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 int nbd_set_size(struct nbd_device *nbd, loff_t bytesize,
 300                 loff_t blksize)
 301 {
 302         if (!blksize)
 303                 blksize = NBD_DEF_BLKSIZE;
 304         if (blksize < 512 || blksize > PAGE_SIZE || !is_power_of_2(blksize))
 305                 return -EINVAL;
 306
 307         nbd->config->bytesize = bytesize;
 308         nbd->config->blksize = blksize;
 309
 310         if (!nbd->task_recv)
 311                 return 0;
 312
 313         if (nbd->config->flags & NBD_FLAG_SEND_TRIM) {
 314                 nbd->disk->queue->limits.discard_granularity = blksize;
 315                 nbd->disk->queue->limits.discard_alignment = blksize;
 316                 blk_queue_max_discard_sectors(nbd->disk->queue, UINT_MAX);
 317         }
 318         blk_queue_logical_block_size(nbd->disk->queue, blksize);
 319         blk_queue_physical_block_size(nbd->disk->queue, blksize);
 320
 321         if (max_part)
 322                 set_bit(GD_NEED_PART_SCAN, &nbd->disk->state);
 323         if (!set_capacity_and_notify(nbd->disk, bytesize >> 9))
 324                 kobject_uevent(&nbd_to_dev(nbd)->kobj, KOBJ_CHANGE);
 325         return 0;
 326 }
 327
 328 static void nbd_complete_rq(struct request *req)
 329 {
 330         struct nbd_cmd *cmd = blk_mq_rq_to_pdu(req);
 331
 332         dev_dbg(nbd_to_dev(cmd->nbd), "request %p: %s\n", req,
 333                 cmd->status ? "failed" : "done");
 334
 335         blk_mq_end_request(req, cmd->status);
 336 }
 337
 338 /*
 339  * Forcibly shutdown the socket causing all listeners to error
 340  */
 341 static void sock_shutdown(struct nbd_device *nbd)
 342 {
 343         struct nbd_config *config = nbd->config;
 344         int i;
 345
 346         if (config->num_connections == 0)
 347                 return;
 348         if (test_and_set_bit(NBD_RT_DISCONNECTED, &config->runtime_flags))
 349                 return;
 350
 351         for (i = 0; i < config->num_connections; i++) {
 352                 struct nbd_sock *nsock = config->socks[i];
 353                 mutex_lock(&nsock->tx_lock);
 354                 nbd_mark_nsock_dead(nbd, nsock, 0);
 355                 mutex_unlock(&nsock->tx_lock);
 356         }
 357         dev_warn(disk_to_dev(nbd->disk), "shutting down sockets\n");
 358 }
 359
 360 static u32 req_to_nbd_cmd_type(struct request *req)
 361 {
 362         switch (req_op(req)) {
 363         case REQ_OP_DISCARD:
 364                 return NBD_CMD_TRIM;
 365         case REQ_OP_FLUSH:
 366                 return NBD_CMD_FLUSH;
 367         case REQ_OP_WRITE:
 368                 return NBD_CMD_WRITE;
 369         case REQ_OP_READ:
 370                 return NBD_CMD_READ;
 371         default:
 372                 return U32_MAX;
 373         }
 374 }
 375
 376 static enum blk_eh_timer_return nbd_xmit_timeout(struct request *req,
 377                                                  bool reserved)
 378 {
 379         struct nbd_cmd *cmd = blk_mq_rq_to_pdu(req);
 380         struct nbd_device *nbd = cmd->nbd;
 381         struct nbd_config *config;
 382
 383         if (!mutex_trylock(&cmd->lock))
 384                 return BLK_EH_RESET_TIMER;
 385
 386         if (!refcount_inc_not_zero(&nbd->config_refs)) {
 387                 cmd->status = BLK_STS_TIMEOUT;
 388                 mutex_unlock(&cmd->lock);
 389                 goto done;
 390         }
 391         config = nbd->config;
 392
 393         if (config->num_connections > 1 ||
 394             (config->num_connections == 1 && nbd->tag_set.timeout)) {
 395                 dev_err_ratelimited(nbd_to_dev(nbd),
 396                                     "Connection timed out, retrying (%d/%d alive)\n",
 397                                     atomic_read(&config->live_connections),
 398                                     config->num_connections);
 399                 /*
 400                  * Hooray we have more connections, requeue this IO, the submit
 401                  * path will put it on a real connection. Or if only one
 402                  * connection is configured, the submit path will wait util
 403                  * a new connection is reconfigured or util dead timeout.
 404                  */
 405                 if (config->socks) {
 406                         if (cmd->index < config->num_connections) {
 407                                 struct nbd_sock *nsock =
 408                                         config->socks[cmd->index];
 409                                 mutex_lock(&nsock->tx_lock);
 410                                 /* We can have multiple outstanding requests, so
 411                                  * we don't want to mark the nsock dead if we've
 412                                  * already reconnected with a new socket, so
 413                                  * only mark it dead if its the same socket we
 414                                  * were sent out on.
 415                                  */
 416                                 if (cmd->cookie == nsock->cookie)
 417                                         nbd_mark_nsock_dead(nbd, nsock, 1);
 418                                 mutex_unlock(&nsock->tx_lock);
 419                         }
 420                         mutex_unlock(&cmd->lock);
 421                         nbd_requeue_cmd(cmd);
 422                         nbd_config_put(nbd);
 423                         return BLK_EH_DONE;
 424                 }
 425         }
 426
 427         if (!nbd->tag_set.timeout) {
 428                 /*
 429                  * Userspace sets timeout=0 to disable socket disconnection,
 430                  * so just warn and reset the timer.
 431                  */
 432                 struct nbd_sock *nsock = config->socks[cmd->index];
 433                 cmd->retries++;
 434                 dev_info(nbd_to_dev(nbd), "Possible stuck request %p: control (%s@%llu,%uB). Runtime %u seconds\n",
 435                         req, nbdcmd_to_ascii(req_to_nbd_cmd_type(req)),
 436                         (unsigned long long)blk_rq_pos(req) << 9,
 437                         blk_rq_bytes(req), (req->timeout / HZ) * cmd->retries);
 438
 439                 mutex_lock(&nsock->tx_lock);
 440                 if (cmd->cookie != nsock->cookie) {
 441                         nbd_requeue_cmd(cmd);
 442                         mutex_unlock(&nsock->tx_lock);
 443                         mutex_unlock(&cmd->lock);
 444                         nbd_config_put(nbd);
 445                         return BLK_EH_DONE;
 446                 }
 447                 mutex_unlock(&nsock->tx_lock);
 448                 mutex_unlock(&cmd->lock);
 449                 nbd_config_put(nbd);
 450                 return BLK_EH_RESET_TIMER;
 451         }
 452
 453         dev_err_ratelimited(nbd_to_dev(nbd), "Connection timed out\n");
 454         set_bit(NBD_RT_TIMEDOUT, &config->runtime_flags);
 455         cmd->status = BLK_STS_IOERR;
 456         mutex_unlock(&cmd->lock);
 457         sock_shutdown(nbd);
 458         nbd_config_put(nbd);
 459 done:
 460         blk_mq_complete_request(req);
 461         return BLK_EH_DONE;
 462 }
 463
 464 /*
 465  *  Send or receive packet.
 466  */
 467 static int sock_xmit(struct nbd_device *nbd, int index, int send,
 468                      struct iov_iter *iter, int msg_flags, int *sent)
 469 {
 470         struct nbd_config *config = nbd->config;
 471         struct socket *sock = config->socks[index]->sock;
 472         int result;
 473         struct msghdr msg;
 474         unsigned int noreclaim_flag;
 475
 476         if (unlikely(!sock)) {
 477                 dev_err_ratelimited(disk_to_dev(nbd->disk),
 478                         "Attempted %s on closed socket in sock_xmit\n",
 479                         (send ? "send" : "recv"));
 480                 return -EINVAL;
 481         }
 482
 483         msg.msg_iter = *iter;
 484
 485         noreclaim_flag = memalloc_noreclaim_save();
 486         do {
 487                 sock->sk->sk_allocation = GFP_NOIO | __GFP_MEMALLOC;
 488                 msg.msg_name = NULL;
 489                 msg.msg_namelen = 0;
 490                 msg.msg_control = NULL;
 491                 msg.msg_controllen = 0;
 492                 msg.msg_flags = msg_flags | MSG_NOSIGNAL;
 493
 494                 if (send)
 495                         result = sock_sendmsg(sock, &msg);
 496                 else
 497                         result = sock_recvmsg(sock, &msg, msg.msg_flags);
 498
 499                 if (result <= 0) {
 500                         if (result == 0)
 501                                 result = -EPIPE; /* short read */
 502                         break;
 503                 }
 504                 if (sent)
 505                         *sent += result;
 506         } while (msg_data_left(&msg));
 507
 508         memalloc_noreclaim_restore(noreclaim_flag);
 509
 510         return result;
 511 }
 512
 513 /*
 514  * Different settings for sk->sk_sndtimeo can result in different return values
 515  * if there is a signal pending when we enter sendmsg, because reasons?
 516  */
 517 static inline int was_interrupted(int result)
 518 {
 519         return result == -ERESTARTSYS || result == -EINTR;
 520 }
 521
 522 /* always call with the tx_lock held */
 523 static int nbd_send_cmd(struct nbd_device *nbd, struct nbd_cmd *cmd, int index)
 524 {
 525         struct request *req = blk_mq_rq_from_pdu(cmd);
 526         struct nbd_config *config = nbd->config;
 527         struct nbd_sock *nsock = config->socks[index];
 528         int result;
 529         struct nbd_request request = {.magic = htonl(NBD_REQUEST_MAGIC)};
 530         struct kvec iov = {.iov_base = &request, .iov_len = sizeof(request)};
 531         struct iov_iter from;
 532         unsigned long size = blk_rq_bytes(req);
 533         struct bio *bio;
 534         u64 handle;
 535         u32 type;
 536         u32 nbd_cmd_flags = 0;
 537         int sent = nsock->sent, skip = 0;
 538
 539         iov_iter_kvec(&from, WRITE, &iov, 1, sizeof(request));
 540
 541         type = req_to_nbd_cmd_type(req);
 542         if (type == U32_MAX)
 543                 return -EIO;
 544
 545         if (rq_data_dir(req) == WRITE &&
 546             (config->flags & NBD_FLAG_READ_ONLY)) {
 547                 dev_err_ratelimited(disk_to_dev(nbd->disk),
 548                                     "Write on read-only\n");
 549                 return -EIO;
 550         }
 551
 552         if (req->cmd_flags & REQ_FUA)
 553                 nbd_cmd_flags |= NBD_CMD_FLAG_FUA;
 554
 555         /* We did a partial send previously, and we at least sent the whole
 556          * request struct, so just go and send the rest of the pages in the
 557          * request.
 558          */
 559         if (sent) {
 560                 if (sent >= sizeof(request)) {
 561                         skip = sent - sizeof(request);
 562
 563                         /* initialize handle for tracing purposes */
 564                         handle = nbd_cmd_handle(cmd);
 565
 566                         goto send_pages;
 567                 }
 568                 iov_iter_advance(&from, sent);
 569         } else {
 570                 cmd->cmd_cookie++;
 571         }
 572         cmd->index = index;
 573         cmd->cookie = nsock->cookie;
 574         cmd->retries = 0;
 575         request.type = htonl(type | nbd_cmd_flags);
 576         if (type != NBD_CMD_FLUSH) {
 577                 request.from = cpu_to_be64((u64)blk_rq_pos(req) << 9);
 578                 request.len = htonl(size);
 579         }
 580         handle = nbd_cmd_handle(cmd);
 581         memcpy(request.handle, &handle, sizeof(handle));
 582
 583         trace_nbd_send_request(&request, nbd->index, blk_mq_rq_from_pdu(cmd));
 584
 585         dev_dbg(nbd_to_dev(nbd), "request %p: sending control (%s@%llu,%uB)\n",
 586                 req, nbdcmd_to_ascii(type),
 587                 (unsigned long long)blk_rq_pos(req) << 9, blk_rq_bytes(req));
 588         result = sock_xmit(nbd, index, 1, &from,
 589                         (type == NBD_CMD_WRITE) ? MSG_MORE : 0, &sent);
 590         trace_nbd_header_sent(req, handle);
 591         if (result <= 0) {
 592                 if (was_interrupted(result)) {
 593                         /* If we havne't sent anything we can just return BUSY,
 594                          * however if we have sent something we need to make
 595                          * sure we only allow this req to be sent until we are
 596                          * completely done.
 597                          */
 598                         if (sent) {
 599                                 nsock->pending = req;
 600                                 nsock->sent = sent;
 601                         }
 602                         set_bit(NBD_CMD_REQUEUED, &cmd->flags);
 603                         return BLK_STS_RESOURCE;
 604                 }
 605                 dev_err_ratelimited(disk_to_dev(nbd->disk),
 606                         "Send control failed (result %d)\n", result);
 607                 return -EAGAIN;
 608         }
 609 send_pages:
 610         if (type != NBD_CMD_WRITE)
 611                 goto out;
 612
 613         bio = req->bio;
 614         while (bio) {
 615                 struct bio *next = bio->bi_next;
 616                 struct bvec_iter iter;
 617                 struct bio_vec bvec;
 618
 619                 bio_for_each_segment(bvec, bio, iter) {
 620                         bool is_last = !next && bio_iter_last(bvec, iter);
 621                         int flags = is_last ? 0 : MSG_MORE;
 622
 623                         dev_dbg(nbd_to_dev(nbd), "request %p: sending %d bytes data\n",
 624                                 req, bvec.bv_len);
 625                         iov_iter_bvec(&from, WRITE, &bvec, 1, bvec.bv_len);
 626                         if (skip) {
 627                                 if (skip >= iov_iter_count(&from)) {
 628                                         skip -= iov_iter_count(&from);
 629                                         continue;
 630                                 }
 631                                 iov_iter_advance(&from, skip);
 632                                 skip = 0;
 633                         }
 634                         result = sock_xmit(nbd, index, 1, &from, flags, &sent);
 635                         if (result <= 0) {
 636                                 if (was_interrupted(result)) {
 637                                         /* We've already sent the header, we
 638                                          * have no choice but to set pending and
 639                                          * return BUSY.
 640                                          */
 641                                         nsock->pending = req;
 642                                         nsock->sent = sent;
 643                                         set_bit(NBD_CMD_REQUEUED, &cmd->flags);
 644                                         return BLK_STS_RESOURCE;
 645                                 }
 646                                 dev_err(disk_to_dev(nbd->disk),
 647                                         "Send data failed (result %d)\n",
 648                                         result);
 649                                 return -EAGAIN;
 650                         }
 651                         /*
 652                          * The completion might already have come in,
 653                          * so break for the last one instead of letting
 654                          * the iterator do it. This prevents use-after-free
 655                          * of the bio.
 656                          */
 657                         if (is_last)
 658                                 break;
 659                 }
 660                 bio = next;
 661         }
 662 out:
 663         trace_nbd_payload_sent(req, handle);
 664         nsock->pending = NULL;
 665         nsock->sent = 0;
 666         return 0;
 667 }
 668
 669 /* NULL returned = something went wrong, inform userspace */
 670 static struct nbd_cmd *nbd_read_stat(struct nbd_device *nbd, int index)
 671 {
 672         struct nbd_config *config = nbd->config;
 673         int result;
 674         struct nbd_reply reply;
 675         struct nbd_cmd *cmd;
 676         struct request *req = NULL;
 677         u64 handle;
 678         u16 hwq;
 679         u32 tag;
 680         struct kvec iov = {.iov_base = &reply, .iov_len = sizeof(reply)};
 681         struct iov_iter to;
 682         int ret = 0;
 683
 684         reply.magic = 0;
 685         iov_iter_kvec(&to, READ, &iov, 1, sizeof(reply));
 686         result = sock_xmit(nbd, index, 0, &to, MSG_WAITALL, NULL);
 687         if (result <= 0) {
 688                 if (!nbd_disconnected(config))
 689                         dev_err(disk_to_dev(nbd->disk),
 690                                 "Receive control failed (result %d)\n", result);
 691                 return ERR_PTR(result);
 692         }
 693
 694         if (ntohl(reply.magic) != NBD_REPLY_MAGIC) {
 695                 dev_err(disk_to_dev(nbd->disk), "Wrong magic (0x%lx)\n",
 696                                 (unsigned long)ntohl(reply.magic));
 697                 return ERR_PTR(-EPROTO);
 698         }
 699
 700         memcpy(&handle, reply.handle, sizeof(handle));
 701         tag = nbd_handle_to_tag(handle);
 702         hwq = blk_mq_unique_tag_to_hwq(tag);
 703         if (hwq < nbd->tag_set.nr_hw_queues)
 704                 req = blk_mq_tag_to_rq(nbd->tag_set.tags[hwq],
 705                                        blk_mq_unique_tag_to_tag(tag));
 706         if (!req || !blk_mq_request_started(req)) {
 707                 dev_err(disk_to_dev(nbd->disk), "Unexpected reply (%d) %p\n",
 708                         tag, req);
 709                 return ERR_PTR(-ENOENT);
 710         }
 711         trace_nbd_header_received(req, handle);
 712         cmd = blk_mq_rq_to_pdu(req);
 713
 714         mutex_lock(&cmd->lock);
 715         if (cmd->cmd_cookie != nbd_handle_to_cookie(handle)) {
 716                 dev_err(disk_to_dev(nbd->disk), "Double reply on req %p, cmd_cookie %u, handle cookie %u\n",
 717                         req, cmd->cmd_cookie, nbd_handle_to_cookie(handle));
 718                 ret = -ENOENT;
 719                 goto out;
 720         }
 721         if (cmd->status != BLK_STS_OK) {
 722                 dev_err(disk_to_dev(nbd->disk), "Command already handled %p\n",
 723                         req);
 724                 ret = -ENOENT;
 725                 goto out;
 726         }
 727         if (test_bit(NBD_CMD_REQUEUED, &cmd->flags)) {
 728                 dev_err(disk_to_dev(nbd->disk), "Raced with timeout on req %p\n",
 729                         req);
 730                 ret = -ENOENT;
 731                 goto out;
 732         }
 733         if (ntohl(reply.error)) {
 734                 dev_err(disk_to_dev(nbd->disk), "Other side returned error (%d)\n",
 735                         ntohl(reply.error));
 736                 cmd->status = BLK_STS_IOERR;
 737                 goto out;
 738         }
 739
 740         dev_dbg(nbd_to_dev(nbd), "request %p: got reply\n", req);
 741         if (rq_data_dir(req) != WRITE) {
 742                 struct req_iterator iter;
 743                 struct bio_vec bvec;
 744
 745                 rq_for_each_segment(bvec, req, iter) {
 746                         iov_iter_bvec(&to, READ, &bvec, 1, bvec.bv_len);
 747                         result = sock_xmit(nbd, index, 0, &to, MSG_WAITALL, NULL);
 748                         if (result <= 0) {
 749                                 dev_err(disk_to_dev(nbd->disk), "Receive data failed (result %d)\n",
 750                                         result);
 751                                 /*
 752                                  * If we've disconnected, we need to make sure we
 753                                  * complete this request, otherwise error out
 754                                  * and let the timeout stuff handle resubmitting
 755                                  * this request onto another connection.
 756                                  */
 757                                 if (nbd_disconnected(config)) {
 758                                         cmd->status = BLK_STS_IOERR;
 759                                         goto out;
 760                                 }
 761                                 ret = -EIO;
 762                                 goto out;
 763                         }
 764                         dev_dbg(nbd_to_dev(nbd), "request %p: got %d bytes data\n",
 765                                 req, bvec.bv_len);
 766                 }
 767         }
 768 out:
 769         trace_nbd_payload_received(req, handle);
 770         mutex_unlock(&cmd->lock);
 771         return ret ? ERR_PTR(ret) : cmd;
 772 }
 773
 774 static void recv_work(struct work_struct *work)
 775 {
 776         struct recv_thread_args *args = container_of(work,
 777                                                      struct recv_thread_args,
 778                                                      work);
 779         struct nbd_device *nbd = args->nbd;
 780         struct nbd_config *config = nbd->config;
 781         struct nbd_cmd *cmd;
 782         struct request *rq;
 783
 784         while (1) {
 785                 cmd = nbd_read_stat(nbd, args->index);
 786                 if (IS_ERR(cmd)) {
 787                         struct nbd_sock *nsock = config->socks[args->index];
 788
 789                         mutex_lock(&nsock->tx_lock);
 790                         nbd_mark_nsock_dead(nbd, nsock, 1);
 791                         mutex_unlock(&nsock->tx_lock);
 792                         break;
 793                 }
 794
 795                 rq = blk_mq_rq_from_pdu(cmd);
 796                 if (likely(!blk_should_fake_timeout(rq->q)))
 797                         blk_mq_complete_request(rq);
 798         }
 799         nbd_config_put(nbd);
 800         atomic_dec(&config->recv_threads);
 801         wake_up(&config->recv_wq);
 802         kfree(args);
 803 }
 804
 805 static bool nbd_clear_req(struct request *req, void *data, bool reserved)
 806 {
 807         struct nbd_cmd *cmd = blk_mq_rq_to_pdu(req);
 808
 809         mutex_lock(&cmd->lock);
 810         cmd->status = BLK_STS_IOERR;
 811         mutex_unlock(&cmd->lock);
 812
 813         blk_mq_complete_request(req);
 814         return true;
 815 }
 816
 817 static void nbd_clear_que(struct nbd_device *nbd)
 818 {
 819         blk_mq_quiesce_queue(nbd->disk->queue);
 820         blk_mq_tagset_busy_iter(&nbd->tag_set, nbd_clear_req, NULL);
 821         blk_mq_unquiesce_queue(nbd->disk->queue);
 822         dev_dbg(disk_to_dev(nbd->disk), "queue cleared\n");
 823 }
 824
 825 static int find_fallback(struct nbd_device *nbd, int index)
 826 {
 827         struct nbd_config *config = nbd->config;
 828         int new_index = -1;
 829         struct nbd_sock *nsock = config->socks[index];
 830         int fallback = nsock->fallback_index;
 831
 832         if (test_bit(NBD_RT_DISCONNECTED, &config->runtime_flags))
 833                 return new_index;
 834
 835         if (config->num_connections <= 1) {
 836                 dev_err_ratelimited(disk_to_dev(nbd->disk),
 837                                     "Dead connection, failed to find a fallback\n");
 838                 return new_index;
 839         }
 840
 841         if (fallback >= 0 && fallback < config->num_connections &&
 842             !config->socks[fallback]->dead)
 843                 return fallback;
 844
 845         if (nsock->fallback_index < 0 ||
 846             nsock->fallback_index >= config->num_connections ||
 847             config->socks[nsock->fallback_index]->dead) {
 848                 int i;
 849                 for (i = 0; i < config->num_connections; i++) {
 850                         if (i == index)
 851                                 continue;
 852                         if (!config->socks[i]->dead) {
 853                                 new_index = i;
 854                                 break;
 855                         }
 856                 }
 857                 nsock->fallback_index = new_index;
 858                 if (new_index < 0) {
 859                         dev_err_ratelimited(disk_to_dev(nbd->disk),
 860                                             "Dead connection, failed to find a fallback\n");
 861                         return new_index;
 862                 }
 863         }
 864         new_index = nsock->fallback_index;
 865         return new_index;
 866 }
 867
 868 static int wait_for_reconnect(struct nbd_device *nbd)
 869 {
 870         struct nbd_config *config = nbd->config;
 871         if (!config->dead_conn_timeout)
 872                 return 0;
 873         if (test_bit(NBD_RT_DISCONNECTED, &config->runtime_flags))
 874                 return 0;
 875         return wait_event_timeout(config->conn_wait,
 876                                   atomic_read(&config->live_connections) > 0,
 877                                   config->dead_conn_timeout) > 0;
 878 }
 879
 880 static int nbd_handle_cmd(struct nbd_cmd *cmd, int index)
 881 {
 882         struct request *req = blk_mq_rq_from_pdu(cmd);
 883         struct nbd_device *nbd = cmd->nbd;
 884         struct nbd_config *config;
 885         struct nbd_sock *nsock;
 886         int ret;
 887
 888         if (!refcount_inc_not_zero(&nbd->config_refs)) {
 889                 dev_err_ratelimited(disk_to_dev(nbd->disk),
 890                                     "Socks array is empty\n");
 891                 blk_mq_start_request(req);
 892                 return -EINVAL;
 893         }
 894         config = nbd->config;
 895
 896         if (index >= config->num_connections) {
 897                 dev_err_ratelimited(disk_to_dev(nbd->disk),
 898                                     "Attempted send on invalid socket\n");
 899                 nbd_config_put(nbd);
 900                 blk_mq_start_request(req);
 901                 return -EINVAL;
 902         }
 903         cmd->status = BLK_STS_OK;
 904 again:
 905         nsock = config->socks[index];
 906         mutex_lock(&nsock->tx_lock);
 907         if (nsock->dead) {
 908                 int old_index = index;
 909                 index = find_fallback(nbd, index);
 910                 mutex_unlock(&nsock->tx_lock);
 911                 if (index < 0) {
 912                         if (wait_for_reconnect(nbd)) {
 913                                 index = old_index;
 914                                 goto again;
 915                         }
 916                         /* All the sockets should already be down at this point,
 917                          * we just want to make sure that DISCONNECTED is set so
 918                          * any requests that come in that were queue'ed waiting
 919                          * for the reconnect timer don't trigger the timer again
 920                          * and instead just error out.
 921                          */
 922                         sock_shutdown(nbd);
 923                         nbd_config_put(nbd);
 924                         blk_mq_start_request(req);
 925                         return -EIO;
 926                 }
 927                 goto again;
 928         }
 929
 930         /* Handle the case that we have a pending request that was partially
 931          * transmitted that _has_ to be serviced first.  We need to call requeue
 932          * here so that it gets put _after_ the request that is already on the
 933          * dispatch list.
 934          */
 935         blk_mq_start_request(req);
 936         if (unlikely(nsock->pending && nsock->pending != req)) {
 937                 nbd_requeue_cmd(cmd);
 938                 ret = 0;
 939                 goto out;
 940         }
 941         /*
 942          * Some failures are related to the link going down, so anything that
 943          * returns EAGAIN can be retried on a different socket.
 944          */
 945         ret = nbd_send_cmd(nbd, cmd, index);
 946         if (ret == -EAGAIN) {
 947                 dev_err_ratelimited(disk_to_dev(nbd->disk),
 948                                     "Request send failed, requeueing\n");
 949                 nbd_mark_nsock_dead(nbd, nsock, 1);
 950                 nbd_requeue_cmd(cmd);
 951                 ret = 0;
 952         }
 953 out:
 954         mutex_unlock(&nsock->tx_lock);
 955         nbd_config_put(nbd);
 956         return ret;
 957 }
 958
 959 static blk_status_t nbd_queue_rq(struct blk_mq_hw_ctx *hctx,
 960                         const struct blk_mq_queue_data *bd)
 961 {
 962         struct nbd_cmd *cmd = blk_mq_rq_to_pdu(bd->rq);
 963         int ret;
 964
 965         /*
 966          * Since we look at the bio's to send the request over the network we
 967          * need to make sure the completion work doesn't mark this request done
 968          * before we are done doing our send.  This keeps us from dereferencing
 969          * freed data if we have particularly fast completions (ie we get the
 970          * completion before we exit sock_xmit on the last bvec) or in the case
 971          * that the server is misbehaving (or there was an error) before we're
 972          * done sending everything over the wire.
 973          */
 974         mutex_lock(&cmd->lock);
 975         clear_bit(NBD_CMD_REQUEUED, &cmd->flags);
 976
 977         /* We can be called directly from the user space process, which means we
 978          * could possibly have signals pending so our sendmsg will fail.  In
 979          * this case we need to return that we are busy, otherwise error out as
 980          * appropriate.
 981          */
 982         ret = nbd_handle_cmd(cmd, hctx->queue_num);
 983         if (ret < 0)
 984                 ret = BLK_STS_IOERR;
 985         else if (!ret)
 986                 ret = BLK_STS_OK;
 987         mutex_unlock(&cmd->lock);
 988
 989         return ret;
 990 }
 991
 992 static struct socket *nbd_get_socket(struct nbd_device *nbd, unsigned long fd,
 993                                      int *err)
 994 {
 995         struct socket *sock;
 996
 997         *err = 0;
 998         sock = sockfd_lookup(fd, err);
 999         if (!sock)
1000                 return NULL;
1001
1002         if (sock->ops->shutdown == sock_no_shutdown) {
1003                 dev_err(disk_to_dev(nbd->disk), "Unsupported socket: shutdown callout must be supported.\n");
1004                 *err = -EINVAL;
1005                 sockfd_put(sock);
1006                 return NULL;
1007         }
1008
1009         return sock;
1010 }
1011
1012 static int nbd_add_socket(struct nbd_device *nbd, unsigned long arg,
1013                           bool netlink)
1014 {
1015         struct nbd_config *config = nbd->config;
1016         struct socket *sock;
1017         struct nbd_sock **socks;
1018         struct nbd_sock *nsock;
1019         int err;
1020
1021         sock = nbd_get_socket(nbd, arg, &err);
1022         if (!sock)
1023                 return err;
1024
1025         /*
1026          * We need to make sure we don't get any errant requests while we're
1027          * reallocating the ->socks array.
1028          */
1029         blk_mq_freeze_queue(nbd->disk->queue);
1030
1031         if (!netlink && !nbd->task_setup &&
1032             !test_bit(NBD_RT_BOUND, &config->runtime_flags))
1033                 nbd->task_setup = current;
1034
1035         if (!netlink &&
1036             (nbd->task_setup != current ||
1037              test_bit(NBD_RT_BOUND, &config->runtime_flags))) {
1038                 dev_err(disk_to_dev(nbd->disk),
1039                         "Device being setup by another task");
1040                 err = -EBUSY;
1041                 goto put_socket;
1042         }
1043
1044         nsock = kzalloc(sizeof(*nsock), GFP_KERNEL);
1045         if (!nsock) {
1046                 err = -ENOMEM;
1047                 goto put_socket;
1048         }
1049
1050         socks = krealloc(config->socks, (config->num_connections + 1) *
1051                          sizeof(struct nbd_sock *), GFP_KERNEL);
1052         if (!socks) {
1053                 kfree(nsock);
1054                 err = -ENOMEM;
1055                 goto put_socket;
1056         }
1057
1058         config->socks = socks;
1059
1060         nsock->fallback_index = -1;
1061         nsock->dead = false;
1062         mutex_init(&nsock->tx_lock);
1063         nsock->sock = sock;
1064         nsock->pending = NULL;
1065         nsock->sent = 0;
1066         nsock->cookie = 0;
1067         socks[config->num_connections++] = nsock;
1068         atomic_inc(&config->live_connections);
1069         blk_mq_unfreeze_queue(nbd->disk->queue);
1070
1071         return 0;
1072
1073 put_socket:
1074         blk_mq_unfreeze_queue(nbd->disk->queue);
1075         sockfd_put(sock);
1076         return err;
1077 }
1078
1079 static int nbd_reconnect_socket(struct nbd_device *nbd, unsigned long arg)
1080 {
1081         struct nbd_config *config = nbd->config;
1082         struct socket *sock, *old;
1083         struct recv_thread_args *args;
1084         int i;
1085         int err;
1086
1087         sock = nbd_get_socket(nbd, arg, &err);
1088         if (!sock)
1089                 return err;
1090
1091         args = kzalloc(sizeof(*args), GFP_KERNEL);
1092         if (!args) {
1093                 sockfd_put(sock);
1094                 return -ENOMEM;
1095         }
1096
1097         for (i = 0; i < config->num_connections; i++) {
1098                 struct nbd_sock *nsock = config->socks[i];
1099
1100                 if (!nsock->dead)
1101                         continue;
1102
1103                 mutex_lock(&nsock->tx_lock);
1104                 if (!nsock->dead) {
1105                         mutex_unlock(&nsock->tx_lock);
1106                         continue;
1107                 }
1108                 sk_set_memalloc(sock->sk);
1109                 if (nbd->tag_set.timeout)
1110                         sock->sk->sk_sndtimeo = nbd->tag_set.timeout;
1111                 atomic_inc(&config->recv_threads);
1112                 refcount_inc(&nbd->config_refs);
1113                 old = nsock->sock;
1114                 nsock->fallback_index = -1;
1115                 nsock->sock = sock;
1116                 nsock->dead = false;
1117                 INIT_WORK(&args->work, recv_work);
1118                 args->index = i;
1119                 args->nbd = nbd;
1120                 nsock->cookie++;
1121                 mutex_unlock(&nsock->tx_lock);
1122                 sockfd_put(old);
1123
1124                 clear_bit(NBD_RT_DISCONNECTED, &config->runtime_flags);
1125
1126                 /* We take the tx_mutex in an error path in the recv_work, so we
1127                  * need to queue_work outside of the tx_mutex.
1128                  */
1129                 queue_work(nbd->recv_workq, &args->work);
1130
1131                 atomic_inc(&config->live_connections);
1132                 wake_up(&config->conn_wait);
1133                 return 0;
1134         }
1135         sockfd_put(sock);
1136         kfree(args);
1137         return -ENOSPC;
1138 }
1139
1140 static void nbd_bdev_reset(struct block_device *bdev)
1141 {
1142         if (bdev->bd_openers > 1)
1143                 return;
1144         set_capacity(bdev->bd_disk, 0);
1145 }
1146
1147 static void nbd_parse_flags(struct nbd_device *nbd)
1148 {
1149         struct nbd_config *config = nbd->config;
1150         if (config->flags & NBD_FLAG_READ_ONLY)
1151                 set_disk_ro(nbd->disk, true);
1152         else
1153                 set_disk_ro(nbd->disk, false);
1154         if (config->flags & NBD_FLAG_SEND_TRIM)
1155                 blk_queue_flag_set(QUEUE_FLAG_DISCARD, nbd->disk->queue);
1156         if (config->flags & NBD_FLAG_SEND_FLUSH) {
1157                 if (config->flags & NBD_FLAG_SEND_FUA)
1158                         blk_queue_write_cache(nbd->disk->queue, true, true);
1159                 else
1160                         blk_queue_write_cache(nbd->disk->queue, true, false);
1161         }
1162         else
1163                 blk_queue_write_cache(nbd->disk->queue, false, false);
1164 }
1165
1166 static void send_disconnects(struct nbd_device *nbd)
1167 {
1168         struct nbd_config *config = nbd->config;
1169         struct nbd_request request = {
1170                 .magic = htonl(NBD_REQUEST_MAGIC),
1171                 .type = htonl(NBD_CMD_DISC),
1172         };
1173         struct kvec iov = {.iov_base = &request, .iov_len = sizeof(request)};
1174         struct iov_iter from;
1175         int i, ret;
1176
1177         for (i = 0; i < config->num_connections; i++) {
1178                 struct nbd_sock *nsock = config->socks[i];
1179
1180                 iov_iter_kvec(&from, WRITE, &iov, 1, sizeof(request));
1181                 mutex_lock(&nsock->tx_lock);
1182                 ret = sock_xmit(nbd, i, 1, &from, 0, NULL);
1183                 if (ret <= 0)
1184                         dev_err(disk_to_dev(nbd->disk),
1185                                 "Send disconnect failed %d\n", ret);
1186                 mutex_unlock(&nsock->tx_lock);
1187         }
1188 }
1189
1190 static int nbd_disconnect(struct nbd_device *nbd)
1191 {
1192         struct nbd_config *config = nbd->config;
1193
1194         dev_info(disk_to_dev(nbd->disk), "NBD_DISCONNECT\n");
1195         set_bit(NBD_RT_DISCONNECT_REQUESTED, &config->runtime_flags);
1196         set_bit(NBD_DISCONNECT_REQUESTED, &nbd->flags);
1197         send_disconnects(nbd);
1198         return 0;
1199 }
1200
1201 static void nbd_clear_sock(struct nbd_device *nbd)
1202 {
1203         sock_shutdown(nbd);
1204         nbd_clear_que(nbd);
1205         nbd->task_setup = NULL;
1206 }
1207
1208 static void nbd_config_put(struct nbd_device *nbd)
1209 {
1210         if (refcount_dec_and_mutex_lock(&nbd->config_refs,
1211                                         &nbd->config_lock)) {
1212                 struct nbd_config *config = nbd->config;
1213                 nbd_dev_dbg_close(nbd);
1214                 nbd_size_clear(nbd);
1215                 if (test_and_clear_bit(NBD_RT_HAS_PID_FILE,
1216                                        &config->runtime_flags))
1217                         device_remove_file(disk_to_dev(nbd->disk), &pid_attr);
1218                 nbd->task_recv = NULL;
1219                 nbd_clear_sock(nbd);
1220                 if (config->num_connections) {
1221                         int i;
1222                         for (i = 0; i < config->num_connections; i++) {
1223                                 sockfd_put(config->socks[i]->sock);
1224                                 kfree(config->socks[i]);
1225                         }
1226                         kfree(config->socks);
1227                 }
1228                 kfree(nbd->config);
1229                 nbd->config = NULL;
1230
1231                 if (nbd->recv_workq)
1232                         destroy_workqueue(nbd->recv_workq);
1233                 nbd->recv_workq = NULL;
1234
1235                 nbd->tag_set.timeout = 0;
1236                 nbd->disk->queue->limits.discard_granularity = 0;
1237                 nbd->disk->queue->limits.discard_alignment = 0;
1238                 blk_queue_max_discard_sectors(nbd->disk->queue, UINT_MAX);
1239                 blk_queue_flag_clear(QUEUE_FLAG_DISCARD, nbd->disk->queue);
1240
1241                 mutex_unlock(&nbd->config_lock);
1242                 nbd_put(nbd);
1243                 module_put(THIS_MODULE);
1244         }
1245 }
1246
1247 static int nbd_start_device(struct nbd_device *nbd)
1248 {
1249         struct nbd_config *config = nbd->config;
1250         int num_connections = config->num_connections;
1251         int error = 0, i;
1252
1253         if (nbd->task_recv)
1254                 return -EBUSY;
1255         if (!config->socks)
1256                 return -EINVAL;
1257         if (num_connections > 1 &&
1258             !(config->flags & NBD_FLAG_CAN_MULTI_CONN)) {
1259                 dev_err(disk_to_dev(nbd->disk), "server does not support multiple connections per device.\n");
1260                 return -EINVAL;
1261         }
1262
1263         nbd->recv_workq = alloc_workqueue("knbd%d-recv",
1264                                           WQ_MEM_RECLAIM | WQ_HIGHPRI |
1265                                           WQ_UNBOUND, 0, nbd->index);
1266         if (!nbd->recv_workq) {
1267                 dev_err(disk_to_dev(nbd->disk), "Could not allocate knbd recv work queue.\n");
1268                 return -ENOMEM;
1269         }
1270
1271         blk_mq_update_nr_hw_queues(&nbd->tag_set, config->num_connections);
1272         nbd->task_recv = current;
1273
1274         nbd_parse_flags(nbd);
1275
1276         error = device_create_file(disk_to_dev(nbd->disk), &pid_attr);
1277         if (error) {
1278                 dev_err(disk_to_dev(nbd->disk), "device_create_file failed!\n");
1279                 return error;
1280         }
1281         set_bit(NBD_RT_HAS_PID_FILE, &config->runtime_flags);
1282
1283         nbd_dev_dbg_init(nbd);
1284         for (i = 0; i < num_connections; i++) {
1285                 struct recv_thread_args *args;
1286
1287                 args = kzalloc(sizeof(*args), GFP_KERNEL);
1288                 if (!args) {
1289                         sock_shutdown(nbd);
1290                         /*
1291                          * If num_connections is m (2 < m),
1292                          * and NO.1 ~ NO.n(1 < n < m) kzallocs are successful.
1293                          * But NO.(n + 1) failed. We still have n recv threads.
1294                          * So, add flush_workqueue here to prevent recv threads
1295                          * dropping the last config_refs and trying to destroy
1296                          * the workqueue from inside the workqueue.
1297                          */
1298                         if (i)
1299                                 flush_workqueue(nbd->recv_workq);
1300                         return -ENOMEM;
1301                 }
1302                 sk_set_memalloc(config->socks[i]->sock->sk);
1303                 if (nbd->tag_set.timeout)
1304                         config->socks[i]->sock->sk->sk_sndtimeo =
1305                                 nbd->tag_set.timeout;
1306                 atomic_inc(&config->recv_threads);
1307                 refcount_inc(&nbd->config_refs);
1308                 INIT_WORK(&args->work, recv_work);
1309                 args->nbd = nbd;
1310                 args->index = i;
1311                 queue_work(nbd->recv_workq, &args->work);
1312         }
1313         return nbd_set_size(nbd, config->bytesize, config->blksize);
1314 }
1315
1316 static int nbd_start_device_ioctl(struct nbd_device *nbd, struct block_device *bdev)
1317 {
1318         struct nbd_config *config = nbd->config;
1319         int ret;
1320
1321         ret = nbd_start_device(nbd);
1322         if (ret)
1323                 return ret;
1324
1325         if (max_part)
1326                 set_bit(GD_NEED_PART_SCAN, &nbd->disk->state);
1327         mutex_unlock(&nbd->config_lock);
1328         ret = wait_event_interruptible(config->recv_wq,
1329                                          atomic_read(&config->recv_threads) == 0);
1330         if (ret)
1331                 sock_shutdown(nbd);
1332         flush_workqueue(nbd->recv_workq);
1333
1334         mutex_lock(&nbd->config_lock);
1335         nbd_bdev_reset(bdev);
1336         /* user requested, ignore socket errors */
1337         if (test_bit(NBD_RT_DISCONNECT_REQUESTED, &config->runtime_flags))
1338                 ret = 0;
1339         if (test_bit(NBD_RT_TIMEDOUT, &config->runtime_flags))
1340                 ret = -ETIMEDOUT;
1341         return ret;
1342 }
1343
1344 static void nbd_clear_sock_ioctl(struct nbd_device *nbd,
1345                                  struct block_device *bdev)
1346 {
1347         sock_shutdown(nbd);
1348         __invalidate_device(bdev, true);
1349         nbd_bdev_reset(bdev);
1350         if (test_and_clear_bit(NBD_RT_HAS_CONFIG_REF,
1351                                &nbd->config->runtime_flags))
1352                 nbd_config_put(nbd);
1353 }
1354
1355 static void nbd_set_cmd_timeout(struct nbd_device *nbd, u64 timeout)
1356 {
1357         nbd->tag_set.timeout = timeout * HZ;
1358         if (timeout)
1359                 blk_queue_rq_timeout(nbd->disk->queue, timeout * HZ);
1360         else
1361                 blk_queue_rq_timeout(nbd->disk->queue, 30 * HZ);
1362 }
1363
1364 /* Must be called with config_lock held */
1365 static int __nbd_ioctl(struct block_device *bdev, struct nbd_device *nbd,
1366                        unsigned int cmd, unsigned long arg)
1367 {
1368         struct nbd_config *config = nbd->config;
1369
1370         switch (cmd) {
1371         case NBD_DISCONNECT:
1372                 return nbd_disconnect(nbd);
1373         case NBD_CLEAR_SOCK:
1374                 nbd_clear_sock_ioctl(nbd, bdev);
1375                 return 0;
1376         case NBD_SET_SOCK:
1377                 return nbd_add_socket(nbd, arg, false);
1378         case NBD_SET_BLKSIZE:
1379                 return nbd_set_size(nbd, config->bytesize, arg);
1380         case NBD_SET_SIZE:
1381                 return nbd_set_size(nbd, arg, config->blksize);
1382         case NBD_SET_SIZE_BLOCKS:
1383                 return nbd_set_size(nbd, arg * config->blksize,
1384                                     config->blksize);
1385         case NBD_SET_TIMEOUT:
1386                 nbd_set_cmd_timeout(nbd, arg);
1387                 return 0;
1388
1389         case NBD_SET_FLAGS:
1390                 config->flags = arg;
1391                 return 0;
1392         case NBD_DO_IT:
1393                 return nbd_start_device_ioctl(nbd, bdev);
1394         case NBD_CLEAR_QUE:
1395                 /*
1396                  * This is for compatibility only.  The queue is always cleared
1397                  * by NBD_DO_IT or NBD_CLEAR_SOCK.
1398                  */
1399                 return 0;
1400         case NBD_PRINT_DEBUG:
1401                 /*
1402                  * For compatibility only, we no longer keep a list of
1403                  * outstanding requests.
1404                  */
1405                 return 0;
1406         }
1407         return -ENOTTY;
1408 }
1409
1410 static int nbd_ioctl(struct block_device *bdev, fmode_t mode,
1411                      unsigned int cmd, unsigned long arg)
1412 {
1413         struct nbd_device *nbd = bdev->bd_disk->private_data;
1414         struct nbd_config *config = nbd->config;
1415         int error = -EINVAL;
1416
1417         if (!capable(CAP_SYS_ADMIN))
1418                 return -EPERM;
1419
1420         /* The block layer will pass back some non-nbd ioctls in case we have
1421          * special handling for them, but we don't so just return an error.
1422          */
1423         if (_IOC_TYPE(cmd) != 0xab)
1424                 return -EINVAL;
1425
1426         mutex_lock(&nbd->config_lock);
1427
1428         /* Don't allow ioctl operations on a nbd device that was created with
1429          * netlink, unless it's DISCONNECT or CLEAR_SOCK, which are fine.
1430          */
1431         if (!test_bit(NBD_RT_BOUND, &config->runtime_flags) ||
1432             (cmd == NBD_DISCONNECT || cmd == NBD_CLEAR_SOCK))
1433                 error = __nbd_ioctl(bdev, nbd, cmd, arg);
1434         else
1435                 dev_err(nbd_to_dev(nbd), "Cannot use ioctl interface on a netlink controlled device.\n");
1436         mutex_unlock(&nbd->config_lock);
1437         return error;
1438 }
1439
1440 static struct nbd_config *nbd_alloc_config(void)
1441 {
1442         struct nbd_config *config;
1443
1444         config = kzalloc(sizeof(struct nbd_config), GFP_NOFS);
1445         if (!config)
1446                 return NULL;
1447         atomic_set(&config->recv_threads, 0);
1448         init_waitqueue_head(&config->recv_wq);
1449         init_waitqueue_head(&config->conn_wait);
1450         config->blksize = NBD_DEF_BLKSIZE;
1451         atomic_set(&config->live_connections, 0);
1452         try_module_get(THIS_MODULE);
1453         return config;
1454 }
1455
1456 static int nbd_open(struct block_device *bdev, fmode_t mode)
1457 {
1458         struct nbd_device *nbd;
1459         int ret = 0;
1460
1461         mutex_lock(&nbd_index_mutex);
1462         nbd = bdev->bd_disk->private_data;
1463         if (!nbd) {
1464                 ret = -ENXIO;
1465                 goto out;
1466         }
1467         if (!refcount_inc_not_zero(&nbd->refs)) {
1468                 ret = -ENXIO;
1469                 goto out;
1470         }
1471         if (!refcount_inc_not_zero(&nbd->config_refs)) {
1472                 struct nbd_config *config;
1473
1474                 mutex_lock(&nbd->config_lock);
1475                 if (refcount_inc_not_zero(&nbd->config_refs)) {
1476                         mutex_unlock(&nbd->config_lock);
1477                         goto out;
1478                 }
1479                 config = nbd->config = nbd_alloc_config();
1480                 if (!config) {
1481                         ret = -ENOMEM;
1482                         mutex_unlock(&nbd->config_lock);
1483                         goto out;
1484                 }
1485                 refcount_set(&nbd->config_refs, 1);
1486                 refcount_inc(&nbd->refs);
1487                 mutex_unlock(&nbd->config_lock);
1488                 if (max_part)
1489                         set_bit(GD_NEED_PART_SCAN, &bdev->bd_disk->state);
1490         } else if (nbd_disconnected(nbd->config)) {
1491                 if (max_part)
1492                         set_bit(GD_NEED_PART_SCAN, &bdev->bd_disk->state);
1493         }
1494 out:
1495         mutex_unlock(&nbd_index_mutex);
1496         return ret;
1497 }
1498
1499 static void nbd_release(struct gendisk *disk, fmode_t mode)
1500 {
1501         struct nbd_device *nbd = disk->private_data;
1502
1503         if (test_bit(NBD_RT_DISCONNECT_ON_CLOSE, &nbd->config->runtime_flags) &&
1504                         disk->part0->bd_openers == 0)
1505                 nbd_disconnect_and_put(nbd);
1506
1507         nbd_config_put(nbd);
1508         nbd_put(nbd);
1509 }
1510
1511 static const struct block_device_operations nbd_fops =
1512 {
1513         .owner =        THIS_MODULE,
1514         .open =         nbd_open,
1515         .release =      nbd_release,
1516         .ioctl =        nbd_ioctl,
1517         .compat_ioctl = nbd_ioctl,
1518 };
1519
1520 #if IS_ENABLED(CONFIG_DEBUG_FS)
1521
1522 static int nbd_dbg_tasks_show(struct seq_file *s, void *unused)
1523 {
1524         struct nbd_device *nbd = s->private;
1525
1526         if (nbd->task_recv)
1527                 seq_printf(s, "recv: %d\n", task_pid_nr(nbd->task_recv));
1528
1529         return 0;
1530 }
1531
1532 DEFINE_SHOW_ATTRIBUTE(nbd_dbg_tasks);
1533
1534 static int nbd_dbg_flags_show(struct seq_file *s, void *unused)
1535 {
1536         struct nbd_device *nbd = s->private;
1537         u32 flags = nbd->config->flags;
1538
1539         seq_printf(s, "Hex: 0x%08x\n\n", flags);
1540
1541         seq_puts(s, "Known flags:\n");
1542
1543         if (flags & NBD_FLAG_HAS_FLAGS)
1544                 seq_puts(s, "NBD_FLAG_HAS_FLAGS\n");
1545         if (flags & NBD_FLAG_READ_ONLY)
1546                 seq_puts(s, "NBD_FLAG_READ_ONLY\n");
1547         if (flags & NBD_FLAG_SEND_FLUSH)
1548                 seq_puts(s, "NBD_FLAG_SEND_FLUSH\n");
1549         if (flags & NBD_FLAG_SEND_FUA)
1550                 seq_puts(s, "NBD_FLAG_SEND_FUA\n");
1551         if (flags & NBD_FLAG_SEND_TRIM)
1552                 seq_puts(s, "NBD_FLAG_SEND_TRIM\n");
1553
1554         return 0;
1555 }
1556
1557 DEFINE_SHOW_ATTRIBUTE(nbd_dbg_flags);
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_fops);
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_fops);
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
1785         if (bytes != config->bytesize || bsize != config->blksize)
1786                 return nbd_set_size(nbd, bytes, bsize);
1787         return 0;
1788 }
1789
1790 static int nbd_genl_connect(struct sk_buff *skb, struct genl_info *info)
1791 {
1792         DECLARE_COMPLETION_ONSTACK(destroy_complete);
1793         struct nbd_device *nbd = NULL;
1794         struct nbd_config *config;
1795         int index = -1;
1796         int ret;
1797         bool put_dev = false;
1798
1799         if (!netlink_capable(skb, CAP_SYS_ADMIN))
1800                 return -EPERM;
1801
1802         if (info->attrs[NBD_ATTR_INDEX])
1803                 index = nla_get_u32(info->attrs[NBD_ATTR_INDEX]);
1804         if (!info->attrs[NBD_ATTR_SOCKETS]) {
1805                 printk(KERN_ERR "nbd: must specify at least one socket\n");
1806                 return -EINVAL;
1807         }
1808         if (!info->attrs[NBD_ATTR_SIZE_BYTES]) {
1809                 printk(KERN_ERR "nbd: must specify a size in bytes for the device\n");
1810                 return -EINVAL;
1811         }
1812 again:
1813         mutex_lock(&nbd_index_mutex);
1814         if (index == -1) {
1815                 ret = idr_for_each(&nbd_index_idr, &find_free_cb, &nbd);
1816                 if (ret == 0) {
1817                         int new_index;
1818                         new_index = nbd_dev_add(-1);
1819                         if (new_index < 0) {
1820                                 mutex_unlock(&nbd_index_mutex);
1821                                 printk(KERN_ERR "nbd: failed to add new device\n");
1822                                 return new_index;
1823                         }
1824                         nbd = idr_find(&nbd_index_idr, new_index);
1825                 }
1826         } else {
1827                 nbd = idr_find(&nbd_index_idr, index);
1828                 if (!nbd) {
1829                         ret = nbd_dev_add(index);
1830                         if (ret < 0) {
1831                                 mutex_unlock(&nbd_index_mutex);
1832                                 printk(KERN_ERR "nbd: failed to add new device\n");
1833                                 return ret;
1834                         }
1835                         nbd = idr_find(&nbd_index_idr, index);
1836                 }
1837         }
1838         if (!nbd) {
1839                 printk(KERN_ERR "nbd: couldn't find device at index %d\n",
1840                        index);
1841                 mutex_unlock(&nbd_index_mutex);
1842                 return -EINVAL;
1843         }
1844
1845         if (test_bit(NBD_DESTROY_ON_DISCONNECT, &nbd->flags) &&
1846             test_bit(NBD_DISCONNECT_REQUESTED, &nbd->flags)) {
1847                 nbd->destroy_complete = &destroy_complete;
1848                 mutex_unlock(&nbd_index_mutex);
1849
1850                 /* Wait untill the the nbd stuff is totally destroyed */
1851                 wait_for_completion(&destroy_complete);
1852                 goto again;
1853         }
1854
1855         if (!refcount_inc_not_zero(&nbd->refs)) {
1856                 mutex_unlock(&nbd_index_mutex);
1857                 if (index == -1)
1858                         goto again;
1859                 printk(KERN_ERR "nbd: device at index %d is going down\n",
1860                        index);
1861                 return -EINVAL;
1862         }
1863         mutex_unlock(&nbd_index_mutex);
1864
1865         mutex_lock(&nbd->config_lock);
1866         if (refcount_read(&nbd->config_refs)) {
1867                 mutex_unlock(&nbd->config_lock);
1868                 nbd_put(nbd);
1869                 if (index == -1)
1870                         goto again;
1871                 printk(KERN_ERR "nbd: nbd%d already in use\n", index);
1872                 return -EBUSY;
1873         }
1874         if (WARN_ON(nbd->config)) {
1875                 mutex_unlock(&nbd->config_lock);
1876                 nbd_put(nbd);
1877                 return -EINVAL;
1878         }
1879         config = nbd->config = nbd_alloc_config();
1880         if (!nbd->config) {
1881                 mutex_unlock(&nbd->config_lock);
1882                 nbd_put(nbd);
1883                 printk(KERN_ERR "nbd: couldn't allocate config\n");
1884                 return -ENOMEM;
1885         }
1886         refcount_set(&nbd->config_refs, 1);
1887         set_bit(NBD_RT_BOUND, &config->runtime_flags);
1888
1889         ret = nbd_genl_size_set(info, nbd);
1890         if (ret)
1891                 goto out;
1892
1893         if (info->attrs[NBD_ATTR_TIMEOUT])
1894                 nbd_set_cmd_timeout(nbd,
1895                                     nla_get_u64(info->attrs[NBD_ATTR_TIMEOUT]));
1896         if (info->attrs[NBD_ATTR_DEAD_CONN_TIMEOUT]) {
1897                 config->dead_conn_timeout =
1898                         nla_get_u64(info->attrs[NBD_ATTR_DEAD_CONN_TIMEOUT]);
1899                 config->dead_conn_timeout *= HZ;
1900         }
1901         if (info->attrs[NBD_ATTR_SERVER_FLAGS])
1902                 config->flags =
1903                         nla_get_u64(info->attrs[NBD_ATTR_SERVER_FLAGS]);
1904         if (info->attrs[NBD_ATTR_CLIENT_FLAGS]) {
1905                 u64 flags = nla_get_u64(info->attrs[NBD_ATTR_CLIENT_FLAGS]);
1906                 if (flags & NBD_CFLAG_DESTROY_ON_DISCONNECT) {
1907                         set_bit(NBD_RT_DESTROY_ON_DISCONNECT,
1908                                 &config->runtime_flags);
1909                         set_bit(NBD_DESTROY_ON_DISCONNECT, &nbd->flags);
1910                         put_dev = true;
1911                 } else {
1912                         clear_bit(NBD_DESTROY_ON_DISCONNECT, &nbd->flags);
1913                 }
1914                 if (flags & NBD_CFLAG_DISCONNECT_ON_CLOSE) {
1915                         set_bit(NBD_RT_DISCONNECT_ON_CLOSE,
1916                                 &config->runtime_flags);
1917                 }
1918         }
1919
1920         if (info->attrs[NBD_ATTR_SOCKETS]) {
1921                 struct nlattr *attr;
1922                 int rem, fd;
1923
1924                 nla_for_each_nested(attr, info->attrs[NBD_ATTR_SOCKETS],
1925                                     rem) {
1926                         struct nlattr *socks[NBD_SOCK_MAX+1];
1927
1928                         if (nla_type(attr) != NBD_SOCK_ITEM) {
1929                                 printk(KERN_ERR "nbd: socks must be embedded in a SOCK_ITEM attr\n");
1930                                 ret = -EINVAL;
1931                                 goto out;
1932                         }
1933                         ret = nla_parse_nested_deprecated(socks, NBD_SOCK_MAX,
1934                                                           attr,
1935                                                           nbd_sock_policy,
1936                                                           info->extack);
1937                         if (ret != 0) {
1938                                 printk(KERN_ERR "nbd: error processing sock list\n");
1939                                 ret = -EINVAL;
1940                                 goto out;
1941                         }
1942                         if (!socks[NBD_SOCK_FD])
1943                                 continue;
1944                         fd = (int)nla_get_u32(socks[NBD_SOCK_FD]);
1945                         ret = nbd_add_socket(nbd, fd, true);
1946                         if (ret)
1947                                 goto out;
1948                 }
1949         }
1950         ret = nbd_start_device(nbd);
1951 out:
1952         mutex_unlock(&nbd->config_lock);
1953         if (!ret) {
1954                 set_bit(NBD_RT_HAS_CONFIG_REF, &config->runtime_flags);
1955                 refcount_inc(&nbd->config_refs);
1956                 nbd_connect_reply(info, nbd->index);
1957         }
1958         nbd_config_put(nbd);
1959         if (put_dev)
1960                 nbd_put(nbd);
1961         return ret;
1962 }
1963
1964 static void nbd_disconnect_and_put(struct nbd_device *nbd)
1965 {
1966         mutex_lock(&nbd->config_lock);
1967         nbd_disconnect(nbd);
1968         nbd_clear_sock(nbd);
1969         mutex_unlock(&nbd->config_lock);
1970         /*
1971          * Make sure recv thread has finished, so it does not drop the last
1972          * config ref and try to destroy the workqueue from inside the work
1973          * queue.
1974          */
1975         flush_workqueue(nbd->recv_workq);
1976         if (test_and_clear_bit(NBD_RT_HAS_CONFIG_REF,
1977                                &nbd->config->runtime_flags))
1978                 nbd_config_put(nbd);
1979 }
1980
1981 static int nbd_genl_disconnect(struct sk_buff *skb, struct genl_info *info)
1982 {
1983         struct nbd_device *nbd;
1984         int index;
1985
1986         if (!netlink_capable(skb, CAP_SYS_ADMIN))
1987                 return -EPERM;
1988
1989         if (!info->attrs[NBD_ATTR_INDEX]) {
1990                 printk(KERN_ERR "nbd: must specify an index to disconnect\n");
1991                 return -EINVAL;
1992         }
1993         index = nla_get_u32(info->attrs[NBD_ATTR_INDEX]);
1994         mutex_lock(&nbd_index_mutex);
1995         nbd = idr_find(&nbd_index_idr, index);
1996         if (!nbd) {
1997                 mutex_unlock(&nbd_index_mutex);
1998                 printk(KERN_ERR "nbd: couldn't find device at index %d\n",
1999                        index);
2000                 return -EINVAL;
2001         }
2002         if (!refcount_inc_not_zero(&nbd->refs)) {
2003                 mutex_unlock(&nbd_index_mutex);
2004                 printk(KERN_ERR "nbd: device at index %d is going down\n",
2005                        index);
2006                 return -EINVAL;
2007         }
2008         mutex_unlock(&nbd_index_mutex);
2009         if (!refcount_inc_not_zero(&nbd->config_refs)) {
2010                 nbd_put(nbd);
2011                 return 0;
2012         }
2013         nbd_disconnect_and_put(nbd);
2014         nbd_config_put(nbd);
2015         nbd_put(nbd);
2016         return 0;
2017 }
2018
2019 static int nbd_genl_reconfigure(struct sk_buff *skb, struct genl_info *info)
2020 {
2021         struct nbd_device *nbd = NULL;
2022         struct nbd_config *config;
2023         int index;
2024         int ret = 0;
2025         bool put_dev = false;
2026
2027         if (!netlink_capable(skb, CAP_SYS_ADMIN))
2028                 return -EPERM;
2029
2030         if (!info->attrs[NBD_ATTR_INDEX]) {
2031                 printk(KERN_ERR "nbd: must specify a device to reconfigure\n");
2032                 return -EINVAL;
2033         }
2034         index = nla_get_u32(info->attrs[NBD_ATTR_INDEX]);
2035         mutex_lock(&nbd_index_mutex);
2036         nbd = idr_find(&nbd_index_idr, index);
2037         if (!nbd) {
2038                 mutex_unlock(&nbd_index_mutex);
2039                 printk(KERN_ERR "nbd: couldn't find a device at index %d\n",
2040                        index);
2041                 return -EINVAL;
2042         }
2043         if (!refcount_inc_not_zero(&nbd->refs)) {
2044                 mutex_unlock(&nbd_index_mutex);
2045                 printk(KERN_ERR "nbd: device at index %d is going down\n",
2046                        index);
2047                 return -EINVAL;
2048         }
2049         mutex_unlock(&nbd_index_mutex);
2050
2051         if (!refcount_inc_not_zero(&nbd->config_refs)) {
2052                 dev_err(nbd_to_dev(nbd),
2053                         "not configured, cannot reconfigure\n");
2054                 nbd_put(nbd);
2055                 return -EINVAL;
2056         }
2057
2058         mutex_lock(&nbd->config_lock);
2059         config = nbd->config;
2060         if (!test_bit(NBD_RT_BOUND, &config->runtime_flags) ||
2061             !nbd->task_recv) {
2062                 dev_err(nbd_to_dev(nbd),
2063                         "not configured, cannot reconfigure\n");
2064                 ret = -EINVAL;
2065                 goto out;
2066         }
2067
2068         ret = nbd_genl_size_set(info, nbd);
2069         if (ret)
2070                 goto out;
2071
2072         if (info->attrs[NBD_ATTR_TIMEOUT])
2073                 nbd_set_cmd_timeout(nbd,
2074                                     nla_get_u64(info->attrs[NBD_ATTR_TIMEOUT]));
2075         if (info->attrs[NBD_ATTR_DEAD_CONN_TIMEOUT]) {
2076                 config->dead_conn_timeout =
2077                         nla_get_u64(info->attrs[NBD_ATTR_DEAD_CONN_TIMEOUT]);
2078                 config->dead_conn_timeout *= HZ;
2079         }
2080         if (info->attrs[NBD_ATTR_CLIENT_FLAGS]) {
2081                 u64 flags = nla_get_u64(info->attrs[NBD_ATTR_CLIENT_FLAGS]);
2082                 if (flags & NBD_CFLAG_DESTROY_ON_DISCONNECT) {
2083                         if (!test_and_set_bit(NBD_RT_DESTROY_ON_DISCONNECT,
2084                                               &config->runtime_flags))
2085                                 put_dev = true;
2086                         set_bit(NBD_DESTROY_ON_DISCONNECT, &nbd->flags);
2087                 } else {
2088                         if (test_and_clear_bit(NBD_RT_DESTROY_ON_DISCONNECT,
2089                                                &config->runtime_flags))
2090                                 refcount_inc(&nbd->refs);
2091                         clear_bit(NBD_DESTROY_ON_DISCONNECT, &nbd->flags);
2092                 }
2093
2094                 if (flags & NBD_CFLAG_DISCONNECT_ON_CLOSE) {
2095                         set_bit(NBD_RT_DISCONNECT_ON_CLOSE,
2096                                         &config->runtime_flags);
2097                 } else {
2098                         clear_bit(NBD_RT_DISCONNECT_ON_CLOSE,
2099                                         &config->runtime_flags);
2100                 }
2101         }
2102
2103         if (info->attrs[NBD_ATTR_SOCKETS]) {
2104                 struct nlattr *attr;
2105                 int rem, fd;
2106
2107                 nla_for_each_nested(attr, info->attrs[NBD_ATTR_SOCKETS],
2108                                     rem) {
2109                         struct nlattr *socks[NBD_SOCK_MAX+1];
2110
2111                         if (nla_type(attr) != NBD_SOCK_ITEM) {
2112                                 printk(KERN_ERR "nbd: socks must be embedded in a SOCK_ITEM attr\n");
2113                                 ret = -EINVAL;
2114                                 goto out;
2115                         }
2116                         ret = nla_parse_nested_deprecated(socks, NBD_SOCK_MAX,
2117                                                           attr,
2118                                                           nbd_sock_policy,
2119                                                           info->extack);
2120                         if (ret != 0) {
2121                                 printk(KERN_ERR "nbd: error processing sock list\n");
2122                                 ret = -EINVAL;
2123                                 goto out;
2124                         }
2125                         if (!socks[NBD_SOCK_FD])
2126                                 continue;
2127                         fd = (int)nla_get_u32(socks[NBD_SOCK_FD]);
2128                         ret = nbd_reconnect_socket(nbd, fd);
2129                         if (ret) {
2130                                 if (ret == -ENOSPC)
2131                                         ret = 0;
2132                                 goto out;
2133                         }
2134                         dev_info(nbd_to_dev(nbd), "reconnected socket\n");
2135                 }
2136         }
2137 out:
2138         mutex_unlock(&nbd->config_lock);
2139         nbd_config_put(nbd);
2140         nbd_put(nbd);
2141         if (put_dev)
2142                 nbd_put(nbd);
2143         return ret;
2144 }
2145
2146 static const struct genl_small_ops nbd_connect_genl_ops[] = {
2147         {
2148                 .cmd    = NBD_CMD_CONNECT,
2149                 .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
2150                 .doit   = nbd_genl_connect,
2151         },
2152         {
2153                 .cmd    = NBD_CMD_DISCONNECT,
2154                 .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
2155                 .doit   = nbd_genl_disconnect,
2156         },
2157         {
2158                 .cmd    = NBD_CMD_RECONFIGURE,
2159                 .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
2160                 .doit   = nbd_genl_reconfigure,
2161         },
2162         {
2163                 .cmd    = NBD_CMD_STATUS,
2164                 .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
2165                 .doit   = nbd_genl_status,
2166         },
2167 };
2168
2169 static const struct genl_multicast_group nbd_mcast_grps[] = {
2170         { .name = NBD_GENL_MCAST_GROUP_NAME, },
2171 };
2172
2173 static struct genl_family nbd_genl_family __ro_after_init = {
2174         .hdrsize        = 0,
2175         .name           = NBD_GENL_FAMILY_NAME,
2176         .version        = NBD_GENL_VERSION,
2177         .module         = THIS_MODULE,
2178         .small_ops      = nbd_connect_genl_ops,
2179         .n_small_ops    = ARRAY_SIZE(nbd_connect_genl_ops),
2180         .maxattr        = NBD_ATTR_MAX,
2181         .policy = nbd_attr_policy,
2182         .mcgrps         = nbd_mcast_grps,
2183         .n_mcgrps       = ARRAY_SIZE(nbd_mcast_grps),
2184 };
2185
2186 static int populate_nbd_status(struct nbd_device *nbd, struct sk_buff *reply)
2187 {
2188         struct nlattr *dev_opt;
2189         u8 connected = 0;
2190         int ret;
2191
2192         /* This is a little racey, but for status it's ok.  The
2193          * reason we don't take a ref here is because we can't
2194          * take a ref in the index == -1 case as we would need
2195          * to put under the nbd_index_mutex, which could
2196          * deadlock if we are configured to remove ourselves
2197          * once we're disconnected.
2198          */
2199         if (refcount_read(&nbd->config_refs))
2200                 connected = 1;
2201         dev_opt = nla_nest_start_noflag(reply, NBD_DEVICE_ITEM);
2202         if (!dev_opt)
2203                 return -EMSGSIZE;
2204         ret = nla_put_u32(reply, NBD_DEVICE_INDEX, nbd->index);
2205         if (ret)
2206                 return -EMSGSIZE;
2207         ret = nla_put_u8(reply, NBD_DEVICE_CONNECTED,
2208                          connected);
2209         if (ret)
2210                 return -EMSGSIZE;
2211         nla_nest_end(reply, dev_opt);
2212         return 0;
2213 }
2214
2215 static int status_cb(int id, void *ptr, void *data)
2216 {
2217         struct nbd_device *nbd = ptr;
2218         return populate_nbd_status(nbd, (struct sk_buff *)data);
2219 }
2220
2221 static int nbd_genl_status(struct sk_buff *skb, struct genl_info *info)
2222 {
2223         struct nlattr *dev_list;
2224         struct sk_buff *reply;
2225         void *reply_head;
2226         size_t msg_size;
2227         int index = -1;
2228         int ret = -ENOMEM;
2229
2230         if (info->attrs[NBD_ATTR_INDEX])
2231                 index = nla_get_u32(info->attrs[NBD_ATTR_INDEX]);
2232
2233         mutex_lock(&nbd_index_mutex);
2234
2235         msg_size = nla_total_size(nla_attr_size(sizeof(u32)) +
2236                                   nla_attr_size(sizeof(u8)));
2237         msg_size *= (index == -1) ? nbd_total_devices : 1;
2238
2239         reply = genlmsg_new(msg_size, GFP_KERNEL);
2240         if (!reply)
2241                 goto out;
2242         reply_head = genlmsg_put_reply(reply, info, &nbd_genl_family, 0,
2243                                        NBD_CMD_STATUS);
2244         if (!reply_head) {
2245                 nlmsg_free(reply);
2246                 goto out;
2247         }
2248
2249         dev_list = nla_nest_start_noflag(reply, NBD_ATTR_DEVICE_LIST);
2250         if (index == -1) {
2251                 ret = idr_for_each(&nbd_index_idr, &status_cb, reply);
2252                 if (ret) {
2253                         nlmsg_free(reply);
2254                         goto out;
2255                 }
2256         } else {
2257                 struct nbd_device *nbd;
2258                 nbd = idr_find(&nbd_index_idr, index);
2259                 if (nbd) {
2260                         ret = populate_nbd_status(nbd, reply);
2261                         if (ret) {
2262                                 nlmsg_free(reply);
2263                                 goto out;
2264                         }
2265                 }
2266         }
2267         nla_nest_end(reply, dev_list);
2268         genlmsg_end(reply, reply_head);
2269         ret = genlmsg_reply(reply, info);
2270 out:
2271         mutex_unlock(&nbd_index_mutex);
2272         return ret;
2273 }
2274
2275 static void nbd_connect_reply(struct genl_info *info, int index)
2276 {
2277         struct sk_buff *skb;
2278         void *msg_head;
2279         int ret;
2280
2281         skb = genlmsg_new(nla_total_size(sizeof(u32)), GFP_KERNEL);
2282         if (!skb)
2283                 return;
2284         msg_head = genlmsg_put_reply(skb, info, &nbd_genl_family, 0,
2285                                      NBD_CMD_CONNECT);
2286         if (!msg_head) {
2287                 nlmsg_free(skb);
2288                 return;
2289         }
2290         ret = nla_put_u32(skb, NBD_ATTR_INDEX, index);
2291         if (ret) {
2292                 nlmsg_free(skb);
2293                 return;
2294         }
2295         genlmsg_end(skb, msg_head);
2296         genlmsg_reply(skb, info);
2297 }
2298
2299 static void nbd_mcast_index(int index)
2300 {
2301         struct sk_buff *skb;
2302         void *msg_head;
2303         int ret;
2304
2305         skb = genlmsg_new(nla_total_size(sizeof(u32)), GFP_KERNEL);
2306         if (!skb)
2307                 return;
2308         msg_head = genlmsg_put(skb, 0, 0, &nbd_genl_family, 0,
2309                                      NBD_CMD_LINK_DEAD);
2310         if (!msg_head) {
2311                 nlmsg_free(skb);
2312                 return;
2313         }
2314         ret = nla_put_u32(skb, NBD_ATTR_INDEX, index);
2315         if (ret) {
2316                 nlmsg_free(skb);
2317                 return;
2318         }
2319         genlmsg_end(skb, msg_head);
2320         genlmsg_multicast(&nbd_genl_family, skb, 0, 0, GFP_KERNEL);
2321 }
2322
2323 static void nbd_dead_link_work(struct work_struct *work)
2324 {
2325         struct link_dead_args *args = container_of(work, struct link_dead_args,
2326                                                    work);
2327         nbd_mcast_index(args->index);
2328         kfree(args);
2329 }
2330
2331 static int __init nbd_init(void)
2332 {
2333         int i;
2334
2335         BUILD_BUG_ON(sizeof(struct nbd_request) != 28);
2336
2337         if (max_part < 0) {
2338                 printk(KERN_ERR "nbd: max_part must be >= 0\n");
2339                 return -EINVAL;
2340         }
2341
2342         part_shift = 0;
2343         if (max_part > 0) {
2344                 part_shift = fls(max_part);
2345
2346                 /*
2347                  * Adjust max_part according to part_shift as it is exported
2348                  * to user space so that user can know the max number of
2349                  * partition kernel should be able to manage.
2350                  *
2351                  * Note that -1 is required because partition 0 is reserved
2352                  * for the whole disk.
2353                  */
2354                 max_part = (1UL << part_shift) - 1;
2355         }
2356
2357         if ((1UL << part_shift) > DISK_MAX_PARTS)
2358                 return -EINVAL;
2359
2360         if (nbds_max > 1UL << (MINORBITS - part_shift))
2361                 return -EINVAL;
2362
2363         if (register_blkdev(NBD_MAJOR, "nbd"))
2364                 return -EIO;
2365
2366         if (genl_register_family(&nbd_genl_family)) {
2367                 unregister_blkdev(NBD_MAJOR, "nbd");
2368                 return -EINVAL;
2369         }
2370         nbd_dbg_init();
2371
2372         mutex_lock(&nbd_index_mutex);
2373         for (i = 0; i < nbds_max; i++)
2374                 nbd_dev_add(i);
2375         mutex_unlock(&nbd_index_mutex);
2376         return 0;
2377 }
2378
2379 static int nbd_exit_cb(int id, void *ptr, void *data)
2380 {
2381         struct list_head *list = (struct list_head *)data;
2382         struct nbd_device *nbd = ptr;
2383
2384         list_add_tail(&nbd->list, list);
2385         return 0;
2386 }
2387
2388 static void __exit nbd_cleanup(void)
2389 {
2390         struct nbd_device *nbd;
2391         LIST_HEAD(del_list);
2392
2393         nbd_dbg_close();
2394
2395         mutex_lock(&nbd_index_mutex);
2396         idr_for_each(&nbd_index_idr, &nbd_exit_cb, &del_list);
2397         mutex_unlock(&nbd_index_mutex);
2398
2399         while (!list_empty(&del_list)) {
2400                 nbd = list_first_entry(&del_list, struct nbd_device, list);
2401                 list_del_init(&nbd->list);
2402                 if (refcount_read(&nbd->refs) != 1)
2403                         printk(KERN_ERR "nbd: possibly leaking a device\n");
2404                 nbd_put(nbd);
2405         }
2406
2407         idr_destroy(&nbd_index_idr);
2408         genl_unregister_family(&nbd_genl_family);
2409         unregister_blkdev(NBD_MAJOR, "nbd");
2410 }
2411
2412 module_init(nbd_init);
2413 module_exit(nbd_cleanup);
2414
2415 MODULE_DESCRIPTION("Network Block Device");
2416 MODULE_LICENSE("GPL");
2417
2418 module_param(nbds_max, int, 0444);
2419 MODULE_PARM_DESC(nbds_max, "number of network block devices to initialize (default: 16)");
2420 module_param(max_part, int, 0444);
2421 MODULE_PARM_DESC(max_part, "number of partitions per device (default: 16)");