->limits.discard_alignment = config->blksize;
 290                 blk_queue_max_discard_sectors(nbd->disk->queue, UINT_MAX);
 291         }
 292         blk_queue_logical_block_size(nbd->disk->queue, config->blksize);
 293         blk_queue_physical_block_size(nbd->disk->queue, config->blksize);
 294         set_capacity(nbd->disk, config->bytesize >> 9);
 295         if (bdev) {
 296                 if (bdev->bd_disk) {
 297                         bd_set_size(bdev, config->bytesize);
 298                         set_blocksize(bdev, config->blksize);
 299                 } else
 300                         bdev->bd_invalidated = 1;
 301                 bdput(bdev);
 302         }
 303         kobject_uevent(&nbd_to_dev(nbd)->kobj, KOBJ_CHANGE);
 304 }
 305
 306 static void nbd_size_set(struct nbd_device *nbd, loff_t blocksize,
 307                          loff_t nr_blocks)
 308 {
 309         struct nbd_config *config = nbd->config;
 310         config->blksize = blocksize;
 311         config->bytesize = blocksize * nr_blocks;
 312         if (nbd->task_recv != NULL)
 313                 nbd_size_update(nbd);
 314 }
 315
 316 static void nbd_complete_rq(struct request *req)
 317 {
 318         struct nbd_cmd *cmd = blk_mq_rq_to_pdu(req);
 319
 320         dev_dbg(nbd_to_dev(cmd->nbd), "request %p: %s\n", req,
 321                 cmd->status ? "failed" : "done");
 322
 323         blk_mq_end_request(req, cmd->status);
 324 }
 325
 326 /*
 327  * Forcibly shutdown the socket causing all listeners to error
 328  */
 329 static void sock_shutdown(struct nbd_device *nbd)
 330 {
 331         struct nbd_config *config = nbd->config;
 332         int i;
 333
 334         if (config->num_connections == 0)
 335                 return;
 336         if (test_and_set_bit(NBD_DISCONNECTED, &config->runtime_flags))
 337                 return;
 338
 339         for (i = 0; i < config->num_connections; i++) {
 340                 struct nbd_sock *nsock = config->socks[i];
 341                 mutex_lock(&nsock->tx_lock);
 342                 nbd_mark_nsock_dead(nbd, nsock, 0);
 343                 mutex_unlock(&nsock->tx_lock);
 344         }
 345         dev_warn(disk_to_dev(nbd->disk), "shutting down sockets\n");
 346 }
 347
 348 static u32 req_to_nbd_cmd_type(struct request *req)
 349 {
 350         switch (req_op(req)) {
 351         case REQ_OP_DISCARD:
 352                 return NBD_CMD_TRIM;
 353         case REQ_OP_FLUSH:
 354                 return NBD_CMD_FLUSH;
 355         case REQ_OP_WRITE:
 356                 return NBD_CMD_WRITE;
 357         case REQ_OP_READ:
 358                 return NBD_CMD_READ;
 359         default:
 360                 return U32_MAX;
 361         }
 362 }
 363
 364 static enum blk_eh_timer_return nbd_xmit_timeout(struct request *req,
 365                                                  bool reserved)
 366 {
 367         struct nbd_cmd *cmd = blk_mq_rq_to_pdu(req);
 368         struct nbd_device *nbd = cmd->nbd;
 369         struct nbd_config *config;
 370
 371         if (!refcount_inc_not_zero(&nbd->config_refs)) {
 372                 cmd->status = BLK_STS_TIMEOUT;
 373                 goto done;
 374         }
 375         config = nbd->config;
 376
 377         if (!mutex_trylock(&cmd->lock)) {
 378                 nbd_config_put(nbd);
 379                 return BLK_EH_RESET_TIMER;
 380         }
 381
 382         if (config->num_connections > 1) {
 383                 dev_err_ratelimited(nbd_to_dev(nbd),
 384                                     "Connection timed out, retrying (%d/%d alive)\n",
 385                                     atomic_read(&config->live_connections),
 386                                     config->num_connections);
 387                 /*
 388                  * Hooray we have more connections, requeue this IO, the submit
 389                  * path will put it on a real connection.
 390                  */
 391                 if (config->socks && config->num_connections > 1) {
 392                         if (cmd->index < config->num_connections) {
 393                                 struct nbd_sock *nsock =
 394                                         config->socks[cmd->index];
 395                                 mutex_lock(&nsock->tx_lock);
 396                                 /* We can have multiple outstanding requests, so
 397                                  * we don't want to mark the nsock dead if we've
 398                                  * already reconnected with a new socket, so
 399                                  * only mark it dead if its the same socket we
 400                                  * were sent out on.
 401                                  */
 402                                 if (cmd->cookie == nsock->cookie)
 403                                         nbd_mark_nsock_dead(nbd, nsock, 1);
 404                                 mutex_unlock(&nsock->tx_lock);
 405                         }
 406                         mutex_unlock(&cmd->lock);
 407                         nbd_requeue_cmd(cmd);
 408                         nbd_config_put(nbd);
 409                         return BLK_EH_DONE;
 410                 }
 411         }
 412
 413         if (!nbd->tag_set.timeout) {
 414                 /*
 415                  * Userspace sets timeout=0 to disable socket disconnection,
 416                  * so just warn and reset the timer.
 417                  */
 418                 cmd->retries++;
 419                 dev_info(nbd_to_dev(nbd), "Possible stuck request %p: control (%s@%llu,%uB). Runtime %u seconds\n",
 420                         req, nbdcmd_to_ascii(req_to_nbd_cmd_type(req)),
 421                         (unsigned long long)blk_rq_pos(req) << 9,
 422                         blk_rq_bytes(req), (req->timeout / HZ) * cmd->retries);
 423
 424                 mutex_unlock(&cmd->lock);
 425                 nbd_config_put(nbd);
 426                 return BLK_EH_RESET_TIMER;
 427         }
 428
 429         dev_err_ratelimited(nbd_to_dev(nbd), "Connection timed out\n");
 430         set_bit(NBD_TIMEDOUT, &config->runtime_flags);
 431         cmd->status = BLK_STS_IOERR;
 432         mutex_unlock(&cmd->lock);
 433         sock_shutdown(nbd);
 434         nbd_config_put(nbd);
 435 done:
 436         blk_mq_complete_request(req);
 437         return BLK_EH_DONE;
 438 }
 439
 440 /*
 441  *  Send or receive packet.
 442  */
 443 static int sock_xmit(struct nbd_device *nbd, int index, int send,
 444                      struct iov_iter *iter, int msg_flags, int *sent)
 445 {
 446         struct nbd_config *config = nbd->config;
 447         struct socket *sock = config->socks[index]->sock;
 448         int result;
 449         struct msghdr msg;
 450         unsigned int noreclaim_flag;
 451
 452         if (unlikely(!sock)) {
 453                 dev_err_ratelimited(disk_to_dev(nbd->disk),
 454                         "Attempted %s on closed socket in sock_xmit\n",
 455                         (send ? "send" : "recv"));
 456                 return -EINVAL;
 457         }
 458
 459         msg.msg_iter = *iter;
 460
 461         noreclaim_flag = memalloc_noreclaim_save();
 462         do {
 463                 sock->sk->sk_allocation = GFP_NOIO | __GFP_MEMALLOC;
 464                 msg.msg_name = NULL;
 465                 msg.msg_namelen = 0;
 466                 msg.msg_control = NULL;
 467                 msg.msg_controllen = 0;
 468                 msg.msg_flags = msg_flags | MSG_NOSIGNAL;
 469
 470                 if (send)
 471                         result = sock_sendmsg(sock, &msg);
 472                 else
 473                         result = sock_recvmsg(sock, &msg, msg.msg_flags);
 474
 475                 if (result <= 0) {
 476                         if (result == 0)
 477                                 result = -EPIPE; /* short read */
 478                         break;
 479                 }
 480                 if (sent)
 481                         *sent += result;
 482         } while (msg_data_left(&msg));
 483
 484         memalloc_noreclaim_restore(noreclaim_flag);
 485
 486         return result;
 487 }
 488
 489 /*
 490  * Different settings for sk->sk_sndtimeo can result in different return values
 491  * if there is a signal pending when we enter sendmsg, because reasons?
 492  */
 493 static inline int was_interrupted(int result)
 494 {
 495         return result == -ERESTARTSYS || result == -EINTR;
 496 }
 497
 498 /* always call with the tx_lock held */
 499 static int nbd_send_cmd(struct nbd_device *nbd, struct nbd_cmd *cmd, int index)
 500 {
 501         struct request *req = blk_mq_rq_from_pdu(cmd);
 502         struct nbd_config *config = nbd->config;
 503         struct nbd_sock *nsock = config->socks[index];
 504         int result;
 505         struct nbd_request request = {.magic = htonl(NBD_REQUEST_MAGIC)};
 506         struct kvec iov = {.iov_base = &request, .iov_len = sizeof(request)};
 507         struct iov_iter from;
 508         unsigned long size = blk_rq_bytes(req);
 509         struct bio *bio;
 510         u64 handle;
 511         u32 type;
 512         u32 nbd_cmd_flags = 0;
 513         int sent = nsock->sent, skip = 0;
 514
 515         iov_iter_kvec(&from, WRITE, &iov, 1, sizeof(request));
 516
 517         type = req_to_nbd_cmd_type(req);
 518         if (type == U32_MAX)
 519                 return -EIO;
 520
 521         if (rq_data_dir(req) == WRITE &&
 522             (config->flags & NBD_FLAG_READ_ONLY)) {
 523                 dev_err_ratelimited(disk_to_dev(nbd->disk),
 524                                     "Write on read-only\n");
 525                 return -EIO;
 526         }
 527
 528         if (req->cmd_flags & REQ_FUA)
 529                 nbd_cmd_flags |= NBD_CMD_FLAG_FUA;
 530
 531         /* We did a partial send previously, and we at least sent the whole
 532          * request struct, so just go and send the rest of the pages in the
 533          * request.
 534          */
 535         if (sent) {
 536                 if (sent >= sizeof(request)) {
 537                         skip = sent - sizeof(request);
 538
 539                         /* initialize handle for tracing purposes */
 540                         handle = nbd_cmd_handle(cmd);
 541
 542                         goto send_pages;
 543                 }
 544                 iov_iter_advance(&from, sent);
 545         } else {
 546                 cmd->cmd_cookie++;
 547         }
 548         cmd->index = index;
 549         cmd->cookie = nsock->cookie;
 550         cmd->retries = 0;
 551         request.type = htonl(type | nbd_cmd_flags);
 552         if (type != NBD_CMD_FLUSH) {
 553                 request.from = cpu_to_be64((u64)blk_rq_pos(req) << 9);
 554                 request.len = htonl(size);
 555         }
 556         handle = nbd_cmd_handle(cmd);
 557         memcpy(request.handle, &handle, sizeof(handle));
 558
 559         trace_nbd_send_request(&request, nbd->index, blk_mq_rq_from_pdu(cmd));
 560
 561         dev_dbg(nbd_to_dev(nbd), "request %p: sending control (%s@%llu,%uB)\n",
 562                 req, nbdcmd_to_ascii(type),
 563                 (unsigned long long)blk_rq_pos(req) << 9, blk_rq_bytes(req));
 564         result = sock_xmit(nbd, index, 1, &from,
 565                         (type == NBD_CMD_WRITE) ? MSG_MORE : 0, &sent);
 566         trace_nbd_header_sent(req, handle);
 567         if (result <= 0) {
 568                 if (was_interrupted(result)) {
 569                         /* If we havne't sent anything we can just return BUSY,
 570                          * however if we have sent something we need to make
 571                          * sure we only allow this req to be sent until we are
 572                          * completely done.
 573                          */
 574                         if (sent) {
 575                                 nsock->pending = req;
 576                                 nsock->sent = sent;
 577                         }
 578                         set_bit(NBD_CMD_REQUEUED, &cmd->flags);
 579                         return BLK_STS_RESOURCE;
 580                 }
 581                 dev_err_ratelimited(disk_to_dev(nbd->disk),
 582                         "Send control failed (result %d)\n", result);
 583                 return -EAGAIN;
 584         }
 585 send_pages:
 586         if (type != NBD_CMD_WRITE)
 587                 goto out;
 588
 589         bio = req->bio;
 590         while (bio) {
 591                 struct bio *next = bio->bi_next;
 592                 struct bvec_iter iter;
 593                 struct bio_vec bvec;
 594
 595                 bio_for_each_segment(bvec, bio, iter) {
 596                         bool is_last = !next && bio_iter_last(bvec, iter);
 597                         int flags = is_last ? 0 : MSG_MORE;
 598
 599                         dev_dbg(nbd_to_dev(nbd), "request %p: sending %d bytes data\n",
 600                                 req, bvec.bv_len);
 601                         iov_iter_bvec(&from, WRITE, &bvec, 1, bvec.bv_len);
 602                         if (skip) {
 603                                 if (skip >= iov_iter_count(&from)) {
 604                                         skip -= iov_iter_count(&from);
 605                                         continue;
 606                                 }
 607                                 iov_iter_advance(&from, skip);
 608                                 skip = 0;
 609                         }
 610                         result = sock_xmit(nbd, index, 1, &from, flags, &sent);
 611                         if (result <= 0) {
 612                                 if (was_interrupted(result)) {
 613                                         /* We've already sent the header, we
 614                                          * have no choice but to set pending and
 615                                          * return BUSY.
 616                                          */
 617                                         nsock->pending = req;
 618                                         nsock->sent = sent;
 619                                         set_bit(NBD_CMD_REQUEUED, &cmd->flags);
 620                                         return BLK_STS_RESOURCE;
 621                                 }
 622                                 dev_err(disk_to_dev(nbd->disk),
 623                                         "Send data failed (result %d)\n",
 624                                         result);
 625                                 return -EAGAIN;
 626                         }
 627                         /*
 628                          * The completion might already have come in,
 629                          * so break for the last one instead of letting
 630                          * the iterator do it. This prevents use-after-free
 631                          * of the bio.
 632                          */
 633                         if (is_last)
 634                                 break;
 635                 }
 636                 bio = next;
 637         }
 638 out:
 639         trace_nbd_payload_sent(req, handle);
 640         nsock->pending = NULL;
 641         nsock->sent = 0;
 642         return 0;
 643 }
 644
 645 /* NULL returned = something went wrong, inform userspace */
 646 static struct nbd_cmd *nbd_read_stat(struct nbd_device *nbd, int index)
 647 {
 648         struct nbd_config *config = nbd->config;
 649         int result;
 650         struct nbd_reply reply;
 651         struct nbd_cmd *cmd;
 652         struct request *req = NULL;
 653         u64 handle;
 654         u16 hwq;
 655         u32 tag;
 656         struct kvec iov = {.iov_base = &reply, .iov_len = sizeof(reply)};
 657         struct iov_iter to;
 658         int ret = 0;
 659
 660         reply.magic = 0;
 661         iov_iter_kvec(&to, READ, &iov, 1, sizeof(reply));
 662         result = sock_xmit(nbd, index, 0, &to, MSG_WAITALL, NULL);
 663         if (result <= 0) {
 664                 if (!nbd_disconnected(config))
 665                         dev_err(disk_to_dev(nbd->disk),
 666                                 "Receive control failed (result %d)\n", result);
 667                 return ERR_PTR(result);
 668         }
 669
 670         if (ntohl(reply.magic) != NBD_REPLY_MAGIC) {
 671                 dev_err(disk_to_dev(nbd->disk), "Wrong magic (0x%lx)\n",
 672                                 (unsigned long)ntohl(reply.magic));
 673                 return ERR_PTR(-EPROTO);
 674         }
 675
 676         memcpy(&handle, reply.handle, sizeof(handle));
 677         tag = nbd_handle_to_tag(handle);
 678         hwq = blk_mq_unique_tag_to_hwq(tag);
 679         if (hwq < nbd->tag_set.nr_hw_queues)
 680                 req = blk_mq_tag_to_rq(nbd->tag_set.tags[hwq],
 681                                        blk_mq_unique_tag_to_tag(tag));
 682         if (!req || !blk_mq_request_started(req)) {
 683                 dev_err(disk_to_dev(nbd->disk), "Unexpected reply (%d) %p\n",
 684                         tag, req);
 685                 return ERR_PTR(-ENOENT);
 686         }
 687         trace_nbd_header_received(req, handle);
 688         cmd = blk_mq_rq_to_pdu(req);
 689
 690         mutex_lock(&cmd->lock);
 691         if (cmd->cmd_cookie != nbd_handle_to_cookie(handle)) {
 692                 dev_err(disk_to_dev(nbd->disk), "Double reply on req %p, cmd_cookie %u, handle cookie %u\n",
 693                         req, cmd->cmd_cookie, nbd_handle_to_cookie(handle));
 694                 ret = -ENOENT;
 695                 goto out;
 696         }
 697         if (test_bit(NBD_CMD_REQUEUED, &cmd->flags)) {
 698                 dev_err(disk_to_dev(nbd->disk), "Raced with timeout on req %p\n",
 699                         req);
 700                 ret = -ENOENT;
 701                 goto out;
 702         }
 703         if (ntohl(reply.error)) {
 704                 dev_err(disk_to_dev(nbd->disk), "Other side returned error (%d)\n",
 705                         ntohl(reply.error));
 706                 cmd->status = BLK_STS_IOERR;
 707                 goto out;
 708         }
 709
 710         dev_dbg(nbd_to_dev(nbd), "request %p: got reply\n", req);
 711         if (rq_data_dir(req) != WRITE) {
 712                 struct req_iterator iter;
 713                 struct bio_vec bvec;
 714
 715                 rq_for_each_segment(bvec, req, iter) {
 716                         iov_iter_bvec(&to, READ, &bvec, 1, bvec.bv_len);
 717                         result = sock_xmit(nbd, index, 0, &to, MSG_WAITALL, NULL);
 718                         if (result <= 0) {
 719                                 dev_err(disk_to_dev(nbd->disk), "Receive data failed (result %d)\n",
 720                                         result);
 721                                 /*
 722                                  * If we've disconnected or we only have 1
 723                                  * connection then we need to make sure we
 724                                  * complete this request, otherwise error out
 725                                  * and let the timeout stuff handle resubmitting
 726                                  * this request onto another connection.
 727                                  */
 728                                 if (nbd_disconnected(config) ||
 729                                     config->num_connections <= 1) {
 730                                         cmd->status = BLK_STS_IOERR;
 731                                         goto out;
 732                                 }
 733                                 ret = -EIO;
 734                                 goto out;
 735                         }
 736                         dev_dbg(nbd_to_dev(nbd), "request %p: got %d bytes data\n",
 737                                 req, bvec.bv_len);
 738                 }
 739         }
 740 out:
 741         trace_nbd_payload_received(req, handle);
 742         mutex_unlock(&cmd->lock);
 743         return ret ? ERR_PTR(ret) : cmd;
 744 }
 745
 746 static void recv_work(struct work_struct *work)
 747 {
 748         struct recv_thread_args *args = container_of(work,
 749                                                      struct recv_thread_args,
 750                                                      work);
 751         struct nbd_device *nbd = args->nbd;
 752         struct nbd_config *config = nbd->config;
 753         struct nbd_cmd *cmd;
 754
 755         while (1) {
 756                 cmd = nbd_read_stat(nbd, args->index);
 757                 if (IS_ERR(cmd)) {
 758                         struct nbd_sock *nsock = config->socks[args->index];
 759
 760                         mutex_lock(&nsock->tx_lock);
 761                         nbd_mark_nsock_dead(nbd, nsock, 1);
 762                         mutex_unlock(&nsock->tx_lock);
 763                         break;
 764                 }
 765
 766                 blk_mq_complete_request(blk_mq_rq_from_pdu(cmd));
 767         }
 768         atomic_dec(&config->recv_threads);
 769         wake_up(&config->recv_wq);
 770         nbd_config_put(nbd);
 771         kfree(args);
 772 }
 773
 774 static bool nbd_clear_req(struct request *req, void *data, bool reserved)
 775 {
 776         struct nbd_cmd *cmd = blk_mq_rq_to_pdu(req);
 777
 778         cmd->status = BLK_STS_IOERR;
 779         blk_mq_complete_request(req);
 780         return true;
 781 }
 782
 783 static void nbd_clear_que(struct nbd_device *nbd)
 784 {
 785         blk_mq_quiesce_queue(nbd->disk->queue);
 786         blk_mq_tagset_busy_iter(&nbd->tag_set, nbd_clear_req, NULL);
 787         blk_mq_unquiesce_queue(nbd->disk->queue);
 788         dev_dbg(disk_to_dev(nbd->disk), "queue cleared\n");
 789 }
 790
 791 static int find_fallback(struct nbd_device *nbd, int index)
 792 {
 793         struct nbd_config *config = nbd->config;
 794         int new_index = -1;
 795         struct nbd_sock *nsock = config->socks[index];
 796         int fallback = nsock->fallback_index;
 797
 798         if (test_bit(NBD_DISCONNECTED, &config->runtime_flags))
 799                 return new_index;
 800
 801         if (config->num_connections <= 1) {
 802                 dev_err_ratelimited(disk_to_dev(nbd->disk),
 803                                     "Attempted send on invalid socket\n");
 804                 return new_index;
 805         }
 806
 807         if (fallback >= 0 && fallback < config->num_connections &&
 808             !config->socks[fallback]->dead)
 809                 return fallback;
 810
 811         if (nsock->fallback_index < 0 ||
 812             nsock->fallback_index >= config->num_connections ||
 813             config->socks[nsock->fallback_index]->dead) {
 814                 int i;
 815                 for (i = 0; i < config->num_connections; i++) {
 816                         if (i == index)
 817                                 continue;
 818                         if (!config->socks[i]->dead) {
 819                                 new_index = i;
 820                                 break;
 821                         }
 822                 }
 823                 nsock->fallback_index = new_index;
 824                 if (new_index < 0) {
 825                         dev_err_ratelimited(disk_to_dev(nbd->disk),
 826                                             "Dead connection, failed to find a fallback\n");
 827                         return new_index;
 828                 }
 829         }
 830         new_index = nsock->fallback_index;
 831         return new_index;
 832 }
 833
 834 static int wait_for_reconnect(struct nbd_device *nbd)
 835 {
 836         struct nbd_config *config = nbd->config;
 837         if (!config->dead_conn_timeout)
 838                 return 0;
 839         if (test_bit(NBD_DISCONNECTED, &config->runtime_flags))
 840                 return 0;
 841         return wait_event_timeout(config->conn_wait,
 842                                   atomic_read(&config->live_connections) > 0,
 843                                   config->dead_conn_timeout) > 0;
 844 }
 845
 846 static int nbd_handle_cmd(struct nbd_cmd *cmd, int index)
 847 {
 848         struct request *req = blk_mq_rq_from_pdu(cmd);
 849         struct nbd_device *nbd = cmd->nbd;
 850         struct nbd_config *config;
 851         struct nbd_sock *nsock;
 852         int ret;
 853
 854         if (!refcount_inc_not_zero(&nbd->config_refs)) {
 855                 dev_err_ratelimited(disk_to_dev(nbd->disk),
 856                                     "Socks array is empty\n");
 857                 blk_mq_start_request(req);
 858                 return -EINVAL;
 859         }
 860         config = nbd->config;
 861
 862         if (index >= config->num_connections) {
 863                 dev_err_ratelimited(disk_to_dev(nbd->disk),
 864                                     "Attempted send on invalid socket\n");
 865                 nbd_config_put(nbd);
 866                 blk_mq_start_request(req);
 867                 return -EINVAL;
 868         }
 869         cmd->status = BLK_STS_OK;
 870 again:
 871         nsock = config->socks[index];
 872         mutex_lock(&nsock->tx_lock);
 873         if (nsock->dead) {
 874                 int old_index = index;
 875                 index = find_fallback(nbd, index);
 876                 mutex_unlock(&nsock->tx_lock);
 877                 if (index < 0) {
 878                         if (wait_for_reconnect(nbd)) {
 879                                 index = old_index;
 880                                 goto again;
 881                         }
 882                         /* All the sockets should already be down at this point,
 883                          * we just want to make sure that DISCONNECTED is set so
 884                          * any requests that come in that were queue'ed waiting
 885                          * for the reconnect timer don't trigger the timer again
 886                          * and instead just error out.
 887                          */
 888                         sock_shutdown(nbd);
 889                         nbd_config_put(nbd);
 890                         blk_mq_start_request(req);
 891                         return -EIO;
 892                 }
 893                 goto again;
 894         }
 895
 896         /* Handle the case that we have a pending request that was partially
 897          * transmitted that _has_ to be serviced first.  We need to call requeue
 898          * here so that it gets put _after_ the request that is already on the
 899          * dispatch list.
 900          */
 901         blk_mq_start_request(req);
 902         if (unlikely(nsock->pending && nsock->pending != req)) {
 903                 nbd_requeue_cmd(cmd);
 904                 ret = 0;
 905                 goto out;
 906         }
 907         /*
 908          * Some failures are related to the link going down, so anything that
 909          * returns EAGAIN can be retried on a different socket.
 910          */
 911         ret = nbd_send_cmd(nbd, cmd, index);
 912         if (ret == -EAGAIN) {
 913                 dev_err_ratelimited(disk_to_dev(nbd->disk),
 914                                     "Request send failed, requeueing\n");
 915                 nbd_mark_nsock_dead(nbd, nsock, 1);
 916                 nbd_requeue_cmd(cmd);
 917                 ret = 0;
 918         }
 919 out:
 920         mutex_unlock(&nsock->tx_lock);
 921         nbd_config_put(nbd);
 922         return ret;
 923 }
 924
 925 static blk_status_t nbd_queue_rq(struct blk_mq_hw_ctx *hctx,
 926                         const struct blk_mq_queue_data *bd)
 927 {
 928         struct nbd_cmd *cmd = blk_mq_rq_to_pdu(bd->rq);
 929         int ret;
 930
 931         /*
 932          * Since we look at the bio's to send the request over the network we
 933          * need to make sure the completion work doesn't mark this request done
 934          * before we are done doing our send.  This keeps us from dereferencing
 935          * freed data if we have particularly fast completions (ie we get the
 936          * completion before we exit sock_xmit on the last bvec) or in the case
 937          * that the server is misbehaving (or there was an error) before we're
 938          * done sending everything over the wire.
 939          */
 940         mutex_lock(&cmd->lock);
 941         clear_bit(NBD_CMD_REQUEUED, &cmd->flags);
 942
 943         /* We can be called directly from the user space process, which means we
 944          * could possibly have signals pending so our sendmsg will fail.  In
 945          * this case we need to return that we are busy, otherwise error out as
 946          * appropriate.
 947          */
 948         ret = nbd_handle_cmd(cmd, hctx->queue_num);
 949         if (ret < 0)
 950                 ret = BLK_STS_IOERR;
 951         else if (!ret)
 952                 ret = BLK_STS_OK;
 953         mutex_unlock(&cmd->lock);
 954
 955         return ret;
 956 }
 957
 958 static int nbd_add_socket(struct nbd_device *nbd, unsigned long arg,
 959                           bool netlink)
 960 {
 961         struct nbd_config *config = nbd->config;
 962         struct socket *sock;
 963         struct nbd_sock **socks;
 964         struct nbd_sock *nsock;
 965         int err;
 966
 967         sock = sockfd_lookup(arg, &err);
 968         if (!sock)
 969                 return err;
 970
 971         if (!netlink && !nbd->task_setup &&
 972             !test_bit(NBD_BOUND, &config->runtime_flags))
 973                 nbd->task_setup = current;
 974
 975         if (!netlink &&
 976             (nbd->task_setup != current ||
 977              test_bit(NBD_BOUND, &config->runtime_flags))) {
 978                 dev_err(disk_to_dev(nbd->disk),
 979                         "Device being setup by another task");
 980                 sockfd_put(sock);
 981                 return -EBUSY;
 982         }
 983
 984         socks = krealloc(config->socks, (config->num_connections + 1) *
 985                          sizeof(struct nbd_sock *), GFP_KERNEL);
 986         if (!socks) {
 987                 sockfd_put(sock);
 988                 return -ENOMEM;
 989         }
 990         nsock = kzalloc(sizeof(struct nbd_sock), GFP_KERNEL);
 991         if (!nsock) {
 992                 sockfd_put(sock);
 993                 return -ENOMEM;
 994         }
 995
 996         config->socks = socks;
 997
 998         nsock->fallback_index = -1;
 999         nsock->dead = false;
1000         mutex_init(&nsock->tx_lock);
1001         nsock->sock = sock;
1002         nsock->pending = NULL;
1003         nsock->sent = 0;
1004         nsock->cookie = 0;
1005         socks[config->num_connections++] = nsock;
1006         atomic_inc(&config->live_connections);
1007
1008         return 0;
1009 }
1010
1011 static int nbd_reconnect_socket(struct nbd_device *nbd, unsigned long arg)
1012 {
1013         struct nbd_config *config = nbd->config;
1014         struct socket *sock, *old;
1015         struct recv_thread_args *args;
1016         int i;
1017         int err;
1018
1019         sock = sockfd_lookup(arg, &err);
1020         if (!sock)
1021                 return err;
1022
1023         args = kzalloc(sizeof(*args), GFP_KERNEL);
1024         if (!args) {
1025                 sockfd_put(sock);
1026                 return -ENOMEM;
1027         }
1028
1029         for (i = 0; i < config->num_connections; i++) {
1030                 struct nbd_sock *nsock = config->socks[i];
1031
1032                 if (!nsock->dead)
1033                         continue;
1034
1035                 mutex_lock(&nsock->tx_lock);
1036                 if (!nsock->dead) {
1037                         mutex_unlock(&nsock->tx_lock);
1038                         continue;
1039                 }
1040                 sk_set_memalloc(sock->sk);
1041                 if (nbd->tag_set.timeout)
1042                         sock->sk->sk_sndtimeo = nbd->tag_set.timeout;
1043                 atomic_inc(&config->recv_threads);
1044                 refcount_inc(&nbd->config_refs);
1045                 old = nsock->sock;
1046                 nsock->fallback_index = -1;
1047                 nsock->sock = sock;
1048                 nsock->dead = false;
1049                 INIT_WORK(&args->work, recv_work);
1050                 args->index = i;
1051                 args->nbd = nbd;
1052                 nsock->cookie++;
1053                 mutex_unlock(&nsock->tx_lock);
1054                 sockfd_put(old);
1055
1056                 clear_bit(NBD_DISCONNECTED, &config->runtime_flags);
1057
1058                 /* We take the tx_mutex in an error path in the recv_work, so we
1059                  * need to queue_work outside of the tx_mutex.
1060                  */
1061                 queue_work(nbd->recv_workq, &args->work);
1062
1063                 atomic_inc(&config->live_connections);
1064                 wake_up(&config->conn_wait);
1065                 return 0;
1066         }
1067         sockfd_put(sock);
1068         kfree(args);
1069         return -ENOSPC;
1070 }
1071
1072 static void nbd_bdev_reset(struct block_device *bdev)
1073 {
1074         if (bdev->bd_openers > 1)
1075                 return;
1076         bd_set_size(bdev, 0);
1077 }
1078
1079 static void nbd_parse_flags(struct nbd_device *nbd)
1080 {
1081         struct nbd_config *config = nbd->config;
1082         if (config->flags & NBD_FLAG_READ_ONLY)
1083                 set_disk_ro(nbd->disk, true);
1084         else
1085                 set_disk_ro(nbd->disk, false);
1086         if (config->flags & NBD_FLAG_SEND_TRIM)
1087                 blk_queue_flag_set(QUEUE_FLAG_DISCARD, nbd->disk->queue);
1088         if (config->flags & NBD_FLAG_SEND_FLUSH) {
1089                 if (config->flags & NBD_FLAG_SEND_FUA)
1090                         blk_queue_write_cache(nbd->disk->queue, true, true);
1091                 else
1092                         blk_queue_write_cache(nbd->disk->queue, true, false);
1093         }
1094         else
1095                 blk_queue_write_cache(nbd->disk->queue, false, false);
1096 }
1097
1098 static void send_disconnects(struct nbd_device *nbd)
1099 {
1100         struct nbd_config *config = nbd->config;
1101         struct nbd_request request = {
1102                 .magic = htonl(NBD_REQUEST_MAGIC),
1103                 .type = htonl(NBD_CMD_DISC),
1104         };
1105         struct kvec iov = {.iov_base = &request, .iov_len = sizeof(request)};
1106         struct iov_iter from;
1107         int i, ret;
1108
1109         for (i = 0; i < config->num_connections; i++) {
1110                 struct nbd_sock *nsock = config->socks[i];
1111
1112                 iov_iter_kvec(&from, WRITE, &iov, 1, sizeof(request));
1113                 mutex_lock(&nsock->tx_lock);
1114                 ret = sock_xmit(nbd, i, 1, &from, 0, NULL);
1115                 if (ret <= 0)
1116                         dev_err(disk_to_dev(nbd->disk),
1117                                 "Send disconnect failed %d\n", ret);
1118                 mutex_unlock(&nsock->tx_lock);
1119         }
1120 }
1121
1122 static int nbd_disconnect(struct nbd_device *nbd)
1123 {
1124         struct nbd_config *config = nbd->config;
1125
1126         dev_info(disk_to_dev(nbd->disk), "NBD_DISCONNECT\n");
1127         set_bit(NBD_DISCONNECT_REQUESTED, &config->runtime_flags);
1128         send_disconnects(nbd);
1129         return 0;
1130 }
1131
1132 static void nbd_clear_sock(struct nbd_device *nbd)
1133 {
1134         sock_shutdown(nbd);
1135         nbd_clear_que(nbd);
1136         nbd->task_setup = NULL;
1137 }
1138
1139 static void nbd_config_put(struct nbd_device *nbd)
1140 {
1141         if (refcount_dec_and_mutex_lock(&nbd->config_refs,
1142                                         &nbd->config_lock)) {
1143                 struct nbd_config *config = nbd->config;
1144                 nbd_dev_dbg_close(nbd);
1145                 nbd_size_clear(nbd);
1146                 if (test_and_clear_bit(NBD_HAS_PID_FILE,
1147                                        &config->runtime_flags))
1148                         device_remove_file(disk_to_dev(nbd->disk), &pid_attr);
1149                 nbd->task_recv = NULL;
1150                 nbd_clear_sock(nbd);
1151                 if (config->num_connections) {
1152                         int i;
1153                         for (i = 0; i < config->num_connections; i++) {
1154                                 sockfd_put(config->socks[i]->sock);
1155                                 kfree(config->socks[i]);
1156                         }
1157                         kfree(config->socks);
1158                 }
1159                 kfree(nbd->config);
1160                 nbd->config = NULL;
1161
1162                 if (nbd->recv_workq)
1163                         destroy_workqueue(nbd->recv_workq);
1164                 nbd->recv_workq = NULL;
1165
1166                 nbd->tag_set.timeout = 0;
1167                 nbd->disk->queue->limits.discard_granularity = 0;
1168                 nbd->disk->queue->limits.discard_alignment = 0;
1169                 blk_queue_max_discard_sectors(nbd->disk->queue, UINT_MAX);
1170                 blk_queue_flag_clear(QUEUE_FLAG_DISCARD, nbd->disk->queue);
1171
1172                 mutex_unlock(&nbd->config_lock);
1173                 nbd_put(nbd);
1174                 module_put(THIS_MODULE);
1175         }
1176 }
1177
1178 static int nbd_start_device(struct nbd_device *nbd)
1179 {
1180         struct nbd_config *config = nbd->config;
1181         int num_connections = config->num_connections;
1182         int error = 0, i;
1183
1184         if (nbd->task_recv)
1185                 return -EBUSY;
1186         if (!config->socks)
1187                 return -EINVAL;
1188         if (num_connections > 1 &&
1189             !(config->flags & NBD_FLAG_CAN_MULTI_CONN)) {
1190                 dev_err(disk_to_dev(nbd->disk), "server does not support multiple connections per device.\n");
1191                 return -EINVAL;
1192         }
1193
1194         nbd->recv_workq = alloc_workqueue("knbd%d-recv",
1195                                           WQ_MEM_RECLAIM | WQ_HIGHPRI |
1196                                           WQ_UNBOUND, 0, nbd->index);
1197         if (!nbd->recv_workq) {
1198                 dev_err(disk_to_dev(nbd->disk), "Could not allocate knbd recv work queue.\n");
1199                 return -ENOMEM;
1200         }
1201
1202         blk_mq_update_nr_hw_queues(&nbd->tag_set, config->num_connections);
1203         nbd->task_recv = current;
1204
1205         nbd_parse_flags(nbd);
1206
1207         error = device_create_file(disk_to_dev(nbd->disk), &pid_attr);
1208         if (error) {
1209                 dev_err(disk_to_dev(nbd->disk), "device_create_file failed!\n");
1210                 return error;
1211         }
1212         set_bit(NBD_HAS_PID_FILE, &config->runtime_flags);
1213
1214         nbd_dev_dbg_init(nbd);
1215         for (i = 0; i < num_connections; i++) {
1216                 struct recv_thread_args *args;
1217
1218                 args = kzalloc(sizeof(*args), GFP_KERNEL);
1219                 if (!args) {
1220                         sock_shutdown(nbd);
1221                         return -ENOMEM;
1222                 }
1223                 sk_set_memalloc(config->socks[i]->sock->sk);
1224                 if (nbd->tag_set.timeout)
1225                         config->socks[i]->sock->sk->sk_sndtimeo =
1226                                 nbd->tag_set.timeout;
1227                 atomic_inc(&config->recv_threads);
1228                 refcount_inc(&nbd->config_refs);
1229                 INIT_WORK(&args->work, recv_work);
1230                 args->nbd = nbd;
1231                 args->index = i;
1232                 queue_work(nbd->recv_workq, &args->work);
1233         }
1234         nbd_size_update(nbd);
1235         return error;
1236 }
1237
1238 static int nbd_start_device_ioctl(struct nbd_device *nbd, struct block_device *bdev)
1239 {
1240         struct nbd_config *config = nbd->config;
1241         int ret;
1242
1243         ret = nbd_start_device(nbd);
1244         if (ret)
1245                 return ret;
1246
1247         if (max_part)
1248                 bdev->bd_invalidated = 1;
1249         mutex_unlock(&nbd->config_lock);
1250         ret = wait_event_interruptible(config->recv_wq,
1251                                          atomic_read(&config->recv_threads) == 0);
1252         if (ret) {
1253                 sock_shutdown(nbd);
1254                 flush_workqueue(nbd->recv_workq);
1255         }
1256         mutex_lock(&nbd->config_lock);
1257         nbd_bdev_reset(bdev);
1258         /* user requested, ignore socket errors */
1259         if (test_bit(NBD_DISCONNECT_REQUESTED, &config->runtime_flags))
1260                 ret = 0;
1261         if (test_bit(NBD_TIMEDOUT, &config->runtime_flags))
1262                 ret = -ETIMEDOUT;
1263         return ret;
1264 }
1265
1266 static void nbd_clear_sock_ioctl(struct nbd_device *nbd,
1267                                  struct block_device *bdev)
1268 {
1269         sock_shutdown(nbd);
1270         __invalidate_device(bdev, true);
1271         nbd_bdev_reset(bdev);
1272         if (test_and_clear_bit(NBD_HAS_CONFIG_REF,
1273                                &nbd->config->runtime_flags))
1274                 nbd_config_put(nbd);
1275 }
1276
1277 static bool nbd_is_valid_blksize(unsigned long blksize)
1278 {
1279         if (!blksize || !is_power_of_2(blksize) || blksize < 512 ||
1280             blksize > PAGE_SIZE)
1281                 return false;
1282         return true;
1283 }
1284
1285 static void nbd_set_cmd_timeout(struct nbd_device *nbd, u64 timeout)
1286 {
1287         nbd->tag_set.timeout = timeout * HZ;
1288         if (timeout)
1289                 blk_queue_rq_timeout(nbd->disk->queue, timeout * HZ);
1290 }
1291
1292 /* Must be called with config_lock held */
1293 static int __nbd_ioctl(struct block_device *bdev, struct nbd_device *nbd,
1294                        unsigned int cmd, unsigned long arg)
1295 {
1296         struct nbd_config *config = nbd->config;
1297
1298         switch (cmd) {
1299         case NBD_DISCONNECT:
1300                 return nbd_disconnect(nbd);
1301         case NBD_CLEAR_SOCK:
1302                 nbd_clear_sock_ioctl(nbd, bdev);
1303                 return 0;
1304         case NBD_SET_SOCK:
1305                 return nbd_add_socket(nbd, arg, false);
1306         case NBD_SET_BLKSIZE:
1307                 if (!arg)
1308                         arg = NBD_DEF_BLKSIZE;
1309                 if (!nbd_is_valid_blksize(arg))
1310                         return -EINVAL;
1311                 nbd_size_set(nbd, arg,
1312                              div_s64(config->bytesize, arg));
1313                 return 0;
1314         case NBD_SET_SIZE:
1315                 nbd_size_set(nbd, config->blksize,
1316                              div_s64(arg, config->blksize));
1317                 return 0;
1318         case NBD_SET_SIZE_BLOCKS:
1319                 nbd_size_set(nbd, config->blksize, arg);
1320                 return 0;
1321         case NBD_SET_TIMEOUT:
1322                 nbd_set_cmd_timeout(nbd, arg);
1323                 return 0;
1324
1325         case NBD_SET_FLAGS:
1326                 config->flags = arg;
1327                 return 0;
1328         case NBD_DO_IT:
1329                 return nbd_start_device_ioctl(nbd, bdev);
1330         case NBD_CLEAR_QUE:
1331                 /*
1332                  * This is for compatibility only.  The queue is always cleared
1333                  * by NBD_DO_IT or NBD_CLEAR_SOCK.
1334                  */
1335                 return 0;
1336         case NBD_PRINT_DEBUG:
1337                 /*
1338                  * For compatibility only, we no longer keep a list of
1339                  * outstanding requests.
1340                  */
1341                 return 0;
1342         }
1343         return -ENOTTY;
1344 }
1345
1346 static int nbd_ioctl(struct block_device *bdev, fmode_t mode,
1347                      unsigned int cmd, unsigned long arg)
1348 {
1349         struct nbd_device *nbd = bdev->bd_disk->private_data;
1350         struct nbd_config *config = nbd->config;
1351         int error = -EINVAL;
1352
1353         if (!capable(CAP_SYS_ADMIN))
1354                 return -EPERM;
1355
1356         /* The block layer will pass back some non-nbd ioctls in case we have
1357          * special handling for them, but we don't so just return an error.
1358          */
1359         if (_IOC_TYPE(cmd) != 0xab)
1360                 return -EINVAL;
1361
1362         mutex_lock(&nbd->config_lock);
1363
1364         /* Don't allow ioctl operations on a nbd device that was created with
1365          * netlink, unless it's DISCONNECT or CLEAR_SOCK, which are fine.
1366          */
1367         if (!test_bit(NBD_BOUND, &config->runtime_flags) ||
1368             (cmd == NBD_DISCONNECT || cmd == NBD_CLEAR_SOCK))
1369                 error = __nbd_ioctl(bdev, nbd, cmd, arg);
1370         else
1371                 dev_err(nbd_to_dev(nbd), "Cannot use ioctl interface on a netlink controlled device.\n");
1372         mutex_unlock(&nbd->config_lock);
1373         return error;
1374 }
1375
1376 static struct nbd_config *nbd_alloc_config(void)
1377 {
1378         struct nbd_config *config;
1379
1380         config = kzalloc(sizeof(struct nbd_config), GFP_NOFS);
1381         if (!config)
1382                 return NULL;
1383         atomic_set(&config->recv_threads, 0);
1384         init_waitqueue_head(&config->recv_wq);
1385         init_waitqueue_head(&config->conn_wait);
1386         config->blksize = NBD_DEF_BLKSIZE;
1387         atomic_set(&config->live_connections, 0);
1388         try_module_get(THIS_MODULE);
1389         return config;
1390 }
1391
1392 static int nbd_open(struct block_device *bdev, fmode_t mode)
1393 {
1394         struct nbd_device *nbd;
1395         int ret = 0;
1396
1397         mutex_lock(&nbd_index_mutex);
1398         nbd = bdev->bd_disk->private_data;
1399         if (!nbd) {
1400                 ret = -ENXIO;
1401                 goto out;
1402         }
1403         if (!refcount_inc_not_zero(&nbd->refs)) {
1404                 ret = -ENXIO;
1405                 goto out;
1406         }
1407         if (!refcount_inc_not_zero(&nbd->config_refs)) {
1408                 struct nbd_config *config;
1409
1410                 mutex_lock(&nbd->config_lock);
1411                 if (refcount_inc_not_zero(&nbd->config_refs)) {
1412                         mutex_unlock(&nbd->config_lock);
1413                         goto out;
1414                 }
1415                 config = nbd->config = nbd_alloc_config();
1416                 if (!config) {
1417                         ret = -ENOMEM;
1418                         mutex_unlock(&nbd->config_lock);
1419                         goto out;
1420                 }
1421                 refcount_set(&nbd->config_refs, 1);
1422                 refcount_inc(&nbd->refs);
1423                 mutex_unlock(&nbd->config_lock);
1424                 bdev->bd_invalidated = 1;
1425         } else if (nbd_disconnected(nbd->config)) {
1426                 bdev->bd_invalidated = 1;
1427         }
1428 out:
1429         mutex_unlock(&nbd_index_mutex);
1430         return ret;
1431 }
1432
1433 static void nbd_release(struct gendisk *disk, fmode_t mode)
1434 {
1435         struct nbd_device *nbd = disk->private_data;
1436         struct block_device *bdev = bdget_disk(disk, 0);
1437
1438         if (test_bit(NBD_DISCONNECT_ON_CLOSE, &nbd->config->runtime_flags) &&
1439                         bdev->bd_openers == 0)
1440                 nbd_disconnect_and_put(nbd);
1441
1442         nbd_config_put(nbd);
1443         nbd_put(nbd);
1444 }
1445
1446 static const struct block_device_operations nbd_fops =
1447 {
1448         .owner =        THIS_MODULE,
1449         .open =         nbd_open,
1450         .release =      nbd_release,
1451         .ioctl =        nbd_ioctl,
1452         .compat_ioctl = nbd_ioctl,
1453 };
1454
1455 #if IS_ENABLED(CONFIG_DEBUG_FS)
1456
1457 static int nbd_dbg_tasks_show(struct seq_file *s, void *unused)
1458 {
1459         struct nbd_device *nbd = s->private;
1460
1461         if (nbd->task_recv)
1462                 seq_printf(s, "recv: %d\n", task_pid_nr(nbd->task_recv));
1463
1464         return 0;
1465 }
1466
1467 static int nbd_dbg_tasks_open(struct inode *inode, struct file *file)
1468 {
1469         return single_open(file, nbd_dbg_tasks_show, inode->i_private);
1470 }
1471
1472 static const struct file_operations nbd_dbg_tasks_ops = {
1473         .open = nbd_dbg_tasks_open,
1474         .read = seq_read,
1475         .llseek = seq_lseek,
1476         .release = single_release,
1477 };
1478
1479 static int nbd_dbg_flags_show(struct seq_file *s, void *unused)
1480 {
1481         struct nbd_device *nbd = s->private;
1482         u32 flags = nbd->config->flags;
1483
1484         seq_printf(s, "Hex: 0x%08x\n\n", flags);
1485
1486         seq_puts(s, "Known flags:\n");
1487
1488         if (flags & NBD_FLAG_HAS_FLAGS)
1489                 seq_puts(s, "NBD_FLAG_HAS_FLAGS\n");
1490         if (flags & NBD_FLAG_READ_ONLY)
1491                 seq_puts(s, "NBD_FLAG_READ_ONLY\n");
1492         if (flags & NBD_FLAG_SEND_FLUSH)
1493                 seq_puts(s, "NBD_FLAG_SEND_FLUSH\n");
1494         if (flags & NBD_FLAG_SEND_FUA)
1495                 seq_puts(s, "NBD_FLAG_SEND_FUA\n");
1496         if (flags & NBD_FLAG_SEND_TRIM)
1497                 seq_puts(s, "NBD_FLAG_SEND_TRIM\n");
1498
1499         return 0;
1500 }
1501
1502 static int nbd_dbg_flags_open(struct inode *inode, struct file *file)
1503 {
1504         return single_open(file, nbd_dbg_flags_show, inode->i_private);
1505 }
1506
1507 static const struct file_operations nbd_dbg_flags_ops = {
1508         .open = nbd_dbg_flags_open,
1509         .read = seq_read,
1510         .llseek = seq_lseek,
1511         .release = single_release,
1512 };
1513
1514 static int nbd_dev_dbg_init(struct nbd_device *nbd)
1515 {
1516         struct dentry *dir;
1517         struct nbd_config *config = nbd->config;
1518
1519         if (!nbd_dbg_dir)
1520                 return -EIO;
1521
1522         dir = debugfs_create_dir(nbd_name(nbd), nbd_dbg_dir);
1523         if (!dir) {
1524                 dev_err(nbd_to_dev(nbd), "Failed to create debugfs dir for '%s'\n",
1525                         nbd_name(nbd));
1526                 return -EIO;
1527         }
1528         config->dbg_dir = dir;
1529
1530         debugfs_create_file("tasks", 0444, dir, nbd, &nbd_dbg_tasks_ops);
1531         debugfs_create_u64("size_bytes", 0444, dir, &config->bytesize);
1532         debugfs_create_u32("timeout", 0444, dir, &nbd->tag_set.timeout);
1533         debugfs_create_u64("blocksize", 0444, dir, &config->blksize);
1534         debugfs_create_file("flags", 0444, dir, nbd, &nbd_dbg_flags_ops);
1535
1536         return 0;
1537 }
1538
1539 static void nbd_dev_dbg_close(struct nbd_device *nbd)
1540 {
1541         debugfs_remove_recursive(nbd->config->dbg_dir);
1542 }
1543
1544 static int nbd_dbg_init(void)
1545 {
1546         struct dentry *dbg_dir;
1547
1548         dbg_dir = debugfs_create_dir("nbd", NULL);
1549         if (!dbg_dir)
1550                 return -EIO;
1551
1552         nbd_dbg_dir = dbg_dir;
1553
1554         return 0;
1555 }
1556
1557 static void nbd_dbg_close(void)
1558 {
1559         debugfs_remove_recursive(nbd_dbg_dir);
1560 }
1561
1562 #else  /* IS_ENABLED(CONFIG_DEBUG_FS) */
1563
1564 static int nbd_dev_dbg_init(struct nbd_device *nbd)
1565 {
1566         return 0;
1567 }
1568
1569 static void nbd_dev_dbg_close(struct nbd_device *nbd)
1570 {
1571 }
1572
1573 static int nbd_dbg_init(void)
1574 {
1575         return 0;
1576 }
1577
1578 static void nbd_dbg_close(void)
1579 {
1580 }
1581
1582 #endif
1583
1584 static int nbd_init_request(struct blk_mq_tag_set *set, struct request *rq,
1585                             unsigned int hctx_idx, unsigned int numa_node)
1586 {
1587         struct nbd_cmd *cmd = blk_mq_rq_to_pdu(rq);
1588         cmd->nbd = set->driver_data;
1589         cmd->flags = 0;
1590         mutex_init(&cmd->lock);
1591         return 0;
1592 }
1593
1594 static const struct blk_mq_ops nbd_mq_ops = {
1595         .queue_rq       = nbd_queue_rq,
1596         .complete       = nbd_complete_rq,
1597         .init_request   = nbd_init_request,
1598         .timeout        = nbd_xmit_timeout,
1599 };
1600
1601 static int nbd_dev_add(int index)
1602 {
1603         struct nbd_device *nbd;
1604         struct gendisk *disk;
1605         struct request_queue *q;
1606         int err = -ENOMEM;
1607
1608         nbd = kzalloc(sizeof(struct nbd_device), GFP_KERNEL);
1609         if (!nbd)
1610                 goto out;
1611
1612         disk = alloc_disk(1 << part_shift);
1613         if (!disk)
1614                 goto out_free_nbd;
1615
1616         if (index >= 0) {
1617                 err = idr_alloc(&nbd_index_idr, nbd, index, index + 1,
1618                                 GFP_KERNEL);
1619                 if (err == -ENOSPC)
1620                         err = -EEXIST;
1621         } else {
1622                 err = idr_alloc(&nbd_index_idr, nbd, 0, 0, GFP_KERNEL);
1623                 if (err >= 0)
1624                         index = err;
1625         }
1626         if (err < 0)
1627                 goto out_free_disk;
1628
1629         nbd->index = index;
1630         nbd->disk = disk;
1631         nbd->tag_set.ops = &nbd_mq_ops;
1632         nbd->tag_set.nr_hw_queues = 1;
1633         nbd->tag_set.queue_depth = 128;
1634         nbd->tag_set.numa_node = NUMA_NO_NODE;
1635         nbd->tag_set.cmd_size = sizeof(struct nbd_cmd);
1636         nbd->tag_set.flags = BLK_MQ_F_SHOULD_MERGE |
1637                 BLK_MQ_F_BLOCKING;
1638         nbd->tag_set.driver_data = nbd;
1639
1640         err = blk_mq_alloc_tag_set(&nbd->tag_set);
1641         if (err)
1642                 goto out_free_idr;
1643
1644         q = blk_mq_init_queue(&nbd->tag_set);
1645         if (IS_ERR(q)) {
1646                 err = PTR_ERR(q);
1647                 goto out_free_tags;
1648         }
1649         disk->queue = q;
1650
1651         /*
1652          * Tell the block layer that we are not a rotational device
1653          */
1654         blk_queue_flag_set(QUEUE_FLAG_NONROT, disk->queue);
1655         blk_queue_flag_clear(QUEUE_FLAG_ADD_RANDOM, disk->queue);
1656         disk->queue->limits.discard_granularity = 0;
1657         disk->queue->limits.discard_alignment = 0;
1658         blk_queue_max_discard_sectors(disk->queue, 0);
1659         blk_queue_max_segment_size(disk->queue, UINT_MAX);
1660         blk_queue_max_segments(disk->queue, USHRT_MAX);
1661         blk_queue_max_hw_sectors(disk->queue, 65536);
1662         disk->queue->limits.max_sectors = 256;
1663
1664         mutex_init(&nbd->config_lock);
1665         refcount_set(&nbd->config_refs, 0);
1666         refcount_set(&nbd->refs, 1);
1667         INIT_LIST_HEAD(&nbd->list);
1668         disk->major = NBD_MAJOR;
1669         disk->first_minor = index << part_shift;
1670         disk->fops = &nbd_fops;
1671         disk->private_data = nbd;
1672         sprintf(disk->disk_name, "nbd%d", index);
1673         add_disk(disk);
1674         nbd_total_devices++;
1675         return index;
1676
1677 out_free_tags:
1678         blk_mq_free_tag_set(&nbd->tag_set);
1679 out_free_idr:
1680         idr_remove(&nbd_index_idr, index);
1681 out_free_disk:
1682         put_disk(disk);
1683 out_free_nbd:
1684         kfree(nbd);
1685 out:
1686         return err;
1687 }
1688
1689 static int find_free_cb(int id, void *ptr, void *data)
1690 {
1691         struct nbd_device *nbd = ptr;
1692         struct nbd_device **found = data;
1693
1694         if (!refcount_read(&nbd->config_refs)) {
1695                 *found = nbd;
1696                 return 1;
1697         }
1698         return 0;
1699 }
1700
1701 /* Netlink interface. */
1702 static const struct nla_policy nbd_attr_policy[NBD_ATTR_MAX + 1] = {
1703         [NBD_ATTR_INDEX]                =       { .type = NLA_U32 },
1704         [NBD_ATTR_SIZE_BYTES]           =       { .type = NLA_U64 },
1705         [NBD_ATTR_BLOCK_SIZE_BYTES]     =       { .type = NLA_U64 },
1706         [NBD_ATTR_TIMEOUT]              =       { .type = NLA_U64 },
1707         [NBD_ATTR_SERVER_FLAGS]         =       { .type = NLA_U64 },
1708         [NBD_ATTR_CLIENT_FLAGS]         =       { .type = NLA_U64 },
1709         [NBD_ATTR_SOCKETS]              =       { .type = NLA_NESTED},
1710         [NBD_ATTR_DEAD_CONN_TIMEOUT]    =       { .type = NLA_U64 },
1711         [NBD_ATTR_DEVICE_LIST]          =       { .type = NLA_NESTED},
1712 };
1713
1714 static const struct nla_policy nbd_sock_policy[NBD_SOCK_MAX + 1] = {
1715         [NBD_SOCK_FD]                   =       { .type = NLA_U32 },
1716 };
1717
1718 /* We don't use this right now since we don't parse the incoming list, but we
1719  * still want it here so userspace knows what to expect.
1720  */
1721 static const struct nla_policy __attribute__((unused))
1722 nbd_device_policy[NBD_DEVICE_ATTR_MAX + 1] = {
1723         [NBD_DEVICE_INDEX]              =       { .type = NLA_U32 },
1724         [NBD_DEVICE_CONNECTED]          =       { .type = NLA_U8 },
1725 };
1726
1727 static int nbd_genl_size_set(struct genl_info *info, struct nbd_device *nbd)
1728 {
1729         struct nbd_config *config = nbd->config;
1730         u64 bsize = config->blksize;
1731         u64 bytes = config->bytesize;
1732
1733         if (info->attrs[NBD_ATTR_SIZE_BYTES])
1734                 bytes = nla_get_u64(info->attrs[NBD_ATTR_SIZE_BYTES]);
1735
1736         if (info->attrs[NBD_ATTR_BLOCK_SIZE_BYTES]) {
1737                 bsize = nla_get_u64(info->attrs[NBD_ATTR_BLOCK_SIZE_BYTES]);
1738                 if (!bsize)
1739                         bsize = NBD_DEF_BLKSIZE;
1740                 if (!nbd_is_valid_blksize(bsize)) {
1741                         printk(KERN_ERR "Invalid block size %llu\n", bsize);
1742                         return -EINVAL;
1743                 }
1744         }
1745
1746         if (bytes != config->bytesize || bsize != config->blksize)
1747                 nbd_size_set(nbd, bsize, div64_u64(bytes, bsize));
1748         return 0;
1749 }
1750
1751 static int nbd_genl_connect(struct sk_buff *skb, struct genl_info *info)
1752 {
1753         struct nbd_device *nbd = NULL;
1754         struct nbd_config *config;
1755         int index = -1;
1756         int ret;
1757         bool put_dev = false;
1758
1759         if (!netlink_capable(skb, CAP_SYS_ADMIN))
1760                 return -EPERM;
1761
1762         if (info->attrs[NBD_ATTR_INDEX])
1763                 index = nla_get_u32(info->attrs[NBD_ATTR_INDEX]);
1764         if (!info->attrs[NBD_ATTR_SOCKETS]) {
1765                 printk(KERN_ERR "nbd: must specify at least one socket\n");
1766                 return -EINVAL;
1767         }
1768         if (!info->attrs[NBD_ATTR_SIZE_BYTES]) {
1769                 printk(KERN_ERR "nbd: must specify a size in bytes for the device\n");
1770                 return -EINVAL;
1771         }
1772 again:
1773         mutex_lock(&nbd_index_mutex);
1774         if (index == -1) {
1775                 ret = idr_for_each(&nbd_index_idr, &find_free_cb, &nbd);
1776                 if (ret == 0) {
1777                         int new_index;
1778                         new_index = nbd_dev_add(-1);
1779                         if (new_index < 0) {
1780                                 mutex_unlock(&nbd_index_mutex);
1781                                 printk(KERN_ERR "nbd: failed to add new device\n");
1782                                 return new_index;
1783                         }
1784                         nbd = idr_find(&nbd_index_idr, new_index);
1785                 }
1786         } else {
1787                 nbd = idr_find(&nbd_index_idr, index);
1788                 if (!nbd) {
1789                         ret = nbd_dev_add(index);
1790                         if (ret < 0) {
1791                                 mutex_unlock(&nbd_index_mutex);
1792                                 printk(KERN_ERR "nbd: failed to add new device\n");
1793                                 return ret;
1794                         }
1795                         nbd = idr_find(&nbd_index_idr, index);
1796                 }
1797         }
1798         if (!nbd) {
1799                 printk(KERN_ERR "nbd: couldn't find device at index %d\n",
1800                        index);
1801                 mutex_unlock(&nbd_index_mutex);
1802                 return -EINVAL;
1803         }
1804         if (!refcount_inc_not_zero(&nbd->refs)) {
1805                 mutex_unlock(&nbd_index_mutex);
1806                 if (index == -1)
1807                         goto again;
1808                 printk(KERN_ERR "nbd: device at index %d is going down\n",
1809                        index);
1810                 return -EINVAL;
1811         }
1812         mutex_unlock(&nbd_index_mutex);
1813
1814         mutex_lock(&nbd->config_lock);
1815         if (refcount_read(&nbd->config_refs)) {
1816                 mutex_unlock(&nbd->config_lock);
1817                 nbd_put(nbd);
1818                 if (index == -1)
1819                         goto again;
1820                 printk(KERN_ERR "nbd: nbd%d already in use\n", index);
1821                 return -EBUSY;
1822         }
1823         if (WARN_ON(nbd->config)) {
1824                 mutex_unlock(&nbd->config_lock);
1825                 nbd_put(nbd);
1826                 return -EINVAL;
1827         }
1828         config = nbd->config = nbd_alloc_config();
1829         if (!nbd->config) {
1830                 mutex_unlock(&nbd->config_lock);
1831                 nbd_put(nbd);
1832                 printk(KERN_ERR "nbd: couldn't allocate config\n");
1833                 return -ENOMEM;
1834         }
1835         refcount_set(&nbd->config_refs, 1);
1836         set_bit(NBD_BOUND, &config->runtime_flags);
1837
1838         ret = nbd_genl_size_set(info, nbd);
1839         if (ret)
1840                 goto out;
1841
1842         if (info->attrs[NBD_ATTR_TIMEOUT])
1843                 nbd_set_cmd_timeout(nbd,
1844                                     nla_get_u64(info->attrs[NBD_ATTR_TIMEOUT]));
1845         if (info->attrs[NBD_ATTR_DEAD_CONN_TIMEOUT]) {
1846                 config->dead_conn_timeout =
1847                         nla_get_u64(info->attrs[NBD_ATTR_DEAD_CONN_TIMEOUT]);
1848                 config->dead_conn_timeout *= HZ;
1849         }
1850         if (info->attrs[NBD_ATTR_SERVER_FLAGS])
1851                 config->flags =
1852                         nla_get_u64(info->attrs[NBD_ATTR_SERVER_FLAGS]);
1853         if (info->attrs[NBD_ATTR_CLIENT_FLAGS]) {
1854                 u64 flags = nla_get_u64(info->attrs[NBD_ATTR_CLIENT_FLAGS]);
1855                 if (flags & NBD_CFLAG_DESTROY_ON_DISCONNECT) {
1856                         set_bit(NBD_DESTROY_ON_DISCONNECT,
1857                                 &config->runtime_flags);
1858                         put_dev = true;
1859                 }
1860                 if (flags & NBD_CFLAG_DISCONNECT_ON_CLOSE) {
1861                         set_bit(NBD_DISCONNECT_ON_CLOSE,
1862                                 &config->runtime_flags);
1863                 }
1864         }
1865
1866         if (info->attrs[NBD_ATTR_SOCKETS]) {
1867                 struct nlattr *attr;
1868                 int rem, fd;
1869
1870                 nla_for_each_nested(attr, info->attrs[NBD_ATTR_SOCKETS],
1871                                     rem) {
1872                         struct nlattr *socks[NBD_SOCK_MAX+1];
1873
1874                         if (nla_type(attr) != NBD_SOCK_ITEM) {
1875                                 printk(KERN_ERR "nbd: socks must be embedded in a SOCK_ITEM attr\n");
1876                                 ret = -EINVAL;
1877                                 goto out;
1878                         }
1879                         ret = nla_parse_nested_deprecated(socks, NBD_SOCK_MAX,
1880                                                           attr,
1881                                                           nbd_sock_policy,
1882                                                           info->extack);
1883                         if (ret != 0) {
1884                                 printk(KERN_ERR "nbd: error processing sock list\n");
1885                                 ret = -EINVAL;
1886                                 goto out;
1887                         }
1888                         if (!socks[NBD_SOCK_FD])
1889                                 continue;
1890                         fd = (int)nla_get_u32(socks[NBD_SOCK_FD]);
1891                         ret = nbd_add_socket(nbd, fd, true);
1892                         if (ret)
1893                                 goto out;
1894                 }
1895         }
1896         ret = nbd_start_device(nbd);
1897 out:
1898         mutex_unlock(&nbd->config_lock);
1899         if (!ret) {
1900                 set_bit(NBD_HAS_CONFIG_REF, &config->runtime_flags);
1901                 refcount_inc(&nbd->config_refs);
1902                 nbd_connect_reply(info, nbd->index);
1903         }
1904         nbd_config_put(nbd);
1905         if (put_dev)
1906                 nbd_put(nbd);
1907         return ret;
1908 }
1909
1910 static void nbd_disconnect_and_put(struct nbd_device *nbd)
1911 {
1912         mutex_lock(&nbd->config_lock);
1913         nbd_disconnect(nbd);
1914         nbd_clear_sock(nbd);
1915         mutex_unlock(&nbd->config_lock);
1916         /*
1917          * Make sure recv thread has finished, so it does not drop the last
1918          * config ref and try to destroy the workqueue from inside the work
1919          * queue.
1920          */
1921         flush_workqueue(nbd->recv_workq);
1922         if (test_and_clear_bit(NBD_HAS_CONFIG_REF,
1923                                &nbd->config->runtime_flags))
1924                 nbd_config_put(nbd);
1925 }
1926
1927 static int nbd_genl_disconnect(struct sk_buff *skb, struct genl_info *info)
1928 {
1929         struct nbd_device *nbd;
1930         int index;
1931
1932         if (!netlink_capable(skb, CAP_SYS_ADMIN))
1933                 return -EPERM;
1934
1935         if (!info->attrs[NBD_ATTR_INDEX]) {
1936                 printk(KERN_ERR "nbd: must specify an index to disconnect\n");
1937                 return -EINVAL;
1938         }
1939         index = nla_get_u32(info->attrs[NBD_ATTR_INDEX]);
1940         mutex_lock(&nbd_index_mutex);
1941         nbd = idr_find(&nbd_index_idr, index);
1942         if (!nbd) {
1943                 mutex_unlock(&nbd_index_mutex);
1944                 printk(KERN_ERR "nbd: couldn't find device at index %d\n",
1945                        index);
1946                 return -EINVAL;
1947         }
1948         if (!refcount_inc_not_zero(&nbd->refs)) {
1949                 mutex_unlock(&nbd_index_mutex);
1950                 printk(KERN_ERR "nbd: device at index %d is going down\n",
1951                        index);
1952                 return -EINVAL;
1953         }
1954         mutex_unlock(&nbd_index_mutex);
1955         if (!refcount_inc_not_zero(&nbd->config_refs)) {
1956                 nbd_put(nbd);
1957                 return 0;
1958         }
1959         nbd_disconnect_and_put(nbd);
1960         nbd_config_put(nbd);
1961         nbd_put(nbd);
1962         return 0;
1963 }
1964
1965 static int nbd_genl_reconfigure(struct sk_buff *skb, struct genl_info *info)
1966 {
1967         struct nbd_device *nbd = NULL;
1968         struct nbd_config *config;
1969         int index;
1970         int ret = 0;
1971         bool put_dev = false;
1972
1973         if (!netlink_capable(skb, CAP_SYS_ADMIN))
1974                 return -EPERM;
1975
1976         if (!info->attrs[NBD_ATTR_INDEX]) {
1977                 printk(KERN_ERR "nbd: must specify a device to reconfigure\n");
1978                 return -EINVAL;
1979         }
1980         index = nla_get_u32(info->attrs[NBD_ATTR_INDEX]);
1981         mutex_lock(&nbd_index_mutex);
1982         nbd = idr_find(&nbd_index_idr, index);
1983         if (!nbd) {
1984                 mutex_unlock(&nbd_index_mutex);
1985                 printk(KERN_ERR "nbd: couldn't find a device at index %d\n",
1986                        index);
1987                 return -EINVAL;
1988         }
1989         if (!refcount_inc_not_zero(&nbd->refs)) {
1990                 mutex_unlock(&nbd_index_mutex);
1991                 printk(KERN_ERR "nbd: device at index %d is going down\n",
1992                        index);
1993                 return -EINVAL;
1994         }
1995         mutex_unlock(&nbd_index_mutex);
1996
1997         if (!refcount_inc_not_zero(&nbd->config_refs)) {
1998                 dev_err(nbd_to_dev(nbd),
1999                         "not configured, cannot reconfigure\n");
2000                 nbd_put(nbd);
2001                 return -EINVAL;
2002         }
2003
2004         mutex_lock(&nbd->config_lock);
2005         config = nbd->config;
2006         if (!test_bit(NBD_BOUND, &config->runtime_flags) ||
2007             !nbd->task_recv) {
2008                 dev_err(nbd_to_dev(nbd),
2009                         "not configured, cannot reconfigure\n");
2010                 ret = -EINVAL;
2011                 goto out;
2012         }
2013
2014         ret = nbd_genl_size_set(info, nbd);
2015         if (ret)
2016                 goto out;
2017
2018         if (info->attrs[NBD_ATTR_TIMEOUT])
2019                 nbd_set_cmd_timeout(nbd,
2020                                     nla_get_u64(info->attrs[NBD_ATTR_TIMEOUT]));
2021         if (info->attrs[NBD_ATTR_DEAD_CONN_TIMEOUT]) {
2022                 config->dead_conn_timeout =
2023                         nla_get_u64(info->attrs[NBD_ATTR_DEAD_CONN_TIMEOUT]);
2024                 config->dead_conn_timeout *= HZ;
2025         }
2026         if (info->attrs[NBD_ATTR_CLIENT_FLAGS]) {
2027                 u64 flags = nla_get_u64(info->attrs[NBD_ATTR_CLIENT_FLAGS]);
2028                 if (flags & NBD_CFLAG_DESTROY_ON_DISCONNECT) {
2029                         if (!test_and_set_bit(NBD_DESTROY_ON_DISCONNECT,
2030                                               &config->runtime_flags))
2031                                 put_dev = true;
2032                 } else {
2033                         if (test_and_clear_bit(NBD_DESTROY_ON_DISCONNECT,
2034                                                &config->runtime_flags))
2035                                 refcount_inc(&nbd->refs);
2036                 }
2037
2038                 if (flags & NBD_CFLAG_DISCONNECT_ON_CLOSE) {
2039                         set_bit(NBD_DISCONNECT_ON_CLOSE,
2040                                         &config->runtime_flags);
2041                 } else {
2042                         clear_bit(NBD_DISCONNECT_ON_CLOSE,
2043                                         &config->runtime_flags);
2044                 }
2045         }
2046
2047         if (info->attrs[NBD_ATTR_SOCKETS]) {
2048                 struct nlattr *attr;
2049                 int rem, fd;
2050
2051                 nla_for_each_nested(attr, info->attrs[NBD_ATTR_SOCKETS],
2052                                     rem) {
2053                         struct nlattr *socks[NBD_SOCK_MAX+1];
2054
2055                         if (nla_type(attr) != NBD_SOCK_ITEM) {
2056                                 printk(KERN_ERR "nbd: socks must be embedded in a SOCK_ITEM attr\n");
2057                                 ret = -EINVAL;
2058                                 goto out;
2059                         }
2060                         ret = nla_parse_nested_deprecated(socks, NBD_SOCK_MAX,
2061                                                           attr,
2062                                                           nbd_sock_policy,
2063                                                           info->extack);
2064                         if (ret != 0) {
2065                                 printk(KERN_ERR "nbd: error processing sock list\n");
2066                                 ret = -EINVAL;
2067                                 goto out;
2068                         }
2069                         if (!socks[NBD_SOCK_FD])
2070                                 continue;
2071                         fd = (int)nla_get_u32(socks[NBD_SOCK_FD]);
2072                         ret = nbd_reconnect_socket(nbd, fd);
2073                         if (ret) {
2074                                 if (ret == -ENOSPC)
2075                                         ret = 0;
2076                                 goto out;
2077                         }
2078                         dev_info(nbd_to_dev(nbd), "reconnected socket\n");
2079                 }
2080         }
2081 out:
2082         mutex_unlock(&nbd->config_lock);
2083         nbd_config_put(nbd);
2084         nbd_put(nbd);
2085         if (put_dev)
2086                 nbd_put(nbd);
2087         return ret;
2088 }
2089
2090 static const struct genl_ops nbd_connect_genl_ops[] = {
2091         {
2092                 .cmd    = NBD_CMD_CONNECT,
2093                 .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
2094                 .doit   = nbd_genl_connect,
2095         },
2096         {
2097                 .cmd    = NBD_CMD_DISCONNECT,
2098                 .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
2099                 .doit   = nbd_genl_disconnect,
2100         },
2101         {
2102                 .cmd    = NBD_CMD_RECONFIGURE,
2103                 .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
2104                 .doit   = nbd_genl_reconfigure,
2105         },
2106         {
2107                 .cmd    = NBD_CMD_STATUS,
2108                 .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
2109                 .doit   = nbd_genl_status,
2110         },
2111 };
2112
2113 static const struct genl_multicast_group nbd_mcast_grps[] = {
2114         { .name = NBD_GENL_MCAST_GROUP_NAME, },
2115 };
2116
2117 static struct genl_family nbd_genl_family __ro_after_init = {
2118         .hdrsize        = 0,
2119         .name           = NBD_GENL_FAMILY_NAME,
2120         .version        = NBD_GENL_VERSION,
2121         .module         = THIS_MODULE,
2122         .ops            = nbd_connect_genl_ops,
2123         .n_ops          = ARRAY_SIZE(nbd_connect_genl_ops),
2124         .maxattr        = NBD_ATTR_MAX,
2125         .policy = nbd_attr_policy,
2126         .mcgrps         = nbd_mcast_grps,
2127         .n_mcgrps       = ARRAY_SIZE(nbd_mcast_grps),
2128 };
2129
2130 static int populate_nbd_status(struct nbd_device *nbd, struct sk_buff *reply)
2131 {
2132         struct nlattr *dev_opt;
2133         u8 connected = 0;
2134         int ret;
2135
2136         /* This is a little racey, but for status it's ok.  The
2137          * reason we don't take a ref here is because we can't
2138          * take a ref in the index == -1 case as we would need
2139          * to put under the nbd_index_mutex, which could
2140          * deadlock if we are configured to remove ourselves
2141          * once we're disconnected.
2142          */
2143         if (refcount_read(&nbd->config_refs))
2144                 connected = 1;
2145         dev_opt = nla_nest_start_noflag(reply, NBD_DEVICE_ITEM);
2146         if (!dev_opt)
2147                 return -EMSGSIZE;
2148         ret = nla_put_u32(reply, NBD_DEVICE_INDEX, nbd->index);
2149         if (ret)
2150                 return -EMSGSIZE;
2151         ret = nla_put_u8(reply, NBD_DEVICE_CONNECTED,
2152                          connected);
2153         if (ret)
2154                 return -EMSGSIZE;
2155         nla_nest_end(reply, dev_opt);
2156         return 0;
2157 }
2158
2159 static int status_cb(int id, void *ptr, void *data)
2160 {
2161         struct nbd_device *nbd = ptr;
2162         return populate_nbd_status(nbd, (struct sk_buff *)data);
2163 }
2164
2165 static int nbd_genl_status(struct sk_buff *skb, struct genl_info *info)
2166 {
2167         struct nlattr *dev_list;
2168         struct sk_buff *reply;
2169         void *reply_head;
2170         size_t msg_size;
2171         int index = -1;
2172         int ret = -ENOMEM;
2173
2174         if (info->attrs[NBD_ATTR_INDEX])
2175                 index = nla_get_u32(info->attrs[NBD_ATTR_INDEX]);
2176
2177         mutex_lock(&nbd_index_mutex);
2178
2179         msg_size = nla_total_size(nla_attr_size(sizeof(u32)) +
2180                                   nla_attr_size(sizeof(u8)));
2181         msg_size *= (index == -1) ? nbd_total_devices : 1;
2182
2183         reply = genlmsg_new(msg_size, GFP_KERNEL);
2184         if (!reply)
2185                 goto out;
2186         reply_head = genlmsg_put_reply(reply, info, &nbd_genl_family, 0,
2187                                        NBD_CMD_STATUS);
2188         if (!reply_head) {
2189                 nlmsg_free(reply);
2190                 goto out;
2191         }
2192
2193         dev_list = nla_nest_start_noflag(reply, NBD_ATTR_DEVICE_LIST);
2194         if (index == -1) {
2195                 ret = idr_for_each(&nbd_index_idr, &status_cb, reply);
2196                 if (ret) {
2197                         nlmsg_free(reply);
2198                         goto out;
2199                 }
2200         } else {
2201                 struct nbd_device *nbd;
2202                 nbd = idr_find(&nbd_index_idr, index);
2203                 if (nbd) {
2204                         ret = populate_nbd_status(nbd, reply);
2205                         if (ret) {
2206                                 nlmsg_free(reply);
2207                                 goto out;
2208                         }
2209                 }
2210         }
2211         nla_nest_end(reply, dev_list);
2212         genlmsg_end(reply, reply_head);
2213         ret = genlmsg_reply(reply, info);
2214 out:
2215         mutex_unlock(&nbd_index_mutex);
2216         return ret;
2217 }
2218
2219 static void nbd_connect_reply(struct genl_info *info, int index)
2220 {
2221         struct sk_buff *skb;
2222         void *msg_head;
2223         int ret;
2224
2225         skb = genlmsg_new(nla_total_size(sizeof(u32)), GFP_KERNEL);
2226         if (!skb)
2227                 return;
2228         msg_head = genlmsg_put_reply(skb, info, &nbd_genl_family, 0,
2229                                      NBD_CMD_CONNECT);
2230         if (!msg_head) {
2231                 nlmsg_free(skb);
2232                 return;
2233         }
2234         ret = nla_put_u32(skb, NBD_ATTR_INDEX, index);
2235         if (ret) {
2236                 nlmsg_free(skb);
2237                 return;
2238         }
2239         genlmsg_end(skb, msg_head);
2240         genlmsg_reply(skb, info);
2241 }
2242
2243 static void nbd_mcast_index(int index)
2244 {
2245         struct sk_buff *skb;
2246         void *msg_head;
2247         int ret;
2248
2249         skb = genlmsg_new(nla_total_size(sizeof(u32)), GFP_KERNEL);
2250         if (!skb)
2251                 return;
2252         msg_head = genlmsg_put(skb, 0, 0, &nbd_genl_family, 0,
2253                                      NBD_CMD_LINK_DEAD);
2254         if (!msg_head) {
2255                 nlmsg_free(skb);
2256                 return;
2257         }
2258         ret = nla_put_u32(skb, NBD_ATTR_INDEX, index);
2259         if (ret) {
2260                 nlmsg_free(skb);
2261                 return;
2262         }
2263         genlmsg_end(skb, msg_head);
2264         genlmsg_multicast(&nbd_genl_family, skb, 0, 0, GFP_KERNEL);
2265 }
2266
2267 static void nbd_dead_link_work(struct work_struct *work)
2268 {
2269         struct link_dead_args *args = container_of(work, struct link_dead_args,
2270                                                    work);
2271         nbd_mcast_index(args->index);
2272         kfree(args);
2273 }
2274
2275 static int __init nbd_init(void)
2276 {
2277         int i;
2278
2279         BUILD_BUG_ON(sizeof(struct nbd_request) != 28);
2280
2281         if (max_part < 0) {
2282                 printk(KERN_ERR "nbd: max_part must be >= 0\n");
2283                 return -EINVAL;
2284         }
2285
2286         part_shift = 0;
2287         if (max_part > 0) {
2288                 part_shift = fls(max_part);
2289
2290                 /*
2291                  * Adjust max_part according to part_shift as it is exported
2292                  * to user space so that user can know the max number of
2293                  * partition kernel should be able to manage.
2294                  *
2295                  * Note that -1 is required because partition 0 is reserved
2296                  * for the whole disk.
2297                  */
2298                 max_part = (1UL << part_shift) - 1;
2299         }
2300
2301         if ((1UL << part_shift) > DISK_MAX_PARTS)
2302                 return -EINVAL;
2303
2304         if (nbds_max > 1UL << (MINORBITS - part_shift))
2305                 return -EINVAL;
2306
2307         if (register_blkdev(NBD_MAJOR, "nbd"))
2308                 return -EIO;
2309
2310         if (genl_register_family(&nbd_genl_family)) {
2311                 unregister_blkdev(NBD_MAJOR, "nbd");
2312                 return -EINVAL;
2313         }
2314         nbd_dbg_init();
2315
2316         mutex_lock(&nbd_index_mutex);
2317         for (i = 0; i < nbds_max; i++)
2318                 nbd_dev_add(i);
2319         mutex_unlock(&nbd_index_mutex);
2320         return 0;
2321 }
2322
2323 static int nbd_exit_cb(int id, void *ptr, void *data)
2324 {
2325         struct list_head *list = (struct list_head *)data;
2326         struct nbd_device *nbd = ptr;
2327
2328         list_add_tail(&nbd->list, list);
2329         return 0;
2330 }
2331
2332 static void __exit nbd_cleanup(void)
2333 {
2334         struct nbd_device *nbd;
2335         LIST_HEAD(del_list);
2336
2337         nbd_dbg_close();
2338
2339         mutex_lock(&nbd_index_mutex);
2340         idr_for_each(&nbd_index_idr, &nbd_exit_cb, &del_list);
2341         mutex_unlock(&nbd_index_mutex);
2342
2343         while (!list_empty(&del_list)) {
2344                 nbd = list_first_entry(&del_list, struct nbd_device, list);
2345                 list_del_init(&nbd->list);
2346                 if (refcount_read(&nbd->refs) != 1)
2347                         printk(KERN_ERR "nbd: possibly leaking a device\n");
2348                 nbd_put(nbd);
2349         }
2350
2351         idr_destroy(&nbd_index_idr);
2352         genl_unregister_family(&nbd_genl_family);
2353         unregister_blkdev(NBD_MAJOR, "nbd");
2354 }
2355
2356 module_init(nbd_init);
2357 module_exit(nbd_cleanup);
2358
2359 MODULE_DESCRIPTION("Network Block Device");
2360 MODULE_LICENSE("GPL");
2361
2362 module_param(nbds_max, int, 0444);
2363 MODULE_PARM_DESC(nbds_max, "number of network block devices to initialize (default: 16)");
2364 module_param(max_part, int, 0444);
2365 MODULE_PARM_DESC(max_part, "number of partitions per device (default: 16)");