drivers/block/nbd.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Network block device - make block devices work over TCP
   4  *
   5  * Note that you can not swap over this thing, yet. Seems to work but
   6  * deadlocks sometimes - you can not swap over TCP in general.
   7  *
   8  * Copyright 1997-2000, 2008 Pavel Machek <pavel@ucw.cz>
   9  * Parts copyright 2001 Steven Whitehouse <steve@chygwyn.com>
  10  *
  11  * (part of code stolen from loop.c)
  12  */
  13
  14 #include <linux/major.h>
  15
  16 #include <linux/blkdev.h>
  17 #include <linux/module.h>
  18 #include <linux/init.h>
  19 #include <linux/sched.h>
  20 #include <linux/sched/mm.h>
  21 #include <linux/fs.h>
  22 #include <linux/bio.h>
  23 #include <linux/stat.h>
  24 #include <linux/errno.h>
  25 #include <linux/file.h>
  26 #include <linux/ioctl.h>
  27 #include <linux/mutex.h>
  28 #include <linux/compiler.h>
  29 #include <linux/completion.h>
  30 #include <linux/err.h>
  31 #include <linux/kernel.h>
  32 #include <linux/slab.h>
  33 #include <net/sock.h>
  34 #include <linux/net.h>
  35 #include <linux/kthread.h>
  36 #include <linux/types.h>
  37 #include <linux/debugfs.h>
  38 #include <linux/blk-mq.h>
  39
  40 #include <linux/uaccess.h>
  41 #include <asm/types.h>
  42
  43 #include <linux/nbd.h>
  44 #include <linux/nbd-netlink.h>
  45 #include <net/genetlink.h>
  46
  47 #define CREATE_TRACE_POINTS
  48 #include <trace/events/nbd.h>
  49
  50 static DEFINE_IDR(nbd_index_idr);
  51 static DEFINE_MUTEX(nbd_index_mutex);
  52 static int nbd_total_devices = 0;
  53
  54 struct nbd_sock {
  55         struct socket *sock;
  56         struct mutex tx_lock;
  57         struct request *pending;
  58         int sent;
  59         bool dead;
  60         int fallback_index;
  61         int cookie;
  62 };
  63
  64 struct recv_thread_args {
  65         struct work_struct work;
  66         struct nbd_device *nbd;
  67         int index;
  68 };
  69
  70 struct link_dead_args {
  71         struct work_struct work;
  72         int index;
  73 };
  74
  75 #define NBD_RT_TIMEDOUT                 0
  76 #define NBD_RT_DISCONNECT_REQUESTED     1
  77 #define NBD_RT_DISCONNECTED             2
  78 #define NBD_RT_HAS_PID_FILE             3
  79 #define NBD_RT_HAS_CONFIG_REF           4
  80 #define NBD_RT_BOUND                    5
  81 #define NBD_RT_DESTROY_ON_DISCONNECT    6
  82 #define NBD_RT_DISCONNECT_ON_CLOSE      7
  83
  84 #define NBD_DESTROY_ON_DISCONNECT       0
  85 #define NBD_DISCONNECT_REQUESTED        1
  86
  87 struct nbd_config {
  88         u32 flags;
  89         unsigned long runtime_flags;
  90         u64 dead_conn_timeout;
  91
  92         struct nbd_sock **socks;
  93         int num_connections;
  94         atomic_t live_connections;
  95         wait_queue_head_t conn_wait;
  96
  97         atomic_t recv_threads;
  98         wait_queue_head_t recv_wq;
  99         loff_t blksize;
 100         loff_t bytesize;
 101 #if IS_ENABLED(CONFIG_DEBUG_FS)
 102         struct dentry *dbg_dir;
 103 #endif
 104 };
 105
 106 struct nbd_device {
 107         struct blk_mq_tag_set tag_set;
 108
 109         int index;
 110         refcount_t config_refs;
 111         refcount_t refs;
 112         struct nbd_config *config;
 113         struct mutex config_lock;
 114         struct gendisk *disk;
 115         struct workqueue_struct *recv_workq;
 116
 117         struct list_head list;
 118         struct task_struct *task_recv;
 119         struct task_struct *task_setup;
 120
 121         struct completion *destroy_complete;
 122         unsigned long flags;
 123 };
 124
 125 #define NBD_CMD_REQUEUED        1
 126
 127 struct nbd_cmd {
 128         struct nbd_device *nbd;
 129         struct mutex lock;
 130         int index;
 131         int cookie;
 132         int retries;
 133         blk_status_t status;
 134         unsigned long flags;
 135         u32 cmd_cookie;
 136 };
 137
 138 #if IS_ENABLED(CONFIG_DEBUG_FS)
 139 static struct dentry *nbd_dbg_dir;
 140 #endif
 141
 142 #define nbd_name(nbd) ((nbd)->disk->disk_name)
 143
 144 #define NBD_MAGIC 0x68797548
 145
 146 #define NBD_DEF_BLKSIZE 1024
 147
 148 static unsigned int nbds_max = 16;
 149 static int max_part = 16;
 150 static int part_shift;
 151
 152 static int nbd_dev_dbg_init(struct nbd_device *nbd);
 153 static void nbd_dev_dbg_close(struct nbd_device *nbd);
 154 static void nbd_config_put(struct nbd_device *nbd);
 155 static void nbd_connect_reply(struct genl_info *info, int index);
 156 static int nbd_genl_status(struct sk_buff *skb, struct genl_info *info);
 157 static void nbd_dead_link_work(struct work_struct *work);
 158 static void nbd_disconnect_and_put(struct nbd_device *nbd);
 159
 160 static inline struct device *nbd_to_dev(struct nbd_device *nbd)
 161 {
 162         return disk_to_dev(nbd->disk);
 163 }
 164
 165 static void nbd_requeue_cmd(struct nbd_cmd *cmd)
 166 {
 167         struct request *req = blk_mq_rq_from_pdu(cmd);
 168
 169         if (!test_and_set_bit(NBD_CMD_REQUEUED, &cmd->flags))
 170                 blk_mq_requeue_request(req, true);
 171 }
 172
 173 #define NBD_COOKIE_BITS 32
 174
 175 static u64 nbd_cmd_handle(struct nbd_cmd *cmd)
 176 {
 177         struct request *req = blk_mq_rq_from_pdu(cmd);
 178         u32 tag = blk_mq_unique_tag(req);
 179         u64 cookie = cmd->cmd_cookie;
 180
 181         return (cookie << NBD_COOKIE_BITS) | tag;
 182 }
 183
 184 static u32 nbd_handle_to_tag(u64 handle)
 185 {
 186         return (u32)handle;
 187 }
 188
 189 static u32 nbd_handle_to_cookie(u64 handle)
 190 {
 191         return (u32)(handle >> NBD_COOKIE_BITS);
 192 }
 193
 194 static const char *nbdcmd_to_ascii(int cmd)
 195 {
 196         switch (cmd) {
 197         case  NBD_CMD_READ: return "read";
 198         case NBD_CMD_WRITE: return "write";
 199         case  NBD_CMD_DISC: return "disconnect";
 200         case NBD_CMD_FLUSH: return "flush";
 201         case  NBD_CMD_TRIM: return "trim/discard";
 202         }
 203         return "invalid";
 204 }
 205
 206 static ssize_t pid_show(struct device *dev,
 207                         struct device_attribute *attr, char *buf)
 208 {
 209         struct gendisk *disk = dev_to_disk(dev);
 210         struct nbd_device *nbd = (struct nbd_device *)disk->private_data;
 211
 212         return sprintf(buf, "%d\n", task_pid_nr(nbd->task_recv));
 213 }
 214
 215 static const struct device_attribute pid_attr = {
 216         .attr = { .name = "pid", .mode = 0444},
 217         .show = pid_show,
 218 };
 219
 220 static void nbd_dev_remove(struct nbd_device *nbd)
 221 {
 222         struct gendisk *disk = nbd->disk;
 223         struct request_queue *q;
 224
 225         if (disk) {
 226                 q = disk->queue;
 227                 del_gendisk(disk);
 228                 blk_cleanup_queue(q);
 229                 blk_mq_free_tag_set(&nbd->tag_set);
 230                 disk->private_data = NULL;
 231                 put_disk(disk);
 232         }
 233
 234         /*
 235          * Place this in the last just before the nbd is freed to
 236          * make sure that the disk and the related kobject are also
 237          * totally removed to avoid duplicate creation of the same
 238          * one.
 239          */
 240         if (test_bit(NBD_DESTROY_ON_DISCONNECT, &nbd->flags) && nbd->destroy_complete)
 241                 complete(nbd->destroy_complete);
 242
 243         kfree(nbd);
 244 }
 245
 246 static void nbd_put(struct nbd_device *nbd)
 247 {
 248         if (refcount_dec_and_mutex_lock(&nbd->refs,
 249                                         &nbd_index_mutex)) {
 250                 idr_remove(&nbd_index_idr, nbd->index);
 251                 nbd_dev_remove(nbd);
 252                 mutex_unlock(&nbd_index_mutex);
 253         }
 254 }
 255
 256 static int nbd_disconnected(struct nbd_config *config)
 257 {
 258         return test_bit(NBD_RT_DISCONNECTED, &config->runtime_flags) ||
 259                 test_bit(NBD_RT_DISCONNECT_REQUESTED, &config->runtime_flags);
 260 }
 261
 262 static void nbd_mark_nsock_dead(struct nbd_device *nbd, struct nbd_sock *nsock,
 263                                 int notify)
 264 {
 265         if (!nsock->dead && notify && !nbd_disconnected(nbd->config)) {
 266                 struct link_dead_args *args;
 267                 args = kmalloc(sizeof(struct link_dead_args), GFP_NOIO);
 268                 if (args) {
 269                         INIT_WORK(&args->work, nbd_dead_link_work);
 270                         args->index = nbd->index;
 271                         queue_work(system_wq, &args->work);
 272                 }
 273         }
 274         if (!nsock->dead) {
 275                 kernel_sock_shutdown(nsock->sock, SHUT_RDWR);
 276                 if (atomic_dec_return(&nbd->config->live_connections) == 0) {
 277                         if (test_and_clear_bit(NBD_RT_DISCONNECT_REQUESTED,
 278                                                &nbd->config->runtime_flags)) {
 279                                 set_bit(NBD_RT_DISCONNECTED,
 280                                         &nbd->config->runtime_flags);
 281                                 dev_info(nbd_to_dev(nbd),
 282                                         "Disconnected due to user request.\n");
 283                         }
 284                 }
 285         }
 286         nsock->dead = true;
 287         nsock->pending = NULL;
 288         nsock->sent = 0;
 289 }
 290
 291 static void nbd_size_clear(struct nbd_device *nbd)
 292 {
 293         if (nbd->config->bytesize) {
 294                 set_capacity(nbd->disk, 0);
 295                 kobject_uevent(&nbd_to_dev(nbd)->kobj, KOBJ_CHANGE);
 296         }
 297 }
 298
 299 static void nbd_size_update(struct nbd_device *nbd)
 300 {
 301         struct nbd_config *config = nbd->config;
 302         struct block_device *bdev = bdget_disk(nbd->disk, 0);
 303
 304         if (config->flags & NBD_FLAG_SEND_TRIM) {
 305                 nbd->disk->queue->limits.discard_granularity = config->blksize;
 306                 nbd->disk->queue->limits.discard_alignment = config->blksize;
 307                 blk_queue_max_discard_sectors(nbd->disk->queue, UINT_MAX);
 308         }
 309         blk_queue_logical_block_size(nbd->disk->queue, config->blksize);
 310         blk_queue_physical_block_size(nbd->disk->queue, config->blksize);
 311         set_capacity(nbd->disk, config->bytesize >> 9);
 312         if (bdev) {
 313                 if (bdev->bd_disk) {
 314                         bd_set_size(bdev, config->bytesize);
 315                         set_blocksize(bdev, config->blksize);
 316                 } else
 317                         bdev->bd_invalidated = 1;
 318                 bdput(bdev);
 319         }
 320         kobject_uevent(&nbd_to_dev(nbd)->kobj, KOBJ_CHANGE);
 321 }
 322
 323 static void nbd_size_set(struct nbd_device *nbd, loff_t blocksize,
 324                          loff_t nr_blocks)
 325 {
 326         struct nbd_config *config = nbd->config;
 327         config->blksize = blocksize;
 328         config->bytesize = blocksize * nr_blocks;
 329         if (nbd->task_recv != NULL)
 330                 nbd_size_update(nbd);
 331 }
 332
 333 static void nbd_complete_rq(struct request *req)
 334 {
 335         struct nbd_cmd *cmd = blk_mq_rq_to_pdu(req);
 336
 337         dev_dbg(nbd_to_dev(cmd->nbd), "request %p: %s\n", req,
 338                 cmd->status ? "failed" : "done");
 339
 340         blk_mq_end_request(req, cmd->status);
 341 }
 342
 343 /*
 344  * Forcibly shutdown the socket causing all listeners to error
 345  */
 346 static void sock_shutdown(struct nbd_device *nbd)
 347 {
 348         struct nbd_config *config = nbd->config;
 349         int i;
 350
 351         if (config->num_connections == 0)
 352                 return;
 353         if (test_and_set_bit(NBD_RT_DISCONNECTED, &config->runtime_flags))
 354                 return;
 355
 356         for (i = 0; i < config->num_connections; i++) {
 357                 struct nbd_sock *nsock = config->socks[i];
 358                 mutex_lock(&nsock->tx_lock);
 359                 nbd_mark_nsock_dead(nbd, nsock, 0);
 360                 mutex_unlock(&nsock->tx_lock);
 361         }
 362         dev_warn(disk_to_dev(nbd->disk), "shutting down sockets\n");
 363 }
 364
 365 static u32 req_to_nbd_cmd_type(struct request *req)
 366 {
 367         switch (req_op(req)) {
 368         case REQ_OP_DISCARD:
 369                 return NBD_CMD_TRIM;
 370         case REQ_OP_FLUSH:
 371                 return NBD_CMD_FLUSH;
 372         case REQ_OP_WRITE:
 373                 return NBD_CMD_WRITE;
 374         case REQ_OP_READ:
 375                 return NBD_CMD_READ;
 376         default:
 377                 return U32_MAX;
 378         }
 379 }
 380
 381 static enum blk_eh_timer_return nbd_xmit_timeout(struct request *req,
 382                                                  bool reserved)
 383 {
 384         struct nbd_cmd *cmd = blk_mq_rq_to_pdu(req);
 385         struct nbd_device *nbd = cmd->nbd;
 386         struct nbd_config *config;
 387
 388         if (!mutex_trylock(&cmd->lock))
 389                 return BLK_EH_RESET_TIMER;
 390
 391         if (!refcount_inc_not_zero(&nbd->config_refs)) {
 392                 cmd->status = BLK_STS_TIMEOUT;
 393                 mutex_unlock(&cmd->lock);
 394                 goto done;
 395         }
 396         config = nbd->config;
 397
 398         if (config->num_connections > 1) {
 399                 dev_err_ratelimited(nbd_to_dev(nbd),
 400                                     "Connection timed out, retrying (%d/%d alive)\n",
 401                                     atomic_read(&config->live_connections),
 402                                     config->num_connections);
 403                 /*
 404                  * Hooray we have more connections, requeue this IO, the submit
 405                  * path will put it on a real connection.
 406                  */
 407                 if (config->socks && config->num_connections > 1) {
 408                         if (cmd->index < config->num_connections) {
 409                                 struct nbd_sock *nsock =
 410                                         config->socks[cmd->index];
 411                                 mutex_lock(&nsock->tx_lock);
 412                                 /* We can have multiple outstanding requests, so
 413                                  * we don't want to mark the nsock dead if we've
 414                                  * already reconnected with a new socket, so
 415                                  * only mark it dead if its the same socket we
 416                                  * were sent out on.
 417                                  */
 418                                 if (cmd->cookie == nsock->cookie)
 419                                         nbd_mark_nsock_dead(nbd, nsock, 1);
 420                                 mutex_unlock(&nsock->tx_lock);
 421                         }
 422                         mutex_unlock(&cmd->lock);
 423                         nbd_requeue_cmd(cmd);
 424                         nbd_config_put(nbd);
 425                         return BLK_EH_DONE;
 426                 }
 427         }
 428
 429         if (!nbd->tag_set.timeout) {
 430                 /*
 431                  * Userspace sets timeout=0 to disable socket disconnection,
 432                  * so just warn and reset the timer.
 433                  */
 434                 cmd->retries++;
 435                 dev_info(nbd_to_dev(nbd), "Possible stuck request %p: control (%s@%llu,%uB). Runtime %u seconds\n",
 436                         req, nbdcmd_to_ascii(req_to_nbd_cmd_type(req)),
 437                         (unsigned long long)blk_rq_pos(req) << 9,
 438                         blk_rq_bytes(req), (req->timeout / HZ) * cmd->retries);
 439
 440                 mutex_unlock(&cmd->lock);
 441                 nbd_config_put(nbd);
 442                 return BLK_EH_RESET_TIMER;
 443         }
 444
 445         dev_err_ratelimited(nbd_to_dev(nbd), "Connection timed out\n");
 446         set_bit(NBD_RT_TIMEDOUT, &config->runtime_flags);
 447         cmd->status = BLK_STS_IOERR;
 448         mutex_unlock(&cmd->lock);
 449         sock_shutdown(nbd);
 450         nbd_config_put(nbd);
 451 done:
 452         blk_mq_complete_request(req);
 453         return BLK_EH_DONE;
 454 }
 455
 456 /*
 457  *  Send or receive packet.
 458  */
 459 static int sock_xmit(struct nbd_device *nbd, int index, int send,
 460                      struct iov_iter *iter, int msg_flags, int *sent)
 461 {
 462         struct nbd_config *config = nbd->config;
 463         struct socket *sock = config->socks[index]->sock;
 464         int result;
 465         struct msghdr msg;
 466         unsigned int noreclaim_flag;
 467
 468         if (unlikely(!sock)) {
 469                 dev_err_ratelimited(disk_to_dev(nbd->disk),
 470                         "Attempted %s on closed socket in sock_xmit\n",
 471                         (send ? "send" : "recv"));
 472                 return -EINVAL;
 473         }
 474
 475         msg.msg_iter = *iter;
 476
 477         noreclaim_flag = memalloc_noreclaim_save();
 478         do {
 479                 sock->sk->sk_allocation = GFP_NOIO | __GFP_MEMALLOC;
 480                 msg.msg_name = NULL;
 481                 msg.msg_namelen = 0;
 482                 msg.msg_control = NULL;
 483                 msg.msg_controllen = 0;
 484                 msg.msg_flags = msg_flags | MSG_NOSIGNAL;
 485
 486                 if (send)
 487                         result = sock_sendmsg(sock, &msg);
 488                 else
 489                         result = sock_recvmsg(sock, &msg, msg.msg_flags);
 490
 491                 if (result <= 0) {
 492                         if (result == 0)
 493                                 result = -EPIPE; /* short read */
 494                         break;
 495                 }
 496                 if (sent)
 497                         *sent += result;
 498         } while (msg_data_left(&msg));
 499
 500         memalloc_noreclaim_restore(noreclaim_flag);
 501
 502         return result;
 503 }
 504
 505 /*
 506  * Different settings for sk->sk_sndtimeo can result in different return values
 507  * if there is a signal pending when we enter sendmsg, because reasons?
 508  */
 509 static inline int was_interrupted(int result)
 510 {
 511         return result == -ERESTARTSYS || result == -EINTR;
 512 }
 513
 514 /* always call with the tx_lock held */
 515 static int nbd_send_cmd(struct nbd_device *nbd, struct nbd_cmd *cmd, int index)
 516 {
 517         struct request *req = blk_mq_rq_from_pdu(cmd);
 518         struct nbd_config *config = nbd->config;
 519         struct nbd_sock *nsock = config->socks[index];
 520         int result;
 521         struct nbd_request request = {.magic = htonl(NBD_REQUEST_MAGIC)};
 522         struct kvec iov = {.iov_base = &request, .iov_len = sizeof(request)};
 523         struct iov_iter from;
 524         unsigned long size = blk_rq_bytes(req);
 525         struct bio *bio;
 526         u64 handle;
 527         u32 type;
 528         u32 nbd_cmd_flags = 0;
 529         int sent = nsock->sent, skip = 0;
 530
 531         iov_iter_kvec(&from, WRITE, &iov, 1, sizeof(request));
 532
 533         type = req_to_nbd_cmd_type(req);
 534         if (type == U32_MAX)
 535                 return -EIO;
 536
 537         if (rq_data_dir(req) == WRITE &&
 538             (config->flags & NBD_FLAG_READ_ONLY)) {
 539                 dev_err_ratelimited(disk_to_dev(nbd->disk),
 540                                     "Write on read-only\n");
 541                 return -EIO;
 542         }
 543
 544         if (req->cmd_flags & REQ_FUA)
 545                 nbd_cmd_flags |= NBD_CMD_FLAG_FUA;
 546
 547         /* We did a partial send previously, and we at least sent the whole
 548          * request struct, so just go and send the rest of the pages in the
 549          * request.
 550          */
 551         if (sent) {
 552                 if (sent >= sizeof(request)) {
 553                         skip = sent - sizeof(request);
 554
 555                         /* initialize handle for tracing purposes */
 556                         handle = nbd_cmd_handle(cmd);
 557
 558                         goto send_pages;
 559                 }
 560                 iov_iter_advance(&from, sent);
 561         } else {
 562                 cmd->cmd_cookie++;
 563         }
 564         cmd->index = index;
 565         cmd->cookie = nsock->cookie;
 566         cmd->retries = 0;
 567         request.type = htonl(type | nbd_cmd_flags);
 568         if (type != NBD_CMD_FLUSH) {
 569                 request.from = cpu_to_be64((u64)blk_rq_pos(req) << 9);
 570                 request.len = htonl(size);
 571         }
 572         handle = nbd_cmd_handle(cmd);
 573         memcpy(request.handle, &handle, sizeof(handle));
 574
 575         trace_nbd_send_request(&request, nbd->index, blk_mq_rq_from_pdu(cmd));
 576
 577         dev_dbg(nbd_to_dev(nbd), "request %p: sending control (%s@%llu,%uB)\n",
 578                 req, nbdcmd_to_ascii(type),
 579                 (unsigned long long)blk_rq_pos(req) << 9, blk_rq_bytes(req));
 580         result = sock_xmit(nbd, index, 1, &from,
 581                         (type == NBD_CMD_WRITE) ? MSG_MORE : 0, &sent);
 582         trace_nbd_header_sent(req, handle);
 583         if (result <= 0) {
 584                 if (was_interrupted(result)) {
 585                         /* If we havne't sent anything we can just return BUSY,
 586                          * however if we have sent something we need to make
 587                          * sure we only allow this req to be sent until we are
 588                          * completely done.
 589                          */
 590                         if (sent) {
 591                                 nsock->pending = req;
 592                                 nsock->sent = sent;
 593                         }
 594                         set_bit(NBD_CMD_REQUEUED, &cmd->flags);
 595                         return BLK_STS_RESOURCE;
 596                 }
 597                 dev_err_ratelimited(disk_to_dev(nbd->disk),
 598                         "Send control failed (result %d)\n", result);
 599                 return -EAGAIN;
 600         }
 601 send_pages:
 602         if (type != NBD_CMD_WRITE)
 603                 goto out;
 604
 605         bio = req->bio;
 606         while (bio) {
 607                 struct bio *next = bio->bi_next;
 608                 struct bvec_iter iter;
 609                 struct bio_vec bvec;
 610
 611                 bio_for_each_segment(bvec, bio, iter) {
 612                         bool is_last = !next && bio_iter_last(bvec, iter);
 613                         int flags = is_last ? 0 : MSG_MORE;
 614
 615                         dev_dbg(nbd_to_dev(nbd), "request %p: sending %d bytes data\n",
 616                                 req, bvec.bv_len);
 617                         iov_iter_bvec(&from, WRITE, &bvec, 1, bvec.bv_len);
 618                         if (skip) {
 619                                 if (skip >= iov_iter_count(&from)) {
 620                                         skip -= iov_iter_count(&from);
 621                                         continue;
 622                                 }
 623                                 iov_iter_advance(&from, skip);
 624                                 skip = 0;
 625                         }
 626                         result = sock_xmit(nbd, index, 1, &from, flags, &sent);
 627                         if (result <= 0) {
 628                                 if (was_interrupted(result)) {
 629                                         /* We've already sent the header, we
 630                                          * have no choice but to set pending and
 631                                          * return BUSY.
 632                                          */
 633                                         nsock->pending = req;
 634                                         nsock->sent = sent;
 635                                         set_bit(NBD_CMD_REQUEUED, &cmd->flags);
 636                                         return BLK_STS_RESOURCE;
 637                                 }
 638                                 dev_err(disk_to_dev(nbd->disk),
 639                                         "Send data failed (result %d)\n",
 640                                         result);
 641                                 return -EAGAIN;
 642                         }
 643                         /*
 644                          * The completion might already have come in,
 645                          * so break for the last one instead of letting
 646                          * the iterator do it. This prevents use-after-free
 647                          * of the bio.
 648                          */
 649                         if (is_last)
 650                                 break;
 651                 }
 652                 bio = next;
 653         }
 654 out:
 655         trace_nbd_payload_sent(req, handle);
 656         nsock->pending = NULL;
 657         nsock->sent = 0;
 658         return 0;
 659 }
 660
 661 /* NULL returned = something went wrong, inform userspace */
 662 static struct nbd_cmd *nbd_read_stat(struct nbd_device *nbd, int index)
 663 {
 664         struct nbd_config *config = nbd->config;
 665         int result;
 666         struct nbd_reply reply;
 667         struct nbd_cmd *cmd;
 668         struct request *req = NULL;
 669         u64 handle;
 670         u16 hwq;
 671         u32 tag;
 672         struct kvec iov = {.iov_base = &reply, .iov_len = sizeof(reply)};
 673         struct iov_iter to;
 674         int ret = 0;
 675
 676         reply.magic = 0;
 677         iov_iter_kvec(&to, READ, &iov, 1, sizeof(reply));
 678         result = sock_xmit(nbd, index, 0, &to, MSG_WAITALL, NULL);
 679         if (result <= 0) {
 680                 if (!nbd_disconnected(config))
 681                         dev_err(disk_to_dev(nbd->disk),
 682                                 "Receive control failed (result %d)\n", result);
 683                 return ERR_PTR(result);
 684         }
 685
 686         if (ntohl(reply.magic) != NBD_REPLY_MAGIC) {
 687                 dev_err(disk_to_dev(nbd->disk), "Wrong magic (0x%lx)\n",
 688                                 (unsigned long)ntohl(reply.magic));
 689                 return ERR_PTR(-EPROTO);
 690         }
 691
 692         memcpy(&handle, reply.handle, sizeof(handle));
 693         tag = nbd_handle_to_tag(handle);
 694         hwq = blk_mq_unique_tag_to_hwq(tag);
 695         if (hwq < nbd->tag_set.nr_hw_queues)
 696                 req = blk_mq_tag_to_rq(nbd->tag_set.tags[hwq],
 697                                        blk_mq_unique_tag_to_tag(tag));
 698         if (!req || !blk_mq_request_started(req)) {
 699                 dev_err(disk_to_dev(nbd->disk), "Unexpected reply (%d) %p\n",
 700                         tag, req);
 701                 return ERR_PTR(-ENOENT);
 702         }
 703         trace_nbd_header_received(req, handle);
 704         cmd = blk_mq_rq_to_pdu(req);
 705
 706         mutex_lock(&cmd->lock);
 707         if (cmd->cmd_cookie != nbd_handle_to_cookie(handle)) {
 708                 dev_err(disk_to_dev(nbd->disk), "Double reply on req %p, cmd_cookie %u, handle cookie %u\n",
 709                         req, cmd->cmd_cookie, nbd_handle_to_cookie(handle));
 710                 ret = -ENOENT;
 711                 goto out;
 712         }
 713         if (cmd->status != BLK_STS_OK) {
 714                 dev_err(disk_to_dev(nbd->disk), "Command already handled %p\n",
 715                         req);
 716                 ret = -ENOENT;
 717                 goto out;
 718         }
 719         if (test_bit(NBD_CMD_REQUEUED, &cmd->flags)) {
 720                 dev_err(disk_to_dev(nbd->disk), "Raced with timeout on req %p\n",
 721                         req);
 722                 ret = -ENOENT;
 723                 goto out;
 724         }
 725         if (ntohl(reply.error)) {
 726                 dev_err(disk_to_dev(nbd->disk), "Other side returned error (%d)\n",
 727                         ntohl(reply.error));
 728                 cmd->status = BLK_STS_IOERR;
 729                 goto out;
 730         }
 731
 732         dev_dbg(nbd_to_dev(nbd), "request %p: got reply\n", req);
 733         if (rq_data_dir(req) != WRITE) {
 734                 struct req_iterator iter;
 735                 struct bio_vec bvec;
 736
 737                 rq_for_each_segment(bvec, req, iter) {
 738                         iov_iter_bvec(&to, READ, &bvec, 1, bvec.bv_len);
 739                         result = sock_xmit(nbd, index, 0, &to, MSG_WAITALL, NULL);
 740                         if (result <= 0) {
 741                                 dev_err(disk_to_dev(nbd->disk), "Receive data failed (result %d)\n",
 742                                         result);
 743                                 /*
 744                                  * If we've disconnected or we only have 1
 745                                  * connection then we need to make sure we
 746                                  * complete this request, otherwise error out
 747                                  * and let the timeout stuff handle resubmitting
 748                                  * this request onto another connection.
 749                                  */
 750                                 if (nbd_disconnected(config) ||
 751                                     config->num_connections <= 1) {
 752                                         cmd->status = BLK_STS_IOERR;
 753                                         goto out;
 754                                 }
 755                                 ret = -EIO;
 756                                 goto out;
 757                         }
 758                         dev_dbg(nbd_to_dev(nbd), "request %p: got %d bytes data\n",
 759                                 req, bvec.bv_len);
 760                 }
 761         }
 762 out:
 763         trace_nbd_payload_received(req, handle);
 764         mutex_unlock(&cmd->lock);
 765         return ret ? ERR_PTR(ret) : cmd;
 766 }
 767
 768 static void recv_work(struct work_struct *work)
 769 {
 770         struct recv_thread_args *args = container_of(work,
 771                                                      struct recv_thread_args,
 772                                                      work);
 773         struct nbd_device *nbd = args->nbd;
 774         struct nbd_config *config = nbd->config;
 775         struct nbd_cmd *cmd;
 776
 777         while (1) {
 778                 cmd = nbd_read_stat(nbd, args->index);
 779                 if (IS_ERR(cmd)) {
 780                         struct nbd_sock *nsock = config->socks[args->index];
 781
 782                         mutex_lock(&nsock->tx_lock);
 783                         nbd_mark_nsock_dead(nbd, nsock, 1);
 784                         mutex_unlock(&nsock->tx_lock);
 785                         break;
 786                 }
 787
 788                 blk_mq_complete_request(blk_mq_rq_from_pdu(cmd));
 789         }
 790         atomic_dec(&config->recv_threads);
 791         wake_up(&config->recv_wq);
 792         nbd_config_put(nbd);
 793         kfree(args);
 794 }
 795
 796 static bool nbd_clear_req(struct request *req, void *data, bool reserved)
 797 {
 798         struct nbd_cmd *cmd = blk_mq_rq_to_pdu(req);
 799
 800         mutex_lock(&cmd->lock);
 801         cmd->status = BLK_STS_IOERR;
 802         mutex_unlock(&cmd->lock);
 803
 804         blk_mq_complete_request(req);
 805         return true;
 806 }
 807
 808 static void nbd_clear_que(struct nbd_device *nbd)
 809 {
 810         blk_mq_quiesce_queue(nbd->disk->queue);
 811         blk_mq_tagset_busy_iter(&nbd->tag_set, nbd_clear_req, NULL);
 812         blk_mq_unquiesce_queue(nbd->disk->queue);
 813         dev_dbg(disk_to_dev(nbd->disk), "queue cleared\n");
 814 }
 815
 816 static int find_fallback(struct nbd_device *nbd, int index)
 817 {
 818         struct nbd_config *config = nbd->config;
 819         int new_index = -1;
 820         struct nbd_sock *nsock = config->socks[index];
 821         int fallback = nsock->fallback_index;
 822
 823         if (test_bit(NBD_RT_DISCONNECTED, &config->runtime_flags))
 824                 return new_index;
 825
 826         if (config->num_connections <= 1) {
 827                 dev_err_ratelimited(disk_to_dev(nbd->disk),
 828                                     "Attempted send on invalid socket\n");
 829                 return new_index;
 830         }
 831
 832         if (fallback >= 0 && fallback < config->num_connections &&
 833             !config->socks[fallback]->dead)
 834                 return fallback;
 835
 836         if (nsock->fallback_index < 0 ||
 837             nsock->fallback_index >= config->num_connections ||
 838             config->socks[nsock->fallback_index]->dead) {
 839                 int i;
 840                 for (i = 0; i < config->num_connections; i++) {
 841                         if (i == index)
 842                                 continue;
 843                         if (!config->socks[i]->dead) {
 844                                 new_index = i;
 845                                 break;
 846                         }
 847                 }
 848                 nsock->fallback_index = new_index;
 849                 if (new_index < 0) {
 850                         dev_err_ratelimited(disk_to_dev(nbd->disk),
 851                                             "Dead connection, failed to find a fallback\n");
 852                         return new_index;
 853                 }
 854         }
 855         new_index = nsock->fallback_index;
 856         return new_index;
 857 }
 858
 859 static int wait_for_reconnect(struct nbd_device *nbd)
 860 {
 861         struct nbd_config *config = nbd->config;
 862         if (!config->dead_conn_timeout)
 863                 return 0;
 864         if (test_bit(NBD_RT_DISCONNECTED, &config->runtime_flags))
 865                 return 0;
 866         return wait_event_timeout(config->conn_wait,
 867                                   atomic_read(&config->live_connections) > 0,
 868                                   config->dead_conn_timeout) > 0;
 869 }
 870
 871 static int nbd_handle_cmd(struct nbd_cmd *cmd, int index)
 872 {
 873         struct request *req = blk_mq_rq_from_pdu(cmd);
 874         struct nbd_device *nbd = cmd->nbd;
 875         struct nbd_config *config;
 876         struct nbd_sock *nsock;
 877         int ret;
 878
 879         if (!refcount_inc_not_zero(&nbd->config_refs)) {
 880                 dev_err_ratelimited(disk_to_dev(nbd->disk),
 881                                     "Socks array is empty\n");
 882                 blk_mq_start_request(req);
 883                 return -EINVAL;
 884         }
 885         config = nbd->config;
 886
 887         if (index >= config->num_connections) {
 888                 dev_err_ratelimited(disk_to_dev(nbd->disk),
 889                                     "Attempted send on invalid socket\n");
 890                 nbd_config_put(nbd);
 891                 blk_mq_start_request(req);
 892                 return -EINVAL;
 893         }
 894         cmd->status = BLK_STS_OK;
 895 again:
 896         nsock = config->socks[index];
 897         mutex_lock(&nsock->tx_lock);
 898         if (nsock->dead) {
 899                 int old_index = index;
 900                 index = find_fallback(nbd, index);
 901                 mutex_unlock(&nsock->tx_lock);
 902                 if (index < 0) {
 903                         if (wait_for_reconnect(nbd)) {
 904                                 index = old_index;
 905                                 goto again;
 906                         }
 907                         /* All the sockets should already be down at this point,
 908                          * we just want to make sure that DISCONNECTED is set so
 909                          * any requests that come in that were queue'ed waiting
 910                          * for the reconnect timer don't trigger the timer again
 911                          * and instead just error out.
 912                          */
 913                         sock_shutdown(nbd);
 914                         nbd_config_put(nbd);
 915                         blk_mq_start_request(req);
 916                         return -EIO;
 917                 }
 918                 goto again;
 919         }
 920
 921         /* Handle the case that we have a pending request that was partially
 922          * transmitted that _has_ to be serviced first.  We need to call requeue
 923          * here so that it gets put _after_ the request that is already on the
 924          * dispatch list.
 925          */
 926         blk_mq_start_request(req);
 927         if (unlikely(nsock->pending && nsock->pending != req)) {
 928                 nbd_requeue_cmd(cmd);
 929                 ret = 0;
 930                 goto out;
 931         }
 932         /*
 933          * Some failures are related to the link going down, so anything that
 934          * returns EAGAIN can be retried on a different socket.
 935          */
 936         ret = nbd_send_cmd(nbd, cmd, index);
 937         if (ret == -EAGAIN) {
 938                 dev_err_ratelimited(disk_to_dev(nbd->disk),
 939                                     "Request send failed, requeueing\n");
 940                 nbd_mark_nsock_dead(nbd, nsock, 1);
 941                 nbd_requeue_cmd(cmd);
 942                 ret = 0;
 943         }
 944 out:
 945         mutex_unlock(&nsock->tx_lock);
 946         nbd_config_put(nbd);
 947         return ret;
 948 }
 949
 950 static blk_status_t nbd_queue_rq(struct blk_mq_hw_ctx *hctx,
 951                         const struct blk_mq_queue_data *bd)
 952 {
 953         struct nbd_cmd *cmd = blk_mq_rq_to_pdu(bd->rq);
 954         int ret;
 955
 956         /*
 957          * Since we look at the bio's to send the request over the network we
 958          * need to make sure the completion work doesn't mark this request done
 959          * before we are done doing our send.  This keeps us from dereferencing
 960          * freed data if we have particularly fast completions (ie we get the
 961          * completion before we exit sock_xmit on the last bvec) or in the case
 962          * that the server is misbehaving (or there was an error) before we're
 963          * done sending everything over the wire.
 964          */
 965         mutex_lock(&cmd->lock);
 966         clear_bit(NBD_CMD_REQUEUED, &cmd->flags);
 967
 968         /* We can be called directly from the user space process, which means we
 969          * could possibly have signals pending so our sendmsg will fail.  In
 970          * this case we need to return that we are busy, otherwise error out as
 971          * appropriate.
 972          */
 973         ret = nbd_handle_cmd(cmd, hctx->queue_num);
 974         if (ret < 0)
 975                 ret = BLK_STS_IOERR;
 976         else if (!ret)
 977                 ret = BLK_STS_OK;
 978         mutex_unlock(&cmd->lock);
 979
 980         return ret;
 981 }
 982
 983 static struct socket *nbd_get_socket(struct nbd_device *nbd, unsigned long fd,
 984                                      int *err)
 985 {
 986         struct socket *sock;
 987
 988         *err = 0;
 989         sock = sockfd_lookup(fd, err);
 990         if (!sock)
 991                 return NULL;
 992
 993         if (sock->ops->shutdown == sock_no_shutdown) {
 994                 dev_err(disk_to_dev(nbd->disk), "Unsupported socket: shutdown callout must be supported.\n");
 995                 *err = -EINVAL;
 996                 return NULL;
 997         }
 998
 999         return sock;
1000 }
1001
1002 static int nbd_add_socket(struct nbd_device *nbd, unsigned long arg,
1003                           bool netlink)
1004 {
1005         struct nbd_config *config = nbd->config;
1006         struct socket *sock;
1007         struct nbd_sock **socks;
1008         struct nbd_sock *nsock;
1009         int err;
1010
1011         sock = nbd_get_socket(nbd, arg, &err);
1012         if (!sock)
1013                 return err;
1014
1015         if (!netlink && !nbd->task_setup &&
1016             !test_bit(NBD_RT_BOUND, &config->runtime_flags))
1017                 nbd->task_setup = current;
1018
1019         if (!netlink &&
1020             (nbd->task_setup != current ||
1021              test_bit(NBD_RT_BOUND, &config->runtime_flags))) {
1022                 dev_err(disk_to_dev(nbd->disk),
1023                         "Device being setup by another task");
1024                 sockfd_put(sock);
1025                 return -EBUSY;
1026         }
1027
1028         socks = krealloc(config->socks, (config->num_connections + 1) *
1029                          sizeof(struct nbd_sock *), GFP_KERNEL);
1030         if (!socks) {
1031                 sockfd_put(sock);
1032                 return -ENOMEM;
1033         }
1034         nsock = kzalloc(sizeof(struct nbd_sock), GFP_KERNEL);
1035         if (!nsock) {
1036                 sockfd_put(sock);
1037                 return -ENOMEM;
1038         }
1039
1040         config->socks = socks;
1041
1042         nsock->fallback_index = -1;
1043         nsock->dead = false;
1044         mutex_init(&nsock->tx_lock);
1045         nsock->sock = sock;
1046         nsock->pending = NULL;
1047         nsock->sent = 0;
1048         nsock->cookie = 0;
1049         socks[config->num_connections++] = nsock;
1050         atomic_inc(&config->live_connections);
1051
1052         return 0;
1053 }
1054
1055 static int nbd_reconnect_socket(struct nbd_device *nbd, unsigned long arg)
1056 {
1057         struct nbd_config *config = nbd->config;
1058         struct socket *sock, *old;
1059         struct recv_thread_args *args;
1060         int i;
1061         int err;
1062
1063         sock = nbd_get_socket(nbd, arg, &err);
1064         if (!sock)
1065                 return err;
1066
1067         args = kzalloc(sizeof(*args), GFP_KERNEL);
1068         if (!args) {
1069                 sockfd_put(sock);
1070                 return -ENOMEM;
1071         }
1072
1073         for (i = 0; i < config->num_connections; i++) {
1074                 struct nbd_sock *nsock = config->socks[i];
1075
1076                 if (!nsock->dead)
1077                         continue;
1078
1079                 mutex_lock(&nsock->tx_lock);
1080                 if (!nsock->dead) {
1081                         mutex_unlock(&nsock->tx_lock);
1082                         continue;
1083                 }
1084                 sk_set_memalloc(sock->sk);
1085                 if (nbd->tag_set.timeout)
1086                         sock->sk->sk_sndtimeo = nbd->tag_set.timeout;
1087                 atomic_inc(&config->recv_threads);
1088                 refcount_inc(&nbd->config_refs);
1089                 old = nsock->sock;
1090                 nsock->fallback_index = -1;
1091                 nsock->sock = sock;
1092                 nsock->dead = false;
1093                 INIT_WORK(&args->work, recv_work);
1094                 args->index = i;
1095                 args->nbd = nbd;
1096                 nsock->cookie++;
1097                 mutex_unlock(&nsock->tx_lock);
1098                 sockfd_put(old);
1099
1100                 clear_bit(NBD_RT_DISCONNECTED, &config->runtime_flags);
1101
1102                 /* We take the tx_mutex in an error path in the recv_work, so we
1103                  * need to queue_work outside of the tx_mutex.
1104                  */
1105                 queue_work(nbd->recv_workq, &args->work);
1106
1107                 atomic_inc(&config->live_connections);
1108                 wake_up(&config->conn_wait);
1109                 return 0;
1110         }
1111         sockfd_put(sock);
1112         kfree(args);
1113         return -ENOSPC;
1114 }
1115
1116 static void nbd_bdev_reset(struct block_device *bdev)
1117 {
1118         if (bdev->bd_openers > 1)
1119                 return;
1120         bd_set_size(bdev, 0);
1121 }
1122
1123 static void nbd_parse_flags(struct nbd_device *nbd)
1124 {
1125         struct nbd_config *config = nbd->config;
1126         if (config->flags & NBD_FLAG_READ_ONLY)
1127                 set_disk_ro(nbd->disk, true);
1128         else
1129                 set_disk_ro(nbd->disk, false);
1130         if (config->flags & NBD_FLAG_SEND_TRIM)
1131                 blk_queue_flag_set(QUEUE_FLAG_DISCARD, nbd->disk->queue);
1132         if (config->flags & NBD_FLAG_SEND_FLUSH) {
1133                 if (config->flags & NBD_FLAG_SEND_FUA)
1134                         blk_queue_write_cache(nbd->disk->queue, true, true);
1135                 else
1136                         blk_queue_write_cache(nbd->disk->queue, true, false);
1137         }
1138         else
1139                 blk_queue_write_cache(nbd->disk->queue, false, false);
1140 }
1141
1142 static void send_disconnects(struct nbd_device *nbd)
1143 {
1144         struct nbd_config *config = nbd->config;
1145         struct nbd_request request = {
1146                 .magic = htonl(NBD_REQUEST_MAGIC),
1147                 .type = htonl(NBD_CMD_DISC),
1148         };
1149         struct kvec iov = {.iov_base = &request, .iov_len = sizeof(request)};
1150         struct iov_iter from;
1151         int i, ret;
1152
1153         for (i = 0; i < config->num_connections; i++) {
1154                 struct nbd_sock *nsock = config->socks[i];
1155
1156                 iov_iter_kvec(&from, WRITE, &iov, 1, sizeof(request));
1157                 mutex_lock(&nsock->tx_lock);
1158                 ret = sock_xmit(nbd, i, 1, &from, 0, NULL);
1159                 if (ret <= 0)
1160                         dev_err(disk_to_dev(nbd->disk),
1161                                 "Send disconnect failed %d\n", ret);
1162                 mutex_unlock(&nsock->tx_lock);
1163         }
1164 }
1165
1166 static int nbd_disconnect(struct nbd_device *nbd)
1167 {
1168         struct nbd_config *config = nbd->config;
1169
1170         dev_info(disk_to_dev(nbd->disk), "NBD_DISCONNECT\n");
1171         set_bit(NBD_RT_DISCONNECT_REQUESTED, &config->runtime_flags);
1172         set_bit(NBD_DISCONNECT_REQUESTED, &nbd->flags);
1173         send_disconnects(nbd);
1174         return 0;
1175 }
1176
1177 static void nbd_clear_sock(struct nbd_device *nbd)
1178 {
1179         sock_shutdown(nbd);
1180         nbd_clear_que(nbd);
1181         nbd->task_setup = NULL;
1182 }
1183
1184 static void nbd_config_put(struct nbd_device *nbd)
1185 {
1186         if (refcount_dec_and_mutex_lock(&nbd->config_refs,
1187                                         &nbd->config_lock)) {
1188                 struct nbd_config *config = nbd->config;
1189                 nbd_dev_dbg_close(nbd);
1190                 nbd_size_clear(nbd);
1191                 if (test_and_clear_bit(NBD_RT_HAS_PID_FILE,
1192                                        &config->runtime_flags))
1193                         device_remove_file(disk_to_dev(nbd->disk), &pid_attr);
1194                 nbd->task_recv = NULL;
1195                 nbd_clear_sock(nbd);
1196                 if (config->num_connections) {
1197                         int i;
1198                         for (i = 0; i < config->num_connections; i++) {
1199                                 sockfd_put(config->socks[i]->sock);
1200                                 kfree(config->socks[i]);
1201                         }
1202                         kfree(config->socks);
1203                 }
1204                 kfree(nbd->config);
1205                 nbd->config = NULL;
1206
1207                 if (nbd->recv_workq)
1208                         destroy_workqueue(nbd->recv_workq);
1209                 nbd->recv_workq = NULL;
1210
1211                 nbd->tag_set.timeout = 0;
1212                 nbd->disk->queue->limits.discard_granularity = 0;
1213                 nbd->disk->queue->limits.discard_alignment = 0;
1214                 blk_queue_max_discard_sectors(nbd->disk->queue, UINT_MAX);
1215                 blk_queue_flag_clear(QUEUE_FLAG_DISCARD, nbd->disk->queue);
1216
1217                 mutex_unlock(&nbd->config_lock);
1218                 nbd_put(nbd);
1219                 module_put(THIS_MODULE);
1220         }
1221 }
1222
1223 static int nbd_start_device(struct nbd_device *nbd)
1224 {
1225         struct nbd_config *config = nbd->config;
1226         int num_connections = config->num_connections;
1227         int error = 0, i;
1228
1229         if (nbd->task_recv)
1230                 return -EBUSY;
1231         if (!config->socks)
1232                 return -EINVAL;
1233         if (num_connections > 1 &&
1234             !(config->flags & NBD_FLAG_CAN_MULTI_CONN)) {
1235                 dev_err(disk_to_dev(nbd->disk), "server does not support multiple connections per device.\n");
1236                 return -EINVAL;
1237         }
1238
1239         nbd->recv_workq = alloc_workqueue("knbd%d-recv",
1240                                           WQ_MEM_RECLAIM | WQ_HIGHPRI |
1241                                           WQ_UNBOUND, 0, nbd->index);
1242         if (!nbd->recv_workq) {
1243                 dev_err(disk_to_dev(nbd->disk), "Could not allocate knbd recv work queue.\n");
1244                 return -ENOMEM;
1245         }
1246
1247         blk_mq_update_nr_hw_queues(&nbd->tag_set, config->num_connections);
1248         nbd->task_recv = current;
1249
1250         nbd_parse_flags(nbd);
1251
1252         error = device_create_file(disk_to_dev(nbd->disk), &pid_attr);
1253         if (error) {
1254                 dev_err(disk_to_dev(nbd->disk), "device_create_file failed!\n");
1255                 return error;
1256         }
1257         set_bit(NBD_RT_HAS_PID_FILE, &config->runtime_flags);
1258
1259         nbd_dev_dbg_init(nbd);
1260         for (i = 0; i < num_connections; i++) {
1261                 struct recv_thread_args *args;
1262
1263                 args = kzalloc(sizeof(*args), GFP_KERNEL);
1264                 if (!args) {
1265                         sock_shutdown(nbd);
1266                         return -ENOMEM;
1267                 }
1268                 sk_set_memalloc(config->socks[i]->sock->sk);
1269                 if (nbd->tag_set.timeout)
1270                         config->socks[i]->sock->sk->sk_sndtimeo =
1271                                 nbd->tag_set.timeout;
1272                 atomic_inc(&config->recv_threads);
1273                 refcount_inc(&nbd->config_refs);
1274                 INIT_WORK(&args->work, recv_work);
1275                 args->nbd = nbd;
1276                 args->index = i;
1277                 queue_work(nbd->recv_workq, &args->work);
1278         }
1279         nbd_size_update(nbd);
1280         return error;
1281 }
1282
1283 static int nbd_start_device_ioctl(struct nbd_device *nbd, struct block_device *bdev)
1284 {
1285         struct nbd_config *config = nbd->config;
1286         int ret;
1287
1288         ret = nbd_start_device(nbd);
1289         if (ret)
1290                 return ret;
1291
1292         if (max_part)
1293                 bdev->bd_invalidated = 1;
1294         mutex_unlock(&nbd->config_lock);
1295         ret = wait_event_interruptible(config->recv_wq,
1296                                          atomic_read(&config->recv_threads) == 0);
1297         if (ret) {
1298                 sock_shutdown(nbd);
1299                 flush_workqueue(nbd->recv_workq);
1300         }
1301         mutex_lock(&nbd->config_lock);
1302         nbd_bdev_reset(bdev);
1303         /* user requested, ignore socket errors */
1304         if (test_bit(NBD_RT_DISCONNECT_REQUESTED, &config->runtime_flags))
1305                 ret = 0;
1306         if (test_bit(NBD_RT_TIMEDOUT, &config->runtime_flags))
1307                 ret = -ETIMEDOUT;
1308         return ret;
1309 }
1310
1311 static void nbd_clear_sock_ioctl(struct nbd_device *nbd,
1312                                  struct block_device *bdev)
1313 {
1314         sock_shutdown(nbd);
1315         __invalidate_device(bdev, true);
1316         nbd_bdev_reset(bdev);
1317         if (test_and_clear_bit(NBD_RT_HAS_CONFIG_REF,
1318                                &nbd->config->runtime_flags))
1319                 nbd_config_put(nbd);
1320 }
1321
1322 static bool nbd_is_valid_blksize(unsigned long blksize)
1323 {
1324         if (!blksize || !is_power_of_2(blksize) || blksize < 512 ||
1325             blksize > PAGE_SIZE)
1326                 return false;
1327         return true;
1328 }
1329
1330 static void nbd_set_cmd_timeout(struct nbd_device *nbd, u64 timeout)
1331 {
1332         nbd->tag_set.timeout = timeout * HZ;
1333         if (timeout)
1334                 blk_queue_rq_timeout(nbd->disk->queue, timeout * HZ);
1335 }
1336
1337 /* Must be called with config_lock held */
1338 static int __nbd_ioctl(struct block_device *bdev, struct nbd_device *nbd,
1339                        unsigned int cmd, unsigned long arg)
1340 {
1341         struct nbd_config *config = nbd->config;
1342
1343         switch (cmd) {
1344         case NBD_DISCONNECT:
1345                 return nbd_disconnect(nbd);
1346         case NBD_CLEAR_SOCK:
1347                 nbd_clear_sock_ioctl(nbd, bdev);
1348                 return 0;
1349         case NBD_SET_SOCK:
1350                 return nbd_add_socket(nbd, arg, false);
1351         case NBD_SET_BLKSIZE:
1352                 if (!arg)
1353                         arg = NBD_DEF_BLKSIZE;
1354                 if (!nbd_is_valid_blksize(arg))
1355                         return -EINVAL;
1356                 nbd_size_set(nbd, arg,
1357                              div_s64(config->bytesize, arg));
1358                 return 0;
1359         case NBD_SET_SIZE:
1360                 nbd_size_set(nbd, config->blksize,
1361                              div_s64(arg, config->blksize));
1362                 return 0;
1363         case NBD_SET_SIZE_BLOCKS:
1364                 nbd_size_set(nbd, config->blksize, arg);
1365                 return 0;
1366         case NBD_SET_TIMEOUT:
1367                 nbd_set_cmd_timeout(nbd, arg);
1368                 return 0;
1369
1370         case NBD_SET_FLAGS:
1371                 config->flags = arg;
1372                 return 0;
1373         case NBD_DO_IT:
1374                 return nbd_start_device_ioctl(nbd, bdev);
1375         case NBD_CLEAR_QUE:
1376                 /*
1377                  * This is for compatibility only.  The queue is always cleared
1378                  * by NBD_DO_IT or NBD_CLEAR_SOCK.
1379                  */
1380                 return 0;
1381         case NBD_PRINT_DEBUG:
1382                 /*
1383                  * For compatibility only, we no longer keep a list of
1384                  * outstanding requests.
1385                  */
1386                 return 0;
1387         }
1388         return -ENOTTY;
1389 }
1390
1391 static int nbd_ioctl(struct block_device *bdev, fmode_t mode,
1392                      unsigned int cmd, unsigned long arg)
1393 {
1394         struct nbd_device *nbd = bdev->bd_disk->private_data;
1395         struct nbd_config *config = nbd->config;
1396         int error = -EINVAL;
1397
1398         if (!capable(CAP_SYS_ADMIN))
1399                 return -EPERM;
1400
1401         /* The block layer will pass back some non-nbd ioctls in case we have
1402          * special handling for them, but we don't so just return an error.
1403          */
1404         if (_IOC_TYPE(cmd) != 0xab)
1405                 return -EINVAL;
1406
1407         mutex_lock(&nbd->config_lock);
1408
1409         /* Don't allow ioctl operations on a nbd device that was created with
1410          * netlink, unless it's DISCONNECT or CLEAR_SOCK, which are fine.
1411          */
1412         if (!test_bit(NBD_RT_BOUND, &config->runtime_flags) ||
1413             (cmd == NBD_DISCONNECT || cmd == NBD_CLEAR_SOCK))
1414                 error = __nbd_ioctl(bdev, nbd, cmd, arg);
1415         else
1416                 dev_err(nbd_to_dev(nbd), "Cannot use ioctl interface on a netlink controlled device.\n");
1417         mutex_unlock(&nbd->config_lock);
1418         return error;
1419 }
1420
1421 static struct nbd_config *nbd_alloc_config(void)
1422 {
1423         struct nbd_config *config;
1424
1425         config = kzalloc(sizeof(struct nbd_config), GFP_NOFS);
1426         if (!config)
1427                 return NULL;
1428         atomic_set(&config->recv_threads, 0);
1429         init_waitqueue_head(&config->recv_wq);
1430         init_waitqueue_head(&config->conn_wait);
1431         config->blksize = NBD_DEF_BLKSIZE;
1432         atomic_set(&config->live_connections, 0);
1433         try_module_get(THIS_MODULE);
1434         return config;
1435 }
1436
1437 static int nbd_open(struct block_device *bdev, fmode_t mode)
1438 {
1439         struct nbd_device *nbd;
1440         int ret = 0;
1441
1442         mutex_lock(&nbd_index_mutex);
1443         nbd = bdev->bd_disk->private_data;
1444         if (!nbd) {
1445                 ret = -ENXIO;
1446                 goto out;
1447         }
1448         if (!refcount_inc_not_zero(&nbd->refs)) {
1449                 ret = -ENXIO;
1450                 goto out;
1451         }
1452         if (!refcount_inc_not_zero(&nbd->config_refs)) {
1453                 struct nbd_config *config;
1454
1455                 mutex_lock(&nbd->config_lock);
1456                 if (refcount_inc_not_zero(&nbd->config_refs)) {
1457                         mutex_unlock(&nbd->config_lock);
1458                         goto out;
1459                 }
1460                 config = nbd->config = nbd_alloc_config();
1461                 if (!config) {
1462                         ret = -ENOMEM;
1463                         mutex_unlock(&nbd->config_lock);
1464                         goto out;
1465                 }
1466                 refcount_set(&nbd->config_refs, 1);
1467                 refcount_inc(&nbd->refs);
1468                 mutex_unlock(&nbd->config_lock);
1469                 bdev->bd_invalidated = 1;
1470         } else if (nbd_disconnected(nbd->config)) {
1471                 bdev->bd_invalidated = 1;
1472         }
1473 out:
1474         mutex_unlock(&nbd_index_mutex);
1475         return ret;
1476 }
1477
1478 static void nbd_release(struct gendisk *disk, fmode_t mode)
1479 {
1480         struct nbd_device *nbd = disk->private_data;
1481         struct block_device *bdev = bdget_disk(disk, 0);
1482
1483         if (test_bit(NBD_RT_DISCONNECT_ON_CLOSE, &nbd->config->runtime_flags) &&
1484                         bdev->bd_openers == 0)
1485                 nbd_disconnect_and_put(nbd);
1486
1487         nbd_config_put(nbd);
1488         nbd_put(nbd);
1489 }
1490
1491 static const struct block_device_operations nbd_fops =
1492 {
1493         .owner =        THIS_MODULE,
1494         .open =         nbd_open,
1495         .release =      nbd_release,
1496         .ioctl =        nbd_ioctl,
1497         .compat_ioctl = nbd_ioctl,
1498 };
1499
1500 #if IS_ENABLED(CONFIG_DEBUG_FS)
1501
1502 static int nbd_dbg_tasks_show(struct seq_file *s, void *unused)
1503 {
1504         struct nbd_device *nbd = s->private;
1505
1506         if (nbd->task_recv)
1507                 seq_printf(s, "recv: %d\n", task_pid_nr(nbd->task_recv));
1508
1509         return 0;
1510 }
1511
1512 static int nbd_dbg_tasks_open(struct inode *inode, struct file *file)
1513 {
1514         return single_open(file, nbd_dbg_tasks_show, inode->i_private);
1515 }
1516
1517 static const struct file_operations nbd_dbg_tasks_ops = {
1518         .open = nbd_dbg_tasks_open,
1519         .read = seq_read,
1520         .llseek = seq_lseek,
1521         .release = single_release,
1522 };
1523
1524 static int nbd_dbg_flags_show(struct seq_file *s, void *unused)
1525 {
1526         struct nbd_device *nbd = s->private;
1527         u32 flags = nbd->config->flags;
1528
1529         seq_printf(s, "Hex: 0x%08x\n\n", flags);
1530
1531         seq_puts(s, "Known flags:\n");
1532
1533         if (flags & NBD_FLAG_HAS_FLAGS)
1534                 seq_puts(s, "NBD_FLAG_HAS_FLAGS\n");
1535         if (flags & NBD_FLAG_READ_ONLY)
1536                 seq_puts(s, "NBD_FLAG_READ_ONLY\n");
1537         if (flags & NBD_FLAG_SEND_FLUSH)
1538                 seq_puts(s, "NBD_FLAG_SEND_FLUSH\n");
1539         if (flags & NBD_FLAG_SEND_FUA)
1540                 seq_puts(s, "NBD_FLAG_SEND_FUA\n");
1541         if (flags & NBD_FLAG_SEND_TRIM)
1542                 seq_puts(s, "NBD_FLAG_SEND_TRIM\n");
1543
1544         return 0;
1545 }
1546
1547 static int nbd_dbg_flags_open(struct inode *inode, struct file *file)
1548 {
1549         return single_open(file, nbd_dbg_flags_show, inode->i_private);
1550 }
1551
1552 static const struct file_operations nbd_dbg_flags_ops = {
1553         .open = nbd_dbg_flags_open,
1554         .read = seq_read,
1555         .llseek = seq_lseek,
1556         .release = single_release,
1557 };
1558
1559 static int nbd_dev_dbg_init(struct nbd_device *nbd)
1560 {
1561         struct dentry *dir;
1562         struct nbd_config *config = nbd->config;
1563
1564         if (!nbd_dbg_dir)
1565                 return -EIO;
1566
1567         dir = debugfs_create_dir(nbd_name(nbd), nbd_dbg_dir);
1568         if (!dir) {
1569                 dev_err(nbd_to_dev(nbd), "Failed to create debugfs dir for '%s'\n",
1570                         nbd_name(nbd));
1571                 return -EIO;
1572         }
1573         config->dbg_dir = dir;
1574
1575         debugfs_create_file("tasks", 0444, dir, nbd, &nbd_dbg_tasks_ops);
1576         debugfs_create_u64("size_bytes", 0444, dir, &config->bytesize);
1577         debugfs_create_u32("timeout", 0444, dir, &nbd->tag_set.timeout);
1578         debugfs_create_u64("blocksize", 0444, dir, &config->blksize);
1579         debugfs_create_file("flags", 0444, dir, nbd, &nbd_dbg_flags_ops);
1580
1581         return 0;
1582 }
1583
1584 static void nbd_dev_dbg_close(struct nbd_device *nbd)
1585 {
1586         debugfs_remove_recursive(nbd->config->dbg_dir);
1587 }
1588
1589 static int nbd_dbg_init(void)
1590 {
1591         struct dentry *dbg_dir;
1592
1593         dbg_dir = debugfs_create_dir("nbd", NULL);
1594         if (!dbg_dir)
1595                 return -EIO;
1596
1597         nbd_dbg_dir = dbg_dir;
1598
1599         return 0;
1600 }
1601
1602 static void nbd_dbg_close(void)
1603 {
1604         debugfs_remove_recursive(nbd_dbg_dir);
1605 }
1606
1607 #else  /* IS_ENABLED(CONFIG_DEBUG_FS) */
1608
1609 static int nbd_dev_dbg_init(struct nbd_device *nbd)
1610 {
1611         return 0;
1612 }
1613
1614 static void nbd_dev_dbg_close(struct nbd_device *nbd)
1615 {
1616 }
1617
1618 static int nbd_dbg_init(void)
1619 {
1620         return 0;
1621 }
1622
1623 static void nbd_dbg_close(void)
1624 {
1625 }
1626
1627 #endif
1628
1629 static int nbd_init_request(struct blk_mq_tag_set *set, struct request *rq,
1630                             unsigned int hctx_idx, unsigned int numa_node)
1631 {
1632         struct nbd_cmd *cmd = blk_mq_rq_to_pdu(rq);
1633         cmd->nbd = set->driver_data;
1634         cmd->flags = 0;
1635         mutex_init(&cmd->lock);
1636         return 0;
1637 }
1638
1639 static const struct blk_mq_ops nbd_mq_ops = {
1640         .queue_rq       = nbd_queue_rq,
1641         .complete       = nbd_complete_rq,
1642         .init_request   = nbd_init_request,
1643         .timeout        = nbd_xmit_timeout,
1644 };
1645
1646 static int nbd_dev_add(int index)
1647 {
1648         struct nbd_device *nbd;
1649         struct gendisk *disk;
1650         struct request_queue *q;
1651         int err = -ENOMEM;
1652
1653         nbd = kzalloc(sizeof(struct nbd_device), GFP_KERNEL);
1654         if (!nbd)
1655                 goto out;
1656
1657         disk = alloc_disk(1 << part_shift);
1658         if (!disk)
1659                 goto out_free_nbd;
1660
1661         if (index >= 0) {
1662                 err = idr_alloc(&nbd_index_idr, nbd, index, index + 1,
1663                                 GFP_KERNEL);
1664                 if (err == -ENOSPC)
1665                         err = -EEXIST;
1666         } else {
1667                 err = idr_alloc(&nbd_index_idr, nbd, 0, 0, GFP_KERNEL);
1668                 if (err >= 0)
1669                         index = err;
1670         }
1671         if (err < 0)
1672                 goto out_free_disk;
1673
1674         nbd->index = index;
1675         nbd->disk = disk;
1676         nbd->tag_set.ops = &nbd_mq_ops;
1677         nbd->tag_set.nr_hw_queues = 1;
1678         nbd->tag_set.queue_depth = 128;
1679         nbd->tag_set.numa_node = NUMA_NO_NODE;
1680         nbd->tag_set.cmd_size = sizeof(struct nbd_cmd);
1681         nbd->tag_set.flags = BLK_MQ_F_SHOULD_MERGE |
1682                 BLK_MQ_F_BLOCKING;
1683         nbd->tag_set.driver_data = nbd;
1684         nbd->destroy_complete = NULL;
1685
1686         err = blk_mq_alloc_tag_set(&nbd->tag_set);
1687         if (err)
1688                 goto out_free_idr;
1689
1690         q = blk_mq_init_queue(&nbd->tag_set);
1691         if (IS_ERR(q)) {
1692                 err = PTR_ERR(q);
1693                 goto out_free_tags;
1694         }
1695         disk->queue = q;
1696
1697         /*
1698          * Tell the block layer that we are not a rotational device
1699          */
1700         blk_queue_flag_set(QUEUE_FLAG_NONROT, disk->queue);
1701         blk_queue_flag_clear(QUEUE_FLAG_ADD_RANDOM, disk->queue);
1702         disk->queue->limits.discard_granularity = 0;
1703         disk->queue->limits.discard_alignment = 0;
1704         blk_queue_max_discard_sectors(disk->queue, 0);
1705         blk_queue_max_segment_size(disk->queue, UINT_MAX);
1706         blk_queue_max_segments(disk->queue, USHRT_MAX);
1707         blk_queue_max_hw_sectors(disk->queue, 65536);
1708         disk->queue->limits.max_sectors = 256;
1709
1710         mutex_init(&nbd->config_lock);
1711         refcount_set(&nbd->config_refs, 0);
1712         refcount_set(&nbd->refs, 1);
1713         INIT_LIST_HEAD(&nbd->list);
1714         disk->major = NBD_MAJOR;
1715         disk->first_minor = index << part_shift;
1716         disk->fops = &nbd_fops;
1717         disk->private_data = nbd;
1718         sprintf(disk->disk_name, "nbd%d", index);
1719         add_disk(disk);
1720         nbd_total_devices++;
1721         return index;
1722
1723 out_free_tags:
1724         blk_mq_free_tag_set(&nbd->tag_set);
1725 out_free_idr:
1726         idr_remove(&nbd_index_idr, index);
1727 out_free_disk:
1728         put_disk(disk);
1729 out_free_nbd:
1730         kfree(nbd);
1731 out:
1732         return err;
1733 }
1734
1735 static int find_free_cb(int id, void *ptr, void *data)
1736 {
1737         struct nbd_device *nbd = ptr;
1738         struct nbd_device **found = data;
1739
1740         if (!refcount_read(&nbd->config_refs)) {
1741                 *found = nbd;
1742                 return 1;
1743         }
1744         return 0;
1745 }
1746
1747 /* Netlink interface. */
1748 static const struct nla_policy nbd_attr_policy[NBD_ATTR_MAX + 1] = {
1749         [NBD_ATTR_INDEX]                =       { .type = NLA_U32 },
1750         [NBD_ATTR_SIZE_BYTES]           =       { .type = NLA_U64 },
1751         [NBD_ATTR_BLOCK_SIZE_BYTES]     =       { .type = NLA_U64 },
1752         [NBD_ATTR_TIMEOUT]              =       { .type = NLA_U64 },
1753         [NBD_ATTR_SERVER_FLAGS]         =       { .type = NLA_U64 },
1754         [NBD_ATTR_CLIENT_FLAGS]         =       { .type = NLA_U64 },
1755         [NBD_ATTR_SOCKETS]              =       { .type = NLA_NESTED},
1756         [NBD_ATTR_DEAD_CONN_TIMEOUT]    =       { .type = NLA_U64 },
1757         [NBD_ATTR_DEVICE_LIST]          =       { .type = NLA_NESTED},
1758 };
1759
1760 static const struct nla_policy nbd_sock_policy[NBD_SOCK_MAX + 1] = {
1761         [NBD_SOCK_FD]                   =       { .type = NLA_U32 },
1762 };
1763
1764 /* We don't use this right now since we don't parse the incoming list, but we
1765  * still want it here so userspace knows what to expect.
1766  */
1767 static const struct nla_policy __attribute__((unused))
1768 nbd_device_policy[NBD_DEVICE_ATTR_MAX + 1] = {
1769         [NBD_DEVICE_INDEX]              =       { .type = NLA_U32 },
1770         [NBD_DEVICE_CONNECTED]          =       { .type = NLA_U8 },
1771 };
1772
1773 static int nbd_genl_size_set(struct genl_info *info, struct nbd_device *nbd)
1774 {
1775         struct nbd_config *config = nbd->config;
1776         u64 bsize = config->blksize;
1777         u64 bytes = config->bytesize;
1778
1779         if (info->attrs[NBD_ATTR_SIZE_BYTES])
1780                 bytes = nla_get_u64(info->attrs[NBD_ATTR_SIZE_BYTES]);
1781
1782         if (info->attrs[NBD_ATTR_BLOCK_SIZE_BYTES]) {
1783                 bsize = nla_get_u64(info->attrs[NBD_ATTR_BLOCK_SIZE_BYTES]);
1784                 if (!bsize)
1785                         bsize = NBD_DEF_BLKSIZE;
1786                 if (!nbd_is_valid_blksize(bsize)) {
1787                         printk(KERN_ERR "Invalid block size %llu\n", bsize);
1788                         return -EINVAL;
1789                 }
1790         }
1791
1792         if (bytes != config->bytesize || bsize != config->blksize)
1793                 nbd_size_set(nbd, bsize, div64_u64(bytes, bsize));
1794         return 0;
1795 }
1796
1797 static int nbd_genl_connect(struct sk_buff *skb, struct genl_info *info)
1798 {
1799         DECLARE_COMPLETION_ONSTACK(destroy_complete);
1800         struct nbd_device *nbd = NULL;
1801         struct nbd_config *config;
1802         int index = -1;
1803         int ret;
1804         bool put_dev = false;
1805
1806         if (!netlink_capable(skb, CAP_SYS_ADMIN))
1807                 return -EPERM;
1808
1809         if (info->attrs[NBD_ATTR_INDEX])
1810                 index = nla_get_u32(info->attrs[NBD_ATTR_INDEX]);
1811         if (!info->attrs[NBD_ATTR_SOCKETS]) {
1812                 printk(KERN_ERR "nbd: must specify at least one socket\n");
1813                 return -EINVAL;
1814         }
1815         if (!info->attrs[NBD_ATTR_SIZE_BYTES]) {
1816                 printk(KERN_ERR "nbd: must specify a size in bytes for the device\n");
1817                 return -EINVAL;
1818         }
1819 again:
1820         mutex_lock(&nbd_index_mutex);
1821         if (index == -1) {
1822                 ret = idr_for_each(&nbd_index_idr, &find_free_cb, &nbd);
1823                 if (ret == 0) {
1824                         int new_index;
1825                         new_index = nbd_dev_add(-1);
1826                         if (new_index < 0) {
1827                                 mutex_unlock(&nbd_index_mutex);
1828                                 printk(KERN_ERR "nbd: failed to add new device\n");
1829                                 return new_index;
1830                         }
1831                         nbd = idr_find(&nbd_index_idr, new_index);
1832                 }
1833         } else {
1834                 nbd = idr_find(&nbd_index_idr, index);
1835                 if (!nbd) {
1836                         ret = nbd_dev_add(index);
1837                         if (ret < 0) {
1838                                 mutex_unlock(&nbd_index_mutex);
1839                                 printk(KERN_ERR "nbd: failed to add new device\n");
1840                                 return ret;
1841                         }
1842                         nbd = idr_find(&nbd_index_idr, index);
1843                 }
1844         }
1845         if (!nbd) {
1846                 printk(KERN_ERR "nbd: couldn't find device at index %d\n",
1847                        index);
1848                 mutex_unlock(&nbd_index_mutex);
1849                 return -EINVAL;
1850         }
1851
1852         if (test_bit(NBD_DESTROY_ON_DISCONNECT, &nbd->flags) &&
1853             test_bit(NBD_DISCONNECT_REQUESTED, &nbd->flags)) {
1854                 nbd->destroy_complete = &destroy_complete;
1855                 mutex_unlock(&nbd_index_mutex);
1856
1857                 /* Wait untill the the nbd stuff is totally destroyed */
1858                 wait_for_completion(&destroy_complete);
1859                 goto again;
1860         }
1861
1862         if (!refcount_inc_not_zero(&nbd->refs)) {
1863                 mutex_unlock(&nbd_index_mutex);
1864                 if (index == -1)
1865                         goto again;
1866                 printk(KERN_ERR "nbd: device at index %d is going down\n",
1867                        index);
1868                 return -EINVAL;
1869         }
1870         mutex_unlock(&nbd_index_mutex);
1871
1872         mutex_lock(&nbd->config_lock);
1873         if (refcount_read(&nbd->config_refs)) {
1874                 mutex_unlock(&nbd->config_lock);
1875                 nbd_put(nbd);
1876                 if (index == -1)
1877                         goto again;
1878                 printk(KERN_ERR "nbd: nbd%d already in use\n", index);
1879                 return -EBUSY;
1880         }
1881         if (WARN_ON(nbd->config)) {
1882                 mutex_unlock(&nbd->config_lock);
1883                 nbd_put(nbd);
1884                 return -EINVAL;
1885         }
1886         config = nbd->config = nbd_alloc_config();
1887         if (!nbd->config) {
1888                 mutex_unlock(&nbd->config_lock);
1889                 nbd_put(nbd);
1890                 printk(KERN_ERR "nbd: couldn't allocate config\n");
1891                 return -ENOMEM;
1892         }
1893         refcount_set(&nbd->config_refs, 1);
1894         set_bit(NBD_RT_BOUND, &config->runtime_flags);
1895
1896         ret = nbd_genl_size_set(info, nbd);
1897         if (ret)
1898                 goto out;
1899
1900         if (info->attrs[NBD_ATTR_TIMEOUT])
1901                 nbd_set_cmd_timeout(nbd,
1902                                     nla_get_u64(info->attrs[NBD_ATTR_TIMEOUT]));
1903         if (info->attrs[NBD_ATTR_DEAD_CONN_TIMEOUT]) {
1904                 config->dead_conn_timeout =
1905                         nla_get_u64(info->attrs[NBD_ATTR_DEAD_CONN_TIMEOUT]);
1906                 config->dead_conn_timeout *= HZ;
1907         }
1908         if (info->attrs[NBD_ATTR_SERVER_FLAGS])
1909                 config->flags =
1910                         nla_get_u64(info->attrs[NBD_ATTR_SERVER_FLAGS]);
1911         if (info->attrs[NBD_ATTR_CLIENT_FLAGS]) {
1912                 u64 flags = nla_get_u64(info->attrs[NBD_ATTR_CLIENT_FLAGS]);
1913                 if (flags & NBD_CFLAG_DESTROY_ON_DISCONNECT) {
1914                         set_bit(NBD_RT_DESTROY_ON_DISCONNECT,
1915                                 &config->runtime_flags);
1916                         set_bit(NBD_DESTROY_ON_DISCONNECT, &nbd->flags);
1917                         put_dev = true;
1918                 } else {
1919                         clear_bit(NBD_DESTROY_ON_DISCONNECT, &nbd->flags);
1920                 }
1921                 if (flags & NBD_CFLAG_DISCONNECT_ON_CLOSE) {
1922                         set_bit(NBD_RT_DISCONNECT_ON_CLOSE,
1923                                 &config->runtime_flags);
1924                 }
1925         }
1926
1927         if (info->attrs[NBD_ATTR_SOCKETS]) {
1928                 struct nlattr *attr;
1929                 int rem, fd;
1930
1931                 nla_for_each_nested(attr, info->attrs[NBD_ATTR_SOCKETS],
1932                                     rem) {
1933                         struct nlattr *socks[NBD_SOCK_MAX+1];
1934
1935                         if (nla_type(attr) != NBD_SOCK_ITEM) {
1936                                 printk(KERN_ERR "nbd: socks must be embedded in a SOCK_ITEM attr\n");
1937                                 ret = -EINVAL;
1938                                 goto out;
1939                         }
1940                         ret = nla_parse_nested_deprecated(socks, NBD_SOCK_MAX,
1941                                                           attr,
1942                                                           nbd_sock_policy,
1943                                                           info->extack);
1944                         if (ret != 0) {
1945                                 printk(KERN_ERR "nbd: error processing sock list\n");
1946                                 ret = -EINVAL;
1947                                 goto out;
1948                         }
1949                         if (!socks[NBD_SOCK_FD])
1950                                 continue;
1951                         fd = (int)nla_get_u32(socks[NBD_SOCK_FD]);
1952                         ret = nbd_add_socket(nbd, fd, true);
1953                         if (ret)
1954                                 goto out;
1955                 }
1956         }
1957         ret = nbd_start_device(nbd);
1958 out:
1959         mutex_unlock(&nbd->config_lock);
1960         if (!ret) {
1961                 set_bit(NBD_RT_HAS_CONFIG_REF, &config->runtime_flags);
1962                 refcount_inc(&nbd->config_refs);
1963                 nbd_connect_reply(info, nbd->index);
1964         }
1965         nbd_config_put(nbd);
1966         if (put_dev)
1967                 nbd_put(nbd);
1968         return ret;
1969 }
1970
1971 static void nbd_disconnect_and_put(struct nbd_device *nbd)
1972 {
1973         mutex_lock(&nbd->config_lock);
1974         nbd_disconnect(nbd);
1975         nbd_clear_sock(nbd);
1976         mutex_unlock(&nbd->config_lock);
1977         /*
1978          * Make sure recv thread has finished, so it does not drop the last
1979          * config ref and try to destroy the workqueue from inside the work
1980          * queue.
1981          */
1982         flush_workqueue(nbd->recv_workq);
1983         if (test_and_clear_bit(NBD_RT_HAS_CONFIG_REF,
1984                                &nbd->config->runtime_flags))
1985                 nbd_config_put(nbd);
1986 }
1987
1988 static int nbd_genl_disconnect(struct sk_buff *skb, struct genl_info *info)
1989 {
1990         struct nbd_device *nbd;
1991         int index;
1992
1993         if (!netlink_capable(skb, CAP_SYS_ADMIN))
1994                 return -EPERM;
1995
1996         if (!info->attrs[NBD_ATTR_INDEX]) {
1997                 printk(KERN_ERR "nbd: must specify an index to disconnect\n");
1998                 return -EINVAL;
1999         }
2000         index = nla_get_u32(info->attrs[NBD_ATTR_INDEX]);
2001         mutex_lock(&nbd_index_mutex);
2002         nbd = idr_find(&nbd_index_idr, index);
2003         if (!nbd) {
2004                 mutex_unlock(&nbd_index_mutex);
2005                 printk(KERN_ERR "nbd: couldn't find device at index %d\n",
2006                        index);
2007                 return -EINVAL;
2008         }
2009         if (!refcount_inc_not_zero(&nbd->refs)) {
2010                 mutex_unlock(&nbd_index_mutex);
2011                 printk(KERN_ERR "nbd: device at index %d is going down\n",
2012                        index);
2013                 return -EINVAL;
2014         }
2015         mutex_unlock(&nbd_index_mutex);
2016         if (!refcount_inc_not_zero(&nbd->config_refs)) {
2017                 nbd_put(nbd);
2018                 return 0;
2019         }
2020         nbd_disconnect_and_put(nbd);
2021         nbd_config_put(nbd);
2022         nbd_put(nbd);
2023         return 0;
2024 }
2025
2026 static int nbd_genl_reconfigure(struct sk_buff *skb, struct genl_info *info)
2027 {
2028         struct nbd_device *nbd = NULL;
2029         struct nbd_config *config;
2030         int index;
2031         int ret = 0;
2032         bool put_dev = false;
2033
2034         if (!netlink_capable(skb, CAP_SYS_ADMIN))
2035                 return -EPERM;
2036
2037         if (!info->attrs[NBD_ATTR_INDEX]) {
2038                 printk(KERN_ERR "nbd: must specify a device to reconfigure\n");
2039                 return -EINVAL;
2040         }
2041         index = nla_get_u32(info->attrs[NBD_ATTR_INDEX]);
2042         mutex_lock(&nbd_index_mutex);
2043         nbd = idr_find(&nbd_index_idr, index);
2044         if (!nbd) {
2045                 mutex_unlock(&nbd_index_mutex);
2046                 printk(KERN_ERR "nbd: couldn't find a device at index %d\n",
2047                        index);
2048                 return -EINVAL;
2049         }
2050         if (!refcount_inc_not_zero(&nbd->refs)) {
2051                 mutex_unlock(&nbd_index_mutex);
2052                 printk(KERN_ERR "nbd: device at index %d is going down\n",
2053                        index);
2054                 return -EINVAL;
2055         }
2056         mutex_unlock(&nbd_index_mutex);
2057
2058         if (!refcount_inc_not_zero(&nbd->config_refs)) {
2059                 dev_err(nbd_to_dev(nbd),
2060                         "not configured, cannot reconfigure\n");
2061                 nbd_put(nbd);
2062                 return -EINVAL;
2063         }
2064
2065         mutex_lock(&nbd->config_lock);
2066         config = nbd->config;
2067         if (!test_bit(NBD_RT_BOUND, &config->runtime_flags) ||
2068             !nbd->task_recv) {
2069                 dev_err(nbd_to_dev(nbd),
2070                         "not configured, cannot reconfigure\n");
2071                 ret = -EINVAL;
2072                 goto out;
2073         }
2074
2075         ret = nbd_genl_size_set(info, nbd);
2076         if (ret)
2077                 goto out;
2078
2079         if (info->attrs[NBD_ATTR_TIMEOUT])
2080                 nbd_set_cmd_timeout(nbd,
2081                                     nla_get_u64(info->attrs[NBD_ATTR_TIMEOUT]));
2082         if (info->attrs[NBD_ATTR_DEAD_CONN_TIMEOUT]) {
2083                 config->dead_conn_timeout =
2084                         nla_get_u64(info->attrs[NBD_ATTR_DEAD_CONN_TIMEOUT]);
2085                 config->dead_conn_timeout *= HZ;
2086         }
2087         if (info->attrs[NBD_ATTR_CLIENT_FLAGS]) {
2088                 u64 flags = nla_get_u64(info->attrs[NBD_ATTR_CLIENT_FLAGS]);
2089                 if (flags & NBD_CFLAG_DESTROY_ON_DISCONNECT) {
2090                         if (!test_and_set_bit(NBD_RT_DESTROY_ON_DISCONNECT,
2091                                               &config->runtime_flags))
2092                                 put_dev = true;
2093                         set_bit(NBD_DESTROY_ON_DISCONNECT, &nbd->flags);
2094                 } else {
2095                         if (test_and_clear_bit(NBD_RT_DESTROY_ON_DISCONNECT,
2096                                                &config->runtime_flags))
2097                                 refcount_inc(&nbd->refs);
2098                         clear_bit(NBD_DESTROY_ON_DISCONNECT, &nbd->flags);
2099                 }
2100
2101                 if (flags & NBD_CFLAG_DISCONNECT_ON_CLOSE) {
2102                         set_bit(NBD_RT_DISCONNECT_ON_CLOSE,
2103                                         &config->runtime_flags);
2104                 } else {
2105                         clear_bit(NBD_RT_DISCONNECT_ON_CLOSE,
2106                                         &config->runtime_flags);
2107                 }
2108         }
2109
2110         if (info->attrs[NBD_ATTR_SOCKETS]) {
2111                 struct nlattr *attr;
2112                 int rem, fd;
2113
2114                 nla_for_each_nested(attr, info->attrs[NBD_ATTR_SOCKETS],
2115                                     rem) {
2116                         struct nlattr *socks[NBD_SOCK_MAX+1];
2117
2118                         if (nla_type(attr) != NBD_SOCK_ITEM) {
2119                                 printk(KERN_ERR "nbd: socks must be embedded in a SOCK_ITEM attr\n");
2120                                 ret = -EINVAL;
2121                                 goto out;
2122                         }
2123                         ret = nla_parse_nested_deprecated(socks, NBD_SOCK_MAX,
2124                                                           attr,
2125                                                           nbd_sock_policy,
2126                                                           info->extack);
2127                         if (ret != 0) {
2128                                 printk(KERN_ERR "nbd: error processing sock list\n");
2129                                 ret = -EINVAL;
2130                                 goto out;
2131                         }
2132                         if (!socks[NBD_SOCK_FD])
2133                                 continue;
2134                         fd = (int)nla_get_u32(socks[NBD_SOCK_FD]);
2135                         ret = nbd_reconnect_socket(nbd, fd);
2136                         if (ret) {
2137                                 if (ret == -ENOSPC)
2138                                         ret = 0;
2139                                 goto out;
2140                         }
2141                         dev_info(nbd_to_dev(nbd), "reconnected socket\n");
2142                 }
2143         }
2144 out:
2145         mutex_unlock(&nbd->config_lock);
2146         nbd_config_put(nbd);
2147         nbd_put(nbd);
2148         if (put_dev)
2149                 nbd_put(nbd);
2150         return ret;
2151 }
2152
2153 static const struct genl_ops nbd_connect_genl_ops[] = {
2154         {
2155                 .cmd    = NBD_CMD_CONNECT,
2156                 .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
2157                 .doit   = nbd_genl_connect,
2158         },
2159         {
2160                 .cmd    = NBD_CMD_DISCONNECT,
2161                 .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
2162                 .doit   = nbd_genl_disconnect,
2163         },
2164         {
2165                 .cmd    = NBD_CMD_RECONFIGURE,
2166                 .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
2167                 .doit   = nbd_genl_reconfigure,
2168         },
2169         {
2170                 .cmd    = NBD_CMD_STATUS,
2171                 .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
2172                 .doit   = nbd_genl_status,
2173         },
2174 };
2175
2176 static const struct genl_multicast_group nbd_mcast_grps[] = {
2177         { .name = NBD_GENL_MCAST_GROUP_NAME, },
2178 };
2179
2180 static struct genl_family nbd_genl_family __ro_after_init = {
2181         .hdrsize        = 0,
2182         .name           = NBD_GENL_FAMILY_NAME,
2183         .version        = NBD_GENL_VERSION,
2184         .module         = THIS_MODULE,
2185         .ops            = nbd_connect_genl_ops,
2186         .n_ops          = ARRAY_SIZE(nbd_connect_genl_ops),
2187         .maxattr        = NBD_ATTR_MAX,
2188         .policy = nbd_attr_policy,
2189         .mcgrps         = nbd_mcast_grps,
2190         .n_mcgrps       = ARRAY_SIZE(nbd_mcast_grps),
2191 };
2192
2193 static int populate_nbd_status(struct nbd_device *nbd, struct sk_buff *reply)
2194 {
2195         struct nlattr *dev_opt;
2196         u8 connected = 0;
2197         int ret;
2198
2199         /* This is a little racey, but for status it's ok.  The
2200          * reason we don't take a ref here is because we can't
2201          * take a ref in the index == -1 case as we would need
2202          * to put under the nbd_index_mutex, which could
2203          * deadlock if we are configured to remove ourselves
2204          * once we're disconnected.
2205          */
2206         if (refcount_read(&nbd->config_refs))
2207                 connected = 1;
2208         dev_opt = nla_nest_start_noflag(reply, NBD_DEVICE_ITEM);
2209         if (!dev_opt)
2210                 return -EMSGSIZE;
2211         ret = nla_put_u32(reply, NBD_DEVICE_INDEX, nbd->index);
2212         if (ret)
2213                 return -EMSGSIZE;
2214         ret = nla_put_u8(reply, NBD_DEVICE_CONNECTED,
2215                          connected);
2216         if (ret)
2217                 return -EMSGSIZE;
2218         nla_nest_end(reply, dev_opt);
2219         return 0;
2220 }
2221
2222 static int status_cb(int id, void *ptr, void *data)
2223 {
2224         struct nbd_device *nbd = ptr;
2225         return populate_nbd_status(nbd, (struct sk_buff *)data);
2226 }
2227
2228 static int nbd_genl_status(struct sk_buff *skb, struct genl_info *info)
2229 {
2230         struct nlattr *dev_list;
2231         struct sk_buff *reply;
2232         void *reply_head;
2233         size_t msg_size;
2234         int index = -1;
2235         int ret = -ENOMEM;
2236
2237         if (info->attrs[NBD_ATTR_INDEX])
2238                 index = nla_get_u32(info->attrs[NBD_ATTR_INDEX]);
2239
2240         mutex_lock(&nbd_index_mutex);
2241
2242         msg_size = nla_total_size(nla_attr_size(sizeof(u32)) +
2243                                   nla_attr_size(sizeof(u8)));
2244         msg_size *= (index == -1) ? nbd_total_devices : 1;
2245
2246         reply = genlmsg_new(msg_size, GFP_KERNEL);
2247         if (!reply)
2248                 goto out;
2249         reply_head = genlmsg_put_reply(reply, info, &nbd_genl_family, 0,
2250                                        NBD_CMD_STATUS);
2251         if (!reply_head) {
2252                 nlmsg_free(reply);
2253                 goto out;
2254         }
2255
2256         dev_list = nla_nest_start_noflag(reply, NBD_ATTR_DEVICE_LIST);
2257         if (index == -1) {
2258                 ret = idr_for_each(&nbd_index_idr, &status_cb, reply);
2259                 if (ret) {
2260                         nlmsg_free(reply);
2261                         goto out;
2262                 }
2263         } else {
2264                 struct nbd_device *nbd;
2265                 nbd = idr_find(&nbd_index_idr, index);
2266                 if (nbd) {
2267                         ret = populate_nbd_status(nbd, reply);
2268                         if (ret) {
2269                                 nlmsg_free(reply);
2270                                 goto out;
2271                         }
2272                 }
2273         }
2274         nla_nest_end(reply, dev_list);
2275         genlmsg_end(reply, reply_head);
2276         ret = genlmsg_reply(reply, info);
2277 out:
2278         mutex_unlock(&nbd_index_mutex);
2279         return ret;
2280 }
2281
2282 static void nbd_connect_reply(struct genl_info *info, int index)
2283 {
2284         struct sk_buff *skb;
2285         void *msg_head;
2286         int ret;
2287
2288         skb = genlmsg_new(nla_total_size(sizeof(u32)), GFP_KERNEL);
2289         if (!skb)
2290                 return;
2291         msg_head = genlmsg_put_reply(skb, info, &nbd_genl_family, 0,
2292                                      NBD_CMD_CONNECT);
2293         if (!msg_head) {
2294                 nlmsg_free(skb);
2295                 return;
2296         }
2297         ret = nla_put_u32(skb, NBD_ATTR_INDEX, index);
2298         if (ret) {
2299                 nlmsg_free(skb);
2300                 return;
2301         }
2302         genlmsg_end(skb, msg_head);
2303         genlmsg_reply(skb, info);
2304 }
2305
2306 static void nbd_mcast_index(int index)
2307 {
2308         struct sk_buff *skb;
2309         void *msg_head;
2310         int ret;
2311
2312         skb = genlmsg_new(nla_total_size(sizeof(u32)), GFP_KERNEL);
2313         if (!skb)
2314                 return;
2315         msg_head = genlmsg_put(skb, 0, 0, &nbd_genl_family, 0,
2316                                      NBD_CMD_LINK_DEAD);
2317         if (!msg_head) {
2318                 nlmsg_free(skb);
2319                 return;
2320         }
2321         ret = nla_put_u32(skb, NBD_ATTR_INDEX, index);
2322         if (ret) {
2323                 nlmsg_free(skb);
2324                 return;
2325         }
2326         genlmsg_end(skb, msg_head);
2327         genlmsg_multicast(&nbd_genl_family, skb, 0, 0, GFP_KERNEL);
2328 }
2329
2330 static void nbd_dead_link_work(struct work_struct *work)
2331 {
2332         struct link_dead_args *args = container_of(work, struct link_dead_args,
2333                                                    work);
2334         nbd_mcast_index(args->index);
2335         kfree(args);
2336 }
2337
2338 static int __init nbd_init(void)
2339 {
2340         int i;
2341
2342         BUILD_BUG_ON(sizeof(struct nbd_request) != 28);
2343
2344         if (max_part < 0) {
2345                 printk(KERN_ERR "nbd: max_part must be >= 0\n");
2346                 return -EINVAL;
2347         }
2348
2349         part_shift = 0;
2350         if (max_part > 0) {
2351                 part_shift = fls(max_part);
2352
2353                 /*
2354                  * Adjust max_part according to part_shift as it is exported
2355                  * to user space so that user can know the max number of
2356                  * partition kernel should be able to manage.
2357                  *
2358                  * Note that -1 is required because partition 0 is reserved
2359                  * for the whole disk.
2360                  */
2361                 max_part = (1UL << part_shift) - 1;
2362         }
2363
2364         if ((1UL << part_shift) > DISK_MAX_PARTS)
2365                 return -EINVAL;
2366
2367         if (nbds_max > 1UL << (MINORBITS - part_shift))
2368                 return -EINVAL;
2369
2370         if (register_blkdev(NBD_MAJOR, "nbd"))
2371                 return -EIO;
2372
2373         if (genl_register_family(&nbd_genl_family)) {
2374                 unregister_blkdev(NBD_MAJOR, "nbd");
2375                 return -EINVAL;
2376         }
2377         nbd_dbg_init();
2378
2379         mutex_lock(&nbd_index_mutex);
2380         for (i = 0; i < nbds_max; i++)
2381                 nbd_dev_add(i);
2382         mutex_unlock(&nbd_index_mutex);
2383         return 0;
2384 }
2385
2386 static int nbd_exit_cb(int id, void *ptr, void *data)
2387 {
2388         struct list_head *list = (struct list_head *)data;
2389         struct nbd_device *nbd = ptr;
2390
2391         list_add_tail(&nbd->list, list);
2392         return 0;
2393 }
2394
2395 static void __exit nbd_cleanup(void)
2396 {
2397         struct nbd_device *nbd;
2398         LIST_HEAD(del_list);
2399
2400         nbd_dbg_close();
2401
2402         mutex_lock(&nbd_index_mutex);
2403         idr_for_each(&nbd_index_idr, &nbd_exit_cb, &del_list);
2404         mutex_unlock(&nbd_index_mutex);
2405
2406         while (!list_empty(&del_list)) {
2407                 nbd = list_first_entry(&del_list, struct nbd_device, list);
2408                 list_del_init(&nbd->list);
2409                 if (refcount_read(&nbd->refs) != 1)
2410                         printk(KERN_ERR "nbd: possibly leaking a device\n");
2411                 nbd_put(nbd);
2412         }
2413
2414         idr_destroy(&nbd_index_idr);
2415         genl_unregister_family(&nbd_genl_family);
2416         unregister_blkdev(NBD_MAJOR, "nbd");
2417 }
2418
2419 module_init(nbd_init);
2420 module_exit(nbd_cleanup);
2421
2422 MODULE_DESCRIPTION("Network Block Device");
2423 MODULE_LICENSE("GPL");
2424
2425 module_param(nbds_max, int, 0444);
2426 MODULE_PARM_DESC(nbds_max, "number of network block devices to initialize (default: 16)");
2427 module_param(max_part, int, 0444);
2428 MODULE_PARM_DESC(max_part, "number of partitions per device (default: 16)");