Introduce rq_for_each_segment replacing rq_for_each_bio
[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         struct request_queue *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, 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 req_iterator iter;
209                 struct bio_vec *bvec;
210                 /*
211                  * we are really probing at internals to determine
212                  * whether to set MSG_MORE or not...
213                  */
214                 rq_for_each_segment(bvec, req, iter) {
215                                 flags = 0;
216                                 if (!rq_iter_last(req, iter))
217                                         flags = MSG_MORE;
218                                 dprintk(DBG_TX, "%s: request %p: sending %d bytes data\n",
219                                                 lo->disk->disk_name, req,
220                                                 bvec->bv_len);
221                                 result = sock_send_bvec(sock, bvec, flags);
222                                 if (result <= 0) {
223                                         printk(KERN_ERR "%s: Send data failed (result %d)\n",
224                                                         lo->disk->disk_name,
225                                                         result);
226                                         goto error_out;
227                                 }
228                 }
229         }
230         return 0;
231
232 error_out:
233         return 1;
234 }
235
236 static struct request *nbd_find_request(struct nbd_device *lo, char *handle)
237 {
238         struct request *req;
239         struct list_head *tmp;
240         struct request *xreq;
241         int err;
242
243         memcpy(&xreq, handle, sizeof(xreq));
244
245         err = wait_event_interruptible(lo->active_wq, lo->active_req != xreq);
246         if (unlikely(err))
247                 goto out;
248
249         spin_lock(&lo->queue_lock);
250         list_for_each(tmp, &lo->queue_head) {
251                 req = list_entry(tmp, struct request, queuelist);
252                 if (req != xreq)
253                         continue;
254                 list_del_init(&req->queuelist);
255                 spin_unlock(&lo->queue_lock);
256                 return req;
257         }
258         spin_unlock(&lo->queue_lock);
259
260         err = -ENOENT;
261
262 out:
263         return ERR_PTR(err);
264 }
265
266 static inline int sock_recv_bvec(struct socket *sock, struct bio_vec *bvec)
267 {
268         int result;
269         void *kaddr = kmap(bvec->bv_page);
270         result = sock_xmit(sock, 0, kaddr + bvec->bv_offset, bvec->bv_len,
271                         MSG_WAITALL);
272         kunmap(bvec->bv_page);
273         return result;
274 }
275
276 /* NULL returned = something went wrong, inform userspace */
277 static struct request *nbd_read_stat(struct nbd_device *lo)
278 {
279         int result;
280         struct nbd_reply reply;
281         struct request *req;
282         struct socket *sock = lo->sock;
283
284         reply.magic = 0;
285         result = sock_xmit(sock, 0, &reply, sizeof(reply), MSG_WAITALL);
286         if (result <= 0) {
287                 printk(KERN_ERR "%s: Receive control failed (result %d)\n",
288                                 lo->disk->disk_name, result);
289                 goto harderror;
290         }
291
292         if (ntohl(reply.magic) != NBD_REPLY_MAGIC) {
293                 printk(KERN_ERR "%s: Wrong magic (0x%lx)\n",
294                                 lo->disk->disk_name,
295                                 (unsigned long)ntohl(reply.magic));
296                 result = -EPROTO;
297                 goto harderror;
298         }
299
300         req = nbd_find_request(lo, reply.handle);
301         if (unlikely(IS_ERR(req))) {
302                 result = PTR_ERR(req);
303                 if (result != -ENOENT)
304                         goto harderror;
305
306                 printk(KERN_ERR "%s: Unexpected reply (%p)\n",
307                                 lo->disk->disk_name, reply.handle);
308                 result = -EBADR;
309                 goto harderror;
310         }
311
312         if (ntohl(reply.error)) {
313                 printk(KERN_ERR "%s: Other side returned error (%d)\n",
314                                 lo->disk->disk_name, ntohl(reply.error));
315                 req->errors++;
316                 return req;
317         }
318
319         dprintk(DBG_RX, "%s: request %p: got reply\n",
320                         lo->disk->disk_name, req);
321         if (nbd_cmd(req) == NBD_CMD_READ) {
322                 struct req_iterator iter;
323                 struct bio_vec *bvec;
324
325                 rq_for_each_segment(bvec, req, iter) {
326                                 result = sock_recv_bvec(sock, bvec);
327                                 if (result <= 0) {
328                                         printk(KERN_ERR "%s: Receive data failed (result %d)\n",
329                                                         lo->disk->disk_name,
330                                                         result);
331                                         req->errors++;
332                                         return req;
333                                 }
334                                 dprintk(DBG_RX, "%s: request %p: got %d bytes data\n",
335                                         lo->disk->disk_name, req, bvec->bv_len);
336                 }
337         }
338         return req;
339 harderror:
340         lo->harderror = result;
341         return NULL;
342 }
343
344 static ssize_t pid_show(struct gendisk *disk, char *page)
345 {
346         return sprintf(page, "%ld\n",
347                 (long) ((struct nbd_device *)disk->private_data)->pid);
348 }
349
350 static struct disk_attribute pid_attr = {
351         .attr = { .name = "pid", .mode = S_IRUGO },
352         .show = pid_show,
353 };
354
355 static int nbd_do_it(struct nbd_device *lo)
356 {
357         struct request *req;
358         int ret;
359
360         BUG_ON(lo->magic != LO_MAGIC);
361
362         lo->pid = current->pid;
363         ret = sysfs_create_file(&lo->disk->kobj, &pid_attr.attr);
364         if (ret) {
365                 printk(KERN_ERR "nbd: sysfs_create_file failed!");
366                 return ret;
367         }
368
369         while ((req = nbd_read_stat(lo)) != NULL)
370                 nbd_end_request(req);
371
372         sysfs_remove_file(&lo->disk->kobj, &pid_attr.attr);
373         return 0;
374 }
375
376 static void nbd_clear_que(struct nbd_device *lo)
377 {
378         struct request *req;
379
380         BUG_ON(lo->magic != LO_MAGIC);
381
382         /*
383          * Because we have set lo->sock to NULL under the tx_lock, all
384          * modifications to the list must have completed by now.  For
385          * the same reason, the active_req must be NULL.
386          *
387          * As a consequence, we don't need to take the spin lock while
388          * purging the list here.
389          */
390         BUG_ON(lo->sock);
391         BUG_ON(lo->active_req);
392
393         while (!list_empty(&lo->queue_head)) {
394                 req = list_entry(lo->queue_head.next, struct request,
395                                  queuelist);
396                 list_del_init(&req->queuelist);
397                 req->errors++;
398                 nbd_end_request(req);
399         }
400 }
401
402 /*
403  * We always wait for result of write, for now. It would be nice to make it optional
404  * in future
405  * if ((rq_data_dir(req) == WRITE) && (lo->flags & NBD_WRITE_NOCHK))
406  *   { printk( "Warning: Ignoring result!\n"); nbd_end_request( req ); }
407  */
408
409 static void do_nbd_request(struct request_queue * q)
410 {
411         struct request *req;
412         
413         while ((req = elv_next_request(q)) != NULL) {
414                 struct nbd_device *lo;
415
416                 blkdev_dequeue_request(req);
417                 dprintk(DBG_BLKDEV, "%s: request %p: dequeued (flags=%x)\n",
418                                 req->rq_disk->disk_name, req, req->cmd_type);
419
420                 if (!blk_fs_request(req))
421                         goto error_out;
422
423                 lo = req->rq_disk->private_data;
424
425                 BUG_ON(lo->magic != LO_MAGIC);
426
427                 nbd_cmd(req) = NBD_CMD_READ;
428                 if (rq_data_dir(req) == WRITE) {
429                         nbd_cmd(req) = NBD_CMD_WRITE;
430                         if (lo->flags & NBD_READ_ONLY) {
431                                 printk(KERN_ERR "%s: Write on read-only\n",
432                                                 lo->disk->disk_name);
433                                 goto error_out;
434                         }
435                 }
436
437                 req->errors = 0;
438                 spin_unlock_irq(q->queue_lock);
439
440                 mutex_lock(&lo->tx_lock);
441                 if (unlikely(!lo->sock)) {
442                         mutex_unlock(&lo->tx_lock);
443                         printk(KERN_ERR "%s: Attempted send on closed socket\n",
444                                lo->disk->disk_name);
445                         req->errors++;
446                         nbd_end_request(req);
447                         spin_lock_irq(q->queue_lock);
448                         continue;
449                 }
450
451                 lo->active_req = req;
452
453                 if (nbd_send_req(lo, req) != 0) {
454                         printk(KERN_ERR "%s: Request send failed\n",
455                                         lo->disk->disk_name);
456                         req->errors++;
457                         nbd_end_request(req);
458                 } else {
459                         spin_lock(&lo->queue_lock);
460                         list_add(&req->queuelist, &lo->queue_head);
461                         spin_unlock(&lo->queue_lock);
462                 }
463
464                 lo->active_req = NULL;
465                 mutex_unlock(&lo->tx_lock);
466                 wake_up_all(&lo->active_wq);
467
468                 spin_lock_irq(q->queue_lock);
469                 continue;
470
471 error_out:
472                 req->errors++;
473                 spin_unlock(q->queue_lock);
474                 nbd_end_request(req);
475                 spin_lock(q->queue_lock);
476         }
477         return;
478 }
479
480 static int nbd_ioctl(struct inode *inode, struct file *file,
481                      unsigned int cmd, unsigned long arg)
482 {
483         struct nbd_device *lo = inode->i_bdev->bd_disk->private_data;
484         int error;
485         struct request sreq ;
486
487         if (!capable(CAP_SYS_ADMIN))
488                 return -EPERM;
489
490         BUG_ON(lo->magic != LO_MAGIC);
491
492         /* Anyone capable of this syscall can do *real bad* things */
493         dprintk(DBG_IOCTL, "%s: nbd_ioctl cmd=%s(0x%x) arg=%lu\n",
494                         lo->disk->disk_name, ioctl_cmd_to_ascii(cmd), cmd, arg);
495
496         switch (cmd) {
497         case NBD_DISCONNECT:
498                 printk(KERN_INFO "%s: NBD_DISCONNECT\n", lo->disk->disk_name);
499                 sreq.cmd_type = REQ_TYPE_SPECIAL;
500                 nbd_cmd(&sreq) = NBD_CMD_DISC;
501                 /*
502                  * Set these to sane values in case server implementation
503                  * fails to check the request type first and also to keep
504                  * debugging output cleaner.
505                  */
506                 sreq.sector = 0;
507                 sreq.nr_sectors = 0;
508                 if (!lo->sock)
509                         return -EINVAL;
510                 nbd_send_req(lo, &sreq);
511                 return 0;
512  
513         case NBD_CLEAR_SOCK:
514                 error = 0;
515                 mutex_lock(&lo->tx_lock);
516                 lo->sock = NULL;
517                 mutex_unlock(&lo->tx_lock);
518                 file = lo->file;
519                 lo->file = NULL;
520                 nbd_clear_que(lo);
521                 BUG_ON(!list_empty(&lo->queue_head));
522                 if (file)
523                         fput(file);
524                 return error;
525         case NBD_SET_SOCK:
526                 if (lo->file)
527                         return -EBUSY;
528                 error = -EINVAL;
529                 file = fget(arg);
530                 if (file) {
531                         inode = file->f_path.dentry->d_inode;
532                         if (S_ISSOCK(inode->i_mode)) {
533                                 lo->file = file;
534                                 lo->sock = SOCKET_I(inode);
535                                 error = 0;
536                         } else {
537                                 fput(file);
538                         }
539                 }
540                 return error;
541         case NBD_SET_BLKSIZE:
542                 lo->blksize = arg;
543                 lo->bytesize &= ~(lo->blksize-1);
544                 inode->i_bdev->bd_inode->i_size = lo->bytesize;
545                 set_blocksize(inode->i_bdev, lo->blksize);
546                 set_capacity(lo->disk, lo->bytesize >> 9);
547                 return 0;
548         case NBD_SET_SIZE:
549                 lo->bytesize = arg & ~(lo->blksize-1);
550                 inode->i_bdev->bd_inode->i_size = lo->bytesize;
551                 set_blocksize(inode->i_bdev, lo->blksize);
552                 set_capacity(lo->disk, lo->bytesize >> 9);
553                 return 0;
554         case NBD_SET_SIZE_BLOCKS:
555                 lo->bytesize = ((u64) arg) * lo->blksize;
556                 inode->i_bdev->bd_inode->i_size = lo->bytesize;
557                 set_blocksize(inode->i_bdev, lo->blksize);
558                 set_capacity(lo->disk, lo->bytesize >> 9);
559                 return 0;
560         case NBD_DO_IT:
561                 if (!lo->file)
562                         return -EINVAL;
563                 error = nbd_do_it(lo);
564                 if (error)
565                         return error;
566                 /* on return tidy up in case we have a signal */
567                 /* Forcibly shutdown the socket causing all listeners
568                  * to error
569                  *
570                  * FIXME: This code is duplicated from sys_shutdown, but
571                  * there should be a more generic interface rather than
572                  * calling socket ops directly here */
573                 mutex_lock(&lo->tx_lock);
574                 if (lo->sock) {
575                         printk(KERN_WARNING "%s: shutting down socket\n",
576                                 lo->disk->disk_name);
577                         lo->sock->ops->shutdown(lo->sock,
578                                 SEND_SHUTDOWN|RCV_SHUTDOWN);
579                         lo->sock = NULL;
580                 }
581                 mutex_unlock(&lo->tx_lock);
582                 file = lo->file;
583                 lo->file = NULL;
584                 nbd_clear_que(lo);
585                 printk(KERN_WARNING "%s: queue cleared\n", lo->disk->disk_name);
586                 if (file)
587                         fput(file);
588                 return lo->harderror;
589         case NBD_CLEAR_QUE:
590                 /*
591                  * This is for compatibility only.  The queue is always cleared
592                  * by NBD_DO_IT or NBD_CLEAR_SOCK.
593                  */
594                 BUG_ON(!lo->sock && !list_empty(&lo->queue_head));
595                 return 0;
596         case NBD_PRINT_DEBUG:
597                 printk(KERN_INFO "%s: next = %p, prev = %p, head = %p\n",
598                         inode->i_bdev->bd_disk->disk_name,
599                         lo->queue_head.next, lo->queue_head.prev,
600                         &lo->queue_head);
601                 return 0;
602         }
603         return -EINVAL;
604 }
605
606 static struct block_device_operations nbd_fops =
607 {
608         .owner =        THIS_MODULE,
609         .ioctl =        nbd_ioctl,
610 };
611
612 /*
613  * And here should be modules and kernel interface 
614  *  (Just smiley confuses emacs :-)
615  */
616
617 static int __init nbd_init(void)
618 {
619         int err = -ENOMEM;
620         int i;
621
622         BUILD_BUG_ON(sizeof(struct nbd_request) != 28);
623
624         if (nbds_max > MAX_NBD) {
625                 printk(KERN_CRIT "nbd: cannot allocate more than %u nbds; %u requested.\n", MAX_NBD,
626                                 nbds_max);
627                 return -EINVAL;
628         }
629
630         for (i = 0; i < nbds_max; i++) {
631                 struct gendisk *disk = alloc_disk(1);
632                 if (!disk)
633                         goto out;
634                 nbd_dev[i].disk = disk;
635                 /*
636                  * The new linux 2.5 block layer implementation requires
637                  * every gendisk to have its very own request_queue struct.
638                  * These structs are big so we dynamically allocate them.
639                  */
640                 disk->queue = blk_init_queue(do_nbd_request, &nbd_lock);
641                 if (!disk->queue) {
642                         put_disk(disk);
643                         goto out;
644                 }
645         }
646
647         if (register_blkdev(NBD_MAJOR, "nbd")) {
648                 err = -EIO;
649                 goto out;
650         }
651
652         printk(KERN_INFO "nbd: registered device at major %d\n", NBD_MAJOR);
653         dprintk(DBG_INIT, "nbd: debugflags=0x%x\n", debugflags);
654
655         for (i = 0; i < nbds_max; i++) {
656                 struct gendisk *disk = nbd_dev[i].disk;
657                 nbd_dev[i].file = NULL;
658                 nbd_dev[i].magic = LO_MAGIC;
659                 nbd_dev[i].flags = 0;
660                 spin_lock_init(&nbd_dev[i].queue_lock);
661                 INIT_LIST_HEAD(&nbd_dev[i].queue_head);
662                 mutex_init(&nbd_dev[i].tx_lock);
663                 init_waitqueue_head(&nbd_dev[i].active_wq);
664                 nbd_dev[i].blksize = 1024;
665                 nbd_dev[i].bytesize = 0x7ffffc00ULL << 10; /* 2TB */
666                 disk->major = NBD_MAJOR;
667                 disk->first_minor = i;
668                 disk->fops = &nbd_fops;
669                 disk->private_data = &nbd_dev[i];
670                 disk->flags |= GENHD_FL_SUPPRESS_PARTITION_INFO;
671                 sprintf(disk->disk_name, "nbd%d", i);
672                 set_capacity(disk, 0x7ffffc00ULL << 1); /* 2 TB */
673                 add_disk(disk);
674         }
675
676         return 0;
677 out:
678         while (i--) {
679                 blk_cleanup_queue(nbd_dev[i].disk->queue);
680                 put_disk(nbd_dev[i].disk);
681         }
682         return err;
683 }
684
685 static void __exit nbd_cleanup(void)
686 {
687         int i;
688         for (i = 0; i < nbds_max; i++) {
689                 struct gendisk *disk = nbd_dev[i].disk;
690                 nbd_dev[i].magic = 0;
691                 if (disk) {
692                         del_gendisk(disk);
693                         blk_cleanup_queue(disk->queue);
694                         put_disk(disk);
695                 }
696         }
697         unregister_blkdev(NBD_MAJOR, "nbd");
698         printk(KERN_INFO "nbd: unregistered device at major %d\n", NBD_MAJOR);
699 }
700
701 module_init(nbd_init);
702 module_exit(nbd_cleanup);
703
704 MODULE_DESCRIPTION("Network Block Device");
705 MODULE_LICENSE("GPL");
706
707 module_param(nbds_max, int, 0444);
708 MODULE_PARM_DESC(nbds_max, "How many network block devices to initialize.");
709 #ifndef NDEBUG
710 module_param(debugflags, int, 0644);
711 MODULE_PARM_DESC(debugflags, "flags for controlling debug output");
712 #endif