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