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
  37 #include <asm/uaccess.h>
  38 #include <asm/types.h>
  39
  40 #include <linux/nbd.h>
  41
  42 struct nbd_device {
  43         int flags;
  44         int harderror;          /* Code of hard error                   */
  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         pid_t pid; /* pid of nbd-client, if attached */
  60         int xmit_timeout;
  61         int disconnect; /* a disconnect has been requested by user */
  62 };
  63
  64 #define NBD_MAGIC 0x68797548
  65
  66 static unsigned int nbds_max = 16;
  67 static struct nbd_device *nbd_dev;
  68 static int max_part;
  69
  70 /*
  71  * Use just one lock (or at most 1 per NIC). Two arguments for this:
  72  * 1. Each NIC is essentially a synchronization point for all servers
  73  *    accessed through that NIC so there's no need to have more locks
  74  *    than NICs anyway.
  75  * 2. More locks lead to more "Dirty cache line bouncing" which will slow
  76  *    down each lock to the point where they're actually slower than just
  77  *    a single lock.
  78  * Thanks go to Jens Axboe and Al Viro for their LKML emails explaining this!
  79  */
  80 static DEFINE_SPINLOCK(nbd_lock);
  81
  82 static inline struct device *nbd_to_dev(struct nbd_device *nbd)
  83 {
  84         return disk_to_dev(nbd->disk);
  85 }
  86
  87 static const char *nbdcmd_to_ascii(int cmd)
  88 {
  89         switch (cmd) {
  90         case  NBD_CMD_READ: return "read";
  91         case NBD_CMD_WRITE: return "write";
  92         case  NBD_CMD_DISC: return "disconnect";
  93         case NBD_CMD_FLUSH: return "flush";
  94         case  NBD_CMD_TRIM: return "trim/discard";
  95         }
  96         return "invalid";
  97 }
  98
  99 static void nbd_end_request(struct nbd_device *nbd, struct request *req)
 100 {
 101         int error = req->errors ? -EIO : 0;
 102         struct request_queue *q = req->q;
 103         unsigned long flags;
 104
 105         dev_dbg(nbd_to_dev(nbd), "request %p: %s\n", req,
 106                 error ? "failed" : "done");
 107
 108         spin_lock_irqsave(q->queue_lock, flags);
 109         __blk_end_request_all(req, error);
 110         spin_unlock_irqrestore(q->queue_lock, flags);
 111 }
 112
 113 static void sock_shutdown(struct nbd_device *nbd, int lock)
 114 {
 115         /* Forcibly shutdown the socket causing all listeners
 116          * to error
 117          *
 118          * FIXME: This code is duplicated from sys_shutdown, but
 119          * there should be a more generic interface rather than
 120          * calling socket ops directly here */
 121         if (lock)
 122                 mutex_lock(&nbd->tx_lock);
 123         if (nbd->sock) {
 124                 dev_warn(disk_to_dev(nbd->disk), "shutting down socket\n");
 125                 kernel_sock_shutdown(nbd->sock, SHUT_RDWR);
 126                 nbd->sock = NULL;
 127         }
 128         if (lock)
 129                 mutex_unlock(&nbd->tx_lock);
 130 }
 131
 132 static void nbd_xmit_timeout(unsigned long arg)
 133 {
 134         struct task_struct *task = (struct task_struct *)arg;
 135
 136         printk(KERN_WARNING "nbd: killing hung xmit (%s, pid: %d)\n",
 137                 task->comm, task->pid);
 138         force_sig(SIGKILL, task);
 139 }
 140
 141 /*
 142  *  Send or receive packet.
 143  */
 144 static int sock_xmit(struct nbd_device *nbd, int send, void *buf, int size,
 145                 int msg_flags)
 146 {
 147         struct socket *sock = nbd->sock;
 148         int result;
 149         struct msghdr msg;
 150         struct kvec iov;
 151         sigset_t blocked, oldset;
 152         unsigned long pflags = current->flags;
 153
 154         if (unlikely(!sock)) {
 155                 dev_err(disk_to_dev(nbd->disk),
 156                         "Attempted %s on closed socket in sock_xmit\n",
 157                         (send ? "send" : "recv"));
 158                 return -EINVAL;
 159         }
 160
 161         /* Allow interception of SIGKILL only
 162          * Don't allow other signals to interrupt the transmission */
 163         siginitsetinv(&blocked, sigmask(SIGKILL));
 164         sigprocmask(SIG_SETMASK, &blocked, &oldset);
 165
 166         current->flags |= PF_MEMALLOC;
 167         do {
 168                 sock->sk->sk_allocation = GFP_NOIO | __GFP_MEMALLOC;
 169                 iov.iov_base = buf;
 170                 iov.iov_len = size;
 171                 msg.msg_name = NULL;
 172                 msg.msg_namelen = 0;
 173                 msg.msg_control = NULL;
 174                 msg.msg_controllen = 0;
 175                 msg.msg_flags = msg_flags | MSG_NOSIGNAL;
 176
 177                 if (send) {
 178                         struct timer_list ti;
 179
 180                         if (nbd->xmit_timeout) {
 181                                 init_timer(&ti);
 182                                 ti.function = nbd_xmit_timeout;
 183                                 ti.data = (unsigned long)current;
 184                                 ti.expires = jiffies + nbd->xmit_timeout;
 185                                 add_timer(&ti);
 186                         }
 187                         result = kernel_sendmsg(sock, &msg, &iov, 1, size);
 188                         if (nbd->xmit_timeout)
 189                                 del_timer_sync(&ti);
 190                 } else
 191                         result = kernel_recvmsg(sock, &msg, &iov, 1, size,
 192                                                 msg.msg_flags);
 193
 194                 if (signal_pending(current)) {
 195                         siginfo_t info;
 196                         printk(KERN_WARNING "nbd (pid %d: %s) got signal %d\n",
 197                                 task_pid_nr(current), current->comm,
 198                                 dequeue_signal_lock(current, &current->blocked, &info));
 199                         result = -EINTR;
 200                         sock_shutdown(nbd, !send);
 201                         break;
 202                 }
 203
 204                 if (result <= 0) {
 205                         if (result == 0)
 206                                 result = -EPIPE; /* short read */
 207                         break;
 208                 }
 209                 size -= result;
 210                 buf += result;
 211         } while (size > 0);
 212
 213         sigprocmask(SIG_SETMASK, &oldset, NULL);
 214         tsk_restore_flags(current, pflags, PF_MEMALLOC);
 215
 216         return result;
 217 }
 218
 219 static inline int sock_send_bvec(struct nbd_device *nbd, struct bio_vec *bvec,
 220                 int flags)
 221 {
 222         int result;
 223         void *kaddr = kmap(bvec->bv_page);
 224         result = sock_xmit(nbd, 1, kaddr + bvec->bv_offset,
 225                            bvec->bv_len, flags);
 226         kunmap(bvec->bv_page);
 227         return result;
 228 }
 229
 230 /* always call with the tx_lock held */
 231 static int nbd_send_req(struct nbd_device *nbd, struct request *req)
 232 {
 233         int result, flags;
 234         struct nbd_request request;
 235         unsigned long size = blk_rq_bytes(req);
 236
 237         memset(&request, 0, sizeof(request));
 238         request.magic = htonl(NBD_REQUEST_MAGIC);
 239         request.type = htonl(nbd_cmd(req));
 240
 241         if (nbd_cmd(req) != NBD_CMD_FLUSH && nbd_cmd(req) != NBD_CMD_DISC) {
 242                 request.from = cpu_to_be64((u64)blk_rq_pos(req) << 9);
 243                 request.len = htonl(size);
 244         }
 245         memcpy(request.handle, &req, sizeof(req));
 246
 247         dev_dbg(nbd_to_dev(nbd), "request %p: sending control (%s@%llu,%uB)\n",
 248                 req, nbdcmd_to_ascii(nbd_cmd(req)),
 249                 (unsigned long long)blk_rq_pos(req) << 9, blk_rq_bytes(req));
 250         result = sock_xmit(nbd, 1, &request, sizeof(request),
 251                         (nbd_cmd(req) == NBD_CMD_WRITE) ? MSG_MORE : 0);
 252         if (result <= 0) {
 253                 dev_err(disk_to_dev(nbd->disk),
 254                         "Send control failed (result %d)\n", result);
 255                 goto error_out;
 256         }
 257
 258         if (nbd_cmd(req) == NBD_CMD_WRITE) {
 259                 struct req_iterator iter;
 260                 struct bio_vec bvec;
 261                 /*
 262                  * we are really probing at internals to determine
 263                  * whether to set MSG_MORE or not...
 264                  */
 265                 rq_for_each_segment(bvec, req, iter) {
 266                         flags = 0;
 267                         if (!rq_iter_last(bvec, iter))
 268                                 flags = MSG_MORE;
 269                         dev_dbg(nbd_to_dev(nbd), "request %p: sending %d bytes data\n",
 270                                 req, bvec.bv_len);
 271                         result = sock_send_bvec(nbd, &bvec, flags);
 272                         if (result <= 0) {
 273                                 dev_err(disk_to_dev(nbd->disk),
 274                                         "Send data failed (result %d)\n",
 275                                         result);
 276                                 goto error_out;
 277                         }
 278                 }
 279         }
 280         return 0;
 281
 282 error_out:
 283         return -EIO;
 284 }
 285
 286 static struct request *nbd_find_request(struct nbd_device *nbd,
 287                                         struct request *xreq)
 288 {
 289         struct request *req, *tmp;
 290         int err;
 291
 292         err = wait_event_interruptible(nbd->active_wq, nbd->active_req != xreq);
 293         if (unlikely(err))
 294                 goto out;
 295
 296         spin_lock(&nbd->queue_lock);
 297         list_for_each_entry_safe(req, tmp, &nbd->queue_head, queuelist) {
 298                 if (req != xreq)
 299                         continue;
 300                 list_del_init(&req->queuelist);
 301                 spin_unlock(&nbd->queue_lock);
 302                 return req;
 303         }
 304         spin_unlock(&nbd->queue_lock);
 305
 306         err = -ENOENT;
 307
 308 out:
 309         return ERR_PTR(err);
 310 }
 311
 312 static inline int sock_recv_bvec(struct nbd_device *nbd, struct bio_vec *bvec)
 313 {
 314         int result;
 315         void *kaddr = kmap(bvec->bv_page);
 316         result = sock_xmit(nbd, 0, kaddr + bvec->bv_offset, bvec->bv_len,
 317                         MSG_WAITALL);
 318         kunmap(bvec->bv_page);
 319         return result;
 320 }
 321
 322 /* NULL returned = something went wrong, inform userspace */
 323 static struct request *nbd_read_stat(struct nbd_device *nbd)
 324 {
 325         int result;
 326         struct nbd_reply reply;
 327         struct request *req;
 328
 329         reply.magic = 0;
 330         result = sock_xmit(nbd, 0, &reply, sizeof(reply), MSG_WAITALL);
 331         if (result <= 0) {
 332                 dev_err(disk_to_dev(nbd->disk),
 333                         "Receive control failed (result %d)\n", result);
 334                 goto harderror;
 335         }
 336
 337         if (ntohl(reply.magic) != NBD_REPLY_MAGIC) {
 338                 dev_err(disk_to_dev(nbd->disk), "Wrong magic (0x%lx)\n",
 339                                 (unsigned long)ntohl(reply.magic));
 340                 result = -EPROTO;
 341                 goto harderror;
 342         }
 343
 344         req = nbd_find_request(nbd, *(struct request **)reply.handle);
 345         if (IS_ERR(req)) {
 346                 result = PTR_ERR(req);
 347                 if (result != -ENOENT)
 348                         goto harderror;
 349
 350                 dev_err(disk_to_dev(nbd->disk), "Unexpected reply (%p)\n",
 351                         reply.handle);
 352                 result = -EBADR;
 353                 goto harderror;
 354         }
 355
 356         if (ntohl(reply.error)) {
 357                 dev_err(disk_to_dev(nbd->disk), "Other side returned error (%d)\n",
 358                         ntohl(reply.error));
 359                 req->errors++;
 360                 return req;
 361         }
 362
 363         dev_dbg(nbd_to_dev(nbd), "request %p: got reply\n", req);
 364         if (nbd_cmd(req) == NBD_CMD_READ) {
 365                 struct req_iterator iter;
 366                 struct bio_vec bvec;
 367
 368                 rq_for_each_segment(bvec, req, iter) {
 369                         result = sock_recv_bvec(nbd, &bvec);
 370                         if (result <= 0) {
 371                                 dev_err(disk_to_dev(nbd->disk), "Receive data failed (result %d)\n",
 372                                         result);
 373                                 req->errors++;
 374                                 return req;
 375                         }
 376                         dev_dbg(nbd_to_dev(nbd), "request %p: got %d bytes data\n",
 377                                 req, bvec.bv_len);
 378                 }
 379         }
 380         return req;
 381 harderror:
 382         nbd->harderror = result;
 383         return NULL;
 384 }
 385
 386 static ssize_t pid_show(struct device *dev,
 387                         struct device_attribute *attr, char *buf)
 388 {
 389         struct gendisk *disk = dev_to_disk(dev);
 390
 391         return sprintf(buf, "%ld\n",
 392                 (long) ((struct nbd_device *)disk->private_data)->pid);
 393 }
 394
 395 static struct device_attribute pid_attr = {
 396         .attr = { .name = "pid", .mode = S_IRUGO},
 397         .show = pid_show,
 398 };
 399
 400 static int nbd_do_it(struct nbd_device *nbd)
 401 {
 402         struct request *req;
 403         int ret;
 404
 405         BUG_ON(nbd->magic != NBD_MAGIC);
 406
 407         sk_set_memalloc(nbd->sock->sk);
 408         nbd->pid = task_pid_nr(current);
 409         ret = device_create_file(disk_to_dev(nbd->disk), &pid_attr);
 410         if (ret) {
 411                 dev_err(disk_to_dev(nbd->disk), "device_create_file failed!\n");
 412                 nbd->pid = 0;
 413                 return ret;
 414         }
 415
 416         while ((req = nbd_read_stat(nbd)) != NULL)
 417                 nbd_end_request(nbd, req);
 418
 419         device_remove_file(disk_to_dev(nbd->disk), &pid_attr);
 420         nbd->pid = 0;
 421         return 0;
 422 }
 423
 424 static void nbd_clear_que(struct nbd_device *nbd)
 425 {
 426         struct request *req;
 427
 428         BUG_ON(nbd->magic != NBD_MAGIC);
 429
 430         /*
 431          * Because we have set nbd->sock to NULL under the tx_lock, all
 432          * modifications to the list must have completed by now.  For
 433          * the same reason, the active_req must be NULL.
 434          *
 435          * As a consequence, we don't need to take the spin lock while
 436          * purging the list here.
 437          */
 438         BUG_ON(nbd->sock);
 439         BUG_ON(nbd->active_req);
 440
 441         while (!list_empty(&nbd->queue_head)) {
 442                 req = list_entry(nbd->queue_head.next, struct request,
 443                                  queuelist);
 444                 list_del_init(&req->queuelist);
 445                 req->errors++;
 446                 nbd_end_request(nbd, req);
 447         }
 448
 449         while (!list_empty(&nbd->waiting_queue)) {
 450                 req = list_entry(nbd->waiting_queue.next, struct request,
 451                                  queuelist);
 452                 list_del_init(&req->queuelist);
 453                 req->errors++;
 454                 nbd_end_request(nbd, req);
 455         }
 456 }
 457
 458
 459 static void nbd_handle_req(struct nbd_device *nbd, struct request *req)
 460 {
 461         if (req->cmd_type != REQ_TYPE_FS)
 462                 goto error_out;
 463
 464         nbd_cmd(req) = NBD_CMD_READ;
 465         if (rq_data_dir(req) == WRITE) {
 466                 if ((req->cmd_flags & REQ_DISCARD)) {
 467                         WARN_ON(!(nbd->flags & NBD_FLAG_SEND_TRIM));
 468                         nbd_cmd(req) = NBD_CMD_TRIM;
 469                 } else
 470                         nbd_cmd(req) = NBD_CMD_WRITE;
 471                 if (nbd->flags & NBD_FLAG_READ_ONLY) {
 472                         dev_err(disk_to_dev(nbd->disk),
 473                                 "Write on read-only\n");
 474                         goto error_out;
 475                 }
 476         }
 477
 478         if (req->cmd_flags & REQ_FLUSH) {
 479                 BUG_ON(unlikely(blk_rq_sectors(req)));
 480                 nbd_cmd(req) = NBD_CMD_FLUSH;
 481         }
 482
 483         req->errors = 0;
 484
 485         mutex_lock(&nbd->tx_lock);
 486         if (unlikely(!nbd->sock)) {
 487                 mutex_unlock(&nbd->tx_lock);
 488                 dev_err(disk_to_dev(nbd->disk),
 489                         "Attempted send on closed socket\n");
 490                 goto error_out;
 491         }
 492
 493         nbd->active_req = req;
 494
 495         if (nbd_send_req(nbd, req) != 0) {
 496                 dev_err(disk_to_dev(nbd->disk), "Request send failed\n");
 497                 req->errors++;
 498                 nbd_end_request(nbd, req);
 499         } else {
 500                 spin_lock(&nbd->queue_lock);
 501                 list_add_tail(&req->queuelist, &nbd->queue_head);
 502                 spin_unlock(&nbd->queue_lock);
 503         }
 504
 505         nbd->active_req = NULL;
 506         mutex_unlock(&nbd->tx_lock);
 507         wake_up_all(&nbd->active_wq);
 508
 509         return;
 510
 511 error_out:
 512         req->errors++;
 513         nbd_end_request(nbd, req);
 514 }
 515
 516 static int nbd_thread(void *data)
 517 {
 518         struct nbd_device *nbd = data;
 519         struct request *req;
 520
 521         set_user_nice(current, MIN_NICE);
 522         while (!kthread_should_stop() || !list_empty(&nbd->waiting_queue)) {
 523                 /* wait for something to do */
 524                 wait_event_interruptible(nbd->waiting_wq,
 525                                          kthread_should_stop() ||
 526                                          !list_empty(&nbd->waiting_queue));
 527
 528                 /* extract request */
 529                 if (list_empty(&nbd->waiting_queue))
 530                         continue;
 531
 532                 spin_lock_irq(&nbd->queue_lock);
 533                 req = list_entry(nbd->waiting_queue.next, struct request,
 534                                  queuelist);
 535                 list_del_init(&req->queuelist);
 536                 spin_unlock_irq(&nbd->queue_lock);
 537
 538                 /* handle request */
 539                 nbd_handle_req(nbd, req);
 540         }
 541         return 0;
 542 }
 543
 544 /*
 545  * We always wait for result of write, for now. It would be nice to make it optional
 546  * in future
 547  * if ((rq_data_dir(req) == WRITE) && (nbd->flags & NBD_WRITE_NOCHK))
 548  *   { printk( "Warning: Ignoring result!\n"); nbd_end_request( req ); }
 549  */
 550
 551 static void do_nbd_request(struct request_queue *q)
 552                 __releases(q->queue_lock) __acquires(q->queue_lock)
 553 {
 554         struct request *req;
 555
 556         while ((req = blk_fetch_request(q)) != NULL) {
 557                 struct nbd_device *nbd;
 558
 559                 spin_unlock_irq(q->queue_lock);
 560
 561                 nbd = req->rq_disk->private_data;
 562
 563                 BUG_ON(nbd->magic != NBD_MAGIC);
 564
 565                 dev_dbg(nbd_to_dev(nbd), "request %p: dequeued (flags=%x)\n",
 566                         req, req->cmd_type);
 567
 568                 if (unlikely(!nbd->sock)) {
 569                         dev_err(disk_to_dev(nbd->disk),
 570                                 "Attempted send on closed socket\n");
 571                         req->errors++;
 572                         nbd_end_request(nbd, req);
 573                         spin_lock_irq(q->queue_lock);
 574                         continue;
 575                 }
 576
 577                 spin_lock_irq(&nbd->queue_lock);
 578                 list_add_tail(&req->queuelist, &nbd->waiting_queue);
 579                 spin_unlock_irq(&nbd->queue_lock);
 580
 581                 wake_up(&nbd->waiting_wq);
 582
 583                 spin_lock_irq(q->queue_lock);
 584         }
 585 }
 586
 587 /* Must be called with tx_lock held */
 588
 589 static int __nbd_ioctl(struct block_device *bdev, struct nbd_device *nbd,
 590                        unsigned int cmd, unsigned long arg)
 591 {
 592         switch (cmd) {
 593         case NBD_DISCONNECT: {
 594                 struct request sreq;
 595
 596                 dev_info(disk_to_dev(nbd->disk), "NBD_DISCONNECT\n");
 597                 if (!nbd->sock)
 598                         return -EINVAL;
 599
 600                 mutex_unlock(&nbd->tx_lock);
 601                 fsync_bdev(bdev);
 602                 mutex_lock(&nbd->tx_lock);
 603                 blk_rq_init(NULL, &sreq);
 604                 sreq.cmd_type = REQ_TYPE_SPECIAL;
 605                 nbd_cmd(&sreq) = NBD_CMD_DISC;
 606
 607                 /* Check again after getting mutex back.  */
 608                 if (!nbd->sock)
 609                         return -EINVAL;
 610
 611                 nbd->disconnect = 1;
 612
 613                 nbd_send_req(nbd, &sreq);
 614                 return 0;
 615         }
 616
 617         case NBD_CLEAR_SOCK: {
 618                 struct socket *sock = nbd->sock;
 619                 nbd->sock = NULL;
 620                 nbd_clear_que(nbd);
 621                 BUG_ON(!list_empty(&nbd->queue_head));
 622                 BUG_ON(!list_empty(&nbd->waiting_queue));
 623                 kill_bdev(bdev);
 624                 if (sock)
 625                         sockfd_put(sock);
 626                 return 0;
 627         }
 628
 629         case NBD_SET_SOCK: {
 630                 struct socket *sock;
 631                 int err;
 632                 if (nbd->sock)
 633                         return -EBUSY;
 634                 sock = sockfd_lookup(arg, &err);
 635                 if (sock) {
 636                         nbd->sock = sock;
 637                         if (max_part > 0)
 638                                 bdev->bd_invalidated = 1;
 639                         nbd->disconnect = 0; /* we're connected now */
 640                         return 0;
 641                 }
 642                 return -EINVAL;
 643         }
 644
 645         case NBD_SET_BLKSIZE:
 646                 nbd->blksize = arg;
 647                 nbd->bytesize &= ~(nbd->blksize-1);
 648                 bdev->bd_inode->i_size = nbd->bytesize;
 649                 set_blocksize(bdev, nbd->blksize);
 650                 set_capacity(nbd->disk, nbd->bytesize >> 9);
 651                 return 0;
 652
 653         case NBD_SET_SIZE:
 654                 nbd->bytesize = arg & ~(nbd->blksize-1);
 655                 bdev->bd_inode->i_size = nbd->bytesize;
 656                 set_blocksize(bdev, nbd->blksize);
 657                 set_capacity(nbd->disk, nbd->bytesize >> 9);
 658                 return 0;
 659
 660         case NBD_SET_TIMEOUT:
 661                 nbd->xmit_timeout = arg * HZ;
 662                 return 0;
 663
 664         case NBD_SET_FLAGS:
 665                 nbd->flags = arg;
 666                 return 0;
 667
 668         case NBD_SET_SIZE_BLOCKS:
 669                 nbd->bytesize = ((u64) arg) * nbd->blksize;
 670                 bdev->bd_inode->i_size = nbd->bytesize;
 671                 set_blocksize(bdev, nbd->blksize);
 672                 set_capacity(nbd->disk, nbd->bytesize >> 9);
 673                 return 0;
 674
 675         case NBD_DO_IT: {
 676                 struct task_struct *thread;
 677                 struct socket *sock;
 678                 int error;
 679
 680                 if (nbd->pid)
 681                         return -EBUSY;
 682                 if (!nbd->sock)
 683                         return -EINVAL;
 684
 685                 mutex_unlock(&nbd->tx_lock);
 686
 687                 if (nbd->flags & NBD_FLAG_READ_ONLY)
 688                         set_device_ro(bdev, true);
 689                 if (nbd->flags & NBD_FLAG_SEND_TRIM)
 690                         queue_flag_set_unlocked(QUEUE_FLAG_DISCARD,
 691                                 nbd->disk->queue);
 692                 if (nbd->flags & NBD_FLAG_SEND_FLUSH)
 693                         blk_queue_flush(nbd->disk->queue, REQ_FLUSH);
 694                 else
 695                         blk_queue_flush(nbd->disk->queue, 0);
 696
 697                 thread = kthread_run(nbd_thread, nbd, "%s",
 698                                      nbd->disk->disk_name);
 699                 if (IS_ERR(thread)) {
 700                         mutex_lock(&nbd->tx_lock);
 701                         return PTR_ERR(thread);
 702                 }
 703
 704                 error = nbd_do_it(nbd);
 705                 kthread_stop(thread);
 706
 707                 mutex_lock(&nbd->tx_lock);
 708                 if (error)
 709                         return error;
 710                 sock_shutdown(nbd, 0);
 711                 sock = nbd->sock;
 712                 nbd->sock = NULL;
 713                 nbd_clear_que(nbd);
 714                 dev_warn(disk_to_dev(nbd->disk), "queue cleared\n");
 715                 kill_bdev(bdev);
 716                 queue_flag_clear_unlocked(QUEUE_FLAG_DISCARD, nbd->disk->queue);
 717                 set_device_ro(bdev, false);
 718                 if (sock)
 719                         sockfd_put(sock);
 720                 nbd->flags = 0;
 721                 nbd->bytesize = 0;
 722                 bdev->bd_inode->i_size = 0;
 723                 set_capacity(nbd->disk, 0);
 724                 if (max_part > 0)
 725                         ioctl_by_bdev(bdev, BLKRRPART, 0);
 726                 if (nbd->disconnect) /* user requested, ignore socket errors */
 727                         return 0;
 728                 return nbd->harderror;
 729         }
 730
 731         case NBD_CLEAR_QUE:
 732                 /*
 733                  * This is for compatibility only.  The queue is always cleared
 734                  * by NBD_DO_IT or NBD_CLEAR_SOCK.
 735                  */
 736                 return 0;
 737
 738         case NBD_PRINT_DEBUG:
 739                 dev_info(disk_to_dev(nbd->disk),
 740                         "next = %p, prev = %p, head = %p\n",
 741                         nbd->queue_head.next, nbd->queue_head.prev,
 742                         &nbd->queue_head);
 743                 return 0;
 744         }
 745         return -ENOTTY;
 746 }
 747
 748 static int nbd_ioctl(struct block_device *bdev, fmode_t mode,
 749                      unsigned int cmd, unsigned long arg)
 750 {
 751         struct nbd_device *nbd = bdev->bd_disk->private_data;
 752         int error;
 753
 754         if (!capable(CAP_SYS_ADMIN))
 755                 return -EPERM;
 756
 757         BUG_ON(nbd->magic != NBD_MAGIC);
 758
 759         mutex_lock(&nbd->tx_lock);
 760         error = __nbd_ioctl(bdev, nbd, cmd, arg);
 761         mutex_unlock(&nbd->tx_lock);
 762
 763         return error;
 764 }
 765
 766 static const struct block_device_operations nbd_fops =
 767 {
 768         .owner =        THIS_MODULE,
 769         .ioctl =        nbd_ioctl,
 770 };
 771
 772 /*
 773  * And here should be modules and kernel interface
 774  *  (Just smiley confuses emacs :-)
 775  */
 776
 777 static int __init nbd_init(void)
 778 {
 779         int err = -ENOMEM;
 780         int i;
 781         int part_shift;
 782
 783         BUILD_BUG_ON(sizeof(struct nbd_request) != 28);
 784
 785         if (max_part < 0) {
 786                 printk(KERN_ERR "nbd: max_part must be >= 0\n");
 787                 return -EINVAL;
 788         }
 789
 790         part_shift = 0;
 791         if (max_part > 0) {
 792                 part_shift = fls(max_part);
 793
 794                 /*
 795                  * Adjust max_part according to part_shift as it is exported
 796                  * to user space so that user can know the max number of
 797                  * partition kernel should be able to manage.
 798                  *
 799                  * Note that -1 is required because partition 0 is reserved
 800                  * for the whole disk.
 801                  */
 802                 max_part = (1UL << part_shift) - 1;
 803         }
 804
 805         if ((1UL << part_shift) > DISK_MAX_PARTS)
 806                 return -EINVAL;
 807
 808         if (nbds_max > 1UL << (MINORBITS - part_shift))
 809                 return -EINVAL;
 810
 811         nbd_dev = kcalloc(nbds_max, sizeof(*nbd_dev), GFP_KERNEL);
 812         if (!nbd_dev)
 813                 return -ENOMEM;
 814
 815         for (i = 0; i < nbds_max; i++) {
 816                 struct gendisk *disk = alloc_disk(1 << part_shift);
 817                 if (!disk)
 818                         goto out;
 819                 nbd_dev[i].disk = disk;
 820                 /*
 821                  * The new linux 2.5 block layer implementation requires
 822                  * every gendisk to have its very own request_queue struct.
 823                  * These structs are big so we dynamically allocate them.
 824                  */
 825                 disk->queue = blk_init_queue(do_nbd_request, &nbd_lock);
 826                 if (!disk->queue) {
 827                         put_disk(disk);
 828                         goto out;
 829                 }
 830                 /*
 831                  * Tell the block layer that we are not a rotational device
 832                  */
 833                 queue_flag_set_unlocked(QUEUE_FLAG_NONROT, disk->queue);
 834                 queue_flag_clear_unlocked(QUEUE_FLAG_ADD_RANDOM, disk->queue);
 835                 disk->queue->limits.discard_granularity = 512;
 836                 disk->queue->limits.max_discard_sectors = UINT_MAX;
 837                 disk->queue->limits.discard_zeroes_data = 0;
 838                 blk_queue_max_hw_sectors(disk->queue, 65536);
 839                 disk->queue->limits.max_sectors = 256;
 840         }
 841
 842         if (register_blkdev(NBD_MAJOR, "nbd")) {
 843                 err = -EIO;
 844                 goto out;
 845         }
 846
 847         printk(KERN_INFO "nbd: registered device at major %d\n", NBD_MAJOR);
 848
 849         for (i = 0; i < nbds_max; i++) {
 850                 struct gendisk *disk = nbd_dev[i].disk;
 851                 nbd_dev[i].magic = NBD_MAGIC;
 852                 INIT_LIST_HEAD(&nbd_dev[i].waiting_queue);
 853                 spin_lock_init(&nbd_dev[i].queue_lock);
 854                 INIT_LIST_HEAD(&nbd_dev[i].queue_head);
 855                 mutex_init(&nbd_dev[i].tx_lock);
 856                 init_waitqueue_head(&nbd_dev[i].active_wq);
 857                 init_waitqueue_head(&nbd_dev[i].waiting_wq);
 858                 nbd_dev[i].blksize = 1024;
 859                 nbd_dev[i].bytesize = 0;
 860                 disk->major = NBD_MAJOR;
 861                 disk->first_minor = i << part_shift;
 862                 disk->fops = &nbd_fops;
 863                 disk->private_data = &nbd_dev[i];
 864                 sprintf(disk->disk_name, "nbd%d", i);
 865                 set_capacity(disk, 0);
 866                 add_disk(disk);
 867         }
 868
 869         return 0;
 870 out:
 871         while (i--) {
 872                 blk_cleanup_queue(nbd_dev[i].disk->queue);
 873                 put_disk(nbd_dev[i].disk);
 874         }
 875         kfree(nbd_dev);
 876         return err;
 877 }
 878
 879 static void __exit nbd_cleanup(void)
 880 {
 881         int i;
 882         for (i = 0; i < nbds_max; i++) {
 883                 struct gendisk *disk = nbd_dev[i].disk;
 884                 nbd_dev[i].magic = 0;
 885                 if (disk) {
 886                         del_gendisk(disk);
 887                         blk_cleanup_queue(disk->queue);
 888                         put_disk(disk);
 889                 }
 890         }
 891         unregister_blkdev(NBD_MAJOR, "nbd");
 892         kfree(nbd_dev);
 893         printk(KERN_INFO "nbd: unregistered device at major %d\n", NBD_MAJOR);
 894 }
 895
 896 module_init(nbd_init);
 897 module_exit(nbd_cleanup);
 898
 899 MODULE_DESCRIPTION("Network Block Device");
 900 MODULE_LICENSE("GPL");
 901
 902 module_param(nbds_max, int, 0444);
 903 MODULE_PARM_DESC(nbds_max, "number of network block devices to initialize (default: 16)");
 904 module_param(max_part, int, 0444);
 905 MODULE_PARM_DESC(max_part, "number of partitions per device (default: 0)");