SAFE public projects git trees. - safe/jmp/linux-2.6/blob - 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 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/compiler.h>
  28 #include <linux/err.h>
  29 #include <linux/kernel.h>
  30 #include <net/sock.h>
  31
  32 #include <asm/uaccess.h>
  33 #include <asm/system.h>
  34 #include <asm/types.h>
  35
  36 #include <linux/nbd.h>
  37
  38 #define LO_MAGIC 0x68797548
  39
  40 #ifdef NDEBUG
  41 #define dprintk(flags, fmt...)
  42 #else /* NDEBUG */
  43 #define dprintk(flags, fmt...) do { \
  44         if (debugflags & (flags)) printk(KERN_DEBUG fmt); \
  45 } while (0)
  46 #define DBG_IOCTL       0x0004
  47 #define DBG_INIT        0x0010
  48 #define DBG_EXIT        0x0020
  49 #define DBG_BLKDEV      0x0100
  50 #define DBG_RX          0x0200
  51 #define DBG_TX          0x0400
  52 static unsigned int debugflags;
  53 #endif /* NDEBUG */
  54
  55 static unsigned int nbds_max = 16;
  56 static struct nbd_device nbd_dev[MAX_NBD];
  57
  58 /*
  59  * Use just one lock (or at most 1 per NIC). Two arguments for this:
  60  * 1. Each NIC is essentially a synchronization point for all servers
  61  *    accessed through that NIC so there's no need to have more locks
  62  *    than NICs anyway.
  63  * 2. More locks lead to more "Dirty cache line bouncing" which will slow
  64  *    down each lock to the point where they're actually slower than just
  65  *    a single lock.
  66  * Thanks go to Jens Axboe and Al Viro for their LKML emails explaining this!
  67  */
  68 static DEFINE_SPINLOCK(nbd_lock);
  69
  70 #ifndef NDEBUG
  71 static const char *ioctl_cmd_to_ascii(int cmd)
  72 {
  73         switch (cmd) {
  74         case NBD_SET_SOCK: return "set-sock";
  75         case NBD_SET_BLKSIZE: return "set-blksize";
  76         case NBD_SET_SIZE: return "set-size";
  77         case NBD_DO_IT: return "do-it";
  78         case NBD_CLEAR_SOCK: return "clear-sock";
  79         case NBD_CLEAR_QUE: return "clear-que";
  80         case NBD_PRINT_DEBUG: return "print-debug";
  81         case NBD_SET_SIZE_BLOCKS: return "set-size-blocks";
  82         case NBD_DISCONNECT: return "disconnect";
  83         case BLKROSET: return "set-read-only";
  84         case BLKFLSBUF: return "flush-buffer-cache";
  85         }
  86         return "unknown";
  87 }
  88
  89 static const char *nbdcmd_to_ascii(int cmd)
  90 {
  91         switch (cmd) {
  92         case  NBD_CMD_READ: return "read";
  93         case NBD_CMD_WRITE: return "write";
  94         case  NBD_CMD_DISC: return "disconnect";
  95         }
  96         return "invalid";
  97 }
  98 #endif /* NDEBUG */
  99
 100 static void nbd_end_request(struct request *req)
 101 {
 102         int uptodate = (req->errors == 0) ? 1 : 0;
 103         struct request_queue *q = req->q;
 104         unsigned long flags;
 105
 106         dprintk(DBG_BLKDEV, "%s: request %p: %s\n", req->rq_disk->disk_name,
 107                         req, uptodate? "done": "failed");
 108
 109         spin_lock_irqsave(q->queue_lock, flags);
 110         if (!end_that_request_first(req, uptodate, req->nr_sectors)) {
 111                 end_that_request_last(req, uptodate);
 112         }
 113         spin_unlock_irqrestore(q->queue_lock, flags);
 114 }
 115
 116 /*
 117  *  Send or receive packet.
 118  */
 119 static int sock_xmit(struct socket *sock, int send, void *buf, int size,
 120                 int msg_flags)
 121 {
 122         int result;
 123         struct msghdr msg;
 124         struct kvec iov;
 125         sigset_t blocked, oldset;
 126
 127         /* Allow interception of SIGKILL only
 128          * Don't allow other signals to interrupt the transmission */
 129         siginitsetinv(&blocked, sigmask(SIGKILL));
 130         sigprocmask(SIG_SETMASK, &blocked, &oldset);
 131
 132         do {
 133                 sock->sk->sk_allocation = GFP_NOIO;
 134                 iov.iov_base = buf;
 135                 iov.iov_len = size;
 136                 msg.msg_name = NULL;
 137                 msg.msg_namelen = 0;
 138                 msg.msg_control = NULL;
 139                 msg.msg_controllen = 0;
 140                 msg.msg_flags = msg_flags | MSG_NOSIGNAL;
 141
 142                 if (send)
 143                         result = kernel_sendmsg(sock, &msg, &iov, 1, size);
 144                 else
 145                         result = kernel_recvmsg(sock, &msg, &iov, 1, size, 0);
 146
 147                 if (signal_pending(current)) {
 148                         siginfo_t info;
 149                         printk(KERN_WARNING "nbd (pid %d: %s) got signal %d\n",
 150                                 current->pid, current->comm,
 151                                 dequeue_signal_lock(current, &current->blocked, &info));
 152                         result = -EINTR;
 153                         break;
 154                 }
 155
 156                 if (result <= 0) {
 157                         if (result == 0)
 158                                 result = -EPIPE; /* short read */
 159                         break;
 160                 }
 161                 size -= result;
 162                 buf += result;
 163         } while (size > 0);
 164
 165         sigprocmask(SIG_SETMASK, &oldset, NULL);
 166
 167         return result;
 168 }
 169
 170 static inline int sock_send_bvec(struct socket *sock, struct bio_vec *bvec,
 171                 int flags)
 172 {
 173         int result;
 174         void *kaddr = kmap(bvec->bv_page);
 175         result = sock_xmit(sock, 1, kaddr + bvec->bv_offset, bvec->bv_len,
 176                         flags);
 177         kunmap(bvec->bv_page);
 178         return result;
 179 }
 180
 181 static int nbd_send_req(struct nbd_device *lo, struct request *req)
 182 {
 183         int result, flags;
 184         struct nbd_request request;
 185         unsigned long size = req->nr_sectors << 9;
 186         struct socket *sock = lo->sock;
 187
 188         request.magic = htonl(NBD_REQUEST_MAGIC);
 189         request.type = htonl(nbd_cmd(req));
 190         request.from = cpu_to_be64((u64) req->sector << 9);
 191         request.len = htonl(size);
 192         memcpy(request.handle, &req, sizeof(req));
 193
 194         dprintk(DBG_TX, "%s: request %p: sending control (%s@%llu,%luB)\n",
 195                         lo->disk->disk_name, req,
 196                         nbdcmd_to_ascii(nbd_cmd(req)),
 197                         (unsigned long long)req->sector << 9,
 198                         req->nr_sectors << 9);
 199         result = sock_xmit(sock, 1, &request, sizeof(request),
 200                         (nbd_cmd(req) == NBD_CMD_WRITE)? MSG_MORE: 0);
 201         if (result <= 0) {
 202                 printk(KERN_ERR "%s: Send control failed (result %d)\n",
 203                                 lo->disk->disk_name, result);
 204                 goto error_out;
 205         }
 206
 207         if (nbd_cmd(req) == NBD_CMD_WRITE) {
 208                 struct req_iterator iter;
 209                 struct bio_vec *bvec;
 210                 /*
 211                  * we are really probing at internals to determine
 212                  * whether to set MSG_MORE or not...
 213                  */
 214                 rq_for_each_segment(bvec, req, iter) {
 215                                 flags = 0;
 216                                 if (!rq_iter_last(req, iter))
 217                                         flags = MSG_MORE;
 218                                 dprintk(DBG_TX, "%s: request %p: sending %d bytes data\n",
 219                                                 lo->disk->disk_name, req,
 220                                                 bvec->bv_len);
 221                                 result = sock_send_bvec(sock, bvec, flags);
 222                                 if (result <= 0) {
 223                                         printk(KERN_ERR "%s: Send data failed (result %d)\n",
 224                                                         lo->disk->disk_name,
 225                                                         result);
 226                                         goto error_out;
 227                                 }
 228                 }
 229         }
 230         return 0;
 231
 232 error_out:
 233         return 1;
 234 }
 235
 236 static struct request *nbd_find_request(struct nbd_device *lo, char *handle)
 237 {
 238         struct request *req;
 239         struct list_head *tmp;
 240         struct request *xreq;
 241         int err;
 242
 243         memcpy(&xreq, handle, sizeof(xreq));
 244
 245         err = wait_event_interruptible(lo->active_wq, lo->active_req != xreq);
 246         if (unlikely(err))
 247                 goto out;
 248
 249         spin_lock(&lo->queue_lock);
 250         list_for_each(tmp, &lo->queue_head) {
 251                 req = list_entry(tmp, struct request, queuelist);
 252                 if (req != xreq)
 253                         continue;
 254                 list_del_init(&req->queuelist);
 255                 spin_unlock(&lo->queue_lock);
 256                 return req;
 257         }
 258         spin_unlock(&lo->queue_lock);
 259
 260         err = -ENOENT;
 261
 262 out:
 263         return ERR_PTR(err);
 264 }
 265
 266 static inline int sock_recv_bvec(struct socket *sock, struct bio_vec *bvec)
 267 {
 268         int result;
 269         void *kaddr = kmap(bvec->bv_page);
 270         result = sock_xmit(sock, 0, kaddr + bvec->bv_offset, bvec->bv_len,
 271                         MSG_WAITALL);
 272         kunmap(bvec->bv_page);
 273         return result;
 274 }
 275
 276 /* NULL returned = something went wrong, inform userspace */
 277 static struct request *nbd_read_stat(struct nbd_device *lo)
 278 {
 279         int result;
 280         struct nbd_reply reply;
 281         struct request *req;
 282         struct socket *sock = lo->sock;
 283
 284         reply.magic = 0;
 285         result = sock_xmit(sock, 0, &reply, sizeof(reply), MSG_WAITALL);
 286         if (result <= 0) {
 287                 printk(KERN_ERR "%s: Receive control failed (result %d)\n",
 288                                 lo->disk->disk_name, result);
 289                 goto harderror;
 290         }
 291
 292         if (ntohl(reply.magic) != NBD_REPLY_MAGIC) {
 293                 printk(KERN_ERR "%s: Wrong magic (0x%lx)\n",
 294                                 lo->disk->disk_name,
 295                                 (unsigned long)ntohl(reply.magic));
 296                 result = -EPROTO;
 297                 goto harderror;
 298         }
 299
 300         req = nbd_find_request(lo, reply.handle);
 301         if (unlikely(IS_ERR(req))) {
 302                 result = PTR_ERR(req);
 303                 if (result != -ENOENT)
 304                         goto harderror;
 305
 306                 printk(KERN_ERR "%s: Unexpected reply (%p)\n",
 307                                 lo->disk->disk_name, reply.handle);
 308                 result = -EBADR;
 309                 goto harderror;
 310         }
 311
 312         if (ntohl(reply.error)) {
 313                 printk(KERN_ERR "%s: Other side returned error (%d)\n",
 314                                 lo->disk->disk_name, ntohl(reply.error));
 315                 req->errors++;
 316                 return req;
 317         }
 318
 319         dprintk(DBG_RX, "%s: request %p: got reply\n",
 320                         lo->disk->disk_name, req);
 321         if (nbd_cmd(req) == NBD_CMD_READ) {
 322                 struct req_iterator iter;
 323                 struct bio_vec *bvec;
 324
 325                 rq_for_each_segment(bvec, req, iter) {
 326                                 result = sock_recv_bvec(sock, bvec);
 327                                 if (result <= 0) {
 328                                         printk(KERN_ERR "%s: Receive data failed (result %d)\n",
 329                                                         lo->disk->disk_name,
 330                                                         result);
 331                                         req->errors++;
 332                                         return req;
 333                                 }
 334                                 dprintk(DBG_RX, "%s: request %p: got %d bytes data\n",
 335                                         lo->disk->disk_name, req, bvec->bv_len);
 336                 }
 337         }
 338         return req;
 339 harderror:
 340         lo->harderror = result;
 341         return NULL;
 342 }
 343
 344 static ssize_t pid_show(struct gendisk *disk, char *page)
 345 {
 346         return sprintf(page, "%ld\n",
 347                 (long) ((struct nbd_device *)disk->private_data)->pid);
 348 }
 349
 350 static struct disk_attribute pid_attr = {
 351         .attr = { .name = "pid", .mode = S_IRUGO },
 352         .show = pid_show,
 353 };
 354
 355 static int nbd_do_it(struct nbd_device *lo)
 356 {
 357         struct request *req;
 358         int ret;
 359
 360         BUG_ON(lo->magic != LO_MAGIC);
 361
 362         lo->pid = current->pid;
 363         ret = sysfs_create_file(&lo->disk->kobj, &pid_attr.attr);
 364         if (ret) {
 365                 printk(KERN_ERR "nbd: sysfs_create_file failed!");
 366                 return ret;
 367         }
 368
 369         while ((req = nbd_read_stat(lo)) != NULL)
 370                 nbd_end_request(req);
 371
 372         sysfs_remove_file(&lo->disk->kobj, &pid_attr.attr);
 373         return 0;
 374 }
 375
 376 static void nbd_clear_que(struct nbd_device *lo)
 377 {
 378         struct request *req;
 379
 380         BUG_ON(lo->magic != LO_MAGIC);
 381
 382         /*
 383          * Because we have set lo->sock to NULL under the tx_lock, all
 384          * modifications to the list must have completed by now.  For
 385          * the same reason, the active_req must be NULL.
 386          *
 387          * As a consequence, we don't need to take the spin lock while
 388          * purging the list here.
 389          */
 390         BUG_ON(lo->sock);
 391         BUG_ON(lo->active_req);
 392
 393         while (!list_empty(&lo->queue_head)) {
 394                 req = list_entry(lo->queue_head.next, struct request,
 395                                  queuelist);
 396                 list_del_init(&req->queuelist);
 397                 req->errors++;
 398                 nbd_end_request(req);
 399         }
 400 }
 401
 402 /*
 403  * We always wait for result of write, for now. It would be nice to make it optional
 404  * in future
 405  * if ((rq_data_dir(req) == WRITE) && (lo->flags & NBD_WRITE_NOCHK))
 406  *   { printk( "Warning: Ignoring result!\n"); nbd_end_request( req ); }
 407  */
 408
 409 static void do_nbd_request(struct request_queue * q)
 410 {
 411         struct request *req;
 412
 413         while ((req = elv_next_request(q)) != NULL) {
 414                 struct nbd_device *lo;
 415
 416                 blkdev_dequeue_request(req);
 417                 dprintk(DBG_BLKDEV, "%s: request %p: dequeued (flags=%x)\n",
 418                                 req->rq_disk->disk_name, req, req->cmd_type);
 419
 420                 if (!blk_fs_request(req))
 421                         goto error_out;
 422
 423                 lo = req->rq_disk->private_data;
 424
 425                 BUG_ON(lo->magic != LO_MAGIC);
 426
 427                 nbd_cmd(req) = NBD_CMD_READ;
 428                 if (rq_data_dir(req) == WRITE) {
 429                         nbd_cmd(req) = NBD_CMD_WRITE;
 430                         if (lo->flags & NBD_READ_ONLY) {
 431                                 printk(KERN_ERR "%s: Write on read-only\n",
 432                                                 lo->disk->disk_name);
 433                                 goto error_out;
 434                         }
 435                 }
 436
 437                 req->errors = 0;
 438                 spin_unlock_irq(q->queue_lock);
 439
 440                 mutex_lock(&lo->tx_lock);
 441                 if (unlikely(!lo->sock)) {
 442                         mutex_unlock(&lo->tx_lock);
 443                         printk(KERN_ERR "%s: Attempted send on closed socket\n",
 444                                lo->disk->disk_name);
 445                         req->errors++;
 446                         nbd_end_request(req);
 447                         spin_lock_irq(q->queue_lock);
 448                         continue;
 449                 }
 450
 451                 lo->active_req = req;
 452
 453                 if (nbd_send_req(lo, req) != 0) {
 454                         printk(KERN_ERR "%s: Request send failed\n",
 455                                         lo->disk->disk_name);
 456                         req->errors++;
 457                         nbd_end_request(req);
 458                 } else {
 459                         spin_lock(&lo->queue_lock);
 460                         list_add(&req->queuelist, &lo->queue_head);
 461                         spin_unlock(&lo->queue_lock);
 462                 }
 463
 464                 lo->active_req = NULL;
 465                 mutex_unlock(&lo->tx_lock);
 466                 wake_up_all(&lo->active_wq);
 467
 468                 spin_lock_irq(q->queue_lock);
 469                 continue;
 470
 471 error_out:
 472                 req->errors++;
 473                 spin_unlock(q->queue_lock);
 474                 nbd_end_request(req);
 475                 spin_lock(q->queue_lock);
 476         }
 477         return;
 478 }
 479
 480 static int nbd_ioctl(struct inode *inode, struct file *file,
 481                      unsigned int cmd, unsigned long arg)
 482 {
 483         struct nbd_device *lo = inode->i_bdev->bd_disk->private_data;
 484         int error;
 485         struct request sreq ;
 486
 487         if (!capable(CAP_SYS_ADMIN))
 488                 return -EPERM;
 489
 490         BUG_ON(lo->magic != LO_MAGIC);
 491
 492         /* Anyone capable of this syscall can do *real bad* things */
 493         dprintk(DBG_IOCTL, "%s: nbd_ioctl cmd=%s(0x%x) arg=%lu\n",
 494                         lo->disk->disk_name, ioctl_cmd_to_ascii(cmd), cmd, arg);
 495
 496         switch (cmd) {
 497         case NBD_DISCONNECT:
 498                 printk(KERN_INFO "%s: NBD_DISCONNECT\n", lo->disk->disk_name);
 499                 sreq.cmd_type = REQ_TYPE_SPECIAL;
 500                 nbd_cmd(&sreq) = NBD_CMD_DISC;
 501                 /*
 502                  * Set these to sane values in case server implementation
 503                  * fails to check the request type first and also to keep
 504                  * debugging output cleaner.
 505                  */
 506                 sreq.sector = 0;
 507                 sreq.nr_sectors = 0;
 508                 if (!lo->sock)
 509                         return -EINVAL;
 510                 nbd_send_req(lo, &sreq);
 511                 return 0;
 512
 513         case NBD_CLEAR_SOCK:
 514                 error = 0;
 515                 mutex_lock(&lo->tx_lock);
 516                 lo->sock = NULL;
 517                 mutex_unlock(&lo->tx_lock);
 518                 file = lo->file;
 519                 lo->file = NULL;
 520                 nbd_clear_que(lo);
 521                 BUG_ON(!list_empty(&lo->queue_head));
 522                 if (file)
 523                         fput(file);
 524                 return error;
 525         case NBD_SET_SOCK:
 526                 if (lo->file)
 527                         return -EBUSY;
 528                 error = -EINVAL;
 529                 file = fget(arg);
 530                 if (file) {
 531                         inode = file->f_path.dentry->d_inode;
 532                         if (S_ISSOCK(inode->i_mode)) {
 533                                 lo->file = file;
 534                                 lo->sock = SOCKET_I(inode);
 535                                 error = 0;
 536                         } else {
 537                                 fput(file);
 538                         }
 539                 }
 540                 return error;
 541         case NBD_SET_BLKSIZE:
 542                 lo->blksize = arg;
 543                 lo->bytesize &= ~(lo->blksize-1);
 544                 inode->i_bdev->bd_inode->i_size = lo->bytesize;
 545                 set_blocksize(inode->i_bdev, lo->blksize);
 546                 set_capacity(lo->disk, lo->bytesize >> 9);
 547                 return 0;
 548         case NBD_SET_SIZE:
 549                 lo->bytesize = arg & ~(lo->blksize-1);
 550                 inode->i_bdev->bd_inode->i_size = lo->bytesize;
 551                 set_blocksize(inode->i_bdev, lo->blksize);
 552                 set_capacity(lo->disk, lo->bytesize >> 9);
 553                 return 0;
 554         case NBD_SET_SIZE_BLOCKS:
 555                 lo->bytesize = ((u64) arg) * lo->blksize;
 556                 inode->i_bdev->bd_inode->i_size = lo->bytesize;
 557                 set_blocksize(inode->i_bdev, lo->blksize);
 558                 set_capacity(lo->disk, lo->bytesize >> 9);
 559                 return 0;
 560         case NBD_DO_IT:
 561                 if (!lo->file)
 562                         return -EINVAL;
 563                 error = nbd_do_it(lo);
 564                 if (error)
 565                         return error;
 566                 /* on return tidy up in case we have a signal */
 567                 /* Forcibly shutdown the socket causing all listeners
 568                  * to error
 569                  *
 570                  * FIXME: This code is duplicated from sys_shutdown, but
 571                  * there should be a more generic interface rather than
 572                  * calling socket ops directly here */
 573                 mutex_lock(&lo->tx_lock);
 574                 if (lo->sock) {
 575                         printk(KERN_WARNING "%s: shutting down socket\n",
 576                                 lo->disk->disk_name);
 577                         lo->sock->ops->shutdown(lo->sock,
 578                                 SEND_SHUTDOWN|RCV_SHUTDOWN);
 579                         lo->sock = NULL;
 580                 }
 581                 mutex_unlock(&lo->tx_lock);
 582                 file = lo->file;
 583                 lo->file = NULL;
 584                 nbd_clear_que(lo);
 585                 printk(KERN_WARNING "%s: queue cleared\n", lo->disk->disk_name);
 586                 if (file)
 587                         fput(file);
 588                 return lo->harderror;
 589         case NBD_CLEAR_QUE:
 590                 /*
 591                  * This is for compatibility only.  The queue is always cleared
 592                  * by NBD_DO_IT or NBD_CLEAR_SOCK.
 593                  */
 594                 BUG_ON(!lo->sock && !list_empty(&lo->queue_head));
 595                 return 0;
 596         case NBD_PRINT_DEBUG:
 597                 printk(KERN_INFO "%s: next = %p, prev = %p, head = %p\n",
 598                         inode->i_bdev->bd_disk->disk_name,
 599                         lo->queue_head.next, lo->queue_head.prev,
 600                         &lo->queue_head);
 601                 return 0;
 602         }
 603         return -EINVAL;
 604 }
 605
 606 static struct block_device_operations nbd_fops =
 607 {
 608         .owner =        THIS_MODULE,
 609         .ioctl =        nbd_ioctl,
 610 };
 611
 612 /*
 613  * And here should be modules and kernel interface
 614  *  (Just smiley confuses emacs :-)
 615  */
 616
 617 static int __init nbd_init(void)
 618 {
 619         int err = -ENOMEM;
 620         int i;
 621
 622         BUILD_BUG_ON(sizeof(struct nbd_request) != 28);
 623
 624         if (nbds_max > MAX_NBD) {
 625                 printk(KERN_CRIT "nbd: cannot allocate more than %u nbds; %u requested.\n", MAX_NBD,
 626                                 nbds_max);
 627                 return -EINVAL;
 628         }
 629
 630         for (i = 0; i < nbds_max; i++) {
 631                 struct gendisk *disk = alloc_disk(1);
 632                 if (!disk)
 633                         goto out;
 634                 nbd_dev[i].disk = disk;
 635                 /*
 636                  * The new linux 2.5 block layer implementation requires
 637                  * every gendisk to have its very own request_queue struct.
 638                  * These structs are big so we dynamically allocate them.
 639                  */
 640                 disk->queue = blk_init_queue(do_nbd_request, &nbd_lock);
 641                 if (!disk->queue) {
 642                         put_disk(disk);
 643                         goto out;
 644                 }
 645         }
 646
 647         if (register_blkdev(NBD_MAJOR, "nbd")) {
 648                 err = -EIO;
 649                 goto out;
 650         }
 651
 652         printk(KERN_INFO "nbd: registered device at major %d\n", NBD_MAJOR);
 653         dprintk(DBG_INIT, "nbd: debugflags=0x%x\n", debugflags);
 654
 655         for (i = 0; i < nbds_max; i++) {
 656                 struct gendisk *disk = nbd_dev[i].disk;
 657                 nbd_dev[i].file = NULL;
 658                 nbd_dev[i].magic = LO_MAGIC;
 659                 nbd_dev[i].flags = 0;
 660                 spin_lock_init(&nbd_dev[i].queue_lock);
 661                 INIT_LIST_HEAD(&nbd_dev[i].queue_head);
 662                 mutex_init(&nbd_dev[i].tx_lock);
 663                 init_waitqueue_head(&nbd_dev[i].active_wq);
 664                 nbd_dev[i].blksize = 1024;
 665                 nbd_dev[i].bytesize = 0x7ffffc00ULL << 10; /* 2TB */
 666                 disk->major = NBD_MAJOR;
 667                 disk->first_minor = i;
 668                 disk->fops = &nbd_fops;
 669                 disk->private_data = &nbd_dev[i];
 670                 disk->flags |= GENHD_FL_SUPPRESS_PARTITION_INFO;
 671                 sprintf(disk->disk_name, "nbd%d", i);
 672                 set_capacity(disk, 0x7ffffc00ULL << 1); /* 2 TB */
 673                 add_disk(disk);
 674         }
 675
 676         return 0;
 677 out:
 678         while (i--) {
 679                 blk_cleanup_queue(nbd_dev[i].disk->queue);
 680                 put_disk(nbd_dev[i].disk);
 681         }
 682         return err;
 683 }
 684
 685 static void __exit nbd_cleanup(void)
 686 {
 687         int i;
 688         for (i = 0; i < nbds_max; i++) {
 689                 struct gendisk *disk = nbd_dev[i].disk;
 690                 nbd_dev[i].magic = 0;
 691                 if (disk) {
 692                         del_gendisk(disk);
 693                         blk_cleanup_queue(disk->queue);
 694                         put_disk(disk);
 695                 }
 696         }
 697         unregister_blkdev(NBD_MAJOR, "nbd");
 698         printk(KERN_INFO "nbd: unregistered device at major %d\n", NBD_MAJOR);
 699 }
 700
 701 module_init(nbd_init);
 702 module_exit(nbd_cleanup);
 703
 704 MODULE_DESCRIPTION("Network Block Device");
 705 MODULE_LICENSE("GPL");
 706
 707 module_param(nbds_max, int, 0444);
 708 MODULE_PARM_DESC(nbds_max, "How many network block devices to initialize.");
 709 #ifndef NDEBUG
 710 module_param(debugflags, int, 0644);
 711 MODULE_PARM_DESC(debugflags, "flags for controlling debug output");
 712 #endif