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
  36 #include <asm/uaccess.h>
  37 #include <asm/types.h>
  38
  39 #include <linux/nbd.h>
  40
  41 #define NBD_MAGIC 0x68797548
  42
  43 #ifdef NDEBUG
  44 #define dprintk(flags, fmt...)
  45 #else /* NDEBUG */
  46 #define dprintk(flags, fmt...) do { \
  47         if (debugflags & (flags)) printk(KERN_DEBUG fmt); \
  48 } while (0)
  49 #define DBG_IOCTL       0x0004
  50 #define DBG_INIT        0x0010
  51 #define DBG_EXIT        0x0020
  52 #define DBG_BLKDEV      0x0100
  53 #define DBG_RX          0x0200
  54 #define DBG_TX          0x0400
  55 static unsigned int debugflags;
  56 #endif /* NDEBUG */
  57
  58 static unsigned int nbds_max = 16;
  59 static struct nbd_device *nbd_dev;
  60 static int max_part;
  61
  62 /*
  63  * Use just one lock (or at most 1 per NIC). Two arguments for this:
  64  * 1. Each NIC is essentially a synchronization point for all servers
  65  *    accessed through that NIC so there's no need to have more locks
  66  *    than NICs anyway.
  67  * 2. More locks lead to more "Dirty cache line bouncing" which will slow
  68  *    down each lock to the point where they're actually slower than just
  69  *    a single lock.
  70  * Thanks go to Jens Axboe and Al Viro for their LKML emails explaining this!
  71  */
  72 static DEFINE_SPINLOCK(nbd_lock);
  73
  74 #ifndef NDEBUG
  75 static const char *ioctl_cmd_to_ascii(int cmd)
  76 {
  77         switch (cmd) {
  78         case NBD_SET_SOCK: return "set-sock";
  79         case NBD_SET_BLKSIZE: return "set-blksize";
  80         case NBD_SET_SIZE: return "set-size";
  81         case NBD_DO_IT: return "do-it";
  82         case NBD_CLEAR_SOCK: return "clear-sock";
  83         case NBD_CLEAR_QUE: return "clear-que";
  84         case NBD_PRINT_DEBUG: return "print-debug";
  85         case NBD_SET_SIZE_BLOCKS: return "set-size-blocks";
  86         case NBD_DISCONNECT: return "disconnect";
  87         case BLKROSET: return "set-read-only";
  88         case BLKFLSBUF: return "flush-buffer-cache";
  89         }
  90         return "unknown";
  91 }
  92
  93 static const char *nbdcmd_to_ascii(int cmd)
  94 {
  95         switch (cmd) {
  96         case  NBD_CMD_READ: return "read";
  97         case NBD_CMD_WRITE: return "write";
  98         case  NBD_CMD_DISC: return "disconnect";
  99         }
 100         return "invalid";
 101 }
 102 #endif /* NDEBUG */
 103
 104 static void nbd_end_request(struct request *req)
 105 {
 106         int error = req->errors ? -EIO : 0;
 107         struct request_queue *q = req->q;
 108         unsigned long flags;
 109
 110         dprintk(DBG_BLKDEV, "%s: request %p: %s\n", req->rq_disk->disk_name,
 111                         req, error ? "failed" : "done");
 112
 113         spin_lock_irqsave(q->queue_lock, flags);
 114         __blk_end_request_all(req, error);
 115         spin_unlock_irqrestore(q->queue_lock, flags);
 116 }
 117
 118 static void sock_shutdown(struct nbd_device *nbd, int lock)
 119 {
 120         /* Forcibly shutdown the socket causing all listeners
 121          * to error
 122          *
 123          * FIXME: This code is duplicated from sys_shutdown, but
 124          * there should be a more generic interface rather than
 125          * calling socket ops directly here */
 126         if (lock)
 127                 mutex_lock(&nbd->tx_lock);
 128         if (nbd->sock) {
 129                 dev_warn(disk_to_dev(nbd->disk), "shutting down socket\n");
 130                 kernel_sock_shutdown(nbd->sock, SHUT_RDWR);
 131                 nbd->sock = NULL;
 132         }
 133         if (lock)
 134                 mutex_unlock(&nbd->tx_lock);
 135 }
 136
 137 static void nbd_xmit_timeout(unsigned long arg)
 138 {
 139         struct task_struct *task = (struct task_struct *)arg;
 140
 141         printk(KERN_WARNING "nbd: killing hung xmit (%s, pid: %d)\n",
 142                 task->comm, task->pid);
 143         force_sig(SIGKILL, task);
 144 }
 145
 146 /*
 147  *  Send or receive packet.
 148  */
 149 static int sock_xmit(struct nbd_device *nbd, int send, void *buf, int size,
 150                 int msg_flags)
 151 {
 152         struct socket *sock = nbd->sock;
 153         int result;
 154         struct msghdr msg;
 155         struct kvec iov;
 156         sigset_t blocked, oldset;
 157
 158         if (unlikely(!sock)) {
 159                 dev_err(disk_to_dev(nbd->disk),
 160                         "Attempted %s on closed socket in sock_xmit\n",
 161                         (send ? "send" : "recv"));
 162                 return -EINVAL;
 163         }
 164
 165         /* Allow interception of SIGKILL only
 166          * Don't allow other signals to interrupt the transmission */
 167         siginitsetinv(&blocked, sigmask(SIGKILL));
 168         sigprocmask(SIG_SETMASK, &blocked, &oldset);
 169
 170         do {
 171                 sock->sk->sk_allocation = GFP_NOIO;
 172                 iov.iov_base = buf;
 173                 iov.iov_len = size;
 174                 msg.msg_name = NULL;
 175                 msg.msg_namelen = 0;
 176                 msg.msg_control = NULL;
 177                 msg.msg_controllen = 0;
 178                 msg.msg_flags = msg_flags | MSG_NOSIGNAL;
 179
 180                 if (send) {
 181                         struct timer_list ti;
 182
 183                         if (nbd->xmit_timeout) {
 184                                 init_timer(&ti);
 185                                 ti.function = nbd_xmit_timeout;
 186                                 ti.data = (unsigned long)current;
 187                                 ti.expires = jiffies + nbd->xmit_timeout;
 188                                 add_timer(&ti);
 189                         }
 190                         result = kernel_sendmsg(sock, &msg, &iov, 1, size);
 191                         if (nbd->xmit_timeout)
 192                                 del_timer_sync(&ti);
 193                 } else
 194                         result = kernel_recvmsg(sock, &msg, &iov, 1, size,
 195                                                 msg.msg_flags);
 196
 197                 if (signal_pending(current)) {
 198                         siginfo_t info;
 199                         printk(KERN_WARNING "nbd (pid %d: %s) got signal %d\n",
 200                                 task_pid_nr(current), current->comm,
 201                                 dequeue_signal_lock(current, &current->blocked, &info));
 202                         result = -EINTR;
 203                         sock_shutdown(nbd, !send);
 204                         break;
 205                 }
 206
 207                 if (result <= 0) {
 208                         if (result == 0)
 209                                 result = -EPIPE; /* short read */
 210                         break;
 211                 }
 212                 size -= result;
 213                 buf += result;
 214         } while (size > 0);
 215
 216         sigprocmask(SIG_SETMASK, &oldset, NULL);
 217
 218         return result;
 219 }
 220
 221 static inline int sock_send_bvec(struct nbd_device *nbd, struct bio_vec *bvec,
 222                 int flags)
 223 {
 224         int result;
 225         void *kaddr = kmap(bvec->bv_page);
 226         result = sock_xmit(nbd, 1, kaddr + bvec->bv_offset,
 227                            bvec->bv_len, flags);
 228         kunmap(bvec->bv_page);
 229         return result;
 230 }
 231
 232 /* always call with the tx_lock held */
 233 static int nbd_send_req(struct nbd_device *nbd, struct request *req)
 234 {
 235         int result, flags;
 236         struct nbd_request request;
 237         unsigned long size = blk_rq_bytes(req);
 238
 239         request.magic = htonl(NBD_REQUEST_MAGIC);
 240         request.type = htonl(nbd_cmd(req));
 241         request.from = cpu_to_be64((u64)blk_rq_pos(req) << 9);
 242         request.len = htonl(size);
 243         memcpy(request.handle, &req, sizeof(req));
 244
 245         dprintk(DBG_TX, "%s: request %p: sending control (%s@%llu,%uB)\n",
 246                         nbd->disk->disk_name, req,
 247                         nbdcmd_to_ascii(nbd_cmd(req)),
 248                         (unsigned long long)blk_rq_pos(req) << 9,
 249                         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(req, iter))
 268                                 flags = MSG_MORE;
 269                         dprintk(DBG_TX, "%s: request %p: sending %d bytes data\n",
 270                                         nbd->disk->disk_name, 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         dprintk(DBG_RX, "%s: request %p: got reply\n",
 364                         nbd->disk->disk_name, req);
 365         if (nbd_cmd(req) == NBD_CMD_READ) {
 366                 struct req_iterator iter;
 367                 struct bio_vec *bvec;
 368
 369                 rq_for_each_segment(bvec, req, iter) {
 370                         result = sock_recv_bvec(nbd, bvec);
 371                         if (result <= 0) {
 372                                 dev_err(disk_to_dev(nbd->disk), "Receive data failed (result %d)\n",
 373                                         result);
 374                                 req->errors++;
 375                                 return req;
 376                         }
 377                         dprintk(DBG_RX, "%s: request %p: got %d bytes data\n",
 378                                 nbd->disk->disk_name, req, bvec->bv_len);
 379                 }
 380         }
 381         return req;
 382 harderror:
 383         nbd->harderror = result;
 384         return NULL;
 385 }
 386
 387 static ssize_t pid_show(struct device *dev,
 388                         struct device_attribute *attr, char *buf)
 389 {
 390         struct gendisk *disk = dev_to_disk(dev);
 391
 392         return sprintf(buf, "%ld\n",
 393                 (long) ((struct nbd_device *)disk->private_data)->pid);
 394 }
 395
 396 static struct device_attribute pid_attr = {
 397         .attr = { .name = "pid", .mode = S_IRUGO},
 398         .show = pid_show,
 399 };
 400
 401 static int nbd_do_it(struct nbd_device *nbd)
 402 {
 403         struct request *req;
 404         int ret;
 405
 406         BUG_ON(nbd->magic != NBD_MAGIC);
 407
 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(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(req);
 447         }
 448 }
 449
 450
 451 static void nbd_handle_req(struct nbd_device *nbd, struct request *req)
 452 {
 453         if (req->cmd_type != REQ_TYPE_FS)
 454                 goto error_out;
 455
 456         nbd_cmd(req) = NBD_CMD_READ;
 457         if (rq_data_dir(req) == WRITE) {
 458                 nbd_cmd(req) = NBD_CMD_WRITE;
 459                 if (nbd->flags & NBD_READ_ONLY) {
 460                         dev_err(disk_to_dev(nbd->disk),
 461                                 "Write on read-only\n");
 462                         goto error_out;
 463                 }
 464         }
 465
 466         req->errors = 0;
 467
 468         mutex_lock(&nbd->tx_lock);
 469         if (unlikely(!nbd->sock)) {
 470                 mutex_unlock(&nbd->tx_lock);
 471                 dev_err(disk_to_dev(nbd->disk),
 472                         "Attempted send on closed socket\n");
 473                 goto error_out;
 474         }
 475
 476         nbd->active_req = req;
 477
 478         if (nbd_send_req(nbd, req) != 0) {
 479                 dev_err(disk_to_dev(nbd->disk), "Request send failed\n");
 480                 req->errors++;
 481                 nbd_end_request(req);
 482         } else {
 483                 spin_lock(&nbd->queue_lock);
 484                 list_add(&req->queuelist, &nbd->queue_head);
 485                 spin_unlock(&nbd->queue_lock);
 486         }
 487
 488         nbd->active_req = NULL;
 489         mutex_unlock(&nbd->tx_lock);
 490         wake_up_all(&nbd->active_wq);
 491
 492         return;
 493
 494 error_out:
 495         req->errors++;
 496         nbd_end_request(req);
 497 }
 498
 499 static int nbd_thread(void *data)
 500 {
 501         struct nbd_device *nbd = data;
 502         struct request *req;
 503
 504         set_user_nice(current, -20);
 505         while (!kthread_should_stop() || !list_empty(&nbd->waiting_queue)) {
 506                 /* wait for something to do */
 507                 wait_event_interruptible(nbd->waiting_wq,
 508                                          kthread_should_stop() ||
 509                                          !list_empty(&nbd->waiting_queue));
 510
 511                 /* extract request */
 512                 if (list_empty(&nbd->waiting_queue))
 513                         continue;
 514
 515                 spin_lock_irq(&nbd->queue_lock);
 516                 req = list_entry(nbd->waiting_queue.next, struct request,
 517                                  queuelist);
 518                 list_del_init(&req->queuelist);
 519                 spin_unlock_irq(&nbd->queue_lock);
 520
 521                 /* handle request */
 522                 nbd_handle_req(nbd, req);
 523         }
 524         return 0;
 525 }
 526
 527 /*
 528  * We always wait for result of write, for now. It would be nice to make it optional
 529  * in future
 530  * if ((rq_data_dir(req) == WRITE) && (nbd->flags & NBD_WRITE_NOCHK))
 531  *   { printk( "Warning: Ignoring result!\n"); nbd_end_request( req ); }
 532  */
 533
 534 static void do_nbd_request(struct request_queue *q)
 535 {
 536         struct request *req;
 537
 538         while ((req = blk_fetch_request(q)) != NULL) {
 539                 struct nbd_device *nbd;
 540
 541                 spin_unlock_irq(q->queue_lock);
 542
 543                 dprintk(DBG_BLKDEV, "%s: request %p: dequeued (flags=%x)\n",
 544                                 req->rq_disk->disk_name, req, req->cmd_type);
 545
 546                 nbd = req->rq_disk->private_data;
 547
 548                 BUG_ON(nbd->magic != NBD_MAGIC);
 549
 550                 if (unlikely(!nbd->sock)) {
 551                         dev_err(disk_to_dev(nbd->disk),
 552                                 "Attempted send on closed socket\n");
 553                         req->errors++;
 554                         nbd_end_request(req);
 555                         spin_lock_irq(q->queue_lock);
 556                         continue;
 557                 }
 558
 559                 spin_lock_irq(&nbd->queue_lock);
 560                 list_add_tail(&req->queuelist, &nbd->waiting_queue);
 561                 spin_unlock_irq(&nbd->queue_lock);
 562
 563                 wake_up(&nbd->waiting_wq);
 564
 565                 spin_lock_irq(q->queue_lock);
 566         }
 567 }
 568
 569 /* Must be called with tx_lock held */
 570
 571 static int __nbd_ioctl(struct block_device *bdev, struct nbd_device *nbd,
 572                        unsigned int cmd, unsigned long arg)
 573 {
 574         switch (cmd) {
 575         case NBD_DISCONNECT: {
 576                 struct request sreq;
 577
 578                 dev_info(disk_to_dev(nbd->disk), "NBD_DISCONNECT\n");
 579
 580                 blk_rq_init(NULL, &sreq);
 581                 sreq.cmd_type = REQ_TYPE_SPECIAL;
 582                 nbd_cmd(&sreq) = NBD_CMD_DISC;
 583                 if (!nbd->sock)
 584                         return -EINVAL;
 585                 nbd_send_req(nbd, &sreq);
 586                 return 0;
 587         }
 588
 589         case NBD_CLEAR_SOCK: {
 590                 struct file *file;
 591
 592                 nbd->sock = NULL;
 593                 file = nbd->file;
 594                 nbd->file = NULL;
 595                 nbd_clear_que(nbd);
 596                 BUG_ON(!list_empty(&nbd->queue_head));
 597                 if (file)
 598                         fput(file);
 599                 return 0;
 600         }
 601
 602         case NBD_SET_SOCK: {
 603                 struct file *file;
 604                 if (nbd->file)
 605                         return -EBUSY;
 606                 file = fget(arg);
 607                 if (file) {
 608                         struct inode *inode = file->f_path.dentry->d_inode;
 609                         if (S_ISSOCK(inode->i_mode)) {
 610                                 nbd->file = file;
 611                                 nbd->sock = SOCKET_I(inode);
 612                                 if (max_part > 0)
 613                                         bdev->bd_invalidated = 1;
 614                                 return 0;
 615                         } else {
 616                                 fput(file);
 617                         }
 618                 }
 619                 return -EINVAL;
 620         }
 621
 622         case NBD_SET_BLKSIZE:
 623                 nbd->blksize = arg;
 624                 nbd->bytesize &= ~(nbd->blksize-1);
 625                 bdev->bd_inode->i_size = nbd->bytesize;
 626                 set_blocksize(bdev, nbd->blksize);
 627                 set_capacity(nbd->disk, nbd->bytesize >> 9);
 628                 return 0;
 629
 630         case NBD_SET_SIZE:
 631                 nbd->bytesize = arg & ~(nbd->blksize-1);
 632                 bdev->bd_inode->i_size = nbd->bytesize;
 633                 set_blocksize(bdev, nbd->blksize);
 634                 set_capacity(nbd->disk, nbd->bytesize >> 9);
 635                 return 0;
 636
 637         case NBD_SET_TIMEOUT:
 638                 nbd->xmit_timeout = arg * HZ;
 639                 return 0;
 640
 641         case NBD_SET_SIZE_BLOCKS:
 642                 nbd->bytesize = ((u64) arg) * nbd->blksize;
 643                 bdev->bd_inode->i_size = nbd->bytesize;
 644                 set_blocksize(bdev, nbd->blksize);
 645                 set_capacity(nbd->disk, nbd->bytesize >> 9);
 646                 return 0;
 647
 648         case NBD_DO_IT: {
 649                 struct task_struct *thread;
 650                 struct file *file;
 651                 int error;
 652
 653                 if (nbd->pid)
 654                         return -EBUSY;
 655                 if (!nbd->file)
 656                         return -EINVAL;
 657
 658                 mutex_unlock(&nbd->tx_lock);
 659
 660                 thread = kthread_create(nbd_thread, nbd, nbd->disk->disk_name);
 661                 if (IS_ERR(thread)) {
 662                         mutex_lock(&nbd->tx_lock);
 663                         return PTR_ERR(thread);
 664                 }
 665                 wake_up_process(thread);
 666                 error = nbd_do_it(nbd);
 667                 kthread_stop(thread);
 668
 669                 mutex_lock(&nbd->tx_lock);
 670                 if (error)
 671                         return error;
 672                 sock_shutdown(nbd, 0);
 673                 file = nbd->file;
 674                 nbd->file = NULL;
 675                 nbd_clear_que(nbd);
 676                 dev_warn(disk_to_dev(nbd->disk), "queue cleared\n");
 677                 if (file)
 678                         fput(file);
 679                 nbd->bytesize = 0;
 680                 bdev->bd_inode->i_size = 0;
 681                 set_capacity(nbd->disk, 0);
 682                 if (max_part > 0)
 683                         ioctl_by_bdev(bdev, BLKRRPART, 0);
 684                 return nbd->harderror;
 685         }
 686
 687         case NBD_CLEAR_QUE:
 688                 /*
 689                  * This is for compatibility only.  The queue is always cleared
 690                  * by NBD_DO_IT or NBD_CLEAR_SOCK.
 691                  */
 692                 BUG_ON(!nbd->sock && !list_empty(&nbd->queue_head));
 693                 return 0;
 694
 695         case NBD_PRINT_DEBUG:
 696                 dev_info(disk_to_dev(nbd->disk),
 697                         "next = %p, prev = %p, head = %p\n",
 698                         nbd->queue_head.next, nbd->queue_head.prev,
 699                         &nbd->queue_head);
 700                 return 0;
 701         }
 702         return -ENOTTY;
 703 }
 704
 705 static int nbd_ioctl(struct block_device *bdev, fmode_t mode,
 706                      unsigned int cmd, unsigned long arg)
 707 {
 708         struct nbd_device *nbd = bdev->bd_disk->private_data;
 709         int error;
 710
 711         if (!capable(CAP_SYS_ADMIN))
 712                 return -EPERM;
 713
 714         BUG_ON(nbd->magic != NBD_MAGIC);
 715
 716         /* Anyone capable of this syscall can do *real bad* things */
 717         dprintk(DBG_IOCTL, "%s: nbd_ioctl cmd=%s(0x%x) arg=%lu\n",
 718                 nbd->disk->disk_name, ioctl_cmd_to_ascii(cmd), cmd, arg);
 719
 720         mutex_lock(&nbd->tx_lock);
 721         error = __nbd_ioctl(bdev, nbd, cmd, arg);
 722         mutex_unlock(&nbd->tx_lock);
 723
 724         return error;
 725 }
 726
 727 static const struct block_device_operations nbd_fops =
 728 {
 729         .owner =        THIS_MODULE,
 730         .ioctl =        nbd_ioctl,
 731 };
 732
 733 /*
 734  * And here should be modules and kernel interface
 735  *  (Just smiley confuses emacs :-)
 736  */
 737
 738 static int __init nbd_init(void)
 739 {
 740         int err = -ENOMEM;
 741         int i;
 742         int part_shift;
 743
 744         BUILD_BUG_ON(sizeof(struct nbd_request) != 28);
 745
 746         if (max_part < 0) {
 747                 printk(KERN_ERR "nbd: max_part must be >= 0\n");
 748                 return -EINVAL;
 749         }
 750
 751         nbd_dev = kcalloc(nbds_max, sizeof(*nbd_dev), GFP_KERNEL);
 752         if (!nbd_dev)
 753                 return -ENOMEM;
 754
 755         part_shift = 0;
 756         if (max_part > 0) {
 757                 part_shift = fls(max_part);
 758
 759                 /*
 760                  * Adjust max_part according to part_shift as it is exported
 761                  * to user space so that user can know the max number of
 762                  * partition kernel should be able to manage.
 763                  *
 764                  * Note that -1 is required because partition 0 is reserved
 765                  * for the whole disk.
 766                  */
 767                 max_part = (1UL << part_shift) - 1;
 768         }
 769
 770         if ((1UL << part_shift) > DISK_MAX_PARTS)
 771                 return -EINVAL;
 772
 773         if (nbds_max > 1UL << (MINORBITS - part_shift))
 774                 return -EINVAL;
 775
 776         for (i = 0; i < nbds_max; i++) {
 777                 struct gendisk *disk = alloc_disk(1 << part_shift);
 778                 if (!disk)
 779                         goto out;
 780                 nbd_dev[i].disk = disk;
 781                 /*
 782                  * The new linux 2.5 block layer implementation requires
 783                  * every gendisk to have its very own request_queue struct.
 784                  * These structs are big so we dynamically allocate them.
 785                  */
 786                 disk->queue = blk_init_queue(do_nbd_request, &nbd_lock);
 787                 if (!disk->queue) {
 788                         put_disk(disk);
 789                         goto out;
 790                 }
 791                 /*
 792                  * Tell the block layer that we are not a rotational device
 793                  */
 794                 queue_flag_set_unlocked(QUEUE_FLAG_NONROT, disk->queue);
 795         }
 796
 797         if (register_blkdev(NBD_MAJOR, "nbd")) {
 798                 err = -EIO;
 799                 goto out;
 800         }
 801
 802         printk(KERN_INFO "nbd: registered device at major %d\n", NBD_MAJOR);
 803         dprintk(DBG_INIT, "nbd: debugflags=0x%x\n", debugflags);
 804
 805         for (i = 0; i < nbds_max; i++) {
 806                 struct gendisk *disk = nbd_dev[i].disk;
 807                 nbd_dev[i].file = NULL;
 808                 nbd_dev[i].magic = NBD_MAGIC;
 809                 nbd_dev[i].flags = 0;
 810                 INIT_LIST_HEAD(&nbd_dev[i].waiting_queue);
 811                 spin_lock_init(&nbd_dev[i].queue_lock);
 812                 INIT_LIST_HEAD(&nbd_dev[i].queue_head);
 813                 mutex_init(&nbd_dev[i].tx_lock);
 814                 init_waitqueue_head(&nbd_dev[i].active_wq);
 815                 init_waitqueue_head(&nbd_dev[i].waiting_wq);
 816                 nbd_dev[i].blksize = 1024;
 817                 nbd_dev[i].bytesize = 0;
 818                 disk->major = NBD_MAJOR;
 819                 disk->first_minor = i << part_shift;
 820                 disk->fops = &nbd_fops;
 821                 disk->private_data = &nbd_dev[i];
 822                 sprintf(disk->disk_name, "nbd%d", i);
 823                 set_capacity(disk, 0);
 824                 add_disk(disk);
 825         }
 826
 827         return 0;
 828 out:
 829         while (i--) {
 830                 blk_cleanup_queue(nbd_dev[i].disk->queue);
 831                 put_disk(nbd_dev[i].disk);
 832         }
 833         kfree(nbd_dev);
 834         return err;
 835 }
 836
 837 static void __exit nbd_cleanup(void)
 838 {
 839         int i;
 840         for (i = 0; i < nbds_max; i++) {
 841                 struct gendisk *disk = nbd_dev[i].disk;
 842                 nbd_dev[i].magic = 0;
 843                 if (disk) {
 844                         del_gendisk(disk);
 845                         blk_cleanup_queue(disk->queue);
 846                         put_disk(disk);
 847                 }
 848         }
 849         unregister_blkdev(NBD_MAJOR, "nbd");
 850         kfree(nbd_dev);
 851         printk(KERN_INFO "nbd: unregistered device at major %d\n", NBD_MAJOR);
 852 }
 853
 854 module_init(nbd_init);
 855 module_exit(nbd_cleanup);
 856
 857 MODULE_DESCRIPTION("Network Block Device");
 858 MODULE_LICENSE("GPL");
 859
 860 module_param(nbds_max, int, 0444);
 861 MODULE_PARM_DESC(nbds_max, "number of network block devices to initialize (default: 16)");
 862 module_param(max_part, int, 0444);
 863 MODULE_PARM_DESC(max_part, "number of partitions per device (default: 0)");
 864 #ifndef NDEBUG
 865 module_param(debugflags, int, 0644);
 866 MODULE_PARM_DESC(debugflags, "flags for controlling debug output");
 867 #endif