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