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