2 * Network block device - make block devices work over TCP
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.
7 * Copyright 1997-2000, 2008 Pavel Machek <pavel@ucw.cz>
8 * Parts copyright 2001 Steven Whitehouse <steve@chygwyn.com>
10 * This file is released under GPLv2 or later.
12 * (part of code stolen from loop.c)
15 #include <linux/major.h>
17 #include <linux/blkdev.h>
18 #include <linux/module.h>
19 #include <linux/init.h>
20 #include <linux/sched.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>
33 #include <linux/net.h>
34 #include <linux/kthread.h>
36 #include <asm/uaccess.h>
37 #include <asm/types.h>
39 #include <linux/nbd.h>
43 int harderror; /* Code of hard error */
44 struct socket * sock; /* If == NULL, device is not ready, yet */
47 spinlock_t queue_lock;
48 struct list_head queue_head; /* Requests waiting result */
49 struct request *active_req;
50 wait_queue_head_t active_wq;
51 struct list_head waiting_queue; /* Requests to be sent */
52 wait_queue_head_t waiting_wq;
58 pid_t pid; /* pid of nbd-client, if attached */
60 int disconnect; /* a disconnect has been requested by user */
63 #define NBD_MAGIC 0x68797548
66 #define dprintk(flags, fmt...)
68 #define dprintk(flags, fmt...) do { \
69 if (debugflags & (flags)) printk(KERN_DEBUG fmt); \
71 #define DBG_IOCTL 0x0004
72 #define DBG_INIT 0x0010
73 #define DBG_EXIT 0x0020
74 #define DBG_BLKDEV 0x0100
77 static unsigned int debugflags;
80 static unsigned int nbds_max = 16;
81 static struct nbd_device *nbd_dev;
85 * Use just one lock (or at most 1 per NIC). Two arguments for this:
86 * 1. Each NIC is essentially a synchronization point for all servers
87 * accessed through that NIC so there's no need to have more locks
89 * 2. More locks lead to more "Dirty cache line bouncing" which will slow
90 * down each lock to the point where they're actually slower than just
92 * Thanks go to Jens Axboe and Al Viro for their LKML emails explaining this!
94 static DEFINE_SPINLOCK(nbd_lock);
97 static const char *ioctl_cmd_to_ascii(int cmd)
100 case NBD_SET_SOCK: return "set-sock";
101 case NBD_SET_BLKSIZE: return "set-blksize";
102 case NBD_SET_SIZE: return "set-size";
103 case NBD_SET_TIMEOUT: return "set-timeout";
104 case NBD_SET_FLAGS: return "set-flags";
105 case NBD_DO_IT: return "do-it";
106 case NBD_CLEAR_SOCK: return "clear-sock";
107 case NBD_CLEAR_QUE: return "clear-que";
108 case NBD_PRINT_DEBUG: return "print-debug";
109 case NBD_SET_SIZE_BLOCKS: return "set-size-blocks";
110 case NBD_DISCONNECT: return "disconnect";
111 case BLKROSET: return "set-read-only";
112 case BLKFLSBUF: return "flush-buffer-cache";
117 static const char *nbdcmd_to_ascii(int cmd)
120 case NBD_CMD_READ: return "read";
121 case NBD_CMD_WRITE: return "write";
122 case NBD_CMD_DISC: return "disconnect";
123 case NBD_CMD_FLUSH: return "flush";
124 case NBD_CMD_TRIM: return "trim/discard";
130 static void nbd_end_request(struct request *req)
132 int error = req->errors ? -EIO : 0;
133 struct request_queue *q = req->q;
136 dprintk(DBG_BLKDEV, "%s: request %p: %s\n", req->rq_disk->disk_name,
137 req, error ? "failed" : "done");
139 spin_lock_irqsave(q->queue_lock, flags);
140 __blk_end_request_all(req, error);
141 spin_unlock_irqrestore(q->queue_lock, flags);
144 static void sock_shutdown(struct nbd_device *nbd, int lock)
146 /* Forcibly shutdown the socket causing all listeners
149 * FIXME: This code is duplicated from sys_shutdown, but
150 * there should be a more generic interface rather than
151 * calling socket ops directly here */
153 mutex_lock(&nbd->tx_lock);
155 dev_warn(disk_to_dev(nbd->disk), "shutting down socket\n");
156 kernel_sock_shutdown(nbd->sock, SHUT_RDWR);
160 mutex_unlock(&nbd->tx_lock);
163 static void nbd_xmit_timeout(unsigned long arg)
165 struct task_struct *task = (struct task_struct *)arg;
167 printk(KERN_WARNING "nbd: killing hung xmit (%s, pid: %d)\n",
168 task->comm, task->pid);
169 force_sig(SIGKILL, task);
173 * Send or receive packet.
175 static int sock_xmit(struct nbd_device *nbd, int send, void *buf, int size,
178 struct socket *sock = nbd->sock;
182 sigset_t blocked, oldset;
183 unsigned long pflags = current->flags;
185 if (unlikely(!sock)) {
186 dev_err(disk_to_dev(nbd->disk),
187 "Attempted %s on closed socket in sock_xmit\n",
188 (send ? "send" : "recv"));
192 /* Allow interception of SIGKILL only
193 * Don't allow other signals to interrupt the transmission */
194 siginitsetinv(&blocked, sigmask(SIGKILL));
195 sigprocmask(SIG_SETMASK, &blocked, &oldset);
197 current->flags |= PF_MEMALLOC;
199 sock->sk->sk_allocation = GFP_NOIO | __GFP_MEMALLOC;
204 msg.msg_control = NULL;
205 msg.msg_controllen = 0;
206 msg.msg_flags = msg_flags | MSG_NOSIGNAL;
209 struct timer_list ti;
211 if (nbd->xmit_timeout) {
213 ti.function = nbd_xmit_timeout;
214 ti.data = (unsigned long)current;
215 ti.expires = jiffies + nbd->xmit_timeout;
218 result = kernel_sendmsg(sock, &msg, &iov, 1, size);
219 if (nbd->xmit_timeout)
222 result = kernel_recvmsg(sock, &msg, &iov, 1, size,
225 if (signal_pending(current)) {
227 printk(KERN_WARNING "nbd (pid %d: %s) got signal %d\n",
228 task_pid_nr(current), current->comm,
229 dequeue_signal_lock(current, ¤t->blocked, &info));
231 sock_shutdown(nbd, !send);
237 result = -EPIPE; /* short read */
244 sigprocmask(SIG_SETMASK, &oldset, NULL);
245 tsk_restore_flags(current, pflags, PF_MEMALLOC);
250 static inline int sock_send_bvec(struct nbd_device *nbd, struct bio_vec *bvec,
254 void *kaddr = kmap(bvec->bv_page);
255 result = sock_xmit(nbd, 1, kaddr + bvec->bv_offset,
256 bvec->bv_len, flags);
257 kunmap(bvec->bv_page);
261 /* always call with the tx_lock held */
262 static int nbd_send_req(struct nbd_device *nbd, struct request *req)
265 struct nbd_request request;
266 unsigned long size = blk_rq_bytes(req);
268 memset(&request, 0, sizeof(request));
269 request.magic = htonl(NBD_REQUEST_MAGIC);
270 request.type = htonl(nbd_cmd(req));
272 if (nbd_cmd(req) != NBD_CMD_FLUSH && nbd_cmd(req) != NBD_CMD_DISC) {
273 request.from = cpu_to_be64((u64)blk_rq_pos(req) << 9);
274 request.len = htonl(size);
276 memcpy(request.handle, &req, sizeof(req));
278 dprintk(DBG_TX, "%s: request %p: sending control (%s@%llu,%uB)\n",
279 nbd->disk->disk_name, req,
280 nbdcmd_to_ascii(nbd_cmd(req)),
281 (unsigned long long)blk_rq_pos(req) << 9,
283 result = sock_xmit(nbd, 1, &request, sizeof(request),
284 (nbd_cmd(req) == NBD_CMD_WRITE) ? MSG_MORE : 0);
286 dev_err(disk_to_dev(nbd->disk),
287 "Send control failed (result %d)\n", result);
291 if (nbd_cmd(req) == NBD_CMD_WRITE) {
292 struct req_iterator iter;
295 * we are really probing at internals to determine
296 * whether to set MSG_MORE or not...
298 rq_for_each_segment(bvec, req, iter) {
300 if (!rq_iter_last(bvec, iter))
302 dprintk(DBG_TX, "%s: request %p: sending %d bytes data\n",
303 nbd->disk->disk_name, req, bvec.bv_len);
304 result = sock_send_bvec(nbd, &bvec, flags);
306 dev_err(disk_to_dev(nbd->disk),
307 "Send data failed (result %d)\n",
319 static struct request *nbd_find_request(struct nbd_device *nbd,
320 struct request *xreq)
322 struct request *req, *tmp;
325 err = wait_event_interruptible(nbd->active_wq, nbd->active_req != xreq);
329 spin_lock(&nbd->queue_lock);
330 list_for_each_entry_safe(req, tmp, &nbd->queue_head, queuelist) {
333 list_del_init(&req->queuelist);
334 spin_unlock(&nbd->queue_lock);
337 spin_unlock(&nbd->queue_lock);
345 static inline int sock_recv_bvec(struct nbd_device *nbd, struct bio_vec *bvec)
348 void *kaddr = kmap(bvec->bv_page);
349 result = sock_xmit(nbd, 0, kaddr + bvec->bv_offset, bvec->bv_len,
351 kunmap(bvec->bv_page);
355 /* NULL returned = something went wrong, inform userspace */
356 static struct request *nbd_read_stat(struct nbd_device *nbd)
359 struct nbd_reply reply;
363 result = sock_xmit(nbd, 0, &reply, sizeof(reply), MSG_WAITALL);
365 dev_err(disk_to_dev(nbd->disk),
366 "Receive control failed (result %d)\n", result);
370 if (ntohl(reply.magic) != NBD_REPLY_MAGIC) {
371 dev_err(disk_to_dev(nbd->disk), "Wrong magic (0x%lx)\n",
372 (unsigned long)ntohl(reply.magic));
377 req = nbd_find_request(nbd, *(struct request **)reply.handle);
379 result = PTR_ERR(req);
380 if (result != -ENOENT)
383 dev_err(disk_to_dev(nbd->disk), "Unexpected reply (%p)\n",
389 if (ntohl(reply.error)) {
390 dev_err(disk_to_dev(nbd->disk), "Other side returned error (%d)\n",
396 dprintk(DBG_RX, "%s: request %p: got reply\n",
397 nbd->disk->disk_name, req);
398 if (nbd_cmd(req) == NBD_CMD_READ) {
399 struct req_iterator iter;
402 rq_for_each_segment(bvec, req, iter) {
403 result = sock_recv_bvec(nbd, &bvec);
405 dev_err(disk_to_dev(nbd->disk), "Receive data failed (result %d)\n",
410 dprintk(DBG_RX, "%s: request %p: got %d bytes data\n",
411 nbd->disk->disk_name, req, bvec.bv_len);
416 nbd->harderror = result;
420 static ssize_t pid_show(struct device *dev,
421 struct device_attribute *attr, char *buf)
423 struct gendisk *disk = dev_to_disk(dev);
425 return sprintf(buf, "%ld\n",
426 (long) ((struct nbd_device *)disk->private_data)->pid);
429 static struct device_attribute pid_attr = {
430 .attr = { .name = "pid", .mode = S_IRUGO},
434 static int nbd_do_it(struct nbd_device *nbd)
439 BUG_ON(nbd->magic != NBD_MAGIC);
441 sk_set_memalloc(nbd->sock->sk);
442 nbd->pid = task_pid_nr(current);
443 ret = device_create_file(disk_to_dev(nbd->disk), &pid_attr);
445 dev_err(disk_to_dev(nbd->disk), "device_create_file failed!\n");
450 while ((req = nbd_read_stat(nbd)) != NULL)
451 nbd_end_request(req);
453 device_remove_file(disk_to_dev(nbd->disk), &pid_attr);
458 static void nbd_clear_que(struct nbd_device *nbd)
462 BUG_ON(nbd->magic != NBD_MAGIC);
465 * Because we have set nbd->sock to NULL under the tx_lock, all
466 * modifications to the list must have completed by now. For
467 * the same reason, the active_req must be NULL.
469 * As a consequence, we don't need to take the spin lock while
470 * purging the list here.
473 BUG_ON(nbd->active_req);
475 while (!list_empty(&nbd->queue_head)) {
476 req = list_entry(nbd->queue_head.next, struct request,
478 list_del_init(&req->queuelist);
480 nbd_end_request(req);
483 while (!list_empty(&nbd->waiting_queue)) {
484 req = list_entry(nbd->waiting_queue.next, struct request,
486 list_del_init(&req->queuelist);
488 nbd_end_request(req);
493 static void nbd_handle_req(struct nbd_device *nbd, struct request *req)
495 if (req->cmd_type != REQ_TYPE_FS)
498 nbd_cmd(req) = NBD_CMD_READ;
499 if (rq_data_dir(req) == WRITE) {
500 if ((req->cmd_flags & REQ_DISCARD)) {
501 WARN_ON(!(nbd->flags & NBD_FLAG_SEND_TRIM));
502 nbd_cmd(req) = NBD_CMD_TRIM;
504 nbd_cmd(req) = NBD_CMD_WRITE;
505 if (nbd->flags & NBD_FLAG_READ_ONLY) {
506 dev_err(disk_to_dev(nbd->disk),
507 "Write on read-only\n");
512 if (req->cmd_flags & REQ_FLUSH) {
513 BUG_ON(unlikely(blk_rq_sectors(req)));
514 nbd_cmd(req) = NBD_CMD_FLUSH;
519 mutex_lock(&nbd->tx_lock);
520 if (unlikely(!nbd->sock)) {
521 mutex_unlock(&nbd->tx_lock);
522 dev_err(disk_to_dev(nbd->disk),
523 "Attempted send on closed socket\n");
527 nbd->active_req = req;
529 if (nbd_send_req(nbd, req) != 0) {
530 dev_err(disk_to_dev(nbd->disk), "Request send failed\n");
532 nbd_end_request(req);
534 spin_lock(&nbd->queue_lock);
535 list_add_tail(&req->queuelist, &nbd->queue_head);
536 spin_unlock(&nbd->queue_lock);
539 nbd->active_req = NULL;
540 mutex_unlock(&nbd->tx_lock);
541 wake_up_all(&nbd->active_wq);
547 nbd_end_request(req);
550 static int nbd_thread(void *data)
552 struct nbd_device *nbd = data;
555 set_user_nice(current, MIN_NICE);
556 while (!kthread_should_stop() || !list_empty(&nbd->waiting_queue)) {
557 /* wait for something to do */
558 wait_event_interruptible(nbd->waiting_wq,
559 kthread_should_stop() ||
560 !list_empty(&nbd->waiting_queue));
562 /* extract request */
563 if (list_empty(&nbd->waiting_queue))
566 spin_lock_irq(&nbd->queue_lock);
567 req = list_entry(nbd->waiting_queue.next, struct request,
569 list_del_init(&req->queuelist);
570 spin_unlock_irq(&nbd->queue_lock);
573 nbd_handle_req(nbd, req);
579 * We always wait for result of write, for now. It would be nice to make it optional
581 * if ((rq_data_dir(req) == WRITE) && (nbd->flags & NBD_WRITE_NOCHK))
582 * { printk( "Warning: Ignoring result!\n"); nbd_end_request( req ); }
585 static void do_nbd_request(struct request_queue *q)
586 __releases(q->queue_lock) __acquires(q->queue_lock)
590 while ((req = blk_fetch_request(q)) != NULL) {
591 struct nbd_device *nbd;
593 spin_unlock_irq(q->queue_lock);
595 dprintk(DBG_BLKDEV, "%s: request %p: dequeued (flags=%x)\n",
596 req->rq_disk->disk_name, req, req->cmd_type);
598 nbd = req->rq_disk->private_data;
600 BUG_ON(nbd->magic != NBD_MAGIC);
602 if (unlikely(!nbd->sock)) {
603 dev_err(disk_to_dev(nbd->disk),
604 "Attempted send on closed socket\n");
606 nbd_end_request(req);
607 spin_lock_irq(q->queue_lock);
611 spin_lock_irq(&nbd->queue_lock);
612 list_add_tail(&req->queuelist, &nbd->waiting_queue);
613 spin_unlock_irq(&nbd->queue_lock);
615 wake_up(&nbd->waiting_wq);
617 spin_lock_irq(q->queue_lock);
621 /* Must be called with tx_lock held */
623 static int __nbd_ioctl(struct block_device *bdev, struct nbd_device *nbd,
624 unsigned int cmd, unsigned long arg)
627 case NBD_DISCONNECT: {
630 dev_info(disk_to_dev(nbd->disk), "NBD_DISCONNECT\n");
634 mutex_unlock(&nbd->tx_lock);
636 mutex_lock(&nbd->tx_lock);
637 blk_rq_init(NULL, &sreq);
638 sreq.cmd_type = REQ_TYPE_SPECIAL;
639 nbd_cmd(&sreq) = NBD_CMD_DISC;
641 /* Check again after getting mutex back. */
647 nbd_send_req(nbd, &sreq);
651 case NBD_CLEAR_SOCK: {
652 struct socket *sock = nbd->sock;
655 BUG_ON(!list_empty(&nbd->queue_head));
656 BUG_ON(!list_empty(&nbd->waiting_queue));
668 sock = sockfd_lookup(arg, &err);
672 bdev->bd_invalidated = 1;
673 nbd->disconnect = 0; /* we're connected now */
679 case NBD_SET_BLKSIZE:
681 nbd->bytesize &= ~(nbd->blksize-1);
682 bdev->bd_inode->i_size = nbd->bytesize;
683 set_blocksize(bdev, nbd->blksize);
684 set_capacity(nbd->disk, nbd->bytesize >> 9);
688 nbd->bytesize = arg & ~(nbd->blksize-1);
689 bdev->bd_inode->i_size = nbd->bytesize;
690 set_blocksize(bdev, nbd->blksize);
691 set_capacity(nbd->disk, nbd->bytesize >> 9);
694 case NBD_SET_TIMEOUT:
695 nbd->xmit_timeout = arg * HZ;
702 case NBD_SET_SIZE_BLOCKS:
703 nbd->bytesize = ((u64) arg) * nbd->blksize;
704 bdev->bd_inode->i_size = nbd->bytesize;
705 set_blocksize(bdev, nbd->blksize);
706 set_capacity(nbd->disk, nbd->bytesize >> 9);
710 struct task_struct *thread;
719 mutex_unlock(&nbd->tx_lock);
721 if (nbd->flags & NBD_FLAG_READ_ONLY)
722 set_device_ro(bdev, true);
723 if (nbd->flags & NBD_FLAG_SEND_TRIM)
724 queue_flag_set_unlocked(QUEUE_FLAG_DISCARD,
726 if (nbd->flags & NBD_FLAG_SEND_FLUSH)
727 blk_queue_flush(nbd->disk->queue, REQ_FLUSH);
729 blk_queue_flush(nbd->disk->queue, 0);
731 thread = kthread_run(nbd_thread, nbd, "%s",
732 nbd->disk->disk_name);
733 if (IS_ERR(thread)) {
734 mutex_lock(&nbd->tx_lock);
735 return PTR_ERR(thread);
738 error = nbd_do_it(nbd);
739 kthread_stop(thread);
741 mutex_lock(&nbd->tx_lock);
744 sock_shutdown(nbd, 0);
748 dev_warn(disk_to_dev(nbd->disk), "queue cleared\n");
750 queue_flag_clear_unlocked(QUEUE_FLAG_DISCARD, nbd->disk->queue);
751 set_device_ro(bdev, false);
756 bdev->bd_inode->i_size = 0;
757 set_capacity(nbd->disk, 0);
759 ioctl_by_bdev(bdev, BLKRRPART, 0);
760 if (nbd->disconnect) /* user requested, ignore socket errors */
762 return nbd->harderror;
767 * This is for compatibility only. The queue is always cleared
768 * by NBD_DO_IT or NBD_CLEAR_SOCK.
772 case NBD_PRINT_DEBUG:
773 dev_info(disk_to_dev(nbd->disk),
774 "next = %p, prev = %p, head = %p\n",
775 nbd->queue_head.next, nbd->queue_head.prev,
782 static int nbd_ioctl(struct block_device *bdev, fmode_t mode,
783 unsigned int cmd, unsigned long arg)
785 struct nbd_device *nbd = bdev->bd_disk->private_data;
788 if (!capable(CAP_SYS_ADMIN))
791 BUG_ON(nbd->magic != NBD_MAGIC);
793 /* Anyone capable of this syscall can do *real bad* things */
794 dprintk(DBG_IOCTL, "%s: nbd_ioctl cmd=%s(0x%x) arg=%lu\n",
795 nbd->disk->disk_name, ioctl_cmd_to_ascii(cmd), cmd, arg);
797 mutex_lock(&nbd->tx_lock);
798 error = __nbd_ioctl(bdev, nbd, cmd, arg);
799 mutex_unlock(&nbd->tx_lock);
804 static const struct block_device_operations nbd_fops =
806 .owner = THIS_MODULE,
811 * And here should be modules and kernel interface
812 * (Just smiley confuses emacs :-)
815 static int __init nbd_init(void)
821 BUILD_BUG_ON(sizeof(struct nbd_request) != 28);
824 printk(KERN_ERR "nbd: max_part must be >= 0\n");
830 part_shift = fls(max_part);
833 * Adjust max_part according to part_shift as it is exported
834 * to user space so that user can know the max number of
835 * partition kernel should be able to manage.
837 * Note that -1 is required because partition 0 is reserved
838 * for the whole disk.
840 max_part = (1UL << part_shift) - 1;
843 if ((1UL << part_shift) > DISK_MAX_PARTS)
846 if (nbds_max > 1UL << (MINORBITS - part_shift))
849 nbd_dev = kcalloc(nbds_max, sizeof(*nbd_dev), GFP_KERNEL);
853 for (i = 0; i < nbds_max; i++) {
854 struct gendisk *disk = alloc_disk(1 << part_shift);
857 nbd_dev[i].disk = disk;
859 * The new linux 2.5 block layer implementation requires
860 * every gendisk to have its very own request_queue struct.
861 * These structs are big so we dynamically allocate them.
863 disk->queue = blk_init_queue(do_nbd_request, &nbd_lock);
869 * Tell the block layer that we are not a rotational device
871 queue_flag_set_unlocked(QUEUE_FLAG_NONROT, disk->queue);
872 queue_flag_clear_unlocked(QUEUE_FLAG_ADD_RANDOM, disk->queue);
873 disk->queue->limits.discard_granularity = 512;
874 disk->queue->limits.max_discard_sectors = UINT_MAX;
875 disk->queue->limits.discard_zeroes_data = 0;
876 blk_queue_max_hw_sectors(disk->queue, 65536);
877 disk->queue->limits.max_sectors = 256;
880 if (register_blkdev(NBD_MAJOR, "nbd")) {
885 printk(KERN_INFO "nbd: registered device at major %d\n", NBD_MAJOR);
886 dprintk(DBG_INIT, "nbd: debugflags=0x%x\n", debugflags);
888 for (i = 0; i < nbds_max; i++) {
889 struct gendisk *disk = nbd_dev[i].disk;
890 nbd_dev[i].magic = NBD_MAGIC;
891 INIT_LIST_HEAD(&nbd_dev[i].waiting_queue);
892 spin_lock_init(&nbd_dev[i].queue_lock);
893 INIT_LIST_HEAD(&nbd_dev[i].queue_head);
894 mutex_init(&nbd_dev[i].tx_lock);
895 init_waitqueue_head(&nbd_dev[i].active_wq);
896 init_waitqueue_head(&nbd_dev[i].waiting_wq);
897 nbd_dev[i].blksize = 1024;
898 nbd_dev[i].bytesize = 0;
899 disk->major = NBD_MAJOR;
900 disk->first_minor = i << part_shift;
901 disk->fops = &nbd_fops;
902 disk->private_data = &nbd_dev[i];
903 sprintf(disk->disk_name, "nbd%d", i);
904 set_capacity(disk, 0);
911 blk_cleanup_queue(nbd_dev[i].disk->queue);
912 put_disk(nbd_dev[i].disk);
918 static void __exit nbd_cleanup(void)
921 for (i = 0; i < nbds_max; i++) {
922 struct gendisk *disk = nbd_dev[i].disk;
923 nbd_dev[i].magic = 0;
926 blk_cleanup_queue(disk->queue);
930 unregister_blkdev(NBD_MAJOR, "nbd");
932 printk(KERN_INFO "nbd: unregistered device at major %d\n", NBD_MAJOR);
935 module_init(nbd_init);
936 module_exit(nbd_cleanup);
938 MODULE_DESCRIPTION("Network Block Device");
939 MODULE_LICENSE("GPL");
941 module_param(nbds_max, int, 0444);
942 MODULE_PARM_DESC(nbds_max, "number of network block devices to initialize (default: 16)");
943 module_param(max_part, int, 0444);
944 MODULE_PARM_DESC(max_part, "number of partitions per device (default: 0)");
946 module_param(debugflags, int, 0644);
947 MODULE_PARM_DESC(debugflags, "flags for controlling debug output");