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/completion.h>
  30 #include <linux/err.h>
  31 #include <linux/kernel.h>
  32 #include <linux/slab.h>
  33 #include <net/sock.h>
  34 #include <linux/net.h>
  35 #include <linux/kthread.h>
  36 #include <linux/types.h>
  37 #include <linux/debugfs.h>
  38 #include <linux/blk-mq.h>
  39
  40 #include <linux/uaccess.h>
  41 #include <asm/types.h>
  42
  43 #include <linux/nbd.h>
  44 #include <linux/nbd-netlink.h>
  45 #include <net/genetlink.h>
  46
  47 #define CREATE_TRACE_POINTS
  48 #include <trace/events/nbd.h>
  49
  50 static DEFINE_IDR(nbd_index_idr);
  51 static DEFINE_MUTEX(nbd_index_mutex);
  52 static int nbd_total_devices = 0;
  53
  54 struct nbd_sock {
  55         struct socket *sock;
  56         struct mutex tx_lock;
  57         struct request *pending;
  58         int sent;
  59         bool dead;
  60         int fallback_index;
  61         int cookie;
  62 };
  63
  64 struct recv_thread_args {
  65         struct work_struct work;
  66         struct nbd_device *nbd;
  67         int index;
  68 };
  69
  70 struct link_dead_args {
  71         struct work_struct work;
  72         int index;
  73 };
  74
  75 #define NBD_RT_TIMEDOUT                 0
  76 #define NBD_RT_DISCONNECT_REQUESTED     1
  77 #define NBD_RT_DISCONNECTED             2
  78 #define NBD_RT_HAS_PID_FILE             3
  79 #define NBD_RT_HAS_CONFIG_REF           4
  80 #define NBD_RT_BOUND                    5
  81 #define NBD_RT_DESTROY_ON_DISCONNECT    6
  82 #define NBD_RT_DISCONNECT_ON_CLOSE      7
  83
  84 #define NBD_DESTROY_ON_DISCONNECT       0
  85 #define NBD_DISCONNECT_REQUESTED        1
  86
  87 struct nbd_config {
  88         u32 flags;
  89         unsigned long runtime_flags;
  90         u64 dead_conn_timeout;
  91
  92         struct nbd_sock **socks;
  93         int num_connections;
  94         atomic_t live_connections;
  95         wait_queue_head_t conn_wait;
  96
  97         atomic_t recv_threads;
  98         wait_queue_head_t recv_wq;
  99         loff_t blksize;
 100         loff_t bytesize;
 101 #if IS_ENABLED(CONFIG_DEBUG_FS)
 102         struct dentry *dbg_dir;
 103 #endif
 104 };
 105
 106 struct nbd_device {
 107         struct blk_mq_tag_set tag_set;
 108
 109         int index;
 110         refcount_t config_refs;
 111         refcount_t refs;
 112         struct nbd_config *config;
 113         struct mutex config_lock;
 114         struct gendisk *disk;
 115         struct workqueue_struct *recv_workq;
 116
 117         struct list_head list;
 118         struct task_struct *task_recv;
 119         struct task_struct *task_setup;
 120
 121         struct completion *destroy_complete;
 122         unsigned long flags;
 123 };
 124
 125 #define NBD_CMD_REQUEUED        1
 126
 127 struct nbd_cmd {
 128         struct nbd_device *nbd;
 129         struct mutex lock;
 130         int index;
 131         int cookie;
 132         int retries;
 133         blk_status_t status;
 134         unsigned long flags;
 135         u32 cmd_cookie;
 136 };
 137
 138 #if IS_ENABLED(CONFIG_DEBUG_FS)
 139 static struct dentry *nbd_dbg_dir;
 140 #endif
 141
 142 #define nbd_name(nbd) ((nbd)->disk->disk_name)
 143
 144 #define NBD_MAGIC 0x68797548
 145
 146 #define NBD_DEF_BLKSIZE 1024
 147
 148 static unsigned int nbds_max = 16;
 149 static int max_part = 16;
 150 static int part_shift;
 151
 152 static int nbd_dev_dbg_init(struct nbd_device *nbd);
 153 static void nbd_dev_dbg_close(struct nbd_device *nbd);
 154 static void nbd_config_put(struct nbd_device *nbd);
 155 static void nbd_connect_reply(struct genl_info *info, int index);
 156 static int nbd_genl_status(struct sk_buff *skb, struct genl_info *info);
 157 static void nbd_dead_link_work(struct work_struct *work);
 158 static void nbd_disconnect_and_put(struct nbd_device *nbd);
 159
 160 static inline struct device *nbd_to_dev(struct nbd_device *nbd)
 161 {
 162         return disk_to_dev(nbd->disk);
 163 }
 164
 165 static void nbd_requeue_cmd(struct nbd_cmd *cmd)
 166 {
 167         struct request *req = blk_mq_rq_from_pdu(cmd);
 168
 169         if (!test_and_set_bit(NBD_CMD_REQUEUED, &cmd->flags))
 170                 blk_mq_requeue_request(req, true);
 171 }
 172
 173 #define NBD_COOKIE_BITS 32
 174
 175 static u64 nbd_cmd_handle(struct nbd_cmd *cmd)
 176 {
 177         struct request *req = blk_mq_rq_from_pdu(cmd);
 178         u32 tag = blk_mq_unique_tag(req);
 179         u64 cookie = cmd->cmd_cookie;
 180
 181         return (cookie << NBD_COOKIE_BITS) | tag;
 182 }
 183
 184 static u32 nbd_handle_to_tag(u64 handle)
 185 {
 186         return (u32)handle;
 187 }
 188
 189 static u32 nbd_handle_to_cookie(u64 handle)
 190 {
 191         return (u32)(handle >> NBD_COOKIE_BITS);
 192 }
 193
 194 static const char *nbdcmd_to_ascii(int cmd)
 195 {
 196         switch (cmd) {
 197         case  NBD_CMD_READ: return "read";
 198         case NBD_CMD_WRITE: return "write";
 199         case  NBD_CMD_DISC: return "disconnect";
 200         case NBD_CMD_FLUSH: return "flush";
 201         case  NBD_CMD_TRIM: return "trim/discard";
 202         }
 203         return "invalid";
 204 }
 205
 206 static ssize_t pid_show(struct device *dev,
 207                         struct device_attribute *attr, char *buf)
 208 {
 209         struct gendisk *disk = dev_to_disk(dev);
 210         struct nbd_device *nbd = (struct nbd_device *)disk->private_data;
 211
 212         return sprintf(buf, "%d\n", task_pid_nr(nbd->task_recv));
 213 }
 214
 215 static const struct device_attribute pid_attr = {
 216         .attr = { .name = "pid", .mode = 0444},
 217         .show = pid_show,
 218 };
 219
 220 static void nbd_dev_remove(struct nbd_device *nbd)
 221 {
 222         struct gendisk *disk = nbd->disk;
 223         struct request_queue *q;
 224
 225         if (disk) {
 226                 q = disk->queue;
 227                 del_gendisk(disk);
 228                 blk_cleanup_queue(q);
 229                 blk_mq_free_tag_set(&nbd->tag_set);
 230                 disk->private_data = NULL;
 231                 put_disk(disk);
 232         }
 233
 234         /*
 235          * Place this in the last just before the nbd is freed to
 236          * make sure that the disk and the related kobject are also
 237          * totally removed to avoid duplicate creation of the same
 238          * one.
 239          */
 240         if (test_bit(NBD_DESTROY_ON_DISCONNECT, &nbd->flags) && nbd->destroy_complete)
 241                 complete(nbd->destroy_complete);
 242
 243         kfree(nbd);
 244 }
 245
 246 static void nbd_put(struct nbd_device *nbd)
 247 {
 248         if (refcount_dec_and_mutex_lock(&nbd->refs,
 249                                         &nbd_index_mutex)) {
 250                 idr_remove(&nbd_index_idr, nbd->index);
 251                 nbd_dev_remove(nbd);
 252                 mutex_unlock(&nbd_index_mutex);
 253         }
 254 }
 255
 256 static int nbd_disconnected(struct nbd_config *config)
 257 {
 258         return test_bit(NBD_RT_DISCONNECTED, &config->runtime_flags) ||
 259                 test_bit(NBD_RT_DISCONNECT_REQUESTED, &config->runtime_flags);
 260 }
 261
 262 static void nbd_mark_nsock_dead(struct nbd_device *nbd, struct nbd_sock *nsock,
 263                                 int notify)
 264 {
 265         if (!nsock->dead && notify && !nbd_disconnected(nbd->config)) {
 266                 struct link_dead_args *args;
 267                 args = kmalloc(sizeof(struct link_dead_args), GFP_NOIO);
 268                 if (args) {
 269                         INIT_WORK(&args->work, nbd_dead_link_work);
 270                         args->index = nbd->index;
 271                         queue_work(system_wq, &args->work);
 272                 }
 273         }
 274         if (!nsock->dead) {
 275                 kernel_sock_shutdown(nsock->sock, SHUT_RDWR);
 276                 if (atomic_dec_return(&nbd->config->live_connections) == 0) {
 277                         if (test_and_clear_bit(NBD_RT_DISCONNECT_REQUESTED,
 278                                                &nbd->config->runtime_flags)) {
 279                                 set_bit(NBD_RT_DISCONNECTED,
 280                                         &nbd->config->runtime_flags);
 281                                 dev_info(nbd_to_dev(nbd),
 282                                         "Disconnected due to user request.\n");
 283                         }
 284                 }
 285         }
 286         nsock->dead = true;
 287         nsock->pending = NULL;
 288         nsock->sent = 0;
 289 }
 290
 291 static void nbd_size_clear(struct nbd_device *nbd)
 292 {
 293         if (nbd->config->bytesize) {
 294                 set_capacity(nbd->disk, 0);
 295                 kobject_uevent(&nbd_to_dev(nbd)->kobj, KOBJ_CHANGE);
 296         }
 297 }
 298
 299 static void nbd_size_update(struct nbd_device *nbd)
 300 {
 301         struct nbd_config *config = nbd->config;
 302         struct block_device *bdev = bdget_disk(nbd->disk, 0);
 303
 304         if (config->flags & NBD_FLAG_SEND_TRIM) {
 305                 nbd->disk->queue->limits.discard_granularity = config->blksize;
 306                 nbd->disk->queue->limits.discard_alignment = config->blksize;
 307                 blk_queue_max_discard_sectors(nbd->disk->queue, UINT_MAX);
 308         }
 309         blk_queue_logical_block_size(nbd->disk->queue, config->blksize);
 310         blk_queue_physical_block_size(nbd->disk->queue, config->blksize);
 311         set_capacity(nbd->disk, config->bytesize >> 9);
 312         if (bdev) {
 313                 if (bdev->bd_disk) {
 314                         bd_set_size(bdev, config->bytesize);
 315                         set_blocksize(bdev, config->blksize);
 316                 } else
 317                         bdev->bd_invalidated = 1;
 318                 bdput(bdev);
 319         }
 320         kobject_uevent(&nbd_to_dev(nbd)->kobj, KOBJ_CHANGE);
 321 }
 322
 323 static void nbd_size_set(struct nbd_device *nbd, loff_t blocksize,
 324                          loff_t nr_blocks)
 325 {
 326         struct nbd_config *config = nbd->config;
 327         config->blksize = blocksize;
 328         config->bytesize = blocksize * nr_blocks;
 329         if (nbd->task_recv != NULL)
 330                 nbd_size_update(nbd);
 331 }
 332
 333 static void nbd_complete_rq(struct request *req)
 334 {
 335         struct nbd_cmd *cmd = blk_mq_rq_to_pdu(req);
 336
 337         dev_dbg(nbd_to_dev(cmd->nbd), "request %p: %s\n", req,
 338                 cmd->status ? "failed" : "done");
 339
 340         blk_mq_end_request(req, cmd->status);
 341 }
 342
 343 /*
 344  * Forcibly shutdown the socket causing all listeners to error
 345  */
 346 static void sock_shutdown(struct nbd_device *nbd)
 347 {
 348         struct nbd_config *config = nbd->config;
 349         int i;
 350
 351         if (config->num_connections == 0)
 352                 return;
 353         if (test_and_set_bit(NBD_RT_DISCONNECTED, &config->runtime_flags))
 354                 return;
 355
 356         for (i = 0; i < config->num_connections; i++) {
 357                 struct nbd_sock *nsock = config->socks[i];
 358                 mutex_lock(&nsock->tx_lock);
 359                 nbd_mark_nsock_dead(nbd, nsock, 0);
 360                 mutex_unlock(&nsock->tx_lock);
 361         }
 362         dev_warn(disk_to_dev(nbd->disk), "shutting down sockets\n");
 363 }
 364
 365 static u32 req_to_nbd_cmd_type(struct request *req)
 366 {
 367         switch (req_op(req)) {
 368         case REQ_OP_DISCARD:
 369                 return NBD_CMD_TRIM;
 370         case REQ_OP_FLUSH:
 371                 return NBD_CMD_FLUSH;
 372         case REQ_OP_WRITE:
 373                 return NBD_CMD_WRITE;
 374         case REQ_OP_READ:
 375                 return NBD_CMD_READ;
 376         default:
 377                 return U32_MAX;
 378         }
 379 }
 380
 381 static enum blk_eh_timer_return nbd_xmit_timeout(struct request *req,
 382                                                  bool reserved)
 383 {
 384         struct nbd_cmd *cmd = blk_mq_rq_to_pdu(req);
 385         struct nbd_device *nbd = cmd->nbd;
 386         struct nbd_config *config;
 387
 388         if (!mutex_trylock(&cmd->lock))
 389                 return BLK_EH_RESET_TIMER;
 390
 391         if (!refcount_inc_not_zero(&nbd->config_refs)) {
 392                 cmd->status = BLK_STS_TIMEOUT;
 393                 mutex_unlock(&cmd->lock);
 394                 goto done;
 395         }
 396         config = nbd->config;
 397
 398         if (config->num_connections > 1) {
 399                 dev_err_ratelimited(nbd_to_dev(nbd),
 400                                     "Connection timed out, retrying (%d/%d alive)\n",
 401                                     atomic_read(&config->live_connections),
 402                                     config->num_connections);
 403                 /*
 404                  * Hooray we have more connections, requeue this IO, the submit
 405                  * path will put it on a real connection.
 406                  */
 407                 if (config->socks && config->num_connections > 1) {
 408                         if (cmd->index < config->num_connections) {
 409                                 struct nbd_sock *nsock =
 410                                         config->socks[cmd->index];
 411                                 mutex_lock(&nsock->tx_lock);
 412                                 /* We can have multiple outstanding requests, so
 413                                  * we don't want to mark the nsock dead if we've
 414                                  * already reconnected with a new socket, so
 415                                  * only mark it dead if its the same socket we
 416                                  * were sent out on.
 417                                  */
 418                                 if (cmd->cookie == nsock->cookie)
 419                                         nbd_mark_nsock_dead(nbd, nsock, 1);
 420                                 mutex_unlock(&nsock->tx_lock);
 421                         }
 422                         mutex_unlock(&cmd->lock);
 423                         nbd_requeue_cmd(cmd);
 424                         nbd_config_put(nbd);
 425                         return BLK_EH_DONE;
 426                 }
 427         }
 428
 429         if (!nbd->tag_set.timeout) {
 430                 /*
 431                  * Userspace sets timeout=0 to disable socket disconnection,
 432                  * so just warn and reset the timer.
 433                  */
 434                 cmd->retries++;
 435                 dev_info(nbd_to_dev(nbd), "Possible stuck request %p: control (%s@%llu,%uB). Runtime %u seconds\n",
 436                         req, nbdcmd_to_ascii(req_to_nbd_cmd_type(req)),
 437                         (unsigned long long)blk_rq_pos(req) << 9,
 438                         blk_rq_bytes(req), (req->timeout / HZ) * cmd->retries);
 439
 440                 mutex_unlock(&cmd->lock);
 441                 nbd_config_put(nbd);
 442                 return BLK_EH_RESET_TIMER;
 443         }
 444
 445         dev_err_ratelimited(nbd_to_dev(nbd), "Connection timed out\n");
 446         set_bit(NBD_RT_TIMEDOUT, &config->runtime_flags);
 447         cmd->status = BLK_STS_IOERR;
 448         mutex_unlock(&cmd->lock);
 449         sock_shutdown(nbd);
 450         nbd_config_put(nbd);
 451 done:
 452         blk_mq_complete_request(req);
 453         return BLK_EH_DONE;
 454 }
 455
 456 /*
 457  *  Send or receive packet.
 458  */
 459 static int sock_xmit(struct nbd_device *nbd, int index, int send,
 460                      struct iov_iter *iter, int msg_flags, int *sent)
 461 {
 462         struct nbd_config *config = nbd->config;
 463         struct socket *sock = config->socks[index]->sock;
 464         int result;
 465         struct msghdr msg;
 466         unsigned int noreclaim_flag;
 467
 468         if (unlikely(!sock)) {
 469                 dev_err_ratelimited(disk_to_dev(nbd->disk),
 470                         "Attempted %s on closed socket in sock_xmit\n",
 471                         (send ? "send" : "recv"));
 472                 return -EINVAL;
 473         }
 474
 475         msg.msg_iter = *iter;
 476
 477         noreclaim_flag = memalloc_noreclaim_save();
 478         do {
 479                 sock->sk->sk_allocation = GFP_NOIO | __GFP_MEMALLOC;
 480                 msg.msg_name = NULL;
 481                 msg.msg_namelen = 0;
 482                 msg.msg_control = NULL;
 483                 msg.msg_controllen = 0;
 484                 msg.msg_flags = msg_flags | MSG_NOSIGNAL;
 485
 486                 if (send)
 487                         result = sock_sendmsg(sock, &msg);
 488                 else
 489                         result = sock_recvmsg(sock, &msg, msg.msg_flags);
 490
 491                 if (result <= 0) {
 492                         if (result == 0)
 493                                 result = -EPIPE; /* short read */
 494                         break;
 495                 }
 496                 if (sent)
 497                         *sent += result;
 498         } while (msg_data_left(&msg));
 499
 500         memalloc_noreclaim_restore(noreclaim_flag);
 501
 502         return result;
 503 }
 504
 505 /*
 506  * Different settings for sk->sk_sndtimeo can result in different return values
 507  * if there is a signal pending when we enter sendmsg, because reasons?
 508  */
 509 static inline int was_interrupted(int result)
 510 {
 511         return result == -ERESTARTSYS || result == -EINTR;
 512 }
 513
 514 /* always call with the tx_lock held */
 515 static int nbd_send_cmd(struct nbd_device *nbd, struct nbd_cmd *cmd, int index)
 516 {
 517         struct request *req = blk_mq_rq_from_pdu(cmd);
 518         struct nbd_config *config = nbd->config;
 519         struct nbd_sock *nsock = config->socks[index];
 520         int result;
 521         struct nbd_request request = {.magic = htonl(NBD_REQUEST_MAGIC)};
 522         struct kvec iov = {.iov_base = &request, .iov_len = sizeof(request)};
 523         struct iov_iter from;
 524         unsigned long size = blk_rq_bytes(req);
 525         struct bio *bio;
 526         u64 handle;
 527         u32 type;
 528         u32 nbd_cmd_flags = 0;
 529         int sent = nsock->sent, skip = 0;
 530
 531         iov_iter_kvec(&from, WRITE, &iov, 1, sizeof(request));
 532
 533         type = req_to_nbd_cmd_type(req);
 534         if (type == U32_MAX)
 535                 return -EIO;
 536
 537         if (rq_data_dir(req) == WRITE &&
 538             (config->flags & NBD_FLAG_READ_ONLY)) {
 539                 dev_err_ratelimited(disk_to_dev(nbd->disk),
 540                                     "Write on read-only\n");
 541                 return -EIO;
 542         }
 543
 544         if (req->cmd_flags & REQ_FUA)
 545                 nbd_cmd_flags |= NBD_CMD_FLAG_FUA;
 546
 547         /* We did a partial send previously, and we at least sent the whole
 548          * request struct, so just go and send the rest of the pages in the
 549          * request.
 550          */
 551         if (sent) {
 552                 if (sent >= sizeof(request)) {
 553                         skip = sent - sizeof(request);
 554
 555                         /* initialize handle for tracing purposes */
 556                         handle = nbd_cmd_handle(cmd);
 557
 558                         goto send_pages;
 559                 }
 560                 iov_iter_advance(&from, sent);
 561         } else {
 562                 cmd->cmd_cookie++;
 563         }
 564         cmd->index = index;
 565         cmd->cookie = nsock->cookie;
 566         cmd->retries = 0;
 567         request.type = htonl(type | nbd_cmd_flags);
 568         if (type != NBD_CMD_FLUSH) {
 569                 request.from = cpu_to_be64((u64)blk_rq_pos(req) << 9);
 570                 request.len = htonl(size);
 571         }
 572         handle = nbd_cmd_handle(cmd);
 573         memcpy(request.handle, &handle, sizeof(handle));
 574
 575         trace_nbd_send_request(&request, nbd->index, blk_mq_rq_from_pdu(cmd));
 576
 577         dev_dbg(nbd_to_dev(nbd), "request %p: sending control (%s@%llu,%uB)\n",
 578                 req, nbdcmd_to_ascii(type),
 579                 (unsigned long long)blk_rq_pos(req) << 9, blk_rq_bytes(req));
 580         result = sock_xmit(nbd, index, 1, &from,
 581                         (type == NBD_CMD_WRITE) ? MSG_MORE : 0, &sent);
 582         trace_nbd_header_sent(req, handle);
 583         if (result <= 0) {
 584                 if (was_interrupted(result)) {
 585                         /* If we havne't sent anything we can just return BUSY,
 586                          * however if we have sent something we need to make
 587                          * sure we only allow this req to be sent until we are
 588                          * completely done.
 589                          */
 590                         if (sent) {
 591                                 nsock->pending = req;
 592                                 nsock->sent = sent;
 593                         }
 594                         set_bit(NBD_CMD_REQUEUED, &cmd->flags);
 595                         return BLK_STS_RESOURCE;
 596                 }
 597                 dev_err_ratelimited(disk_to_dev(nbd->disk),
 598                         "Send control failed (result %d)\n", result);
 599                 return -EAGAIN;
 600         }
 601 send_pages:
 602         if (type != NBD_CMD_WRITE)
 603                 goto out;
 604
 605         bio = req->bio;
 606         while (bio) {
 607                 struct bio *next = bio->bi_next;
 608                 struct bvec_iter iter;
 609                 struct bio_vec bvec;
 610
 611                 bio_for_each_segment(bvec, bio, iter) {
 612                         bool is_last = !next && bio_iter_last(bvec, iter);
 613                         int flags = is_last ? 0 : MSG_MORE;
 614
 615                         dev_dbg(nbd_to_dev(nbd), "request %p: sending %d bytes data\n",
 616                                 req, bvec.bv_len);
 617                         iov_iter_bvec(&from, WRITE, &bvec, 1, bvec.bv_len);
 618                         if (skip) {
 619                                 if (skip >= iov_iter_count(&from)) {
 620                                         skip -= iov_iter_count(&from);
 621                                         continue;
 622                                 }
 623                                 iov_iter_advance(&from, skip);
 624                                 skip = 0;
 625                         }
 626                         result = sock_xmit(nbd, index, 1, &from, flags, &sent);
 627                         if (result <= 0) {
 628                                 if (was_interrupted(result)) {
 629                                         /* We've already sent the header, we
 630                                          * have no choice but to set pending and
 631                                          * return BUSY.
 632                                          */
 633                                         nsock->pending = req;
 634                                         nsock->sent = sent;
 635                                         set_bit(NBD_CMD_REQUEUED, &cmd->flags);
 636                                         return BLK_STS_RESOURCE;
 637                                 }
 638                                 dev_err(disk_to_dev(nbd->disk),
 639                                         "Send data failed (result %d)\n",
 640                                         result);
 641                                 return -EAGAIN;
 642                         }
 643                         /*
 644                          * The completion might already have come in,
 645                          * so break for the last one instead of letting
 646                          * the iterator do it. This prevents use-after-free
 647                          * of the bio.
 648                          */
 649                         if (is_last)
 650                                 break;
 651                 }
 652                 bio = next;
 653         }
 654 out:
 655         trace_nbd_payload_sent(req, handle);
 656         nsock->pending = NULL;
 657         nsock->sent = 0;
 658         return 0;
 659 }
 660
 661 /* NULL returned = something went wrong, inform userspace */
 662 static struct nbd_cmd *nbd_read_stat(struct nbd_device *nbd, int index)
 663 {
 664         struct nbd_config *config = nbd->config;
 665         int result;
 666         struct nbd_reply reply;
 667         struct nbd_cmd *cmd;
 668         struct request *req = NULL;
 669         u64 handle;
 670         u16 hwq;
 671         u32 tag;
 672         struct kvec iov = {.iov_base = &reply, .iov_len = sizeof(reply)};
 673         struct iov_iter to;
 674         int ret = 0;
 675
 676         reply.magic = 0;
 677         iov_iter_kvec(&to, READ, &iov, 1, sizeof(reply));
 678         result = sock_xmit(nbd, index, 0, &to, MSG_WAITALL, NULL);
 679         if (result <= 0) {
 680                 if (!nbd_disconnected(config))
 681                         dev_err(disk_to_dev(nbd->disk),
 682                                 "Receive control failed (result %d)\n", result);
 683                 return ERR_PTR(result);
 684         }
 685
 686         if (ntohl(reply.magic) != NBD_REPLY_MAGIC) {
 687                 dev_err(disk_to_dev(nbd->disk), "Wrong magic (0x%lx)\n",
 688                                 (unsigned long)ntohl(reply.magic));
 689                 return ERR_PTR(-EPROTO);
 690         }
 691
 692         memcpy(&handle, reply.handle, sizeof(handle));
 693         tag = nbd_handle_to_tag(handle);
 694         hwq = blk_mq_unique_tag_to_hwq(tag);
 695         if (hwq < nbd->tag_set.nr_hw_queues)
 696                 req = blk_mq_tag_to_rq(nbd->tag_set.tags[hwq],
 697                                        blk_mq_unique_tag_to_tag(tag));
 698         if (!req || !blk_mq_request_started(req)) {
 699                 dev_err(disk_to_dev(nbd->disk), "Unexpected reply (%d) %p\n",
 700                         tag, req);
 701                 return ERR_PTR(-ENOENT);
 702         }
 703         trace_nbd_header_received(req, handle);
 704         cmd = blk_mq_rq_to_pdu(req);
 705
 706         mutex_lock(&cmd->lock);
 707         if (cmd->cmd_cookie != nbd_handle_to_cookie(handle)) {
 708                 dev_err(disk_to_dev(nbd->disk), "Double reply on req %p, cmd_cookie %u, handle cookie %u\n",
 709                         req, cmd->cmd_cookie, nbd_handle_to_cookie(handle));
 710                 ret = -ENOENT;
 711                 goto out;
 712         }
 713         if (cmd->status != BLK_STS_OK) {
 714                 dev_err(disk_to_dev(nbd->disk), "Command already handled %p\n",
 715                         req);
 716                 ret = -ENOENT;
 717                 goto out;
 718         }
 719         if (test_bit(NBD_CMD_REQUEUED, &cmd->flags)) {
 720                 dev_err(disk_to_dev(nbd->disk), "Raced with timeout on req %p\n",
 721                         req);
 722                 ret = -ENOENT;
 723                 goto out;
 724         }
 725         if (ntohl(reply.error)) {
 726                 dev_err(disk_to_dev(nbd->disk), "Other side returned error (%d)\n",
 727                         ntohl(reply.error));
 728                 cmd->status = BLK_STS_IOERR;
 729                 goto out;
 730         }
 731
 732         dev_dbg(nbd_to_dev(nbd), "request %p: got reply\n", req);
 733         if (rq_data_dir(req) != WRITE) {
 734                 struct req_iterator iter;
 735                 struct bio_vec bvec;
 736
 737                 rq_for_each_segment(bvec, req, iter) {
 738                         iov_iter_bvec(&to, READ, &bvec, 1, bvec.bv_len);
 739                         result = sock_xmit(nbd, index, 0, &to, MSG_WAITALL, NULL);
 740                         if (result <= 0) {
 741                                 dev_err(disk_to_dev(nbd->disk), "Receive data failed (result %d)\n",
 742                                         result);
 743                                 /*
 744                                  * If we've disconnected or we only have 1
 745                                  * connection then we need to make sure we
 746                                  * complete this request, otherwise error out
 747                                  * and let the timeout stuff handle resubmitting
 748                                  * this request onto another connection.
 749                                  */
 750                                 if (nbd_disconnected(config) ||
 751                                     config->num_connections <= 1) {
 752                                         cmd->status = BLK_STS_IOERR;
 753                                         goto out;
 754                                 }
 755                                 ret = -EIO;
 756                                 goto out;
 757                         }
 758                         dev_dbg(nbd_to_dev(nbd), "request %p: got %d bytes data\n",
 759                                 req, bvec.bv_len);
 760                 }
 761         }
 762 out:
 763         trace_nbd_payload_received(req, handle);
 764         mutex_unlock(&cmd->lock);
 765         return ret ? ERR_PTR(ret) : cmd;
 766 }
 767
 768 static void recv_work(struct work_struct *work)
 769 {
 770         struct recv_thread_args *args = container_of(work,
 771                                                      struct recv_thread_args,
 772                                                      work);
 773         struct nbd_device *nbd = args->nbd;
 774         struct nbd_config *config = nbd->config;
 775         struct nbd_cmd *cmd;
 776
 777         while (1) {
 778                 cmd = nbd_read_stat(nbd, args->index);
 779                 if (IS_ERR(cmd)) {
 780                         struct nbd_sock *nsock = config->socks[args->index];
 781
 782                         mutex_lock(&nsock->tx_lock);
 783                         nbd_mark_nsock_dead(nbd, nsock, 1);
 784                         mutex_unlock(&nsock->tx_lock);
 785                         break;
 786                 }
 787
 788                 blk_mq_complete_request(blk_mq_rq_from_pdu(cmd));
 789         }
 790         atomic_dec(&config->recv_threads);
 791         wake_up(&config->recv_wq);
 792         nbd_config_put(nbd);
 793         kfree(args);
 794 }
 795
 796 static bool nbd_clear_req(struct request *req, void *data, bool reserved)
 797 {
 798         struct nbd_cmd *cmd = blk_mq_rq_to_pdu(req);
 799
 800         mutex_lock(&cmd->lock);
 801         cmd->status = BLK_STS_IOERR;
 802         mutex_unlock(&cmd->lock);
 803
 804         blk_mq_complete_request(req);
 805         return true;
 806 }
 807
 808 static void nbd_clear_que(struct nbd_device *nbd)
 809 {
 810         blk_mq_quiesce_queue(nbd->disk->queue);
 811         blk_mq_tagset_busy_iter(&nbd->tag_set, nbd_clear_req, NULL);
 812         blk_mq_unquiesce_queue(nbd->disk->queue);
 813         dev_dbg(disk_to_dev(nbd->disk), "queue cleared\n");
 814 }
 815
 816 static int find_fallback(struct nbd_device *nbd, int index)
 817 {
 818         struct nbd_config *config = nbd->config;
 819         int new_index = -1;
 820         struct nbd_sock *nsock = config->socks[index];
 821         int fallback = nsock->fallback_index;
 822
 823         if (test_bit(NBD_RT_DISCONNECTED, &config->runtime_flags))
 824                 return new_index;
 825
 826         if (config->num_connections <= 1) {
 827                 dev_err_ratelimited(disk_to_dev(nbd->disk),
 828                                     "Attempted send on invalid socket\n");
 829                 return new_index;
 830         }
 831
 832         if (fallback >= 0 && fallback < config->num_connections &&
 833             !config->socks[fallback]->dead)
 834                 return fallback;
 835
 836         if (nsock->fallback_index < 0 ||
 837             nsock->fallback_index >= config->num_connections ||
 838             config->socks[nsock->fallback_index]->dead) {
 839                 int i;
 840                 for (i = 0; i < config->num_connections; i++) {
 841                         if (i == index)
 842                                 continue;
 843                         if (!config->socks[i]->dead) {
 844                                 new_index = i;
 845                                 break;
 846                         }
 847                 }
 848                 nsock->fallback_index = new_index;
 849                 if (new_index < 0) {
 850                         dev_err_ratelimited(disk_to_dev(nbd->disk),
 851                                             "Dead connection, failed to find a fallback\n");
 852                         return new_index;
 853                 }
 854         }
 855         new_index = nsock->fallback_index;
 856         return new_index;
 857 }
 858
 859 static int wait_for_reconnect(struct nbd_device *nbd)
 860 {
 861         struct nbd_config *config = nbd->config;
 862         if (!config->dead_conn_timeout)
 863                 return 0;
 864         if (test_bit(NBD_RT_DISCONNECTED, &config->runtime_flags))
 865                 return 0;
 866         return wait_event_timeout(config->conn_wait,
 867                                   atomic_read(&config->live_connections) > 0,
 868                                   config->dead_conn_timeout) > 0;
 869 }
 870
 871 static int nbd_handle_cmd(struct nbd_cmd *cmd, int index)
 872 {
 873         struct request *req = blk_mq_rq_from_pdu(cmd);
 874         struct nbd_device *nbd = cmd->nbd;
 875         struct nbd_config *config;
 876         struct nbd_sock *nsock;
 877         int ret;
 878
 879         if (!refcount_inc_not_zero(&nbd->config_refs)) {
 880                 dev_err_ratelimited(disk_to_dev(nbd->disk),
 881                                     "Socks array is empty\n");
 882                 blk_mq_start_request(req);
 883                 return -EINVAL;
 884         }
 885         config = nbd->config;
 886
 887         if (index >= config->num_connections) {
 888                 dev_err_ratelimited(disk_to_dev(nbd->disk),
 889                                     "Attempted send on invalid socket\n");
 890                 nbd_config_put(nbd);
 891                 blk_mq_start_request(req);
 892                 return -EINVAL;
 893         }
 894         cmd->status = BLK_STS_OK;
 895 again:
 896         nsock = config->socks[index];
 897         mutex_lock(&nsock->tx_lock);
 898         if (nsock->dead) {
 899                 int old_index = index;
 900                 index = find_fallback(nbd, index);
 901                 mutex_unlock(&nsock->tx_lock);
 902                 if (index < 0) {
 903                         if (wait_for_reconnect(nbd)) {
 904                                 index = old_index;
 905                                 goto again;
 906                         }
 907                         /* All the sockets should already be down at this point,
 908                          * we just want to make sure that DISCONNECTED is set so
 909                          * any requests that come in that were queue'ed waiting
 910                          * for the reconnect timer don't trigger the timer again
 911                          * and instead just error out.
 912                          */
 913                         sock_shutdown(nbd);
 914                         nbd_config_put(nbd);
 915                         blk_mq_start_request(req);
 916                         return -EIO;
 917                 }
 918                 goto again;
 919         }
 920
 921         /* Handle the case that we have a pending request that was partially
 922          * transmitted that _has_ to be serviced first.  We need to call requeue
 923          * here so that it gets put _after_ the request that is already on the
 924          * dispatch list.
 925          */
 926         blk_mq_start_request(req);
 927         if (unlikely(nsock->pending && nsock->pending != req)) {
 928                 nbd_requeue_cmd(cmd);
 929                 ret = 0;
 930                 goto out;
 931         }
 932         /*
 933          * Some failures are related to the link going down, so anything that
 934          * returns EAGAIN can be retried on a different socket.
 935          */
 936         ret = nbd_send_cmd(nbd, cmd, index);
 937         if (ret == -EAGAIN) {
 938                 dev_err_ratelimited(disk_to_dev(nbd->disk),
 939                                     "Request send failed, requeueing\n");
 940                 nbd_mark_nsock_dead(nbd, nsock, 1);
 941                 nbd_requeue_cmd(cmd);
 942                 ret = 0;
 943         }
 944 out:
 945         mutex_unlock(&nsock->tx_lock);
 946         nbd_config_put(nbd);
 947         return ret;
 948 }
 949
 950 static blk_status_t nbd_queue_rq(struct blk_mq_hw_ctx *hctx,
 951                         const struct blk_mq_queue_data *bd)
 952 {
 953         struct nbd_cmd *cmd = blk_mq_rq_to_pdu(bd->rq);
 954         int ret;
 955
 956         /*
 957          * Since we look at the bio's to send the request over the network we
 958          * need to make sure the completion work doesn't mark this request done
 959          * before we are done doing our send.  This keeps us from dereferencing
 960          * freed data if we have particularly fast completions (ie we get the
 961          * completion before we exit sock_xmit on the last bvec) or in the case
 962          * that the server is misbehaving (or there was an error) before we're
 963          * done sending everything over the wire.
 964          */
 965         mutex_lock(&cmd->lock);
 966         clear_bit(NBD_CMD_REQUEUED, &cmd->flags);
 967
 968         /* We can be called directly from the user space process, which means we
 969          * could possibly have signals pending so our sendmsg will fail.  In
 970          * this case we need to return that we are busy, otherwise error out as
 971          * appropriate.
 972          */
 973         ret = nbd_handle_cmd(cmd, hctx->queue_num);
 974         if (ret < 0)
 975                 ret = BLK_STS_IOERR;
 976         else if (!ret)
 977                 ret = BLK_STS_OK;
 978         mutex_unlock(&cmd->lock);
 979
 980         return ret;
 981 }
 982
 983 static struct socket *nbd_get_socket(struct nbd_device *nbd, unsigned long fd,
 984                                      int *err)
 985 {
 986         struct socket *sock;
 987
 988         *err = 0;
 989         sock = sockfd_lookup(fd, err);
 990         if (!sock)
 991                 return NULL;
 992
 993         if (sock->ops->shutdown == sock_no_shutdown) {
 994                 dev_err(disk_to_dev(nbd->disk), "Unsupported socket: shutdown callout must be supported.\n");
 995                 *err = -EINVAL;
 996                 sockfd_put(sock);
 997                 return NULL;
 998         }
 999
1000         return sock;
1001 }
1002
1003 static int nbd_add_socket(struct nbd_device *nbd, unsigned long arg,
1004                           bool netlink)
1005 {
1006         struct nbd_config *config = nbd->config;
1007         struct socket *sock;
1008         struct nbd_sock **socks;
1009         struct nbd_sock *nsock;
1010         int err;
1011
1012         sock = nbd_get_socket(nbd, arg, &err);
1013         if (!sock)
1014                 return err;
1015
1016         if (!netlink && !nbd->task_setup &&
1017             !test_bit(NBD_RT_BOUND, &config->runtime_flags))
1018                 nbd->task_setup = current;
1019
1020         if (!netlink &&
1021             (nbd->task_setup != current ||
1022              test_bit(NBD_RT_BOUND, &config->runtime_flags))) {
1023                 dev_err(disk_to_dev(nbd->disk),
1024                         "Device being setup by another task");
1025                 sockfd_put(sock);
1026                 return -EBUSY;
1027         }
1028
1029         socks = krealloc(config->socks, (config->num_connections + 1) *
1030                          sizeof(struct nbd_sock *), GFP_KERNEL);
1031         if (!socks) {
1032                 sockfd_put(sock);
1033                 return -ENOMEM;
1034         }
1035
1036         config->socks = socks;
1037
1038         nsock = kzalloc(sizeof(struct nbd_sock), GFP_KERNEL);
1039         if (!nsock) {
1040                 sockfd_put(sock);
1041                 return -ENOMEM;
1042         }
1043
1044         nsock->fallback_index = -1;
1045         nsock->dead = false;
1046         mutex_init(&nsock->tx_lock);
1047         nsock->sock = sock;
1048         nsock->pending = NULL;
1049         nsock->sent = 0;
1050         nsock->cookie = 0;
1051         socks[config->num_connections++] = nsock;
1052         atomic_inc(&config->live_connections);
1053
1054         return 0;
1055 }
1056
1057 static int nbd_reconnect_socket(struct nbd_device *nbd, unsigned long arg)
1058 {
1059         struct nbd_config *config = nbd->config;
1060         struct socket *sock, *old;
1061         struct recv_thread_args *args;
1062         int i;
1063         int err;
1064
1065         sock = nbd_get_socket(nbd, arg, &err);
1066         if (!sock)
1067                 return err;
1068
1069         args = kzalloc(sizeof(*args), GFP_KERNEL);
1070         if (!args) {
1071                 sockfd_put(sock);
1072                 return -ENOMEM;
1073         }
1074
1075         for (i = 0; i < config->num_connections; i++) {
1076                 struct nbd_sock *nsock = config->socks[i];
1077
1078                 if (!nsock->dead)
1079                         continue;
1080
1081                 mutex_lock(&nsock->tx_lock);
1082                 if (!nsock->dead) {
1083                         mutex_unlock(&nsock->tx_lock);
1084                         continue;
1085                 }
1086                 sk_set_memalloc(sock->sk);
1087                 if (nbd->tag_set.timeout)
1088                         sock->sk->sk_sndtimeo = nbd->tag_set.timeout;
1089                 atomic_inc(&config->recv_threads);
1090                 refcount_inc(&nbd->config_refs);
1091                 old = nsock->sock;
1092                 nsock->fallback_index = -1;
1093                 nsock->sock = sock;
1094                 nsock->dead = false;
1095                 INIT_WORK(&args->work, recv_work);
1096                 args->index = i;
1097                 args->nbd = nbd;
1098                 nsock->cookie++;
1099                 mutex_unlock(&nsock->tx_lock);
1100                 sockfd_put(old);
1101
1102                 clear_bit(NBD_RT_DISCONNECTED, &config->runtime_flags);
1103
1104                 /* We take the tx_mutex in an error path in the recv_work, so we
1105                  * need to queue_work outside of the tx_mutex.
1106                  */
1107                 queue_work(nbd->recv_workq, &args->work);
1108
1109                 atomic_inc(&config->live_connections);
1110                 wake_up(&config->conn_wait);
1111                 return 0;
1112         }
1113         sockfd_put(sock);
1114         kfree(args);
1115         return -ENOSPC;
1116 }
1117
1118 static void nbd_bdev_reset(struct block_device *bdev)
1119 {
1120         if (bdev->bd_openers > 1)
1121                 return;
1122         bd_set_size(bdev, 0);
1123 }
1124
1125 static void nbd_parse_flags(struct nbd_device *nbd)
1126 {
1127         struct nbd_config *config = nbd->config;
1128         if (config->flags & NBD_FLAG_READ_ONLY)
1129                 set_disk_ro(nbd->disk, true);
1130         else
1131                 set_disk_ro(nbd->disk, false);
1132         if (config->flags & NBD_FLAG_SEND_TRIM)
1133                 blk_queue_flag_set(QUEUE_FLAG_DISCARD, nbd->disk->queue);
1134         if (config->flags & NBD_FLAG_SEND_FLUSH) {
1135                 if (config->flags & NBD_FLAG_SEND_FUA)
1136                         blk_queue_write_cache(nbd->disk->queue, true, true);
1137                 else
1138                         blk_queue_write_cache(nbd->disk->queue, true, false);
1139         }
1140         else
1141                 blk_queue_write_cache(nbd->disk->queue, false, false);
1142 }
1143
1144 static void send_disconnects(struct nbd_device *nbd)
1145 {
1146         struct nbd_config *config = nbd->config;
1147         struct nbd_request request = {
1148                 .magic = htonl(NBD_REQUEST_MAGIC),
1149                 .type = htonl(NBD_CMD_DISC),
1150         };
1151         struct kvec iov = {.iov_base = &request, .iov_len = sizeof(request)};
1152         struct iov_iter from;
1153         int i, ret;
1154
1155         for (i = 0; i < config->num_connections; i++) {
1156                 struct nbd_sock *nsock = config->socks[i];
1157
1158                 iov_iter_kvec(&from, WRITE, &iov, 1, sizeof(request));
1159                 mutex_lock(&nsock->tx_lock);
1160                 ret = sock_xmit(nbd, i, 1, &from, 0, NULL);
1161                 if (ret <= 0)
1162                         dev_err(disk_to_dev(nbd->disk),
1163                                 "Send disconnect failed %d\n", ret);
1164                 mutex_unlock(&nsock->tx_lock);
1165         }
1166 }
1167
1168 static int nbd_disconnect(struct nbd_device *nbd)
1169 {
1170         struct nbd_config *config = nbd->config;
1171
1172         dev_info(disk_to_dev(nbd->disk), "NBD_DISCONNECT\n");
1173         set_bit(NBD_RT_DISCONNECT_REQUESTED, &config->runtime_flags);
1174         set_bit(NBD_DISCONNECT_REQUESTED, &nbd->flags);
1175         send_disconnects(nbd);
1176         return 0;
1177 }
1178
1179 static void nbd_clear_sock(struct nbd_device *nbd)
1180 {
1181         sock_shutdown(nbd);
1182         nbd_clear_que(nbd);
1183         nbd->task_setup = NULL;
1184 }
1185
1186 static void nbd_config_put(struct nbd_device *nbd)
1187 {
1188         if (refcount_dec_and_mutex_lock(&nbd->config_refs,
1189                                         &nbd->config_lock)) {
1190                 struct nbd_config *config = nbd->config;
1191                 nbd_dev_dbg_close(nbd);
1192                 nbd_size_clear(nbd);
1193                 if (test_and_clear_bit(NBD_RT_HAS_PID_FILE,
1194                                        &config->runtime_flags))
1195                         device_remove_file(disk_to_dev(nbd->disk), &pid_attr);
1196                 nbd->task_recv = NULL;
1197                 nbd_clear_sock(nbd);
1198                 if (config->num_connections) {
1199                         int i;
1200                         for (i = 0; i < config->num_connections; i++) {
1201                                 sockfd_put(config->socks[i]->sock);
1202                                 kfree(config->socks[i]);
1203                         }
1204                         kfree(config->socks);
1205                 }
1206                 kfree(nbd->config);
1207                 nbd->config = NULL;
1208
1209                 if (nbd->recv_workq)
1210                         destroy_workqueue(nbd->recv_workq);
1211                 nbd->recv_workq = NULL;
1212
1213                 nbd->tag_set.timeout = 0;
1214                 nbd->disk->queue->limits.discard_granularity = 0;
1215                 nbd->disk->queue->limits.discard_alignment = 0;
1216                 blk_queue_max_discard_sectors(nbd->disk->queue, UINT_MAX);
1217                 blk_queue_flag_clear(QUEUE_FLAG_DISCARD, nbd->disk->queue);
1218
1219                 mutex_unlock(&nbd->config_lock);
1220                 nbd_put(nbd);
1221                 module_put(THIS_MODULE);
1222         }
1223 }
1224
1225 static int nbd_start_device(struct nbd_device *nbd)
1226 {
1227         struct nbd_config *config = nbd->config;
1228         int num_connections = config->num_connections;
1229         int error = 0, i;
1230
1231         if (nbd->task_recv)
1232                 return -EBUSY;
1233         if (!config->socks)
1234                 return -EINVAL;
1235         if (num_connections > 1 &&
1236             !(config->flags & NBD_FLAG_CAN_MULTI_CONN)) {
1237                 dev_err(disk_to_dev(nbd->disk), "server does not support multiple connections per device.\n");
1238                 return -EINVAL;
1239         }
1240
1241         nbd->recv_workq = alloc_workqueue("knbd%d-recv",
1242                                           WQ_MEM_RECLAIM | WQ_HIGHPRI |
1243                                           WQ_UNBOUND, 0, nbd->index);
1244         if (!nbd->recv_workq) {
1245                 dev_err(disk_to_dev(nbd->disk), "Could not allocate knbd recv work queue.\n");
1246                 return -ENOMEM;
1247         }
1248
1249         blk_mq_update_nr_hw_queues(&nbd->tag_set, config->num_connections);
1250         nbd->task_recv = current;
1251
1252         nbd_parse_flags(nbd);
1253
1254         error = device_create_file(disk_to_dev(nbd->disk), &pid_attr);
1255         if (error) {
1256                 dev_err(disk_to_dev(nbd->disk), "device_create_file failed!\n");
1257                 return error;
1258         }
1259         set_bit(NBD_RT_HAS_PID_FILE, &config->runtime_flags);
1260
1261         nbd_dev_dbg_init(nbd);
1262         for (i = 0; i < num_connections; i++) {
1263                 struct recv_thread_args *args;
1264
1265                 args = kzalloc(sizeof(*args), GFP_KERNEL);
1266                 if (!args) {
1267                         sock_shutdown(nbd);
1268                         /*
1269                          * If num_connections is m (2 < m),
1270                          * and NO.1 ~ NO.n(1 < n < m) kzallocs are successful.
1271                          * But NO.(n + 1) failed. We still have n recv threads.
1272                          * So, add flush_workqueue here to prevent recv threads
1273                          * dropping the last config_refs and trying to destroy
1274                          * the workqueue from inside the workqueue.
1275                          */
1276                         if (i)
1277                                 flush_workqueue(nbd->recv_workq);
1278                         return -ENOMEM;
1279                 }
1280                 sk_set_memalloc(config->socks[i]->sock->sk);
1281                 if (nbd->tag_set.timeout)
1282                         config->socks[i]->sock->sk->sk_sndtimeo =
1283                                 nbd->tag_set.timeout;
1284                 atomic_inc(&config->recv_threads);
1285                 refcount_inc(&nbd->config_refs);
1286                 INIT_WORK(&args->work, recv_work);
1287                 args->nbd = nbd;
1288                 args->index = i;
1289                 queue_work(nbd->recv_workq, &args->work);
1290         }
1291         nbd_size_update(nbd);
1292         return error;
1293 }
1294
1295 static int nbd_start_device_ioctl(struct nbd_device *nbd, struct block_device *bdev)
1296 {
1297         struct nbd_config *config = nbd->config;
1298         int ret;
1299
1300         ret = nbd_start_device(nbd);
1301         if (ret)
1302                 return ret;
1303
1304         if (max_part)
1305                 bdev->bd_invalidated = 1;
1306         mutex_unlock(&nbd->config_lock);
1307         ret = wait_event_interruptible(config->recv_wq,
1308                                          atomic_read(&config->recv_threads) == 0);
1309         if (ret)
1310                 sock_shutdown(nbd);
1311         flush_workqueue(nbd->recv_workq);
1312
1313         mutex_lock(&nbd->config_lock);
1314         nbd_bdev_reset(bdev);
1315         /* user requested, ignore socket errors */
1316         if (test_bit(NBD_RT_DISCONNECT_REQUESTED, &config->runtime_flags))
1317                 ret = 0;
1318         if (test_bit(NBD_RT_TIMEDOUT, &config->runtime_flags))
1319                 ret = -ETIMEDOUT;
1320         return ret;
1321 }
1322
1323 static void nbd_clear_sock_ioctl(struct nbd_device *nbd,
1324                                  struct block_device *bdev)
1325 {
1326         sock_shutdown(nbd);
1327         __invalidate_device(bdev, true);
1328         nbd_bdev_reset(bdev);
1329         if (test_and_clear_bit(NBD_RT_HAS_CONFIG_REF,
1330                                &nbd->config->runtime_flags))
1331                 nbd_config_put(nbd);
1332 }
1333
1334 static bool nbd_is_valid_blksize(unsigned long blksize)
1335 {
1336         if (!blksize || !is_power_of_2(blksize) || blksize < 512 ||
1337             blksize > PAGE_SIZE)
1338                 return false;
1339         return true;
1340 }
1341
1342 static void nbd_set_cmd_timeout(struct nbd_device *nbd, u64 timeout)
1343 {
1344         nbd->tag_set.timeout = timeout * HZ;
1345         if (timeout)
1346                 blk_queue_rq_timeout(nbd->disk->queue, timeout * HZ);
1347 }
1348
1349 /* Must be called with config_lock held */
1350 static int __nbd_ioctl(struct block_device *bdev, struct nbd_device *nbd,
1351                        unsigned int cmd, unsigned long arg)
1352 {
1353         struct nbd_config *config = nbd->config;
1354
1355         switch (cmd) {
1356         case NBD_DISCONNECT:
1357                 return nbd_disconnect(nbd);
1358         case NBD_CLEAR_SOCK:
1359                 nbd_clear_sock_ioctl(nbd, bdev);
1360                 return 0;
1361         case NBD_SET_SOCK:
1362                 return nbd_add_socket(nbd, arg, false);
1363         case NBD_SET_BLKSIZE:
1364                 if (!arg)
1365                         arg = NBD_DEF_BLKSIZE;
1366                 if (!nbd_is_valid_blksize(arg))
1367                         return -EINVAL;
1368                 nbd_size_set(nbd, arg,
1369                              div_s64(config->bytesize, arg));
1370                 return 0;
1371         case NBD_SET_SIZE:
1372                 nbd_size_set(nbd, config->blksize,
1373                              div_s64(arg, config->blksize));
1374                 return 0;
1375         case NBD_SET_SIZE_BLOCKS:
1376                 nbd_size_set(nbd, config->blksize, arg);
1377                 return 0;
1378         case NBD_SET_TIMEOUT:
1379                 nbd_set_cmd_timeout(nbd, arg);
1380                 return 0;
1381
1382         case NBD_SET_FLAGS:
1383                 config->flags = arg;
1384                 return 0;
1385         case NBD_DO_IT:
1386                 return nbd_start_device_ioctl(nbd, bdev);
1387         case NBD_CLEAR_QUE:
1388                 /*
1389                  * This is for compatibility only.  The queue is always cleared
1390                  * by NBD_DO_IT or NBD_CLEAR_SOCK.
1391                  */
1392                 return 0;
1393         case NBD_PRINT_DEBUG:
1394                 /*
1395                  * For compatibility only, we no longer keep a list of
1396                  * outstanding requests.
1397                  */
1398                 return 0;
1399         }
1400         return -ENOTTY;
1401 }
1402
1403 static int nbd_ioctl(struct block_device *bdev, fmode_t mode,
1404                      unsigned int cmd, unsigned long arg)
1405 {
1406         struct nbd_device *nbd = bdev->bd_disk->private_data;
1407         struct nbd_config *config = nbd->config;
1408         int error = -EINVAL;
1409
1410         if (!capable(CAP_SYS_ADMIN))
1411                 return -EPERM;
1412
1413         /* The block layer will pass back some non-nbd ioctls in case we have
1414          * special handling for them, but we don't so just return an error.
1415          */
1416         if (_IOC_TYPE(cmd) != 0xab)
1417                 return -EINVAL;
1418
1419         mutex_lock(&nbd->config_lock);
1420
1421         /* Don't allow ioctl operations on a nbd device that was created with
1422          * netlink, unless it's DISCONNECT or CLEAR_SOCK, which are fine.
1423          */
1424         if (!test_bit(NBD_RT_BOUND, &config->runtime_flags) ||
1425             (cmd == NBD_DISCONNECT || cmd == NBD_CLEAR_SOCK))
1426                 error = __nbd_ioctl(bdev, nbd, cmd, arg);
1427         else
1428                 dev_err(nbd_to_dev(nbd), "Cannot use ioctl interface on a netlink controlled device.\n");
1429         mutex_unlock(&nbd->config_lock);
1430         return error;
1431 }
1432
1433 static struct nbd_config *nbd_alloc_config(void)
1434 {
1435         struct nbd_config *config;
1436
1437         config = kzalloc(sizeof(struct nbd_config), GFP_NOFS);
1438         if (!config)
1439                 return NULL;
1440         atomic_set(&config->recv_threads, 0);
1441         init_waitqueue_head(&config->recv_wq);
1442         init_waitqueue_head(&config->conn_wait);
1443         config->blksize = NBD_DEF_BLKSIZE;
1444         atomic_set(&config->live_connections, 0);
1445         try_module_get(THIS_MODULE);
1446         return config;
1447 }
1448
1449 static int nbd_open(struct block_device *bdev, fmode_t mode)
1450 {
1451         struct nbd_device *nbd;
1452         int ret = 0;
1453
1454         mutex_lock(&nbd_index_mutex);
1455         nbd = bdev->bd_disk->private_data;
1456         if (!nbd) {
1457                 ret = -ENXIO;
1458                 goto out;
1459         }
1460         if (!refcount_inc_not_zero(&nbd->refs)) {
1461                 ret = -ENXIO;
1462                 goto out;
1463         }
1464         if (!refcount_inc_not_zero(&nbd->config_refs)) {
1465                 struct nbd_config *config;
1466
1467                 mutex_lock(&nbd->config_lock);
1468                 if (refcount_inc_not_zero(&nbd->config_refs)) {
1469                         mutex_unlock(&nbd->config_lock);
1470                         goto out;
1471                 }
1472                 config = nbd->config = nbd_alloc_config();
1473                 if (!config) {
1474                         ret = -ENOMEM;
1475                         mutex_unlock(&nbd->config_lock);
1476                         goto out;
1477                 }
1478                 refcount_set(&nbd->config_refs, 1);
1479                 refcount_inc(&nbd->refs);
1480                 mutex_unlock(&nbd->config_lock);
1481                 bdev->bd_invalidated = 1;
1482         } else if (nbd_disconnected(nbd->config)) {
1483                 bdev->bd_invalidated = 1;
1484         }
1485 out:
1486         mutex_unlock(&nbd_index_mutex);
1487         return ret;
1488 }
1489
1490 static void nbd_release(struct gendisk *disk, fmode_t mode)
1491 {
1492         struct nbd_device *nbd = disk->private_data;
1493         struct block_device *bdev = bdget_disk(disk, 0);
1494
1495         if (test_bit(NBD_RT_DISCONNECT_ON_CLOSE, &nbd->config->runtime_flags) &&
1496                         bdev->bd_openers == 0)
1497                 nbd_disconnect_and_put(nbd);
1498
1499         nbd_config_put(nbd);
1500         nbd_put(nbd);
1501 }
1502
1503 static const struct block_device_operations nbd_fops =
1504 {
1505         .owner =        THIS_MODULE,
1506         .open =         nbd_open,
1507         .release =      nbd_release,
1508         .ioctl =        nbd_ioctl,
1509         .compat_ioctl = nbd_ioctl,
1510 };
1511
1512 #if IS_ENABLED(CONFIG_DEBUG_FS)
1513
1514 static int nbd_dbg_tasks_show(struct seq_file *s, void *unused)
1515 {
1516         struct nbd_device *nbd = s->private;
1517
1518         if (nbd->task_recv)
1519                 seq_printf(s, "recv: %d\n", task_pid_nr(nbd->task_recv));
1520
1521         return 0;
1522 }
1523
1524 static int nbd_dbg_tasks_open(struct inode *inode, struct file *file)
1525 {
1526         return single_open(file, nbd_dbg_tasks_show, inode->i_private);
1527 }
1528
1529 static const struct file_operations nbd_dbg_tasks_ops = {
1530         .open = nbd_dbg_tasks_open,
1531         .read = seq_read,
1532         .llseek = seq_lseek,
1533         .release = single_release,
1534 };
1535
1536 static int nbd_dbg_flags_show(struct seq_file *s, void *unused)
1537 {
1538         struct nbd_device *nbd = s->private;
1539         u32 flags = nbd->config->flags;
1540
1541         seq_printf(s, "Hex: 0x%08x\n\n", flags);
1542
1543         seq_puts(s, "Known flags:\n");
1544
1545         if (flags & NBD_FLAG_HAS_FLAGS)
1546                 seq_puts(s, "NBD_FLAG_HAS_FLAGS\n");
1547         if (flags & NBD_FLAG_READ_ONLY)
1548                 seq_puts(s, "NBD_FLAG_READ_ONLY\n");
1549         if (flags & NBD_FLAG_SEND_FLUSH)
1550                 seq_puts(s, "NBD_FLAG_SEND_FLUSH\n");
1551         if (flags & NBD_FLAG_SEND_FUA)
1552                 seq_puts(s, "NBD_FLAG_SEND_FUA\n");
1553         if (flags & NBD_FLAG_SEND_TRIM)
1554                 seq_puts(s, "NBD_FLAG_SEND_TRIM\n");
1555
1556         return 0;
1557 }
1558
1559 static int nbd_dbg_flags_open(struct inode *inode, struct file *file)
1560 {
1561         return single_open(file, nbd_dbg_flags_show, inode->i_private);
1562 }
1563
1564 static const struct file_operations nbd_dbg_flags_ops = {
1565         .open = nbd_dbg_flags_open,
1566         .read = seq_read,
1567         .llseek = seq_lseek,
1568         .release = single_release,
1569 };
1570
1571 static int nbd_dev_dbg_init(struct nbd_device *nbd)
1572 {
1573         struct dentry *dir;
1574         struct nbd_config *config = nbd->config;
1575
1576         if (!nbd_dbg_dir)
1577                 return -EIO;
1578
1579         dir = debugfs_create_dir(nbd_name(nbd), nbd_dbg_dir);
1580         if (!dir) {
1581                 dev_err(nbd_to_dev(nbd), "Failed to create debugfs dir for '%s'\n",
1582                         nbd_name(nbd));
1583                 return -EIO;
1584         }
1585         config->dbg_dir = dir;
1586
1587         debugfs_create_file("tasks", 0444, dir, nbd, &nbd_dbg_tasks_ops);
1588         debugfs_create_u64("size_bytes", 0444, dir, &config->bytesize);
1589         debugfs_create_u32("timeout", 0444, dir, &nbd->tag_set.timeout);
1590         debugfs_create_u64("blocksize", 0444, dir, &config->blksize);
1591         debugfs_create_file("flags", 0444, dir, nbd, &nbd_dbg_flags_ops);
1592
1593         return 0;
1594 }
1595
1596 static void nbd_dev_dbg_close(struct nbd_device *nbd)
1597 {
1598         debugfs_remove_recursive(nbd->config->dbg_dir);
1599 }
1600
1601 static int nbd_dbg_init(void)
1602 {
1603         struct dentry *dbg_dir;
1604
1605         dbg_dir = debugfs_create_dir("nbd", NULL);
1606         if (!dbg_dir)
1607                 return -EIO;
1608
1609         nbd_dbg_dir = dbg_dir;
1610
1611         return 0;
1612 }
1613
1614 static void nbd_dbg_close(void)
1615 {
1616         debugfs_remove_recursive(nbd_dbg_dir);
1617 }
1618
1619 #else  /* IS_ENABLED(CONFIG_DEBUG_FS) */
1620
1621 static int nbd_dev_dbg_init(struct nbd_device *nbd)
1622 {
1623         return 0;
1624 }
1625
1626 static void nbd_dev_dbg_close(struct nbd_device *nbd)
1627 {
1628 }
1629
1630 static int nbd_dbg_init(void)
1631 {
1632         return 0;
1633 }
1634
1635 static void nbd_dbg_close(void)
1636 {
1637 }
1638
1639 #endif
1640
1641 static int nbd_init_request(struct blk_mq_tag_set *set, struct request *rq,
1642                             unsigned int hctx_idx, unsigned int numa_node)
1643 {
1644         struct nbd_cmd *cmd = blk_mq_rq_to_pdu(rq);
1645         cmd->nbd = set->driver_data;
1646         cmd->flags = 0;
1647         mutex_init(&cmd->lock);
1648         return 0;
1649 }
1650
1651 static const struct blk_mq_ops nbd_mq_ops = {
1652         .queue_rq       = nbd_queue_rq,
1653         .complete       = nbd_complete_rq,
1654         .init_request   = nbd_init_request,
1655         .timeout        = nbd_xmit_timeout,
1656 };
1657
1658 static int nbd_dev_add(int index)
1659 {
1660         struct nbd_device *nbd;
1661         struct gendisk *disk;
1662         struct request_queue *q;
1663         int err = -ENOMEM;
1664
1665         nbd = kzalloc(sizeof(struct nbd_device), GFP_KERNEL);
1666         if (!nbd)
1667                 goto out;
1668
1669         disk = alloc_disk(1 << part_shift);
1670         if (!disk)
1671                 goto out_free_nbd;
1672
1673         if (index >= 0) {
1674                 err = idr_alloc(&nbd_index_idr, nbd, index, index + 1,
1675                                 GFP_KERNEL);
1676                 if (err == -ENOSPC)
1677                         err = -EEXIST;
1678         } else {
1679                 err = idr_alloc(&nbd_index_idr, nbd, 0, 0, GFP_KERNEL);
1680                 if (err >= 0)
1681                         index = err;
1682         }
1683         if (err < 0)
1684                 goto out_free_disk;
1685
1686         nbd->index = index;
1687         nbd->disk = disk;
1688         nbd->tag_set.ops = &nbd_mq_ops;
1689         nbd->tag_set.nr_hw_queues = 1;
1690         nbd->tag_set.queue_depth = 128;
1691         nbd->tag_set.numa_node = NUMA_NO_NODE;
1692         nbd->tag_set.cmd_size = sizeof(struct nbd_cmd);
1693         nbd->tag_set.flags = BLK_MQ_F_SHOULD_MERGE |
1694                 BLK_MQ_F_BLOCKING;
1695         nbd->tag_set.driver_data = nbd;
1696         nbd->destroy_complete = NULL;
1697
1698         err = blk_mq_alloc_tag_set(&nbd->tag_set);
1699         if (err)
1700                 goto out_free_idr;
1701
1702         q = blk_mq_init_queue(&nbd->tag_set);
1703         if (IS_ERR(q)) {
1704                 err = PTR_ERR(q);
1705                 goto out_free_tags;
1706         }
1707         disk->queue = q;
1708
1709         /*
1710          * Tell the block layer that we are not a rotational device
1711          */
1712         blk_queue_flag_set(QUEUE_FLAG_NONROT, disk->queue);
1713         blk_queue_flag_clear(QUEUE_FLAG_ADD_RANDOM, disk->queue);
1714         disk->queue->limits.discard_granularity = 0;
1715         disk->queue->limits.discard_alignment = 0;
1716         blk_queue_max_discard_sectors(disk->queue, 0);
1717         blk_queue_max_segment_size(disk->queue, UINT_MAX);
1718         blk_queue_max_segments(disk->queue, USHRT_MAX);
1719         blk_queue_max_hw_sectors(disk->queue, 65536);
1720         disk->queue->limits.max_sectors = 256;
1721
1722         mutex_init(&nbd->config_lock);
1723         refcount_set(&nbd->config_refs, 0);
1724         refcount_set(&nbd->refs, 1);
1725         INIT_LIST_HEAD(&nbd->list);
1726         disk->major = NBD_MAJOR;
1727         disk->first_minor = index << part_shift;
1728         disk->fops = &nbd_fops;
1729         disk->private_data = nbd;
1730         sprintf(disk->disk_name, "nbd%d", index);
1731         add_disk(disk);
1732         nbd_total_devices++;
1733         return index;
1734
1735 out_free_tags:
1736         blk_mq_free_tag_set(&nbd->tag_set);
1737 out_free_idr:
1738         idr_remove(&nbd_index_idr, index);
1739 out_free_disk:
1740         put_disk(disk);
1741 out_free_nbd:
1742         kfree(nbd);
1743 out:
1744         return err;
1745 }
1746
1747 static int find_free_cb(int id, void *ptr, void *data)
1748 {
1749         struct nbd_device *nbd = ptr;
1750         struct nbd_device **found = data;
1751
1752         if (!refcount_read(&nbd->config_refs)) {
1753                 *found = nbd;
1754                 return 1;
1755         }
1756         return 0;
1757 }
1758
1759 /* Netlink interface. */
1760 static const struct nla_policy nbd_attr_policy[NBD_ATTR_MAX + 1] = {
1761         [NBD_ATTR_INDEX]                =       { .type = NLA_U32 },
1762         [NBD_ATTR_SIZE_BYTES]           =       { .type = NLA_U64 },
1763         [NBD_ATTR_BLOCK_SIZE_BYTES]     =       { .type = NLA_U64 },
1764         [NBD_ATTR_TIMEOUT]              =       { .type = NLA_U64 },
1765         [NBD_ATTR_SERVER_FLAGS]         =       { .type = NLA_U64 },
1766         [NBD_ATTR_CLIENT_FLAGS]         =       { .type = NLA_U64 },
1767         [NBD_ATTR_SOCKETS]              =       { .type = NLA_NESTED},
1768         [NBD_ATTR_DEAD_CONN_TIMEOUT]    =       { .type = NLA_U64 },
1769         [NBD_ATTR_DEVICE_LIST]          =       { .type = NLA_NESTED},
1770 };
1771
1772 static const struct nla_policy nbd_sock_policy[NBD_SOCK_MAX + 1] = {
1773         [NBD_SOCK_FD]                   =       { .type = NLA_U32 },
1774 };
1775
1776 /* We don't use this right now since we don't parse the incoming list, but we
1777  * still want it here so userspace knows what to expect.
1778  */
1779 static const struct nla_policy __attribute__((unused))
1780 nbd_device_policy[NBD_DEVICE_ATTR_MAX + 1] = {
1781         [NBD_DEVICE_INDEX]              =       { .type = NLA_U32 },
1782         [NBD_DEVICE_CONNECTED]          =       { .type = NLA_U8 },
1783 };
1784
1785 static int nbd_genl_size_set(struct genl_info *info, struct nbd_device *nbd)
1786 {
1787         struct nbd_config *config = nbd->config;
1788         u64 bsize = config->blksize;
1789         u64 bytes = config->bytesize;
1790
1791         if (info->attrs[NBD_ATTR_SIZE_BYTES])
1792                 bytes = nla_get_u64(info->attrs[NBD_ATTR_SIZE_BYTES]);
1793
1794         if (info->attrs[NBD_ATTR_BLOCK_SIZE_BYTES]) {
1795                 bsize = nla_get_u64(info->attrs[NBD_ATTR_BLOCK_SIZE_BYTES]);
1796                 if (!bsize)
1797                         bsize = NBD_DEF_BLKSIZE;
1798                 if (!nbd_is_valid_blksize(bsize)) {
1799                         printk(KERN_ERR "Invalid block size %llu\n", bsize);
1800                         return -EINVAL;
1801                 }
1802         }
1803
1804         if (bytes != config->bytesize || bsize != config->blksize)
1805                 nbd_size_set(nbd, bsize, div64_u64(bytes, bsize));
1806         return 0;
1807 }
1808
1809 static int nbd_genl_connect(struct sk_buff *skb, struct genl_info *info)
1810 {
1811         DECLARE_COMPLETION_ONSTACK(destroy_complete);
1812         struct nbd_device *nbd = NULL;
1813         struct nbd_config *config;
1814         int index = -1;
1815         int ret;
1816         bool put_dev = false;
1817
1818         if (!netlink_capable(skb, CAP_SYS_ADMIN))
1819                 return -EPERM;
1820
1821         if (info->attrs[NBD_ATTR_INDEX])
1822                 index = nla_get_u32(info->attrs[NBD_ATTR_INDEX]);
1823         if (!info->attrs[NBD_ATTR_SOCKETS]) {
1824                 printk(KERN_ERR "nbd: must specify at least one socket\n");
1825                 return -EINVAL;
1826         }
1827         if (!info->attrs[NBD_ATTR_SIZE_BYTES]) {
1828                 printk(KERN_ERR "nbd: must specify a size in bytes for the device\n");
1829                 return -EINVAL;
1830         }
1831 again:
1832         mutex_lock(&nbd_index_mutex);
1833         if (index == -1) {
1834                 ret = idr_for_each(&nbd_index_idr, &find_free_cb, &nbd);
1835                 if (ret == 0) {
1836                         int new_index;
1837                         new_index = nbd_dev_add(-1);
1838                         if (new_index < 0) {
1839                                 mutex_unlock(&nbd_index_mutex);
1840                                 printk(KERN_ERR "nbd: failed to add new device\n");
1841                                 return new_index;
1842                         }
1843                         nbd = idr_find(&nbd_index_idr, new_index);
1844                 }
1845         } else {
1846                 nbd = idr_find(&nbd_index_idr, index);
1847                 if (!nbd) {
1848                         ret = nbd_dev_add(index);
1849                         if (ret < 0) {
1850                                 mutex_unlock(&nbd_index_mutex);
1851                                 printk(KERN_ERR "nbd: failed to add new device\n");
1852                                 return ret;
1853                         }
1854                         nbd = idr_find(&nbd_index_idr, index);
1855                 }
1856         }
1857         if (!nbd) {
1858                 printk(KERN_ERR "nbd: couldn't find device at index %d\n",
1859                        index);
1860                 mutex_unlock(&nbd_index_mutex);
1861                 return -EINVAL;
1862         }
1863
1864         if (test_bit(NBD_DESTROY_ON_DISCONNECT, &nbd->flags) &&
1865             test_bit(NBD_DISCONNECT_REQUESTED, &nbd->flags)) {
1866                 nbd->destroy_complete = &destroy_complete;
1867                 mutex_unlock(&nbd_index_mutex);
1868
1869                 /* Wait untill the the nbd stuff is totally destroyed */
1870                 wait_for_completion(&destroy_complete);
1871                 goto again;
1872         }
1873
1874         if (!refcount_inc_not_zero(&nbd->refs)) {
1875                 mutex_unlock(&nbd_index_mutex);
1876                 if (index == -1)
1877                         goto again;
1878                 printk(KERN_ERR "nbd: device at index %d is going down\n",
1879                        index);
1880                 return -EINVAL;
1881         }
1882         mutex_unlock(&nbd_index_mutex);
1883
1884         mutex_lock(&nbd->config_lock);
1885         if (refcount_read(&nbd->config_refs)) {
1886                 mutex_unlock(&nbd->config_lock);
1887                 nbd_put(nbd);
1888                 if (index == -1)
1889                         goto again;
1890                 printk(KERN_ERR "nbd: nbd%d already in use\n", index);
1891                 return -EBUSY;
1892         }
1893         if (WARN_ON(nbd->config)) {
1894                 mutex_unlock(&nbd->config_lock);
1895                 nbd_put(nbd);
1896                 return -EINVAL;
1897         }
1898         config = nbd->config = nbd_alloc_config();
1899         if (!nbd->config) {
1900                 mutex_unlock(&nbd->config_lock);
1901                 nbd_put(nbd);
1902                 printk(KERN_ERR "nbd: couldn't allocate config\n");
1903                 return -ENOMEM;
1904         }
1905         refcount_set(&nbd->config_refs, 1);
1906         set_bit(NBD_RT_BOUND, &config->runtime_flags);
1907
1908         ret = nbd_genl_size_set(info, nbd);
1909         if (ret)
1910                 goto out;
1911
1912         if (info->attrs[NBD_ATTR_TIMEOUT])
1913                 nbd_set_cmd_timeout(nbd,
1914                                     nla_get_u64(info->attrs[NBD_ATTR_TIMEOUT]));
1915         if (info->attrs[NBD_ATTR_DEAD_CONN_TIMEOUT]) {
1916                 config->dead_conn_timeout =
1917                         nla_get_u64(info->attrs[NBD_ATTR_DEAD_CONN_TIMEOUT]);
1918                 config->dead_conn_timeout *= HZ;
1919         }
1920         if (info->attrs[NBD_ATTR_SERVER_FLAGS])
1921                 config->flags =
1922                         nla_get_u64(info->attrs[NBD_ATTR_SERVER_FLAGS]);
1923         if (info->attrs[NBD_ATTR_CLIENT_FLAGS]) {
1924                 u64 flags = nla_get_u64(info->attrs[NBD_ATTR_CLIENT_FLAGS]);
1925                 if (flags & NBD_CFLAG_DESTROY_ON_DISCONNECT) {
1926                         set_bit(NBD_RT_DESTROY_ON_DISCONNECT,
1927                                 &config->runtime_flags);
1928                         set_bit(NBD_DESTROY_ON_DISCONNECT, &nbd->flags);
1929                         put_dev = true;
1930                 } else {
1931                         clear_bit(NBD_DESTROY_ON_DISCONNECT, &nbd->flags);
1932                 }
1933                 if (flags & NBD_CFLAG_DISCONNECT_ON_CLOSE) {
1934                         set_bit(NBD_RT_DISCONNECT_ON_CLOSE,
1935                                 &config->runtime_flags);
1936                 }
1937         }
1938
1939         if (info->attrs[NBD_ATTR_SOCKETS]) {
1940                 struct nlattr *attr;
1941                 int rem, fd;
1942
1943                 nla_for_each_nested(attr, info->attrs[NBD_ATTR_SOCKETS],
1944                                     rem) {
1945                         struct nlattr *socks[NBD_SOCK_MAX+1];
1946
1947                         if (nla_type(attr) != NBD_SOCK_ITEM) {
1948                                 printk(KERN_ERR "nbd: socks must be embedded in a SOCK_ITEM attr\n");
1949                                 ret = -EINVAL;
1950                                 goto out;
1951                         }
1952                         ret = nla_parse_nested_deprecated(socks, NBD_SOCK_MAX,
1953                                                           attr,
1954                                                           nbd_sock_policy,
1955                                                           info->extack);
1956                         if (ret != 0) {
1957                                 printk(KERN_ERR "nbd: error processing sock list\n");
1958                                 ret = -EINVAL;
1959                                 goto out;
1960                         }
1961                         if (!socks[NBD_SOCK_FD])
1962                                 continue;
1963                         fd = (int)nla_get_u32(socks[NBD_SOCK_FD]);
1964                         ret = nbd_add_socket(nbd, fd, true);
1965                         if (ret)
1966                                 goto out;
1967                 }
1968         }
1969         ret = nbd_start_device(nbd);
1970 out:
1971         mutex_unlock(&nbd->config_lock);
1972         if (!ret) {
1973                 set_bit(NBD_RT_HAS_CONFIG_REF, &config->runtime_flags);
1974                 refcount_inc(&nbd->config_refs);
1975                 nbd_connect_reply(info, nbd->index);
1976         }
1977         nbd_config_put(nbd);
1978         if (put_dev)
1979                 nbd_put(nbd);
1980         return ret;
1981 }
1982
1983 static void nbd_disconnect_and_put(struct nbd_device *nbd)
1984 {
1985         mutex_lock(&nbd->config_lock);
1986         nbd_disconnect(nbd);
1987         nbd_clear_sock(nbd);
1988         mutex_unlock(&nbd->config_lock);
1989         /*
1990          * Make sure recv thread has finished, so it does not drop the last
1991          * config ref and try to destroy the workqueue from inside the work
1992          * queue.
1993          */
1994         flush_workqueue(nbd->recv_workq);
1995         if (test_and_clear_bit(NBD_RT_HAS_CONFIG_REF,
1996                                &nbd->config->runtime_flags))
1997                 nbd_config_put(nbd);
1998 }
1999
2000 static int nbd_genl_disconnect(struct sk_buff *skb, struct genl_info *info)
2001 {
2002         struct nbd_device *nbd;
2003         int index;
2004
2005         if (!netlink_capable(skb, CAP_SYS_ADMIN))
2006                 return -EPERM;
2007
2008         if (!info->attrs[NBD_ATTR_INDEX]) {
2009                 printk(KERN_ERR "nbd: must specify an index to disconnect\n");
2010                 return -EINVAL;
2011         }
2012         index = nla_get_u32(info->attrs[NBD_ATTR_INDEX]);
2013         mutex_lock(&nbd_index_mutex);
2014         nbd = idr_find(&nbd_index_idr, index);
2015         if (!nbd) {
2016                 mutex_unlock(&nbd_index_mutex);
2017                 printk(KERN_ERR "nbd: couldn't find device at index %d\n",
2018                        index);
2019                 return -EINVAL;
2020         }
2021         if (!refcount_inc_not_zero(&nbd->refs)) {
2022                 mutex_unlock(&nbd_index_mutex);
2023                 printk(KERN_ERR "nbd: device at index %d is going down\n",
2024                        index);
2025                 return -EINVAL;
2026         }
2027         mutex_unlock(&nbd_index_mutex);
2028         if (!refcount_inc_not_zero(&nbd->config_refs)) {
2029                 nbd_put(nbd);
2030                 return 0;
2031         }
2032         nbd_disconnect_and_put(nbd);
2033         nbd_config_put(nbd);
2034         nbd_put(nbd);
2035         return 0;
2036 }
2037
2038 static int nbd_genl_reconfigure(struct sk_buff *skb, struct genl_info *info)
2039 {
2040         struct nbd_device *nbd = NULL;
2041         struct nbd_config *config;
2042         int index;
2043         int ret = 0;
2044         bool put_dev = false;
2045
2046         if (!netlink_capable(skb, CAP_SYS_ADMIN))
2047                 return -EPERM;
2048
2049         if (!info->attrs[NBD_ATTR_INDEX]) {
2050                 printk(KERN_ERR "nbd: must specify a device to reconfigure\n");
2051                 return -EINVAL;
2052         }
2053         index = nla_get_u32(info->attrs[NBD_ATTR_INDEX]);
2054         mutex_lock(&nbd_index_mutex);
2055         nbd = idr_find(&nbd_index_idr, index);
2056         if (!nbd) {
2057                 mutex_unlock(&nbd_index_mutex);
2058                 printk(KERN_ERR "nbd: couldn't find a device at index %d\n",
2059                        index);
2060                 return -EINVAL;
2061         }
2062         if (!refcount_inc_not_zero(&nbd->refs)) {
2063                 mutex_unlock(&nbd_index_mutex);
2064                 printk(KERN_ERR "nbd: device at index %d is going down\n",
2065                        index);
2066                 return -EINVAL;
2067         }
2068         mutex_unlock(&nbd_index_mutex);
2069
2070         if (!refcount_inc_not_zero(&nbd->config_refs)) {
2071                 dev_err(nbd_to_dev(nbd),
2072                         "not configured, cannot reconfigure\n");
2073                 nbd_put(nbd);
2074                 return -EINVAL;
2075         }
2076
2077         mutex_lock(&nbd->config_lock);
2078         config = nbd->config;
2079         if (!test_bit(NBD_RT_BOUND, &config->runtime_flags) ||
2080             !nbd->task_recv) {
2081                 dev_err(nbd_to_dev(nbd),
2082                         "not configured, cannot reconfigure\n");
2083                 ret = -EINVAL;
2084                 goto out;
2085         }
2086
2087         ret = nbd_genl_size_set(info, nbd);
2088         if (ret)
2089                 goto out;
2090
2091         if (info->attrs[NBD_ATTR_TIMEOUT])
2092                 nbd_set_cmd_timeout(nbd,
2093                                     nla_get_u64(info->attrs[NBD_ATTR_TIMEOUT]));
2094         if (info->attrs[NBD_ATTR_DEAD_CONN_TIMEOUT]) {
2095                 config->dead_conn_timeout =
2096                         nla_get_u64(info->attrs[NBD_ATTR_DEAD_CONN_TIMEOUT]);
2097                 config->dead_conn_timeout *= HZ;
2098         }
2099         if (info->attrs[NBD_ATTR_CLIENT_FLAGS]) {
2100                 u64 flags = nla_get_u64(info->attrs[NBD_ATTR_CLIENT_FLAGS]);
2101                 if (flags & NBD_CFLAG_DESTROY_ON_DISCONNECT) {
2102                         if (!test_and_set_bit(NBD_RT_DESTROY_ON_DISCONNECT,
2103                                               &config->runtime_flags))
2104                                 put_dev = true;
2105                         set_bit(NBD_DESTROY_ON_DISCONNECT, &nbd->flags);
2106                 } else {
2107                         if (test_and_clear_bit(NBD_RT_DESTROY_ON_DISCONNECT,
2108                                                &config->runtime_flags))
2109                                 refcount_inc(&nbd->refs);
2110                         clear_bit(NBD_DESTROY_ON_DISCONNECT, &nbd->flags);
2111                 }
2112
2113                 if (flags & NBD_CFLAG_DISCONNECT_ON_CLOSE) {
2114                         set_bit(NBD_RT_DISCONNECT_ON_CLOSE,
2115                                         &config->runtime_flags);
2116                 } else {
2117                         clear_bit(NBD_RT_DISCONNECT_ON_CLOSE,
2118                                         &config->runtime_flags);
2119                 }
2120         }
2121
2122         if (info->attrs[NBD_ATTR_SOCKETS]) {
2123                 struct nlattr *attr;
2124                 int rem, fd;
2125
2126                 nla_for_each_nested(attr, info->attrs[NBD_ATTR_SOCKETS],
2127                                     rem) {
2128                         struct nlattr *socks[NBD_SOCK_MAX+1];
2129
2130                         if (nla_type(attr) != NBD_SOCK_ITEM) {
2131                                 printk(KERN_ERR "nbd: socks must be embedded in a SOCK_ITEM attr\n");
2132                                 ret = -EINVAL;
2133                                 goto out;
2134                         }
2135                         ret = nla_parse_nested_deprecated(socks, NBD_SOCK_MAX,
2136                                                           attr,
2137                                                           nbd_sock_policy,
2138                                                           info->extack);
2139                         if (ret != 0) {
2140                                 printk(KERN_ERR "nbd: error processing sock list\n");
2141                                 ret = -EINVAL;
2142                                 goto out;
2143                         }
2144                         if (!socks[NBD_SOCK_FD])
2145                                 continue;
2146                         fd = (int)nla_get_u32(socks[NBD_SOCK_FD]);
2147                         ret = nbd_reconnect_socket(nbd, fd);
2148                         if (ret) {
2149                                 if (ret == -ENOSPC)
2150                                         ret = 0;
2151                                 goto out;
2152                         }
2153                         dev_info(nbd_to_dev(nbd), "reconnected socket\n");
2154                 }
2155         }
2156 out:
2157         mutex_unlock(&nbd->config_lock);
2158         nbd_config_put(nbd);
2159         nbd_put(nbd);
2160         if (put_dev)
2161                 nbd_put(nbd);
2162         return ret;
2163 }
2164
2165 static const struct genl_ops nbd_connect_genl_ops[] = {
2166         {
2167                 .cmd    = NBD_CMD_CONNECT,
2168                 .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
2169                 .doit   = nbd_genl_connect,
2170         },
2171         {
2172                 .cmd    = NBD_CMD_DISCONNECT,
2173                 .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
2174                 .doit   = nbd_genl_disconnect,
2175         },
2176         {
2177                 .cmd    = NBD_CMD_RECONFIGURE,
2178                 .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
2179                 .doit   = nbd_genl_reconfigure,
2180         },
2181         {
2182                 .cmd    = NBD_CMD_STATUS,
2183                 .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
2184                 .doit   = nbd_genl_status,
2185         },
2186 };
2187
2188 static const struct genl_multicast_group nbd_mcast_grps[] = {
2189         { .name = NBD_GENL_MCAST_GROUP_NAME, },
2190 };
2191
2192 static struct genl_family nbd_genl_family __ro_after_init = {
2193         .hdrsize        = 0,
2194         .name           = NBD_GENL_FAMILY_NAME,
2195         .version        = NBD_GENL_VERSION,
2196         .module         = THIS_MODULE,
2197         .ops            = nbd_connect_genl_ops,
2198         .n_ops          = ARRAY_SIZE(nbd_connect_genl_ops),
2199         .maxattr        = NBD_ATTR_MAX,
2200         .policy = nbd_attr_policy,
2201         .mcgrps         = nbd_mcast_grps,
2202         .n_mcgrps       = ARRAY_SIZE(nbd_mcast_grps),
2203 };
2204
2205 static int populate_nbd_status(struct nbd_device *nbd, struct sk_buff *reply)
2206 {
2207         struct nlattr *dev_opt;
2208         u8 connected = 0;
2209         int ret;
2210
2211         /* This is a little racey, but for status it's ok.  The
2212          * reason we don't take a ref here is because we can't
2213          * take a ref in the index == -1 case as we would need
2214          * to put under the nbd_index_mutex, which could
2215          * deadlock if we are configured to remove ourselves
2216          * once we're disconnected.
2217          */
2218         if (refcount_read(&nbd->config_refs))
2219                 connected = 1;
2220         dev_opt = nla_nest_start_noflag(reply, NBD_DEVICE_ITEM);
2221         if (!dev_opt)
2222                 return -EMSGSIZE;
2223         ret = nla_put_u32(reply, NBD_DEVICE_INDEX, nbd->index);
2224         if (ret)
2225                 return -EMSGSIZE;
2226         ret = nla_put_u8(reply, NBD_DEVICE_CONNECTED,
2227                          connected);
2228         if (ret)
2229                 return -EMSGSIZE;
2230         nla_nest_end(reply, dev_opt);
2231         return 0;
2232 }
2233
2234 static int status_cb(int id, void *ptr, void *data)
2235 {
2236         struct nbd_device *nbd = ptr;
2237         return populate_nbd_status(nbd, (struct sk_buff *)data);
2238 }
2239
2240 static int nbd_genl_status(struct sk_buff *skb, struct genl_info *info)
2241 {
2242         struct nlattr *dev_list;
2243         struct sk_buff *reply;
2244         void *reply_head;
2245         size_t msg_size;
2246         int index = -1;
2247         int ret = -ENOMEM;
2248
2249         if (info->attrs[NBD_ATTR_INDEX])
2250                 index = nla_get_u32(info->attrs[NBD_ATTR_INDEX]);
2251
2252         mutex_lock(&nbd_index_mutex);
2253
2254         msg_size = nla_total_size(nla_attr_size(sizeof(u32)) +
2255                                   nla_attr_size(sizeof(u8)));
2256         msg_size *= (index == -1) ? nbd_total_devices : 1;
2257
2258         reply = genlmsg_new(msg_size, GFP_KERNEL);
2259         if (!reply)
2260                 goto out;
2261         reply_head = genlmsg_put_reply(reply, info, &nbd_genl_family, 0,
2262                                        NBD_CMD_STATUS);
2263         if (!reply_head) {
2264                 nlmsg_free(reply);
2265                 goto out;
2266         }
2267
2268         dev_list = nla_nest_start_noflag(reply, NBD_ATTR_DEVICE_LIST);
2269         if (index == -1) {
2270                 ret = idr_for_each(&nbd_index_idr, &status_cb, reply);
2271                 if (ret) {
2272                         nlmsg_free(reply);
2273                         goto out;
2274                 }
2275         } else {
2276                 struct nbd_device *nbd;
2277                 nbd = idr_find(&nbd_index_idr, index);
2278                 if (nbd) {
2279                         ret = populate_nbd_status(nbd, reply);
2280                         if (ret) {
2281                                 nlmsg_free(reply);
2282                                 goto out;
2283                         }
2284                 }
2285         }
2286         nla_nest_end(reply, dev_list);
2287         genlmsg_end(reply, reply_head);
2288         ret = genlmsg_reply(reply, info);
2289 out:
2290         mutex_unlock(&nbd_index_mutex);
2291         return ret;
2292 }
2293
2294 static void nbd_connect_reply(struct genl_info *info, int index)
2295 {
2296         struct sk_buff *skb;
2297         void *msg_head;
2298         int ret;
2299
2300         skb = genlmsg_new(nla_total_size(sizeof(u32)), GFP_KERNEL);
2301         if (!skb)
2302                 return;
2303         msg_head = genlmsg_put_reply(skb, info, &nbd_genl_family, 0,
2304                                      NBD_CMD_CONNECT);
2305         if (!msg_head) {
2306                 nlmsg_free(skb);
2307                 return;
2308         }
2309         ret = nla_put_u32(skb, NBD_ATTR_INDEX, index);
2310         if (ret) {
2311                 nlmsg_free(skb);
2312                 return;
2313         }
2314         genlmsg_end(skb, msg_head);
2315         genlmsg_reply(skb, info);
2316 }
2317
2318 static void nbd_mcast_index(int index)
2319 {
2320         struct sk_buff *skb;
2321         void *msg_head;
2322         int ret;
2323
2324         skb = genlmsg_new(nla_total_size(sizeof(u32)), GFP_KERNEL);
2325         if (!skb)
2326                 return;
2327         msg_head = genlmsg_put(skb, 0, 0, &nbd_genl_family, 0,
2328                                      NBD_CMD_LINK_DEAD);
2329         if (!msg_head) {
2330                 nlmsg_free(skb);
2331                 return;
2332         }
2333         ret = nla_put_u32(skb, NBD_ATTR_INDEX, index);
2334         if (ret) {
2335                 nlmsg_free(skb);
2336                 return;
2337         }
2338         genlmsg_end(skb, msg_head);
2339         genlmsg_multicast(&nbd_genl_family, skb, 0, 0, GFP_KERNEL);
2340 }
2341
2342 static void nbd_dead_link_work(struct work_struct *work)
2343 {
2344         struct link_dead_args *args = container_of(work, struct link_dead_args,
2345                                                    work);
2346         nbd_mcast_index(args->index);
2347         kfree(args);
2348 }
2349
2350 static int __init nbd_init(void)
2351 {
2352         int i;
2353
2354         BUILD_BUG_ON(sizeof(struct nbd_request) != 28);
2355
2356         if (max_part < 0) {
2357                 printk(KERN_ERR "nbd: max_part must be >= 0\n");
2358                 return -EINVAL;
2359         }
2360
2361         part_shift = 0;
2362         if (max_part > 0) {
2363                 part_shift = fls(max_part);
2364
2365                 /*
2366                  * Adjust max_part according to part_shift as it is exported
2367                  * to user space so that user can know the max number of
2368                  * partition kernel should be able to manage.
2369                  *
2370                  * Note that -1 is required because partition 0 is reserved
2371                  * for the whole disk.
2372                  */
2373                 max_part = (1UL << part_shift) - 1;
2374         }
2375
2376         if ((1UL << part_shift) > DISK_MAX_PARTS)
2377                 return -EINVAL;
2378
2379         if (nbds_max > 1UL << (MINORBITS - part_shift))
2380                 return -EINVAL;
2381
2382         if (register_blkdev(NBD_MAJOR, "nbd"))
2383                 return -EIO;
2384
2385         if (genl_register_family(&nbd_genl_family)) {
2386                 unregister_blkdev(NBD_MAJOR, "nbd");
2387                 return -EINVAL;
2388         }
2389         nbd_dbg_init();
2390
2391         mutex_lock(&nbd_index_mutex);
2392         for (i = 0; i < nbds_max; i++)
2393                 nbd_dev_add(i);
2394         mutex_unlock(&nbd_index_mutex);
2395         return 0;
2396 }
2397
2398 static int nbd_exit_cb(int id, void *ptr, void *data)
2399 {
2400         struct list_head *list = (struct list_head *)data;
2401         struct nbd_device *nbd = ptr;
2402
2403         list_add_tail(&nbd->list, list);
2404         return 0;
2405 }
2406
2407 static void __exit nbd_cleanup(void)
2408 {
2409         struct nbd_device *nbd;
2410         LIST_HEAD(del_list);
2411
2412         nbd_dbg_close();
2413
2414         mutex_lock(&nbd_index_mutex);
2415         idr_for_each(&nbd_index_idr, &nbd_exit_cb, &del_list);
2416         mutex_unlock(&nbd_index_mutex);
2417
2418         while (!list_empty(&del_list)) {
2419                 nbd = list_first_entry(&del_list, struct nbd_device, list);
2420                 list_del_init(&nbd->list);
2421                 if (refcount_read(&nbd->refs) != 1)
2422                         printk(KERN_ERR "nbd: possibly leaking a device\n");
2423                 nbd_put(nbd);
2424         }
2425
2426         idr_destroy(&nbd_index_idr);
2427         genl_unregister_family(&nbd_genl_family);
2428         unregister_blkdev(NBD_MAJOR, "nbd");
2429 }
2430
2431 module_init(nbd_init);
2432 module_exit(nbd_cleanup);
2433
2434 MODULE_DESCRIPTION("Network Block Device");
2435 MODULE_LICENSE("GPL");
2436
2437 module_param(nbds_max, int, 0444);
2438 MODULE_PARM_DESC(nbds_max, "number of network block devices to initialize (default: 16)");
2439 module_param(max_part, int, 0444);
2440 MODULE_PARM_DESC(max_part, "number of partitions per device (default: 16)");