drivers/block/nbd.c

   1 /*
   2  * Network block device - make block devices work over TCP
   3  *
   4  * Note that you can not swap over this thing, yet. Seems to work but
   5  * deadlocks sometimes - you can not swap over TCP in general.
   6  *
   7  * Copyright 1997-2000, 2008 Pavel Machek <pavel@ucw.cz>
   8  * Parts copyright 2001 Steven Whitehouse <steve@chygwyn.com>
   9  *
  10  * This file is released under GPLv2 or later.
  11  *
  12  * (part of code stolen from loop.c)
  13  */
  14
  15 #include <linux/major.h>
  16
  17 #include <linux/blkdev.h>
  18 #include <linux/module.h>
  19 #include <linux/init.h>
  20 #include <linux/sched.h>
  21 #include <linux/fs.h>
  22 #include <linux/bio.h>
  23 #include <linux/stat.h>
  24 #include <linux/errno.h>
  25 #include <linux/file.h>
  26 #include <linux/ioctl.h>
  27 #include <linux/mutex.h>
  28 #include <linux/compiler.h>
  29 #include <linux/err.h>
  30 #include <linux/kernel.h>
  31 #include <linux/slab.h>
  32 #include <net/sock.h>
  33 #include <linux/net.h>
  34 #include <linux/kthread.h>
  35 #include <linux/types.h>
  36 #include <linux/debugfs.h>
  37
  38 #include <asm/uaccess.h>
  39 #include <asm/types.h>
  40
  41 #include <linux/nbd.h>
  42
  43 struct nbd_device {
  44         u32 flags;
  45         struct socket * sock;   /* If == NULL, device is not ready, yet */
  46         int magic;
  47
  48         spinlock_t queue_lock;
  49         struct list_head queue_head;    /* Requests waiting result */
  50         struct request *active_req;
  51         wait_queue_head_t active_wq;
  52         struct list_head waiting_queue; /* Requests to be sent */
  53         wait_queue_head_t waiting_wq;
  54
  55         struct mutex tx_lock;
  56         struct gendisk *disk;
  57         int blksize;
  58         loff_t bytesize;
  59         int xmit_timeout;
  60         bool disconnect; /* a disconnect has been requested by user */
  61
  62         struct timer_list timeout_timer;
  63         spinlock_t tasks_lock;
  64         struct task_struct *task_recv;
  65         struct task_struct *task_send;
  66
  67 #if IS_ENABLED(CONFIG_DEBUG_FS)
  68         struct dentry *dbg_dir;
  69 #endif
  70 };
  71
  72 #if IS_ENABLED(CONFIG_DEBUG_FS)
  73 static struct dentry *nbd_dbg_dir;
  74 #endif
  75
  76 #define nbd_name(nbd) ((nbd)->disk->disk_name)
  77
  78 #define NBD_MAGIC 0x68797548
  79
  80 static unsigned int nbds_max = 16;
  81 static struct nbd_device *nbd_dev;
  82 static int max_part;
  83
  84 /*
  85  * Use just one lock (or at most 1 per NIC). Two arguments for this:
  86  * 1. Each NIC is essentially a synchronization point for all servers
  87  *    accessed through that NIC so there's no need to have more locks
  88  *    than NICs anyway.
  89  * 2. More locks lead to more "Dirty cache line bouncing" which will slow
  90  *    down each lock to the point where they're actually slower than just
  91  *    a single lock.
  92  * Thanks go to Jens Axboe and Al Viro for their LKML emails explaining this!
  93  */
  94 static DEFINE_SPINLOCK(nbd_lock);
  95
  96 static inline struct device *nbd_to_dev(struct nbd_device *nbd)
  97 {
  98         return disk_to_dev(nbd->disk);
  99 }
 100
 101 static const char *nbdcmd_to_ascii(int cmd)
 102 {
 103         switch (cmd) {
 104         case  NBD_CMD_READ: return "read";
 105         case NBD_CMD_WRITE: return "write";
 106         case  NBD_CMD_DISC: return "disconnect";
 107         case NBD_CMD_FLUSH: return "flush";
 108         case  NBD_CMD_TRIM: return "trim/discard";
 109         }
 110         return "invalid";
 111 }
 112
 113 static void nbd_end_request(struct nbd_device *nbd, struct request *req)
 114 {
 115         int error = req->errors ? -EIO : 0;
 116         struct request_queue *q = req->q;
 117         unsigned long flags;
 118
 119         dev_dbg(nbd_to_dev(nbd), "request %p: %s\n", req,
 120                 error ? "failed" : "done");
 121
 122         spin_lock_irqsave(q->queue_lock, flags);
 123         __blk_end_request_all(req, error);
 124         spin_unlock_irqrestore(q->queue_lock, flags);
 125 }
 126
 127 /*
 128  * Forcibly shutdown the socket causing all listeners to error
 129  */
 130 static void sock_shutdown(struct nbd_device *nbd)
 131 {
 132         if (!nbd->sock)
 133                 return;
 134
 135         dev_warn(disk_to_dev(nbd->disk), "shutting down socket\n");
 136         kernel_sock_shutdown(nbd->sock, SHUT_RDWR);
 137         nbd->sock = NULL;
 138         del_timer_sync(&nbd->timeout_timer);
 139 }
 140
 141 static void nbd_xmit_timeout(unsigned long arg)
 142 {
 143         struct nbd_device *nbd = (struct nbd_device *)arg;
 144         unsigned long flags;
 145
 146         if (list_empty(&nbd->queue_head))
 147                 return;
 148
 149         nbd->disconnect = true;
 150
 151         spin_lock_irqsave(&nbd->tasks_lock, flags);
 152
 153         if (nbd->task_recv)
 154                 force_sig(SIGKILL, nbd->task_recv);
 155
 156         if (nbd->task_send)
 157                 force_sig(SIGKILL, nbd->task_send);
 158
 159         spin_unlock_irqrestore(&nbd->tasks_lock, flags);
 160
 161         dev_err(nbd_to_dev(nbd), "Connection timed out, killed receiver and sender, shutting down connection\n");
 162 }
 163
 164 /*
 165  *  Send or receive packet.
 166  */
 167 static int sock_xmit(struct nbd_device *nbd, int send, void *buf, int size,
 168                 int msg_flags)
 169 {
 170         struct socket *sock = nbd->sock;
 171         int result;
 172         struct msghdr msg;
 173         struct kvec iov;
 174         sigset_t blocked, oldset;
 175         unsigned long pflags = current->flags;
 176
 177         if (unlikely(!sock)) {
 178                 dev_err(disk_to_dev(nbd->disk),
 179                         "Attempted %s on closed socket in sock_xmit\n",
 180                         (send ? "send" : "recv"));
 181                 return -EINVAL;
 182         }
 183
 184         /* Allow interception of SIGKILL only
 185          * Don't allow other signals to interrupt the transmission */
 186         siginitsetinv(&blocked, sigmask(SIGKILL));
 187         sigprocmask(SIG_SETMASK, &blocked, &oldset);
 188
 189         current->flags |= PF_MEMALLOC;
 190         do {
 191                 sock->sk->sk_allocation = GFP_NOIO | __GFP_MEMALLOC;
 192                 iov.iov_base = buf;
 193                 iov.iov_len = size;
 194                 msg.msg_name = NULL;
 195                 msg.msg_namelen = 0;
 196                 msg.msg_control = NULL;
 197                 msg.msg_controllen = 0;
 198                 msg.msg_flags = msg_flags | MSG_NOSIGNAL;
 199
 200                 if (send)
 201                         result = kernel_sendmsg(sock, &msg, &iov, 1, size);
 202                 else
 203                         result = kernel_recvmsg(sock, &msg, &iov, 1, size,
 204                                                 msg.msg_flags);
 205
 206                 if (result <= 0) {
 207                         if (result == 0)
 208                                 result = -EPIPE; /* short read */
 209                         break;
 210                 }
 211                 size -= result;
 212                 buf += result;
 213         } while (size > 0);
 214
 215         sigprocmask(SIG_SETMASK, &oldset, NULL);
 216         tsk_restore_flags(current, pflags, PF_MEMALLOC);
 217
 218         if (!send && nbd->xmit_timeout)
 219                 mod_timer(&nbd->timeout_timer, jiffies + nbd->xmit_timeout);
 220
 221         return result;
 222 }
 223
 224 static inline int sock_send_bvec(struct nbd_device *nbd, struct bio_vec *bvec,
 225                 int flags)
 226 {
 227         int result;
 228         void *kaddr = kmap(bvec->bv_page);
 229         result = sock_xmit(nbd, 1, kaddr + bvec->bv_offset,
 230                            bvec->bv_len, flags);
 231         kunmap(bvec->bv_page);
 232         return result;
 233 }
 234
 235 /* always call with the tx_lock held */
 236 static int nbd_send_req(struct nbd_device *nbd, struct request *req)
 237 {
 238         int result, flags;
 239         struct nbd_request request;
 240         unsigned long size = blk_rq_bytes(req);
 241         u32 type;
 242
 243         if (req->cmd_type == REQ_TYPE_DRV_PRIV)
 244                 type = NBD_CMD_DISC;
 245         else if (req->cmd_flags & REQ_DISCARD)
 246                 type = NBD_CMD_TRIM;
 247         else if (req->cmd_flags & REQ_FLUSH)
 248                 type = NBD_CMD_FLUSH;
 249         else if (rq_data_dir(req) == WRITE)
 250                 type = NBD_CMD_WRITE;
 251         else
 252                 type = NBD_CMD_READ;
 253
 254         memset(&request, 0, sizeof(request));
 255         request.magic = htonl(NBD_REQUEST_MAGIC);
 256         request.type = htonl(type);
 257         if (type != NBD_CMD_FLUSH && type != NBD_CMD_DISC) {
 258                 request.from = cpu_to_be64((u64)blk_rq_pos(req) << 9);
 259                 request.len = htonl(size);
 260         }
 261         memcpy(request.handle, &req, sizeof(req));
 262
 263         dev_dbg(nbd_to_dev(nbd), "request %p: sending control (%s@%llu,%uB)\n",
 264                 req, nbdcmd_to_ascii(type),
 265                 (unsigned long long)blk_rq_pos(req) << 9, blk_rq_bytes(req));
 266         result = sock_xmit(nbd, 1, &request, sizeof(request),
 267                         (type == NBD_CMD_WRITE) ? MSG_MORE : 0);
 268         if (result <= 0) {
 269                 dev_err(disk_to_dev(nbd->disk),
 270                         "Send control failed (result %d)\n", result);
 271                 return -EIO;
 272         }
 273
 274         if (type == NBD_CMD_WRITE) {
 275                 struct req_iterator iter;
 276                 struct bio_vec bvec;
 277                 /*
 278                  * we are really probing at internals to determine
 279                  * whether to set MSG_MORE or not...
 280                  */
 281                 rq_for_each_segment(bvec, req, iter) {
 282                         flags = 0;
 283                         if (!rq_iter_last(bvec, iter))
 284                                 flags = MSG_MORE;
 285                         dev_dbg(nbd_to_dev(nbd), "request %p: sending %d bytes data\n",
 286                                 req, bvec.bv_len);
 287                         result = sock_send_bvec(nbd, &bvec, flags);
 288                         if (result <= 0) {
 289                                 dev_err(disk_to_dev(nbd->disk),
 290                                         "Send data failed (result %d)\n",
 291                                         result);
 292                                 return -EIO;
 293                         }
 294                 }
 295         }
 296         return 0;
 297 }
 298
 299 static struct request *nbd_find_request(struct nbd_device *nbd,
 300                                         struct request *xreq)
 301 {
 302         struct request *req, *tmp;
 303         int err;
 304
 305         err = wait_event_interruptible(nbd->active_wq, nbd->active_req != xreq);
 306         if (unlikely(err))
 307                 return ERR_PTR(err);
 308
 309         spin_lock(&nbd->queue_lock);
 310         list_for_each_entry_safe(req, tmp, &nbd->queue_head, queuelist) {
 311                 if (req != xreq)
 312                         continue;
 313                 list_del_init(&req->queuelist);
 314                 spin_unlock(&nbd->queue_lock);
 315                 return req;
 316         }
 317         spin_unlock(&nbd->queue_lock);
 318
 319         return ERR_PTR(-ENOENT);
 320 }
 321
 322 static inline int sock_recv_bvec(struct nbd_device *nbd, struct bio_vec *bvec)
 323 {
 324         int result;
 325         void *kaddr = kmap(bvec->bv_page);
 326         result = sock_xmit(nbd, 0, kaddr + bvec->bv_offset, bvec->bv_len,
 327                         MSG_WAITALL);
 328         kunmap(bvec->bv_page);
 329         return result;
 330 }
 331
 332 /* NULL returned = something went wrong, inform userspace */
 333 static struct request *nbd_read_stat(struct nbd_device *nbd)
 334 {
 335         int result;
 336         struct nbd_reply reply;
 337         struct request *req;
 338
 339         reply.magic = 0;
 340         result = sock_xmit(nbd, 0, &reply, sizeof(reply), MSG_WAITALL);
 341         if (result <= 0) {
 342                 dev_err(disk_to_dev(nbd->disk),
 343                         "Receive control failed (result %d)\n", result);
 344                 return ERR_PTR(result);
 345         }
 346
 347         if (ntohl(reply.magic) != NBD_REPLY_MAGIC) {
 348                 dev_err(disk_to_dev(nbd->disk), "Wrong magic (0x%lx)\n",
 349                                 (unsigned long)ntohl(reply.magic));
 350                 return ERR_PTR(-EPROTO);
 351         }
 352
 353         req = nbd_find_request(nbd, *(struct request **)reply.handle);
 354         if (IS_ERR(req)) {
 355                 result = PTR_ERR(req);
 356                 if (result != -ENOENT)
 357                         return ERR_PTR(result);
 358
 359                 dev_err(disk_to_dev(nbd->disk), "Unexpected reply (%p)\n",
 360                         reply.handle);
 361                 return ERR_PTR(-EBADR);
 362         }
 363
 364         if (ntohl(reply.error)) {
 365                 dev_err(disk_to_dev(nbd->disk), "Other side returned error (%d)\n",
 366                         ntohl(reply.error));
 367                 req->errors++;
 368                 return req;
 369         }
 370
 371         dev_dbg(nbd_to_dev(nbd), "request %p: got reply\n", req);
 372         if (rq_data_dir(req) != WRITE) {
 373                 struct req_iterator iter;
 374                 struct bio_vec bvec;
 375
 376                 rq_for_each_segment(bvec, req, iter) {
 377                         result = sock_recv_bvec(nbd, &bvec);
 378                         if (result <= 0) {
 379                                 dev_err(disk_to_dev(nbd->disk), "Receive data failed (result %d)\n",
 380                                         result);
 381                                 req->errors++;
 382                                 return req;
 383                         }
 384                         dev_dbg(nbd_to_dev(nbd), "request %p: got %d bytes data\n",
 385                                 req, bvec.bv_len);
 386                 }
 387         }
 388         return req;
 389 }
 390
 391 static ssize_t pid_show(struct device *dev,
 392                         struct device_attribute *attr, char *buf)
 393 {
 394         struct gendisk *disk = dev_to_disk(dev);
 395         struct nbd_device *nbd = (struct nbd_device *)disk->private_data;
 396
 397         return sprintf(buf, "%d\n", task_pid_nr(nbd->task_recv));
 398 }
 399
 400 static struct device_attribute pid_attr = {
 401         .attr = { .name = "pid", .mode = S_IRUGO},
 402         .show = pid_show,
 403 };
 404
 405 static int nbd_thread_recv(struct nbd_device *nbd)
 406 {
 407         struct request *req;
 408         int ret;
 409         unsigned long flags;
 410
 411         BUG_ON(nbd->magic != NBD_MAGIC);
 412
 413         sk_set_memalloc(nbd->sock->sk);
 414
 415         spin_lock_irqsave(&nbd->tasks_lock, flags);
 416         nbd->task_recv = current;
 417         spin_unlock_irqrestore(&nbd->tasks_lock, flags);
 418
 419         ret = device_create_file(disk_to_dev(nbd->disk), &pid_attr);
 420         if (ret) {
 421                 dev_err(disk_to_dev(nbd->disk), "device_create_file failed!\n");
 422
 423                 spin_lock_irqsave(&nbd->tasks_lock, flags);
 424                 nbd->task_recv = NULL;
 425                 spin_unlock_irqrestore(&nbd->tasks_lock, flags);
 426
 427                 return ret;
 428         }
 429
 430         while (1) {
 431                 req = nbd_read_stat(nbd);
 432                 if (IS_ERR(req)) {
 433                         ret = PTR_ERR(req);
 434                         break;
 435                 }
 436
 437                 nbd_end_request(nbd, req);
 438         }
 439
 440         device_remove_file(disk_to_dev(nbd->disk), &pid_attr);
 441
 442         spin_lock_irqsave(&nbd->tasks_lock, flags);
 443         nbd->task_recv = NULL;
 444         spin_unlock_irqrestore(&nbd->tasks_lock, flags);
 445
 446         if (signal_pending(current)) {
 447                 ret = kernel_dequeue_signal(NULL);
 448                 dev_warn(nbd_to_dev(nbd), "pid %d, %s, got signal %d\n",
 449                          task_pid_nr(current), current->comm, ret);
 450                 mutex_lock(&nbd->tx_lock);
 451                 sock_shutdown(nbd);
 452                 mutex_unlock(&nbd->tx_lock);
 453                 ret = -ETIMEDOUT;
 454         }
 455
 456         return ret;
 457 }
 458
 459 static void nbd_clear_que(struct nbd_device *nbd)
 460 {
 461         struct request *req;
 462
 463         BUG_ON(nbd->magic != NBD_MAGIC);
 464
 465         /*
 466          * Because we have set nbd->sock to NULL under the tx_lock, all
 467          * modifications to the list must have completed by now.  For
 468          * the same reason, the active_req must be NULL.
 469          *
 470          * As a consequence, we don't need to take the spin lock while
 471          * purging the list here.
 472          */
 473         BUG_ON(nbd->sock);
 474         BUG_ON(nbd->active_req);
 475
 476         while (!list_empty(&nbd->queue_head)) {
 477                 req = list_entry(nbd->queue_head.next, struct request,
 478                                  queuelist);
 479                 list_del_init(&req->queuelist);
 480                 req->errors++;
 481                 nbd_end_request(nbd, req);
 482         }
 483
 484         while (!list_empty(&nbd->waiting_queue)) {
 485                 req = list_entry(nbd->waiting_queue.next, struct request,
 486                                  queuelist);
 487                 list_del_init(&req->queuelist);
 488                 req->errors++;
 489                 nbd_end_request(nbd, req);
 490         }
 491         dev_dbg(disk_to_dev(nbd->disk), "queue cleared\n");
 492 }
 493
 494
 495 static void nbd_handle_req(struct nbd_device *nbd, struct request *req)
 496 {
 497         if (req->cmd_type != REQ_TYPE_FS)
 498                 goto error_out;
 499
 500         if (rq_data_dir(req) == WRITE &&
 501             (nbd->flags & NBD_FLAG_READ_ONLY)) {
 502                 dev_err(disk_to_dev(nbd->disk),
 503                         "Write on read-only\n");
 504                 goto error_out;
 505         }
 506
 507         req->errors = 0;
 508
 509         mutex_lock(&nbd->tx_lock);
 510         if (unlikely(!nbd->sock)) {
 511                 mutex_unlock(&nbd->tx_lock);
 512                 dev_err(disk_to_dev(nbd->disk),
 513                         "Attempted send on closed socket\n");
 514                 goto error_out;
 515         }
 516
 517         nbd->active_req = req;
 518
 519         if (nbd->xmit_timeout && list_empty_careful(&nbd->queue_head))
 520                 mod_timer(&nbd->timeout_timer, jiffies + nbd->xmit_timeout);
 521
 522         if (nbd_send_req(nbd, req) != 0) {
 523                 dev_err(disk_to_dev(nbd->disk), "Request send failed\n");
 524                 req->errors++;
 525                 nbd_end_request(nbd, req);
 526         } else {
 527                 spin_lock(&nbd->queue_lock);
 528                 list_add_tail(&req->queuelist, &nbd->queue_head);
 529                 spin_unlock(&nbd->queue_lock);
 530         }
 531
 532         nbd->active_req = NULL;
 533         mutex_unlock(&nbd->tx_lock);
 534         wake_up_all(&nbd->active_wq);
 535
 536         return;
 537
 538 error_out:
 539         req->errors++;
 540         nbd_end_request(nbd, req);
 541 }
 542
 543 static int nbd_thread_send(void *data)
 544 {
 545         struct nbd_device *nbd = data;
 546         struct request *req;
 547         unsigned long flags;
 548
 549         spin_lock_irqsave(&nbd->tasks_lock, flags);
 550         nbd->task_send = current;
 551         spin_unlock_irqrestore(&nbd->tasks_lock, flags);
 552
 553         set_user_nice(current, MIN_NICE);
 554         while (!kthread_should_stop() || !list_empty(&nbd->waiting_queue)) {
 555                 /* wait for something to do */
 556                 wait_event_interruptible(nbd->waiting_wq,
 557                                          kthread_should_stop() ||
 558                                          !list_empty(&nbd->waiting_queue));
 559
 560                 if (signal_pending(current)) {
 561                         int ret = kernel_dequeue_signal(NULL);
 562
 563                         dev_warn(nbd_to_dev(nbd), "pid %d, %s, got signal %d\n",
 564                                  task_pid_nr(current), current->comm, ret);
 565                         mutex_lock(&nbd->tx_lock);
 566                         sock_shutdown(nbd);
 567                         mutex_unlock(&nbd->tx_lock);
 568                         break;
 569                 }
 570
 571                 /* extract request */
 572                 if (list_empty(&nbd->waiting_queue))
 573                         continue;
 574
 575                 spin_lock_irq(&nbd->queue_lock);
 576                 req = list_entry(nbd->waiting_queue.next, struct request,
 577                                  queuelist);
 578                 list_del_init(&req->queuelist);
 579                 spin_unlock_irq(&nbd->queue_lock);
 580
 581                 /* handle request */
 582                 nbd_handle_req(nbd, req);
 583         }
 584
 585         spin_lock_irqsave(&nbd->tasks_lock, flags);
 586         nbd->task_send = NULL;
 587         spin_unlock_irqrestore(&nbd->tasks_lock, flags);
 588
 589         /* Clear maybe pending signals */
 590         if (signal_pending(current))
 591                 kernel_dequeue_signal(NULL);
 592
 593         return 0;
 594 }
 595
 596 /*
 597  * We always wait for result of write, for now. It would be nice to make it optional
 598  * in future
 599  * if ((rq_data_dir(req) == WRITE) && (nbd->flags & NBD_WRITE_NOCHK))
 600  *   { printk( "Warning: Ignoring result!\n"); nbd_end_request( req ); }
 601  */
 602
 603 static void nbd_request_handler(struct request_queue *q)
 604                 __releases(q->queue_lock) __acquires(q->queue_lock)
 605 {
 606         struct request *req;
 607
 608         while ((req = blk_fetch_request(q)) != NULL) {
 609                 struct nbd_device *nbd;
 610
 611                 spin_unlock_irq(q->queue_lock);
 612
 613                 nbd = req->rq_disk->private_data;
 614
 615                 BUG_ON(nbd->magic != NBD_MAGIC);
 616
 617                 dev_dbg(nbd_to_dev(nbd), "request %p: dequeued (flags=%x)\n",
 618                         req, req->cmd_type);
 619
 620                 if (unlikely(!nbd->sock)) {
 621                         dev_err(disk_to_dev(nbd->disk),
 622                                 "Attempted send on closed socket\n");
 623                         req->errors++;
 624                         nbd_end_request(nbd, req);
 625                         spin_lock_irq(q->queue_lock);
 626                         continue;
 627                 }
 628
 629                 spin_lock_irq(&nbd->queue_lock);
 630                 list_add_tail(&req->queuelist, &nbd->waiting_queue);
 631                 spin_unlock_irq(&nbd->queue_lock);
 632
 633                 wake_up(&nbd->waiting_wq);
 634
 635                 spin_lock_irq(q->queue_lock);
 636         }
 637 }
 638
 639 static int nbd_dev_dbg_init(struct nbd_device *nbd);
 640 static void nbd_dev_dbg_close(struct nbd_device *nbd);
 641
 642 /* Must be called with tx_lock held */
 643
 644 static int __nbd_ioctl(struct block_device *bdev, struct nbd_device *nbd,
 645                        unsigned int cmd, unsigned long arg)
 646 {
 647         switch (cmd) {
 648         case NBD_DISCONNECT: {
 649                 struct request sreq;
 650
 651                 dev_info(disk_to_dev(nbd->disk), "NBD_DISCONNECT\n");
 652                 if (!nbd->sock)
 653                         return -EINVAL;
 654
 655                 mutex_unlock(&nbd->tx_lock);
 656                 fsync_bdev(bdev);
 657                 mutex_lock(&nbd->tx_lock);
 658                 blk_rq_init(NULL, &sreq);
 659                 sreq.cmd_type = REQ_TYPE_DRV_PRIV;
 660
 661                 /* Check again after getting mutex back.  */
 662                 if (!nbd->sock)
 663                         return -EINVAL;
 664
 665                 nbd->disconnect = true;
 666
 667                 nbd_send_req(nbd, &sreq);
 668                 return 0;
 669         }
 670
 671         case NBD_CLEAR_SOCK: {
 672                 struct socket *sock = nbd->sock;
 673                 nbd->sock = NULL;
 674                 nbd_clear_que(nbd);
 675                 BUG_ON(!list_empty(&nbd->queue_head));
 676                 BUG_ON(!list_empty(&nbd->waiting_queue));
 677                 kill_bdev(bdev);
 678                 if (sock)
 679                         sockfd_put(sock);
 680                 return 0;
 681         }
 682
 683         case NBD_SET_SOCK: {
 684                 struct socket *sock;
 685                 int err;
 686                 if (nbd->sock)
 687                         return -EBUSY;
 688                 sock = sockfd_lookup(arg, &err);
 689                 if (sock) {
 690                         nbd->sock = sock;
 691                         if (max_part > 0)
 692                                 bdev->bd_invalidated = 1;
 693                         nbd->disconnect = false; /* we're connected now */
 694                         return 0;
 695                 }
 696                 return -EINVAL;
 697         }
 698
 699         case NBD_SET_BLKSIZE:
 700                 nbd->blksize = arg;
 701                 nbd->bytesize &= ~(nbd->blksize-1);
 702                 bdev->bd_inode->i_size = nbd->bytesize;
 703                 set_blocksize(bdev, nbd->blksize);
 704                 set_capacity(nbd->disk, nbd->bytesize >> 9);
 705                 return 0;
 706
 707         case NBD_SET_SIZE:
 708                 nbd->bytesize = arg & ~(nbd->blksize-1);
 709                 bdev->bd_inode->i_size = nbd->bytesize;
 710                 set_blocksize(bdev, nbd->blksize);
 711                 set_capacity(nbd->disk, nbd->bytesize >> 9);
 712                 return 0;
 713
 714         case NBD_SET_TIMEOUT:
 715                 nbd->xmit_timeout = arg * HZ;
 716                 if (arg)
 717                         mod_timer(&nbd->timeout_timer,
 718                                   jiffies + nbd->xmit_timeout);
 719                 else
 720                         del_timer_sync(&nbd->timeout_timer);
 721
 722                 return 0;
 723
 724         case NBD_SET_FLAGS:
 725                 nbd->flags = arg;
 726                 return 0;
 727
 728         case NBD_SET_SIZE_BLOCKS:
 729                 nbd->bytesize = ((u64) arg) * nbd->blksize;
 730                 bdev->bd_inode->i_size = nbd->bytesize;
 731                 set_blocksize(bdev, nbd->blksize);
 732                 set_capacity(nbd->disk, nbd->bytesize >> 9);
 733                 return 0;
 734
 735         case NBD_DO_IT: {
 736                 struct task_struct *thread;
 737                 struct socket *sock;
 738                 int error;
 739
 740                 if (nbd->task_recv)
 741                         return -EBUSY;
 742                 if (!nbd->sock)
 743                         return -EINVAL;
 744
 745                 mutex_unlock(&nbd->tx_lock);
 746
 747                 if (nbd->flags & NBD_FLAG_READ_ONLY)
 748                         set_device_ro(bdev, true);
 749                 if (nbd->flags & NBD_FLAG_SEND_TRIM)
 750                         queue_flag_set_unlocked(QUEUE_FLAG_DISCARD,
 751                                 nbd->disk->queue);
 752                 if (nbd->flags & NBD_FLAG_SEND_FLUSH)
 753                         blk_queue_flush(nbd->disk->queue, REQ_FLUSH);
 754                 else
 755                         blk_queue_flush(nbd->disk->queue, 0);
 756
 757                 thread = kthread_run(nbd_thread_send, nbd, "%s",
 758                                      nbd_name(nbd));
 759                 if (IS_ERR(thread)) {
 760                         mutex_lock(&nbd->tx_lock);
 761                         return PTR_ERR(thread);
 762                 }
 763
 764                 nbd_dev_dbg_init(nbd);
 765                 error = nbd_thread_recv(nbd);
 766                 nbd_dev_dbg_close(nbd);
 767                 kthread_stop(thread);
 768
 769                 mutex_lock(&nbd->tx_lock);
 770
 771                 sock_shutdown(nbd);
 772                 sock = nbd->sock;
 773                 nbd->sock = NULL;
 774                 nbd_clear_que(nbd);
 775                 kill_bdev(bdev);
 776                 queue_flag_clear_unlocked(QUEUE_FLAG_DISCARD, nbd->disk->queue);
 777                 set_device_ro(bdev, false);
 778                 if (sock)
 779                         sockfd_put(sock);
 780                 nbd->flags = 0;
 781                 nbd->bytesize = 0;
 782                 bdev->bd_inode->i_size = 0;
 783                 set_capacity(nbd->disk, 0);
 784                 if (max_part > 0)
 785                         blkdev_reread_part(bdev);
 786                 if (nbd->disconnect) /* user requested, ignore socket errors */
 787                         return 0;
 788                 return error;
 789         }
 790
 791         case NBD_CLEAR_QUE:
 792                 /*
 793                  * This is for compatibility only.  The queue is always cleared
 794                  * by NBD_DO_IT or NBD_CLEAR_SOCK.
 795                  */
 796                 return 0;
 797
 798         case NBD_PRINT_DEBUG:
 799                 dev_info(disk_to_dev(nbd->disk),
 800                         "next = %p, prev = %p, head = %p\n",
 801                         nbd->queue_head.next, nbd->queue_head.prev,
 802                         &nbd->queue_head);
 803                 return 0;
 804         }
 805         return -ENOTTY;
 806 }
 807
 808 static int nbd_ioctl(struct block_device *bdev, fmode_t mode,
 809                      unsigned int cmd, unsigned long arg)
 810 {
 811         struct nbd_device *nbd = bdev->bd_disk->private_data;
 812         int error;
 813
 814         if (!capable(CAP_SYS_ADMIN))
 815                 return -EPERM;
 816
 817         BUG_ON(nbd->magic != NBD_MAGIC);
 818
 819         mutex_lock(&nbd->tx_lock);
 820         error = __nbd_ioctl(bdev, nbd, cmd, arg);
 821         mutex_unlock(&nbd->tx_lock);
 822
 823         return error;
 824 }
 825
 826 static const struct block_device_operations nbd_fops =
 827 {
 828         .owner =        THIS_MODULE,
 829         .ioctl =        nbd_ioctl,
 830 };
 831
 832 #if IS_ENABLED(CONFIG_DEBUG_FS)
 833
 834 static int nbd_dbg_tasks_show(struct seq_file *s, void *unused)
 835 {
 836         struct nbd_device *nbd = s->private;
 837
 838         if (nbd->task_recv)
 839                 seq_printf(s, "recv: %d\n", task_pid_nr(nbd->task_recv));
 840         if (nbd->task_send)
 841                 seq_printf(s, "send: %d\n", task_pid_nr(nbd->task_send));
 842
 843         return 0;
 844 }
 845
 846 static int nbd_dbg_tasks_open(struct inode *inode, struct file *file)
 847 {
 848         return single_open(file, nbd_dbg_tasks_show, inode->i_private);
 849 }
 850
 851 static const struct file_operations nbd_dbg_tasks_ops = {
 852         .open = nbd_dbg_tasks_open,
 853         .read = seq_read,
 854         .llseek = seq_lseek,
 855         .release = single_release,
 856 };
 857
 858 static int nbd_dbg_flags_show(struct seq_file *s, void *unused)
 859 {
 860         struct nbd_device *nbd = s->private;
 861         u32 flags = nbd->flags;
 862
 863         seq_printf(s, "Hex: 0x%08x\n\n", flags);
 864
 865         seq_puts(s, "Known flags:\n");
 866
 867         if (flags & NBD_FLAG_HAS_FLAGS)
 868                 seq_puts(s, "NBD_FLAG_HAS_FLAGS\n");
 869         if (flags & NBD_FLAG_READ_ONLY)
 870                 seq_puts(s, "NBD_FLAG_READ_ONLY\n");
 871         if (flags & NBD_FLAG_SEND_FLUSH)
 872                 seq_puts(s, "NBD_FLAG_SEND_FLUSH\n");
 873         if (flags & NBD_FLAG_SEND_TRIM)
 874                 seq_puts(s, "NBD_FLAG_SEND_TRIM\n");
 875
 876         return 0;
 877 }
 878
 879 static int nbd_dbg_flags_open(struct inode *inode, struct file *file)
 880 {
 881         return single_open(file, nbd_dbg_flags_show, inode->i_private);
 882 }
 883
 884 static const struct file_operations nbd_dbg_flags_ops = {
 885         .open = nbd_dbg_flags_open,
 886         .read = seq_read,
 887         .llseek = seq_lseek,
 888         .release = single_release,
 889 };
 890
 891 static int nbd_dev_dbg_init(struct nbd_device *nbd)
 892 {
 893         struct dentry *dir;
 894         struct dentry *f;
 895
 896         dir = debugfs_create_dir(nbd_name(nbd), nbd_dbg_dir);
 897         if (IS_ERR_OR_NULL(dir)) {
 898                 dev_err(nbd_to_dev(nbd), "Failed to create debugfs dir for '%s' (%ld)\n",
 899                         nbd_name(nbd), PTR_ERR(dir));
 900                 return PTR_ERR(dir);
 901         }
 902         nbd->dbg_dir = dir;
 903
 904         f = debugfs_create_file("tasks", 0444, dir, nbd, &nbd_dbg_tasks_ops);
 905         if (IS_ERR_OR_NULL(f)) {
 906                 dev_err(nbd_to_dev(nbd), "Failed to create debugfs file 'tasks', %ld\n",
 907                         PTR_ERR(f));
 908                 return PTR_ERR(f);
 909         }
 910
 911         f = debugfs_create_u64("size_bytes", 0444, dir, &nbd->bytesize);
 912         if (IS_ERR_OR_NULL(f)) {
 913                 dev_err(nbd_to_dev(nbd), "Failed to create debugfs file 'size_bytes', %ld\n",
 914                         PTR_ERR(f));
 915                 return PTR_ERR(f);
 916         }
 917
 918         f = debugfs_create_u32("timeout", 0444, dir, &nbd->xmit_timeout);
 919         if (IS_ERR_OR_NULL(f)) {
 920                 dev_err(nbd_to_dev(nbd), "Failed to create debugfs file 'timeout', %ld\n",
 921                         PTR_ERR(f));
 922                 return PTR_ERR(f);
 923         }
 924
 925         f = debugfs_create_u32("blocksize", 0444, dir, &nbd->blksize);
 926         if (IS_ERR_OR_NULL(f)) {
 927                 dev_err(nbd_to_dev(nbd), "Failed to create debugfs file 'blocksize', %ld\n",
 928                         PTR_ERR(f));
 929                 return PTR_ERR(f);
 930         }
 931
 932         f = debugfs_create_file("flags", 0444, dir, &nbd, &nbd_dbg_flags_ops);
 933         if (IS_ERR_OR_NULL(f)) {
 934                 dev_err(nbd_to_dev(nbd), "Failed to create debugfs file 'flags', %ld\n",
 935                         PTR_ERR(f));
 936                 return PTR_ERR(f);
 937         }
 938
 939         return 0;
 940 }
 941
 942 static void nbd_dev_dbg_close(struct nbd_device *nbd)
 943 {
 944         debugfs_remove_recursive(nbd->dbg_dir);
 945 }
 946
 947 static int nbd_dbg_init(void)
 948 {
 949         struct dentry *dbg_dir;
 950
 951         dbg_dir = debugfs_create_dir("nbd", NULL);
 952         if (IS_ERR(dbg_dir))
 953                 return PTR_ERR(dbg_dir);
 954
 955         nbd_dbg_dir = dbg_dir;
 956
 957         return 0;
 958 }
 959
 960 static void nbd_dbg_close(void)
 961 {
 962         debugfs_remove_recursive(nbd_dbg_dir);
 963 }
 964
 965 #else  /* IS_ENABLED(CONFIG_DEBUG_FS) */
 966
 967 static int nbd_dev_dbg_init(struct nbd_device *nbd)
 968 {
 969         return 0;
 970 }
 971
 972 static void nbd_dev_dbg_close(struct nbd_device *nbd)
 973 {
 974 }
 975
 976 static int nbd_dbg_init(void)
 977 {
 978         return 0;
 979 }
 980
 981 static void nbd_dbg_close(void)
 982 {
 983 }
 984
 985 #endif
 986
 987 /*
 988  * And here should be modules and kernel interface
 989  *  (Just smiley confuses emacs :-)
 990  */
 991
 992 static int __init nbd_init(void)
 993 {
 994         int err = -ENOMEM;
 995         int i;
 996         int part_shift;
 997
 998         BUILD_BUG_ON(sizeof(struct nbd_request) != 28);
 999
1000         if (max_part < 0) {
1001                 printk(KERN_ERR "nbd: max_part must be >= 0\n");
1002                 return -EINVAL;
1003         }
1004
1005         part_shift = 0;
1006         if (max_part > 0) {
1007                 part_shift = fls(max_part);
1008
1009                 /*
1010                  * Adjust max_part according to part_shift as it is exported
1011                  * to user space so that user can know the max number of
1012                  * partition kernel should be able to manage.
1013                  *
1014                  * Note that -1 is required because partition 0 is reserved
1015                  * for the whole disk.
1016                  */
1017                 max_part = (1UL << part_shift) - 1;
1018         }
1019
1020         if ((1UL << part_shift) > DISK_MAX_PARTS)
1021                 return -EINVAL;
1022
1023         if (nbds_max > 1UL << (MINORBITS - part_shift))
1024                 return -EINVAL;
1025
1026         nbd_dev = kcalloc(nbds_max, sizeof(*nbd_dev), GFP_KERNEL);
1027         if (!nbd_dev)
1028                 return -ENOMEM;
1029
1030         for (i = 0; i < nbds_max; i++) {
1031                 struct gendisk *disk = alloc_disk(1 << part_shift);
1032                 if (!disk)
1033                         goto out;
1034                 nbd_dev[i].disk = disk;
1035                 /*
1036                  * The new linux 2.5 block layer implementation requires
1037                  * every gendisk to have its very own request_queue struct.
1038                  * These structs are big so we dynamically allocate them.
1039                  */
1040                 disk->queue = blk_init_queue(nbd_request_handler, &nbd_lock);
1041                 if (!disk->queue) {
1042                         put_disk(disk);
1043                         goto out;
1044                 }
1045                 /*
1046                  * Tell the block layer that we are not a rotational device
1047                  */
1048                 queue_flag_set_unlocked(QUEUE_FLAG_NONROT, disk->queue);
1049                 queue_flag_clear_unlocked(QUEUE_FLAG_ADD_RANDOM, disk->queue);
1050                 disk->queue->limits.discard_granularity = 512;
1051                 blk_queue_max_discard_sectors(disk->queue, UINT_MAX);
1052                 disk->queue->limits.discard_zeroes_data = 0;
1053                 blk_queue_max_hw_sectors(disk->queue, 65536);
1054                 disk->queue->limits.max_sectors = 256;
1055         }
1056
1057         if (register_blkdev(NBD_MAJOR, "nbd")) {
1058                 err = -EIO;
1059                 goto out;
1060         }
1061
1062         printk(KERN_INFO "nbd: registered device at major %d\n", NBD_MAJOR);
1063
1064         nbd_dbg_init();
1065
1066         for (i = 0; i < nbds_max; i++) {
1067                 struct gendisk *disk = nbd_dev[i].disk;
1068                 nbd_dev[i].magic = NBD_MAGIC;
1069                 INIT_LIST_HEAD(&nbd_dev[i].waiting_queue);
1070                 spin_lock_init(&nbd_dev[i].queue_lock);
1071                 spin_lock_init(&nbd_dev[i].tasks_lock);
1072                 INIT_LIST_HEAD(&nbd_dev[i].queue_head);
1073                 mutex_init(&nbd_dev[i].tx_lock);
1074                 init_timer(&nbd_dev[i].timeout_timer);
1075                 nbd_dev[i].timeout_timer.function = nbd_xmit_timeout;
1076                 nbd_dev[i].timeout_timer.data = (unsigned long)&nbd_dev[i];
1077                 init_waitqueue_head(&nbd_dev[i].active_wq);
1078                 init_waitqueue_head(&nbd_dev[i].waiting_wq);
1079                 nbd_dev[i].blksize = 1024;
1080                 nbd_dev[i].bytesize = 0;
1081                 disk->major = NBD_MAJOR;
1082                 disk->first_minor = i << part_shift;
1083                 disk->fops = &nbd_fops;
1084                 disk->private_data = &nbd_dev[i];
1085                 sprintf(disk->disk_name, "nbd%d", i);
1086                 set_capacity(disk, 0);
1087                 add_disk(disk);
1088         }
1089
1090         return 0;
1091 out:
1092         while (i--) {
1093                 blk_cleanup_queue(nbd_dev[i].disk->queue);
1094                 put_disk(nbd_dev[i].disk);
1095         }
1096         kfree(nbd_dev);
1097         return err;
1098 }
1099
1100 static void __exit nbd_cleanup(void)
1101 {
1102         int i;
1103
1104         nbd_dbg_close();
1105
1106         for (i = 0; i < nbds_max; i++) {
1107                 struct gendisk *disk = nbd_dev[i].disk;
1108                 nbd_dev[i].magic = 0;
1109                 if (disk) {
1110                         del_gendisk(disk);
1111                         blk_cleanup_queue(disk->queue);
1112                         put_disk(disk);
1113                 }
1114         }
1115         unregister_blkdev(NBD_MAJOR, "nbd");
1116         kfree(nbd_dev);
1117         printk(KERN_INFO "nbd: unregistered device at major %d\n", NBD_MAJOR);
1118 }
1119
1120 module_init(nbd_init);
1121 module_exit(nbd_cleanup);
1122
1123 MODULE_DESCRIPTION("Network Block Device");
1124 MODULE_LICENSE("GPL");
1125
1126 module_param(nbds_max, int, 0444);
1127 MODULE_PARM_DESC(nbds_max, "number of network block devices to initialize (default: 16)");
1128 module_param(max_part, int, 0444);
1129 MODULE_PARM_DESC(max_part, "number of partitions per device (default: 0)");