git.oblomov.eu Git - 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  * (part of code stolen from loop.c)
  11  *
  12  * 97-3-25 compiled 0-th version, not yet tested it
  13  *   (it did not work, BTW) (later that day) HEY! it works!
  14  *   (bit later) hmm, not that much... 2:00am next day:
  15  *   yes, it works, but it gives something like 50kB/sec
  16  * 97-4-01 complete rewrite to make it possible for many requests at
  17  *   once to be processed
  18  * 97-4-11 Making protocol independent of endianity etc.
  19  * 97-9-13 Cosmetic changes
  20  * 98-5-13 Attempt to make 64-bit-clean on 64-bit machines
  21  * 99-1-11 Attempt to make 64-bit-clean on 32-bit machines <ankry@mif.pg.gda.pl>
  22  * 01-2-27 Fix to store proper blockcount for kernel (calculated using
  23  *   BLOCK_SIZE_BITS, not device blocksize) <aga@permonline.ru>
  24  * 01-3-11 Make nbd work with new Linux block layer code. It now supports
  25  *   plugging like all the other block devices. Also added in MSG_MORE to
  26  *   reduce number of partial TCP segments sent. <steve@chygwyn.com>
  27  * 01-12-6 Fix deadlock condition by making queue locks independent of
  28  *   the transmit lock. <steve@chygwyn.com>
  29  * 02-10-11 Allow hung xmit to be aborted via SIGKILL & various fixes.
  30  *   <Paul.Clements@SteelEye.com> <James.Bottomley@SteelEye.com>
  31  * 03-06-22 Make nbd work with new linux 2.5 block layer design. This fixes
  32  *   memory corruption from module removal and possible memory corruption
  33  *   from sending/receiving disk data. <ldl@aros.net>
  34  * 03-06-23 Cosmetic changes. <ldl@aros.net>
  35  * 03-06-23 Enhance diagnostics support. <ldl@aros.net>
  36  * 03-06-24 Remove unneeded blksize_bits field from nbd_device struct.
  37  *   <ldl@aros.net>
  38  * 03-06-24 Cleanup PARANOIA usage & code. <ldl@aros.net>
  39  * 04-02-19 Remove PARANOIA, plus various cleanups (Paul Clements)
  40  * possible FIXME: make set_sock / set_blksize / set_size / do_it one syscall
  41  * why not: would need access_ok and friends, would share yet another
  42  *          structure with userland
  43  */
  44
  45 #include <linux/major.h>
  46
  47 #include <linux/blkdev.h>
  48 #include <linux/module.h>
  49 #include <linux/init.h>
  50 #include <linux/sched.h>
  51 #include <linux/fs.h>
  52 #include <linux/bio.h>
  53 #include <linux/stat.h>
  54 #include <linux/errno.h>
  55 #include <linux/file.h>
  56 #include <linux/ioctl.h>
  57 #include <linux/compiler.h>
  58 #include <linux/err.h>
  59 #include <linux/kernel.h>
  60 #include <net/sock.h>
  61
  62 #include <linux/devfs_fs_kernel.h>
  63
  64 #include <asm/uaccess.h>
  65 #include <asm/system.h>
  66 #include <asm/types.h>
  67
  68 #include <linux/nbd.h>
  69
  70 #define LO_MAGIC 0x68797548
  71
  72 #ifdef NDEBUG
  73 #define dprintk(flags, fmt...)
  74 #else /* NDEBUG */
  75 #define dprintk(flags, fmt...) do { \
  76         if (debugflags & (flags)) printk(KERN_DEBUG fmt); \
  77 } while (0)
  78 #define DBG_IOCTL       0x0004
  79 #define DBG_INIT        0x0010
  80 #define DBG_EXIT        0x0020
  81 #define DBG_BLKDEV      0x0100
  82 #define DBG_RX          0x0200
  83 #define DBG_TX          0x0400
  84 static unsigned int debugflags;
  85 static unsigned int nbds_max = 16;
  86 #endif /* NDEBUG */
  87
  88 static struct nbd_device nbd_dev[MAX_NBD];
  89
  90 /*
  91  * Use just one lock (or at most 1 per NIC). Two arguments for this:
  92  * 1. Each NIC is essentially a synchronization point for all servers
  93  *    accessed through that NIC so there's no need to have more locks
  94  *    than NICs anyway.
  95  * 2. More locks lead to more "Dirty cache line bouncing" which will slow
  96  *    down each lock to the point where they're actually slower than just
  97  *    a single lock.
  98  * Thanks go to Jens Axboe and Al Viro for their LKML emails explaining this!
  99  */
 100 static DEFINE_SPINLOCK(nbd_lock);
 101
 102 #ifndef NDEBUG
 103 static const char *ioctl_cmd_to_ascii(int cmd)
 104 {
 105         switch (cmd) {
 106         case NBD_SET_SOCK: return "set-sock";
 107         case NBD_SET_BLKSIZE: return "set-blksize";
 108         case NBD_SET_SIZE: return "set-size";
 109         case NBD_DO_IT: return "do-it";
 110         case NBD_CLEAR_SOCK: return "clear-sock";
 111         case NBD_CLEAR_QUE: return "clear-que";
 112         case NBD_PRINT_DEBUG: return "print-debug";
 113         case NBD_SET_SIZE_BLOCKS: return "set-size-blocks";
 114         case NBD_DISCONNECT: return "disconnect";
 115         case BLKROSET: return "set-read-only";
 116         case BLKFLSBUF: return "flush-buffer-cache";
 117         }
 118         return "unknown";
 119 }
 120
 121 static const char *nbdcmd_to_ascii(int cmd)
 122 {
 123         switch (cmd) {
 124         case  NBD_CMD_READ: return "read";
 125         case NBD_CMD_WRITE: return "write";
 126         case  NBD_CMD_DISC: return "disconnect";
 127         }
 128         return "invalid";
 129 }
 130 #endif /* NDEBUG */
 131
 132 static void nbd_end_request(struct request *req)
 133 {
 134         int uptodate = (req->errors == 0) ? 1 : 0;
 135         request_queue_t *q = req->q;
 136         unsigned long flags;
 137
 138         dprintk(DBG_BLKDEV, "%s: request %p: %s\n", req->rq_disk->disk_name,
 139                         req, uptodate? "done": "failed");
 140
 141         spin_lock_irqsave(q->queue_lock, flags);
 142         if (!end_that_request_first(req, uptodate, req->nr_sectors)) {
 143                 end_that_request_last(req, uptodate);
 144         }
 145         spin_unlock_irqrestore(q->queue_lock, flags);
 146 }
 147
 148 /*
 149  *  Send or receive packet.
 150  */
 151 static int sock_xmit(struct socket *sock, int send, void *buf, int size,
 152                 int msg_flags)
 153 {
 154         int result;
 155         struct msghdr msg;
 156         struct kvec iov;
 157         unsigned long flags;
 158         sigset_t oldset;
 159
 160         /* Allow interception of SIGKILL only
 161          * Don't allow other signals to interrupt the transmission */
 162         spin_lock_irqsave(&current->sighand->siglock, flags);
 163         oldset = current->blocked;
 164         sigfillset(&current->blocked);
 165         sigdelsetmask(&current->blocked, sigmask(SIGKILL));
 166         recalc_sigpending();
 167         spin_unlock_irqrestore(&current->sighand->siglock, flags);
 168
 169         do {
 170                 sock->sk->sk_allocation = GFP_NOIO;
 171                 iov.iov_base = buf;
 172                 iov.iov_len = size;
 173                 msg.msg_name = NULL;
 174                 msg.msg_namelen = 0;
 175                 msg.msg_control = NULL;
 176                 msg.msg_controllen = 0;
 177                 msg.msg_flags = msg_flags | MSG_NOSIGNAL;
 178
 179                 if (send)
 180                         result = kernel_sendmsg(sock, &msg, &iov, 1, size);
 181                 else
 182                         result = kernel_recvmsg(sock, &msg, &iov, 1, size, 0);
 183
 184                 if (signal_pending(current)) {
 185                         siginfo_t info;
 186                         spin_lock_irqsave(&current->sighand->siglock, flags);
 187                         printk(KERN_WARNING "nbd (pid %d: %s) got signal %d\n",
 188                                 current->pid, current->comm,
 189                                 dequeue_signal(current, &current->blocked, &info));
 190                         spin_unlock_irqrestore(&current->sighand->siglock, flags);
 191                         result = -EINTR;
 192                         break;
 193                 }
 194
 195                 if (result <= 0) {
 196                         if (result == 0)
 197                                 result = -EPIPE; /* short read */
 198                         break;
 199                 }
 200                 size -= result;
 201                 buf += result;
 202         } while (size > 0);
 203
 204         spin_lock_irqsave(&current->sighand->siglock, flags);
 205         current->blocked = oldset;
 206         recalc_sigpending();
 207         spin_unlock_irqrestore(&current->sighand->siglock, flags);
 208
 209         return result;
 210 }
 211
 212 static inline int sock_send_bvec(struct socket *sock, struct bio_vec *bvec,
 213                 int flags)
 214 {
 215         int result;
 216         void *kaddr = kmap(bvec->bv_page);
 217         result = sock_xmit(sock, 1, kaddr + bvec->bv_offset, bvec->bv_len,
 218                         flags);
 219         kunmap(bvec->bv_page);
 220         return result;
 221 }
 222
 223 static int nbd_send_req(struct nbd_device *lo, struct request *req)
 224 {
 225         int result, i, flags;
 226         struct nbd_request request;
 227         unsigned long size = req->nr_sectors << 9;
 228         struct socket *sock = lo->sock;
 229
 230         request.magic = htonl(NBD_REQUEST_MAGIC);
 231         request.type = htonl(nbd_cmd(req));
 232         request.from = cpu_to_be64((u64) req->sector << 9);
 233         request.len = htonl(size);
 234         memcpy(request.handle, &req, sizeof(req));
 235
 236         dprintk(DBG_TX, "%s: request %p: sending control (%s@%llu,%luB)\n",
 237                         lo->disk->disk_name, req,
 238                         nbdcmd_to_ascii(nbd_cmd(req)),
 239                         (unsigned long long)req->sector << 9,
 240                         req->nr_sectors << 9);
 241         result = sock_xmit(sock, 1, &request, sizeof(request),
 242                         (nbd_cmd(req) == NBD_CMD_WRITE)? MSG_MORE: 0);
 243         if (result <= 0) {
 244                 printk(KERN_ERR "%s: Send control failed (result %d)\n",
 245                                 lo->disk->disk_name, result);
 246                 goto error_out;
 247         }
 248
 249         if (nbd_cmd(req) == NBD_CMD_WRITE) {
 250                 struct bio *bio;
 251                 /*
 252                  * we are really probing at internals to determine
 253                  * whether to set MSG_MORE or not...
 254                  */
 255                 rq_for_each_bio(bio, req) {
 256                         struct bio_vec *bvec;
 257                         bio_for_each_segment(bvec, bio, i) {
 258                                 flags = 0;
 259                                 if ((i < (bio->bi_vcnt - 1)) || bio->bi_next)
 260                                         flags = MSG_MORE;
 261                                 dprintk(DBG_TX, "%s: request %p: sending %d bytes data\n",
 262                                                 lo->disk->disk_name, req,
 263                                                 bvec->bv_len);
 264                                 result = sock_send_bvec(sock, bvec, flags);
 265                                 if (result <= 0) {
 266                                         printk(KERN_ERR "%s: Send data failed (result %d)\n",
 267                                                         lo->disk->disk_name,
 268                                                         result);
 269                                         goto error_out;
 270                                 }
 271                         }
 272                 }
 273         }
 274         return 0;
 275
 276 error_out:
 277         return 1;
 278 }
 279
 280 static struct request *nbd_find_request(struct nbd_device *lo, char *handle)
 281 {
 282         struct request *req;
 283         struct list_head *tmp;
 284         struct request *xreq;
 285         int err;
 286
 287         memcpy(&xreq, handle, sizeof(xreq));
 288
 289         err = wait_event_interruptible(lo->active_wq, lo->active_req != xreq);
 290         if (unlikely(err))
 291                 goto out;
 292
 293         spin_lock(&lo->queue_lock);
 294         list_for_each(tmp, &lo->queue_head) {
 295                 req = list_entry(tmp, struct request, queuelist);
 296                 if (req != xreq)
 297                         continue;
 298                 list_del_init(&req->queuelist);
 299                 spin_unlock(&lo->queue_lock);
 300                 return req;
 301         }
 302         spin_unlock(&lo->queue_lock);
 303
 304         err = -ENOENT;
 305
 306 out:
 307         return ERR_PTR(err);
 308 }
 309
 310 static inline int sock_recv_bvec(struct socket *sock, struct bio_vec *bvec)
 311 {
 312         int result;
 313         void *kaddr = kmap(bvec->bv_page);
 314         result = sock_xmit(sock, 0, kaddr + bvec->bv_offset, bvec->bv_len,
 315                         MSG_WAITALL);
 316         kunmap(bvec->bv_page);
 317         return result;
 318 }
 319
 320 /* NULL returned = something went wrong, inform userspace */
 321 static struct request *nbd_read_stat(struct nbd_device *lo)
 322 {
 323         int result;
 324         struct nbd_reply reply;
 325         struct request *req;
 326         struct socket *sock = lo->sock;
 327
 328         reply.magic = 0;
 329         result = sock_xmit(sock, 0, &reply, sizeof(reply), MSG_WAITALL);
 330         if (result <= 0) {
 331                 printk(KERN_ERR "%s: Receive control failed (result %d)\n",
 332                                 lo->disk->disk_name, result);
 333                 goto harderror;
 334         }
 335         req = nbd_find_request(lo, reply.handle);
 336         if (unlikely(IS_ERR(req))) {
 337                 result = PTR_ERR(req);
 338                 if (result != -ENOENT)
 339                         goto harderror;
 340
 341                 printk(KERN_ERR "%s: Unexpected reply (%p)\n",
 342                                 lo->disk->disk_name, reply.handle);
 343                 result = -EBADR;
 344                 goto harderror;
 345         }
 346
 347         if (ntohl(reply.magic) != NBD_REPLY_MAGIC) {
 348                 printk(KERN_ERR "%s: Wrong magic (0x%lx)\n",
 349                                 lo->disk->disk_name,
 350                                 (unsigned long)ntohl(reply.magic));
 351                 result = -EPROTO;
 352                 goto harderror;
 353         }
 354         if (ntohl(reply.error)) {
 355                 printk(KERN_ERR "%s: Other side returned error (%d)\n",
 356                                 lo->disk->disk_name, ntohl(reply.error));
 357                 req->errors++;
 358                 return req;
 359         }
 360
 361         dprintk(DBG_RX, "%s: request %p: got reply\n",
 362                         lo->disk->disk_name, req);
 363         if (nbd_cmd(req) == NBD_CMD_READ) {
 364                 int i;
 365                 struct bio *bio;
 366                 rq_for_each_bio(bio, req) {
 367                         struct bio_vec *bvec;
 368                         bio_for_each_segment(bvec, bio, i) {
 369                                 result = sock_recv_bvec(sock, bvec);
 370                                 if (result <= 0) {
 371                                         printk(KERN_ERR "%s: Receive data failed (result %d)\n",
 372                                                         lo->disk->disk_name,
 373                                                         result);
 374                                         goto harderror;
 375                                 }
 376                                 dprintk(DBG_RX, "%s: request %p: got %d bytes data\n",
 377                                         lo->disk->disk_name, req, bvec->bv_len);
 378                         }
 379                 }
 380         }
 381         return req;
 382 harderror:
 383         lo->harderror = result;
 384         return NULL;
 385 }
 386
 387 static void nbd_do_it(struct nbd_device *lo)
 388 {
 389         struct request *req;
 390
 391         BUG_ON(lo->magic != LO_MAGIC);
 392
 393         while ((req = nbd_read_stat(lo)) != NULL)
 394                 nbd_end_request(req);
 395         return;
 396 }
 397
 398 static void nbd_clear_que(struct nbd_device *lo)
 399 {
 400         struct request *req;
 401
 402         BUG_ON(lo->magic != LO_MAGIC);
 403
 404         /*
 405          * Because we have set lo->sock to NULL under the tx_lock, all
 406          * modifications to the list must have completed by now.  For
 407          * the same reason, the active_req must be NULL.
 408          *
 409          * As a consequence, we don't need to take the spin lock while
 410          * purging the list here.
 411          */
 412         BUG_ON(lo->sock);
 413         BUG_ON(lo->active_req);
 414
 415         while (!list_empty(&lo->queue_head)) {
 416                 req = list_entry(lo->queue_head.next, struct request,
 417                                  queuelist);
 418                 list_del_init(&req->queuelist);
 419                 req->errors++;
 420                 nbd_end_request(req);
 421         }
 422 }
 423
 424 /*
 425  * We always wait for result of write, for now. It would be nice to make it optional
 426  * in future
 427  * if ((req->cmd == WRITE) && (lo->flags & NBD_WRITE_NOCHK))
 428  *   { printk( "Warning: Ignoring result!\n"); nbd_end_request( req ); }
 429  */
 430
 431 static void do_nbd_request(request_queue_t * q)
 432 {
 433         struct request *req;
 434
 435         while ((req = elv_next_request(q)) != NULL) {
 436                 struct nbd_device *lo;
 437
 438                 blkdev_dequeue_request(req);
 439                 dprintk(DBG_BLKDEV, "%s: request %p: dequeued (flags=%lx)\n",
 440                                 req->rq_disk->disk_name, req, req->flags);
 441
 442                 if (!(req->flags & REQ_CMD))
 443                         goto error_out;
 444
 445                 lo = req->rq_disk->private_data;
 446
 447                 BUG_ON(lo->magic != LO_MAGIC);
 448
 449                 nbd_cmd(req) = NBD_CMD_READ;
 450                 if (rq_data_dir(req) == WRITE) {
 451                         nbd_cmd(req) = NBD_CMD_WRITE;
 452                         if (lo->flags & NBD_READ_ONLY) {
 453                                 printk(KERN_ERR "%s: Write on read-only\n",
 454                                                 lo->disk->disk_name);
 455                                 goto error_out;
 456                         }
 457                 }
 458
 459                 req->errors = 0;
 460                 spin_unlock_irq(q->queue_lock);
 461
 462                 mutex_lock(&lo->tx_lock);
 463                 if (unlikely(!lo->sock)) {
 464                         mutex_unlock(&lo->tx_lock);
 465                         printk(KERN_ERR "%s: Attempted send on closed socket\n",
 466                                lo->disk->disk_name);
 467                         req->errors++;
 468                         nbd_end_request(req);
 469                         spin_lock_irq(q->queue_lock);
 470                         continue;
 471                 }
 472
 473                 lo->active_req = req;
 474
 475                 if (nbd_send_req(lo, req) != 0) {
 476                         printk(KERN_ERR "%s: Request send failed\n",
 477                                         lo->disk->disk_name);
 478                         req->errors++;
 479                         nbd_end_request(req);
 480                 } else {
 481                         spin_lock(&lo->queue_lock);
 482                         list_add(&req->queuelist, &lo->queue_head);
 483                         spin_unlock(&lo->queue_lock);
 484                 }
 485
 486                 lo->active_req = NULL;
 487                 mutex_unlock(&lo->tx_lock);
 488                 wake_up_all(&lo->active_wq);
 489
 490                 spin_lock_irq(q->queue_lock);
 491                 continue;
 492
 493 error_out:
 494                 req->errors++;
 495                 spin_unlock(q->queue_lock);
 496                 nbd_end_request(req);
 497                 spin_lock(q->queue_lock);
 498         }
 499         return;
 500 }
 501
 502 static int nbd_ioctl(struct inode *inode, struct file *file,
 503                      unsigned int cmd, unsigned long arg)
 504 {
 505         struct nbd_device *lo = inode->i_bdev->bd_disk->private_data;
 506         int error;
 507         struct request sreq ;
 508
 509         if (!capable(CAP_SYS_ADMIN))
 510                 return -EPERM;
 511
 512         BUG_ON(lo->magic != LO_MAGIC);
 513
 514         /* Anyone capable of this syscall can do *real bad* things */
 515         dprintk(DBG_IOCTL, "%s: nbd_ioctl cmd=%s(0x%x) arg=%lu\n",
 516                         lo->disk->disk_name, ioctl_cmd_to_ascii(cmd), cmd, arg);
 517
 518         switch (cmd) {
 519         case NBD_DISCONNECT:
 520                 printk(KERN_INFO "%s: NBD_DISCONNECT\n", lo->disk->disk_name);
 521                 sreq.flags = REQ_SPECIAL;
 522                 nbd_cmd(&sreq) = NBD_CMD_DISC;
 523                 /*
 524                  * Set these to sane values in case server implementation
 525                  * fails to check the request type first and also to keep
 526                  * debugging output cleaner.
 527                  */
 528                 sreq.sector = 0;
 529                 sreq.nr_sectors = 0;
 530                 if (!lo->sock)
 531                         return -EINVAL;
 532                 nbd_send_req(lo, &sreq);
 533                 return 0;
 534
 535         case NBD_CLEAR_SOCK:
 536                 error = 0;
 537                 mutex_lock(&lo->tx_lock);
 538                 lo->sock = NULL;
 539                 mutex_unlock(&lo->tx_lock);
 540                 file = lo->file;
 541                 lo->file = NULL;
 542                 nbd_clear_que(lo);
 543                 BUG_ON(!list_empty(&lo->queue_head));
 544                 if (file)
 545                         fput(file);
 546                 return error;
 547         case NBD_SET_SOCK:
 548                 if (lo->file)
 549                         return -EBUSY;
 550                 error = -EINVAL;
 551                 file = fget(arg);
 552                 if (file) {
 553                         inode = file->f_dentry->d_inode;
 554                         if (S_ISSOCK(inode->i_mode)) {
 555                                 lo->file = file;
 556                                 lo->sock = SOCKET_I(inode);
 557                                 error = 0;
 558                         } else {
 559                                 fput(file);
 560                         }
 561                 }
 562                 return error;
 563         case NBD_SET_BLKSIZE:
 564                 lo->blksize = arg;
 565                 lo->bytesize &= ~(lo->blksize-1);
 566                 inode->i_bdev->bd_inode->i_size = lo->bytesize;
 567                 set_blocksize(inode->i_bdev, lo->blksize);
 568                 set_capacity(lo->disk, lo->bytesize >> 9);
 569                 return 0;
 570         case NBD_SET_SIZE:
 571                 lo->bytesize = arg & ~(lo->blksize-1);
 572                 inode->i_bdev->bd_inode->i_size = lo->bytesize;
 573                 set_blocksize(inode->i_bdev, lo->blksize);
 574                 set_capacity(lo->disk, lo->bytesize >> 9);
 575                 return 0;
 576         case NBD_SET_SIZE_BLOCKS:
 577                 lo->bytesize = ((u64) arg) * lo->blksize;
 578                 inode->i_bdev->bd_inode->i_size = lo->bytesize;
 579                 set_blocksize(inode->i_bdev, lo->blksize);
 580                 set_capacity(lo->disk, lo->bytesize >> 9);
 581                 return 0;
 582         case NBD_DO_IT:
 583                 if (!lo->file)
 584                         return -EINVAL;
 585                 nbd_do_it(lo);
 586                 /* on return tidy up in case we have a signal */
 587                 /* Forcibly shutdown the socket causing all listeners
 588                  * to error
 589                  *
 590                  * FIXME: This code is duplicated from sys_shutdown, but
 591                  * there should be a more generic interface rather than
 592                  * calling socket ops directly here */
 593                 mutex_lock(&lo->tx_lock);
 594                 if (lo->sock) {
 595                         printk(KERN_WARNING "%s: shutting down socket\n",
 596                                 lo->disk->disk_name);
 597                         lo->sock->ops->shutdown(lo->sock,
 598                                 SEND_SHUTDOWN|RCV_SHUTDOWN);
 599                         lo->sock = NULL;
 600                 }
 601                 mutex_unlock(&lo->tx_lock);
 602                 file = lo->file;
 603                 lo->file = NULL;
 604                 nbd_clear_que(lo);
 605                 printk(KERN_WARNING "%s: queue cleared\n", lo->disk->disk_name);
 606                 if (file)
 607                         fput(file);
 608                 return lo->harderror;
 609         case NBD_CLEAR_QUE:
 610                 /*
 611                  * This is for compatibility only.  The queue is always cleared
 612                  * by NBD_DO_IT or NBD_CLEAR_SOCK.
 613                  */
 614                 BUG_ON(!lo->sock && !list_empty(&lo->queue_head));
 615                 return 0;
 616         case NBD_PRINT_DEBUG:
 617                 printk(KERN_INFO "%s: next = %p, prev = %p, head = %p\n",
 618                         inode->i_bdev->bd_disk->disk_name,
 619                         lo->queue_head.next, lo->queue_head.prev,
 620                         &lo->queue_head);
 621                 return 0;
 622         }
 623         return -EINVAL;
 624 }
 625
 626 static struct block_device_operations nbd_fops =
 627 {
 628         .owner =        THIS_MODULE,
 629         .ioctl =        nbd_ioctl,
 630 };
 631
 632 /*
 633  * And here should be modules and kernel interface
 634  *  (Just smiley confuses emacs :-)
 635  */
 636
 637 static int __init nbd_init(void)
 638 {
 639         int err = -ENOMEM;
 640         int i;
 641
 642         BUILD_BUG_ON(sizeof(struct nbd_request) != 28);
 643
 644         if (nbds_max > MAX_NBD) {
 645                 printk(KERN_CRIT "nbd: cannot allocate more than %u nbds; %u requested.\n", MAX_NBD,
 646                                 nbds_max);
 647                 return -EINVAL;
 648         }
 649
 650         for (i = 0; i < nbds_max; i++) {
 651                 struct gendisk *disk = alloc_disk(1);
 652                 if (!disk)
 653                         goto out;
 654                 nbd_dev[i].disk = disk;
 655                 /*
 656                  * The new linux 2.5 block layer implementation requires
 657                  * every gendisk to have its very own request_queue struct.
 658                  * These structs are big so we dynamically allocate them.
 659                  */
 660                 disk->queue = blk_init_queue(do_nbd_request, &nbd_lock);
 661                 if (!disk->queue) {
 662                         put_disk(disk);
 663                         goto out;
 664                 }
 665         }
 666
 667         if (register_blkdev(NBD_MAJOR, "nbd")) {
 668                 err = -EIO;
 669                 goto out;
 670         }
 671
 672         printk(KERN_INFO "nbd: registered device at major %d\n", NBD_MAJOR);
 673         dprintk(DBG_INIT, "nbd: debugflags=0x%x\n", debugflags);
 674
 675         devfs_mk_dir("nbd");
 676         for (i = 0; i < nbds_max; i++) {
 677                 struct gendisk *disk = nbd_dev[i].disk;
 678                 nbd_dev[i].file = NULL;
 679                 nbd_dev[i].magic = LO_MAGIC;
 680                 nbd_dev[i].flags = 0;
 681                 spin_lock_init(&nbd_dev[i].queue_lock);
 682                 INIT_LIST_HEAD(&nbd_dev[i].queue_head);
 683                 mutex_init(&nbd_dev[i].tx_lock);
 684                 init_waitqueue_head(&nbd_dev[i].active_wq);
 685                 nbd_dev[i].blksize = 1024;
 686                 nbd_dev[i].bytesize = 0x7ffffc00ULL << 10; /* 2TB */
 687                 disk->major = NBD_MAJOR;
 688                 disk->first_minor = i;
 689                 disk->fops = &nbd_fops;
 690                 disk->private_data = &nbd_dev[i];
 691                 disk->flags |= GENHD_FL_SUPPRESS_PARTITION_INFO;
 692                 sprintf(disk->disk_name, "nbd%d", i);
 693                 sprintf(disk->devfs_name, "nbd/%d", i);
 694                 set_capacity(disk, 0x7ffffc00ULL << 1); /* 2 TB */
 695                 add_disk(disk);
 696         }
 697
 698         return 0;
 699 out:
 700         while (i--) {
 701                 blk_cleanup_queue(nbd_dev[i].disk->queue);
 702                 put_disk(nbd_dev[i].disk);
 703         }
 704         return err;
 705 }
 706
 707 static void __exit nbd_cleanup(void)
 708 {
 709         int i;
 710         for (i = 0; i < nbds_max; i++) {
 711                 struct gendisk *disk = nbd_dev[i].disk;
 712                 nbd_dev[i].magic = 0;
 713                 if (disk) {
 714                         del_gendisk(disk);
 715                         blk_cleanup_queue(disk->queue);
 716                         put_disk(disk);
 717                 }
 718         }
 719         devfs_remove("nbd");
 720         unregister_blkdev(NBD_MAJOR, "nbd");
 721         printk(KERN_INFO "nbd: unregistered device at major %d\n", NBD_MAJOR);
 722 }
 723
 724 module_init(nbd_init);
 725 module_exit(nbd_cleanup);
 726
 727 MODULE_DESCRIPTION("Network Block Device");
 728 MODULE_LICENSE("GPL");
 729
 730 module_param(nbds_max, int, 0444);
 731 MODULE_PARM_DESC(nbds_max, "How many network block devices to initialize.");
 732 #ifndef NDEBUG
 733 module_param(debugflags, int, 0644);
 734 MODULE_PARM_DESC(debugflags, "flags for controlling debug output");
 735 #endif