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 static void sock_shutdown(struct nbd_device *lo, int lock)
 117 {
 118         /* Forcibly shutdown the socket causing all listeners
 119          * to error
 120          *
 121          * FIXME: This code is duplicated from sys_shutdown, but
 122          * there should be a more generic interface rather than
 123          * calling socket ops directly here */
 124         if (lock)
 125                 mutex_lock(&lo->tx_lock);
 126         if (lo->sock) {
 127                 printk(KERN_WARNING "%s: shutting down socket\n",
 128                         lo->disk->disk_name);
 129                 lo->sock->ops->shutdown(lo->sock, SEND_SHUTDOWN|RCV_SHUTDOWN);
 130                 lo->sock = NULL;
 131         }
 132         if (lock)
 133                 mutex_unlock(&lo->tx_lock);
 134 }
 135
 136 static void nbd_xmit_timeout(unsigned long arg)
 137 {
 138         struct task_struct *task = (struct task_struct *)arg;
 139
 140         printk(KERN_WARNING "nbd: killing hung xmit (%s, pid: %d)\n",
 141                 task->comm, task->pid);
 142         force_sig(SIGKILL, task);
 143 }
 144
 145 /*
 146  *  Send or receive packet.
 147  */
 148 static int sock_xmit(struct nbd_device *lo, int send, void *buf, int size,
 149                 int msg_flags)
 150 {
 151         struct socket *sock = lo->sock;
 152         int result;
 153         struct msghdr msg;
 154         struct kvec iov;
 155         sigset_t blocked, oldset;
 156
 157         /* Allow interception of SIGKILL only
 158          * Don't allow other signals to interrupt the transmission */
 159         siginitsetinv(&blocked, sigmask(SIGKILL));
 160         sigprocmask(SIG_SETMASK, &blocked, &oldset);
 161
 162         do {
 163                 sock->sk->sk_allocation = GFP_NOIO;
 164                 iov.iov_base = buf;
 165                 iov.iov_len = size;
 166                 msg.msg_name = NULL;
 167                 msg.msg_namelen = 0;
 168                 msg.msg_control = NULL;
 169                 msg.msg_controllen = 0;
 170                 msg.msg_flags = msg_flags | MSG_NOSIGNAL;
 171
 172                 if (send) {
 173                         struct timer_list ti;
 174
 175                         if (lo->xmit_timeout) {
 176                                 init_timer(&ti);
 177                                 ti.function = nbd_xmit_timeout;
 178                                 ti.data = (unsigned long)current;
 179                                 ti.expires = jiffies + lo->xmit_timeout;
 180                                 add_timer(&ti);
 181                         }
 182                         result = kernel_sendmsg(sock, &msg, &iov, 1, size);
 183                         if (lo->xmit_timeout)
 184                                 del_timer_sync(&ti);
 185                 } else
 186                         result = kernel_recvmsg(sock, &msg, &iov, 1, size, 0);
 187
 188                 if (signal_pending(current)) {
 189                         siginfo_t info;
 190                         printk(KERN_WARNING "nbd (pid %d: %s) got signal %d\n",
 191                                 task_pid_nr(current), current->comm,
 192                                 dequeue_signal_lock(current, &current->blocked, &info));
 193                         result = -EINTR;
 194                         sock_shutdown(lo, !send);
 195                         break;
 196                 }
 197
 198                 if (result <= 0) {
 199                         if (result == 0)
 200                                 result = -EPIPE; /* short read */
 201                         break;
 202                 }
 203                 size -= result;
 204                 buf += result;
 205         } while (size > 0);
 206
 207         sigprocmask(SIG_SETMASK, &oldset, NULL);
 208
 209         return result;
 210 }
 211
 212 static inline int sock_send_bvec(struct nbd_device *lo, struct bio_vec *bvec,
 213                 int flags)
 214 {
 215         int result;
 216         void *kaddr = kmap(bvec->bv_page);
 217         result = sock_xmit(lo, 1, kaddr + bvec->bv_offset, bvec->bv_len, flags);
 218         kunmap(bvec->bv_page);
 219         return result;
 220 }
 221
 222 /* always call with the tx_lock held */
 223 static int nbd_send_req(struct nbd_device *lo, struct request *req)
 224 {
 225         int result, flags;
 226         struct nbd_request request;
 227         unsigned long size = req->nr_sectors << 9;
 228
 229         request.magic = htonl(NBD_REQUEST_MAGIC);
 230         request.type = htonl(nbd_cmd(req));
 231         request.from = cpu_to_be64((u64) req->sector << 9);
 232         request.len = htonl(size);
 233         memcpy(request.handle, &req, sizeof(req));
 234
 235         dprintk(DBG_TX, "%s: request %p: sending control (%s@%llu,%luB)\n",
 236                         lo->disk->disk_name, req,
 237                         nbdcmd_to_ascii(nbd_cmd(req)),
 238                         (unsigned long long)req->sector << 9,
 239                         req->nr_sectors << 9);
 240         result = sock_xmit(lo, 1, &request, sizeof(request),
 241                         (nbd_cmd(req) == NBD_CMD_WRITE) ? MSG_MORE : 0);
 242         if (result <= 0) {
 243                 printk(KERN_ERR "%s: Send control failed (result %d)\n",
 244                                 lo->disk->disk_name, result);
 245                 goto error_out;
 246         }
 247
 248         if (nbd_cmd(req) == NBD_CMD_WRITE) {
 249                 struct req_iterator iter;
 250                 struct bio_vec *bvec;
 251                 /*
 252                  * we are really probing at internals to determine
 253                  * whether to set MSG_MORE or not...
 254                  */
 255                 rq_for_each_segment(bvec, req, iter) {
 256                         flags = 0;
 257                         if (!rq_iter_last(req, iter))
 258                                 flags = MSG_MORE;
 259                         dprintk(DBG_TX, "%s: request %p: sending %d bytes data\n",
 260                                         lo->disk->disk_name, req, bvec->bv_len);
 261                         result = sock_send_bvec(lo, bvec, flags);
 262                         if (result <= 0) {
 263                                 printk(KERN_ERR "%s: Send data failed (result %d)\n",
 264                                                 lo->disk->disk_name, result);
 265                                 goto error_out;
 266                         }
 267                 }
 268         }
 269         return 0;
 270
 271 error_out:
 272         return 1;
 273 }
 274
 275 static struct request *nbd_find_request(struct nbd_device *lo,
 276                                         struct request *xreq)
 277 {
 278         struct request *req, *tmp;
 279         int err;
 280
 281         err = wait_event_interruptible(lo->active_wq, lo->active_req != xreq);
 282         if (unlikely(err))
 283                 goto out;
 284
 285         spin_lock(&lo->queue_lock);
 286         list_for_each_entry_safe(req, tmp, &lo->queue_head, queuelist) {
 287                 if (req != xreq)
 288                         continue;
 289                 list_del_init(&req->queuelist);
 290                 spin_unlock(&lo->queue_lock);
 291                 return req;
 292         }
 293         spin_unlock(&lo->queue_lock);
 294
 295         err = -ENOENT;
 296
 297 out:
 298         return ERR_PTR(err);
 299 }
 300
 301 static inline int sock_recv_bvec(struct nbd_device *lo, struct bio_vec *bvec)
 302 {
 303         int result;
 304         void *kaddr = kmap(bvec->bv_page);
 305         result = sock_xmit(lo, 0, kaddr + bvec->bv_offset, bvec->bv_len,
 306                         MSG_WAITALL);
 307         kunmap(bvec->bv_page);
 308         return result;
 309 }
 310
 311 /* NULL returned = something went wrong, inform userspace */
 312 static struct request *nbd_read_stat(struct nbd_device *lo)
 313 {
 314         int result;
 315         struct nbd_reply reply;
 316         struct request *req;
 317
 318         reply.magic = 0;
 319         result = sock_xmit(lo, 0, &reply, sizeof(reply), MSG_WAITALL);
 320         if (result <= 0) {
 321                 printk(KERN_ERR "%s: Receive control failed (result %d)\n",
 322                                 lo->disk->disk_name, result);
 323                 goto harderror;
 324         }
 325
 326         if (ntohl(reply.magic) != NBD_REPLY_MAGIC) {
 327                 printk(KERN_ERR "%s: Wrong magic (0x%lx)\n",
 328                                 lo->disk->disk_name,
 329                                 (unsigned long)ntohl(reply.magic));
 330                 result = -EPROTO;
 331                 goto harderror;
 332         }
 333
 334         req = nbd_find_request(lo, *(struct request **)reply.handle);
 335         if (unlikely(IS_ERR(req))) {
 336                 result = PTR_ERR(req);
 337                 if (result != -ENOENT)
 338                         goto harderror;
 339
 340                 printk(KERN_ERR "%s: Unexpected reply (%p)\n",
 341                                 lo->disk->disk_name, reply.handle);
 342                 result = -EBADR;
 343                 goto harderror;
 344         }
 345
 346         if (ntohl(reply.error)) {
 347                 printk(KERN_ERR "%s: Other side returned error (%d)\n",
 348                                 lo->disk->disk_name, ntohl(reply.error));
 349                 req->errors++;
 350                 return req;
 351         }
 352
 353         dprintk(DBG_RX, "%s: request %p: got reply\n",
 354                         lo->disk->disk_name, req);
 355         if (nbd_cmd(req) == NBD_CMD_READ) {
 356                 struct req_iterator iter;
 357                 struct bio_vec *bvec;
 358
 359                 rq_for_each_segment(bvec, req, iter) {
 360                         result = sock_recv_bvec(lo, bvec);
 361                         if (result <= 0) {
 362                                 printk(KERN_ERR "%s: Receive data failed (result %d)\n",
 363                                                 lo->disk->disk_name, result);
 364                                 req->errors++;
 365                                 return req;
 366                         }
 367                         dprintk(DBG_RX, "%s: request %p: got %d bytes data\n",
 368                                 lo->disk->disk_name, req, bvec->bv_len);
 369                 }
 370         }
 371         return req;
 372 harderror:
 373         lo->harderror = result;
 374         return NULL;
 375 }
 376
 377 static ssize_t pid_show(struct gendisk *disk, char *page)
 378 {
 379         return sprintf(page, "%ld\n",
 380                 (long) ((struct nbd_device *)disk->private_data)->pid);
 381 }
 382
 383 static struct disk_attribute pid_attr = {
 384         .attr = { .name = "pid", .mode = S_IRUGO },
 385         .show = pid_show,
 386 };
 387
 388 static int nbd_do_it(struct nbd_device *lo)
 389 {
 390         struct request *req;
 391         int ret;
 392
 393         BUG_ON(lo->magic != LO_MAGIC);
 394
 395         lo->pid = current->pid;
 396         ret = sysfs_create_file(&lo->disk->kobj, &pid_attr.attr);
 397         if (ret) {
 398                 printk(KERN_ERR "nbd: sysfs_create_file failed!");
 399                 return ret;
 400         }
 401
 402         while ((req = nbd_read_stat(lo)) != NULL)
 403                 nbd_end_request(req);
 404
 405         sysfs_remove_file(&lo->disk->kobj, &pid_attr.attr);
 406         return 0;
 407 }
 408
 409 static void nbd_clear_que(struct nbd_device *lo)
 410 {
 411         struct request *req;
 412
 413         BUG_ON(lo->magic != LO_MAGIC);
 414
 415         /*
 416          * Because we have set lo->sock to NULL under the tx_lock, all
 417          * modifications to the list must have completed by now.  For
 418          * the same reason, the active_req must be NULL.
 419          *
 420          * As a consequence, we don't need to take the spin lock while
 421          * purging the list here.
 422          */
 423         BUG_ON(lo->sock);
 424         BUG_ON(lo->active_req);
 425
 426         while (!list_empty(&lo->queue_head)) {
 427                 req = list_entry(lo->queue_head.next, struct request,
 428                                  queuelist);
 429                 list_del_init(&req->queuelist);
 430                 req->errors++;
 431                 nbd_end_request(req);
 432         }
 433 }
 434
 435
 436 /*
 437  * We always wait for result of write, for now. It would be nice to make it optional
 438  * in future
 439  * if ((rq_data_dir(req) == WRITE) && (lo->flags & NBD_WRITE_NOCHK))
 440  *   { printk( "Warning: Ignoring result!\n"); nbd_end_request( req ); }
 441  */
 442
 443 static void do_nbd_request(struct request_queue * q)
 444 {
 445         struct request *req;
 446
 447         while ((req = elv_next_request(q)) != NULL) {
 448                 struct nbd_device *lo;
 449
 450                 blkdev_dequeue_request(req);
 451                 dprintk(DBG_BLKDEV, "%s: request %p: dequeued (flags=%x)\n",
 452                                 req->rq_disk->disk_name, req, req->cmd_type);
 453
 454                 if (!blk_fs_request(req))
 455                         goto error_out;
 456
 457                 lo = req->rq_disk->private_data;
 458
 459                 BUG_ON(lo->magic != LO_MAGIC);
 460
 461                 nbd_cmd(req) = NBD_CMD_READ;
 462                 if (rq_data_dir(req) == WRITE) {
 463                         nbd_cmd(req) = NBD_CMD_WRITE;
 464                         if (lo->flags & NBD_READ_ONLY) {
 465                                 printk(KERN_ERR "%s: Write on read-only\n",
 466                                                 lo->disk->disk_name);
 467                                 goto error_out;
 468                         }
 469                 }
 470
 471                 req->errors = 0;
 472                 spin_unlock_irq(q->queue_lock);
 473
 474                 mutex_lock(&lo->tx_lock);
 475                 if (unlikely(!lo->sock)) {
 476                         mutex_unlock(&lo->tx_lock);
 477                         printk(KERN_ERR "%s: Attempted send on closed socket\n",
 478                                lo->disk->disk_name);
 479                         req->errors++;
 480                         nbd_end_request(req);
 481                         spin_lock_irq(q->queue_lock);
 482                         continue;
 483                 }
 484
 485                 lo->active_req = req;
 486
 487                 if (nbd_send_req(lo, req) != 0) {
 488                         printk(KERN_ERR "%s: Request send failed\n",
 489                                         lo->disk->disk_name);
 490                         req->errors++;
 491                         nbd_end_request(req);
 492                 } else {
 493                         spin_lock(&lo->queue_lock);
 494                         list_add(&req->queuelist, &lo->queue_head);
 495                         spin_unlock(&lo->queue_lock);
 496                 }
 497
 498                 lo->active_req = NULL;
 499                 mutex_unlock(&lo->tx_lock);
 500                 wake_up_all(&lo->active_wq);
 501
 502                 spin_lock_irq(q->queue_lock);
 503                 continue;
 504
 505 error_out:
 506                 req->errors++;
 507                 spin_unlock(q->queue_lock);
 508                 nbd_end_request(req);
 509                 spin_lock(q->queue_lock);
 510         }
 511         return;
 512 }
 513
 514 static int nbd_ioctl(struct inode *inode, struct file *file,
 515                      unsigned int cmd, unsigned long arg)
 516 {
 517         struct nbd_device *lo = inode->i_bdev->bd_disk->private_data;
 518         int error;
 519         struct request sreq ;
 520
 521         if (!capable(CAP_SYS_ADMIN))
 522                 return -EPERM;
 523
 524         BUG_ON(lo->magic != LO_MAGIC);
 525
 526         /* Anyone capable of this syscall can do *real bad* things */
 527         dprintk(DBG_IOCTL, "%s: nbd_ioctl cmd=%s(0x%x) arg=%lu\n",
 528                         lo->disk->disk_name, ioctl_cmd_to_ascii(cmd), cmd, arg);
 529
 530         switch (cmd) {
 531         case NBD_DISCONNECT:
 532                 printk(KERN_INFO "%s: NBD_DISCONNECT\n", lo->disk->disk_name);
 533                 sreq.cmd_type = REQ_TYPE_SPECIAL;
 534                 nbd_cmd(&sreq) = NBD_CMD_DISC;
 535                 /*
 536                  * Set these to sane values in case server implementation
 537                  * fails to check the request type first and also to keep
 538                  * debugging output cleaner.
 539                  */
 540                 sreq.sector = 0;
 541                 sreq.nr_sectors = 0;
 542                 if (!lo->sock)
 543                         return -EINVAL;
 544                 mutex_lock(&lo->tx_lock);
 545                 nbd_send_req(lo, &sreq);
 546                 mutex_unlock(&lo->tx_lock);
 547                 return 0;
 548
 549         case NBD_CLEAR_SOCK:
 550                 error = 0;
 551                 mutex_lock(&lo->tx_lock);
 552                 lo->sock = NULL;
 553                 mutex_unlock(&lo->tx_lock);
 554                 file = lo->file;
 555                 lo->file = NULL;
 556                 nbd_clear_que(lo);
 557                 BUG_ON(!list_empty(&lo->queue_head));
 558                 if (file)
 559                         fput(file);
 560                 return error;
 561         case NBD_SET_SOCK:
 562                 if (lo->file)
 563                         return -EBUSY;
 564                 error = -EINVAL;
 565                 file = fget(arg);
 566                 if (file) {
 567                         inode = file->f_path.dentry->d_inode;
 568                         if (S_ISSOCK(inode->i_mode)) {
 569                                 lo->file = file;
 570                                 lo->sock = SOCKET_I(inode);
 571                                 error = 0;
 572                         } else {
 573                                 fput(file);
 574                         }
 575                 }
 576                 return error;
 577         case NBD_SET_BLKSIZE:
 578                 lo->blksize = arg;
 579                 lo->bytesize &= ~(lo->blksize-1);
 580                 inode->i_bdev->bd_inode->i_size = lo->bytesize;
 581                 set_blocksize(inode->i_bdev, lo->blksize);
 582                 set_capacity(lo->disk, lo->bytesize >> 9);
 583                 return 0;
 584         case NBD_SET_SIZE:
 585                 lo->bytesize = arg & ~(lo->blksize-1);
 586                 inode->i_bdev->bd_inode->i_size = lo->bytesize;
 587                 set_blocksize(inode->i_bdev, lo->blksize);
 588                 set_capacity(lo->disk, lo->bytesize >> 9);
 589                 return 0;
 590         case NBD_SET_TIMEOUT:
 591                 lo->xmit_timeout = arg * HZ;
 592                 return 0;
 593         case NBD_SET_SIZE_BLOCKS:
 594                 lo->bytesize = ((u64) arg) * lo->blksize;
 595                 inode->i_bdev->bd_inode->i_size = lo->bytesize;
 596                 set_blocksize(inode->i_bdev, lo->blksize);
 597                 set_capacity(lo->disk, lo->bytesize >> 9);
 598                 return 0;
 599         case NBD_DO_IT:
 600                 if (!lo->file)
 601                         return -EINVAL;
 602                 error = nbd_do_it(lo);
 603                 if (error)
 604                         return error;
 605                 sock_shutdown(lo, 1);
 606                 file = lo->file;
 607                 lo->file = NULL;
 608                 nbd_clear_que(lo);
 609                 printk(KERN_WARNING "%s: queue cleared\n", lo->disk->disk_name);
 610                 if (file)
 611                         fput(file);
 612                 lo->bytesize = 0;
 613                 inode->i_bdev->bd_inode->i_size = 0;
 614                 set_capacity(lo->disk, 0);
 615                 return lo->harderror;
 616         case NBD_CLEAR_QUE:
 617                 /*
 618                  * This is for compatibility only.  The queue is always cleared
 619                  * by NBD_DO_IT or NBD_CLEAR_SOCK.
 620                  */
 621                 BUG_ON(!lo->sock && !list_empty(&lo->queue_head));
 622                 return 0;
 623         case NBD_PRINT_DEBUG:
 624                 printk(KERN_INFO "%s: next = %p, prev = %p, head = %p\n",
 625                         inode->i_bdev->bd_disk->disk_name,
 626                         lo->queue_head.next, lo->queue_head.prev,
 627                         &lo->queue_head);
 628                 return 0;
 629         }
 630         return -EINVAL;
 631 }
 632
 633 static struct block_device_operations nbd_fops =
 634 {
 635         .owner =        THIS_MODULE,
 636         .ioctl =        nbd_ioctl,
 637 };
 638
 639 /*
 640  * And here should be modules and kernel interface
 641  *  (Just smiley confuses emacs :-)
 642  */
 643
 644 static int __init nbd_init(void)
 645 {
 646         int err = -ENOMEM;
 647         int i;
 648
 649         BUILD_BUG_ON(sizeof(struct nbd_request) != 28);
 650
 651         if (nbds_max > MAX_NBD) {
 652                 printk(KERN_CRIT "nbd: cannot allocate more than %u nbds; %u requested.\n", MAX_NBD,
 653                                 nbds_max);
 654                 return -EINVAL;
 655         }
 656
 657         for (i = 0; i < nbds_max; i++) {
 658                 struct gendisk *disk = alloc_disk(1);
 659                 if (!disk)
 660                         goto out;
 661                 nbd_dev[i].disk = disk;
 662                 /*
 663                  * The new linux 2.5 block layer implementation requires
 664                  * every gendisk to have its very own request_queue struct.
 665                  * These structs are big so we dynamically allocate them.
 666                  */
 667                 disk->queue = blk_init_queue(do_nbd_request, &nbd_lock);
 668                 if (!disk->queue) {
 669                         put_disk(disk);
 670                         goto out;
 671                 }
 672         }
 673
 674         if (register_blkdev(NBD_MAJOR, "nbd")) {
 675                 err = -EIO;
 676                 goto out;
 677         }
 678
 679         printk(KERN_INFO "nbd: registered device at major %d\n", NBD_MAJOR);
 680         dprintk(DBG_INIT, "nbd: debugflags=0x%x\n", debugflags);
 681
 682         for (i = 0; i < nbds_max; i++) {
 683                 struct gendisk *disk = nbd_dev[i].disk;
 684                 nbd_dev[i].file = NULL;
 685                 nbd_dev[i].magic = LO_MAGIC;
 686                 nbd_dev[i].flags = 0;
 687                 spin_lock_init(&nbd_dev[i].queue_lock);
 688                 INIT_LIST_HEAD(&nbd_dev[i].queue_head);
 689                 mutex_init(&nbd_dev[i].tx_lock);
 690                 init_waitqueue_head(&nbd_dev[i].active_wq);
 691                 nbd_dev[i].blksize = 1024;
 692                 nbd_dev[i].bytesize = 0;
 693                 disk->major = NBD_MAJOR;
 694                 disk->first_minor = i;
 695                 disk->fops = &nbd_fops;
 696                 disk->private_data = &nbd_dev[i];
 697                 disk->flags |= GENHD_FL_SUPPRESS_PARTITION_INFO;
 698                 sprintf(disk->disk_name, "nbd%d", i);
 699                 set_capacity(disk, 0);
 700                 add_disk(disk);
 701         }
 702
 703         return 0;
 704 out:
 705         while (i--) {
 706                 blk_cleanup_queue(nbd_dev[i].disk->queue);
 707                 put_disk(nbd_dev[i].disk);
 708         }
 709         return err;
 710 }
 711
 712 static void __exit nbd_cleanup(void)
 713 {
 714         int i;
 715         for (i = 0; i < nbds_max; i++) {
 716                 struct gendisk *disk = nbd_dev[i].disk;
 717                 nbd_dev[i].magic = 0;
 718                 if (disk) {
 719                         del_gendisk(disk);
 720                         blk_cleanup_queue(disk->queue);
 721                         put_disk(disk);
 722                 }
 723         }
 724         unregister_blkdev(NBD_MAJOR, "nbd");
 725         printk(KERN_INFO "nbd: unregistered device at major %d\n", NBD_MAJOR);
 726 }
 727
 728 module_init(nbd_init);
 729 module_exit(nbd_cleanup);
 730
 731 MODULE_DESCRIPTION("Network Block Device");
 732 MODULE_LICENSE("GPL");
 733
 734 module_param(nbds_max, int, 0444);
 735 MODULE_PARM_DESC(nbds_max, "How many network block devices to initialize.");
 736 #ifndef NDEBUG
 737 module_param(debugflags, int, 0644);
 738 MODULE_PARM_DESC(debugflags, "flags for controlling debug output");
 739 #endif