[PATCH] struct path: convert nbd
[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         unsigned long flags;
126         sigset_t oldset;
127
128         /* Allow interception of SIGKILL only
129          * Don't allow other signals to interrupt the transmission */
130         spin_lock_irqsave(&current->sighand->siglock, flags);
131         oldset = current->blocked;
132         sigfillset(&current->blocked);
133         sigdelsetmask(&current->blocked, sigmask(SIGKILL));
134         recalc_sigpending();
135         spin_unlock_irqrestore(&current->sighand->siglock, flags);
136
137         do {
138                 sock->sk->sk_allocation = GFP_NOIO;
139                 iov.iov_base = buf;
140                 iov.iov_len = size;
141                 msg.msg_name = NULL;
142                 msg.msg_namelen = 0;
143                 msg.msg_control = NULL;
144                 msg.msg_controllen = 0;
145                 msg.msg_flags = msg_flags | MSG_NOSIGNAL;
146
147                 if (send)
148                         result = kernel_sendmsg(sock, &msg, &iov, 1, size);
149                 else
150                         result = kernel_recvmsg(sock, &msg, &iov, 1, size, 0);
151
152                 if (signal_pending(current)) {
153                         siginfo_t info;
154                         spin_lock_irqsave(&current->sighand->siglock, flags);
155                         printk(KERN_WARNING "nbd (pid %d: %s) got signal %d\n",
156                                 current->pid, current->comm, 
157                                 dequeue_signal(current, &current->blocked, &info));
158                         spin_unlock_irqrestore(&current->sighand->siglock, flags);
159                         result = -EINTR;
160                         break;
161                 }
162
163                 if (result <= 0) {
164                         if (result == 0)
165                                 result = -EPIPE; /* short read */
166                         break;
167                 }
168                 size -= result;
169                 buf += result;
170         } while (size > 0);
171
172         spin_lock_irqsave(&current->sighand->siglock, flags);
173         current->blocked = oldset;
174         recalc_sigpending();
175         spin_unlock_irqrestore(&current->sighand->siglock, flags);
176
177         return result;
178 }
179
180 static inline int sock_send_bvec(struct socket *sock, struct bio_vec *bvec,
181                 int flags)
182 {
183         int result;
184         void *kaddr = kmap(bvec->bv_page);
185         result = sock_xmit(sock, 1, kaddr + bvec->bv_offset, bvec->bv_len,
186                         flags);
187         kunmap(bvec->bv_page);
188         return result;
189 }
190
191 static int nbd_send_req(struct nbd_device *lo, struct request *req)
192 {
193         int result, i, flags;
194         struct nbd_request request;
195         unsigned long size = req->nr_sectors << 9;
196         struct socket *sock = lo->sock;
197
198         request.magic = htonl(NBD_REQUEST_MAGIC);
199         request.type = htonl(nbd_cmd(req));
200         request.from = cpu_to_be64((u64) req->sector << 9);
201         request.len = htonl(size);
202         memcpy(request.handle, &req, sizeof(req));
203
204         dprintk(DBG_TX, "%s: request %p: sending control (%s@%llu,%luB)\n",
205                         lo->disk->disk_name, req,
206                         nbdcmd_to_ascii(nbd_cmd(req)),
207                         (unsigned long long)req->sector << 9,
208                         req->nr_sectors << 9);
209         result = sock_xmit(sock, 1, &request, sizeof(request),
210                         (nbd_cmd(req) == NBD_CMD_WRITE)? MSG_MORE: 0);
211         if (result <= 0) {
212                 printk(KERN_ERR "%s: Send control failed (result %d)\n",
213                                 lo->disk->disk_name, result);
214                 goto error_out;
215         }
216
217         if (nbd_cmd(req) == NBD_CMD_WRITE) {
218                 struct bio *bio;
219                 /*
220                  * we are really probing at internals to determine
221                  * whether to set MSG_MORE or not...
222                  */
223                 rq_for_each_bio(bio, req) {
224                         struct bio_vec *bvec;
225                         bio_for_each_segment(bvec, bio, i) {
226                                 flags = 0;
227                                 if ((i < (bio->bi_vcnt - 1)) || bio->bi_next)
228                                         flags = MSG_MORE;
229                                 dprintk(DBG_TX, "%s: request %p: sending %d bytes data\n",
230                                                 lo->disk->disk_name, req,
231                                                 bvec->bv_len);
232                                 result = sock_send_bvec(sock, bvec, flags);
233                                 if (result <= 0) {
234                                         printk(KERN_ERR "%s: Send data failed (result %d)\n",
235                                                         lo->disk->disk_name,
236                                                         result);
237                                         goto error_out;
238                                 }
239                         }
240                 }
241         }
242         return 0;
243
244 error_out:
245         return 1;
246 }
247
248 static struct request *nbd_find_request(struct nbd_device *lo, char *handle)
249 {
250         struct request *req;
251         struct list_head *tmp;
252         struct request *xreq;
253         int err;
254
255         memcpy(&xreq, handle, sizeof(xreq));
256
257         err = wait_event_interruptible(lo->active_wq, lo->active_req != xreq);
258         if (unlikely(err))
259                 goto out;
260
261         spin_lock(&lo->queue_lock);
262         list_for_each(tmp, &lo->queue_head) {
263                 req = list_entry(tmp, struct request, queuelist);
264                 if (req != xreq)
265                         continue;
266                 list_del_init(&req->queuelist);
267                 spin_unlock(&lo->queue_lock);
268                 return req;
269         }
270         spin_unlock(&lo->queue_lock);
271
272         err = -ENOENT;
273
274 out:
275         return ERR_PTR(err);
276 }
277
278 static inline int sock_recv_bvec(struct socket *sock, struct bio_vec *bvec)
279 {
280         int result;
281         void *kaddr = kmap(bvec->bv_page);
282         result = sock_xmit(sock, 0, kaddr + bvec->bv_offset, bvec->bv_len,
283                         MSG_WAITALL);
284         kunmap(bvec->bv_page);
285         return result;
286 }
287
288 /* NULL returned = something went wrong, inform userspace */
289 static struct request *nbd_read_stat(struct nbd_device *lo)
290 {
291         int result;
292         struct nbd_reply reply;
293         struct request *req;
294         struct socket *sock = lo->sock;
295
296         reply.magic = 0;
297         result = sock_xmit(sock, 0, &reply, sizeof(reply), MSG_WAITALL);
298         if (result <= 0) {
299                 printk(KERN_ERR "%s: Receive control failed (result %d)\n",
300                                 lo->disk->disk_name, result);
301                 goto harderror;
302         }
303
304         if (ntohl(reply.magic) != NBD_REPLY_MAGIC) {
305                 printk(KERN_ERR "%s: Wrong magic (0x%lx)\n",
306                                 lo->disk->disk_name,
307                                 (unsigned long)ntohl(reply.magic));
308                 result = -EPROTO;
309                 goto harderror;
310         }
311
312         req = nbd_find_request(lo, reply.handle);
313         if (unlikely(IS_ERR(req))) {
314                 result = PTR_ERR(req);
315                 if (result != -ENOENT)
316                         goto harderror;
317
318                 printk(KERN_ERR "%s: Unexpected reply (%p)\n",
319                                 lo->disk->disk_name, reply.handle);
320                 result = -EBADR;
321                 goto harderror;
322         }
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                                         req->errors++;
345                                         return req;
346                                 }
347                                 dprintk(DBG_RX, "%s: request %p: got %d bytes data\n",
348                                         lo->disk->disk_name, req, bvec->bv_len);
349                         }
350                 }
351         }
352         return req;
353 harderror:
354         lo->harderror = result;
355         return NULL;
356 }
357
358 static ssize_t pid_show(struct gendisk *disk, char *page)
359 {
360         return sprintf(page, "%ld\n",
361                 (long) ((struct nbd_device *)disk->private_data)->pid);
362 }
363
364 static struct disk_attribute pid_attr = {
365         .attr = { .name = "pid", .mode = S_IRUGO },
366         .show = pid_show,
367 };
368
369 static void nbd_do_it(struct nbd_device *lo)
370 {
371         struct request *req;
372
373         BUG_ON(lo->magic != LO_MAGIC);
374
375         lo->pid = current->pid;
376         sysfs_create_file(&lo->disk->kobj, &pid_attr.attr);
377
378         while ((req = nbd_read_stat(lo)) != NULL)
379                 nbd_end_request(req);
380
381         sysfs_remove_file(&lo->disk->kobj, &pid_attr.attr);
382         return;
383 }
384
385 static void nbd_clear_que(struct nbd_device *lo)
386 {
387         struct request *req;
388
389         BUG_ON(lo->magic != LO_MAGIC);
390
391         /*
392          * Because we have set lo->sock to NULL under the tx_lock, all
393          * modifications to the list must have completed by now.  For
394          * the same reason, the active_req must be NULL.
395          *
396          * As a consequence, we don't need to take the spin lock while
397          * purging the list here.
398          */
399         BUG_ON(lo->sock);
400         BUG_ON(lo->active_req);
401
402         while (!list_empty(&lo->queue_head)) {
403                 req = list_entry(lo->queue_head.next, struct request,
404                                  queuelist);
405                 list_del_init(&req->queuelist);
406                 req->errors++;
407                 nbd_end_request(req);
408         }
409 }
410
411 /*
412  * We always wait for result of write, for now. It would be nice to make it optional
413  * in future
414  * if ((req->cmd == WRITE) && (lo->flags & NBD_WRITE_NOCHK)) 
415  *   { printk( "Warning: Ignoring result!\n"); nbd_end_request( req ); }
416  */
417
418 static void do_nbd_request(request_queue_t * q)
419 {
420         struct request *req;
421         
422         while ((req = elv_next_request(q)) != NULL) {
423                 struct nbd_device *lo;
424
425                 blkdev_dequeue_request(req);
426                 dprintk(DBG_BLKDEV, "%s: request %p: dequeued (flags=%x)\n",
427                                 req->rq_disk->disk_name, req, req->cmd_type);
428
429                 if (!blk_fs_request(req))
430                         goto error_out;
431
432                 lo = req->rq_disk->private_data;
433
434                 BUG_ON(lo->magic != LO_MAGIC);
435
436                 nbd_cmd(req) = NBD_CMD_READ;
437                 if (rq_data_dir(req) == WRITE) {
438                         nbd_cmd(req) = NBD_CMD_WRITE;
439                         if (lo->flags & NBD_READ_ONLY) {
440                                 printk(KERN_ERR "%s: Write on read-only\n",
441                                                 lo->disk->disk_name);
442                                 goto error_out;
443                         }
444                 }
445
446                 req->errors = 0;
447                 spin_unlock_irq(q->queue_lock);
448
449                 mutex_lock(&lo->tx_lock);
450                 if (unlikely(!lo->sock)) {
451                         mutex_unlock(&lo->tx_lock);
452                         printk(KERN_ERR "%s: Attempted send on closed socket\n",
453                                lo->disk->disk_name);
454                         req->errors++;
455                         nbd_end_request(req);
456                         spin_lock_irq(q->queue_lock);
457                         continue;
458                 }
459
460                 lo->active_req = req;
461
462                 if (nbd_send_req(lo, req) != 0) {
463                         printk(KERN_ERR "%s: Request send failed\n",
464                                         lo->disk->disk_name);
465                         req->errors++;
466                         nbd_end_request(req);
467                 } else {
468                         spin_lock(&lo->queue_lock);
469                         list_add(&req->queuelist, &lo->queue_head);
470                         spin_unlock(&lo->queue_lock);
471                 }
472
473                 lo->active_req = NULL;
474                 mutex_unlock(&lo->tx_lock);
475                 wake_up_all(&lo->active_wq);
476
477                 spin_lock_irq(q->queue_lock);
478                 continue;
479
480 error_out:
481                 req->errors++;
482                 spin_unlock(q->queue_lock);
483                 nbd_end_request(req);
484                 spin_lock(q->queue_lock);
485         }
486         return;
487 }
488
489 static int nbd_ioctl(struct inode *inode, struct file *file,
490                      unsigned int cmd, unsigned long arg)
491 {
492         struct nbd_device *lo = inode->i_bdev->bd_disk->private_data;
493         int error;
494         struct request sreq ;
495
496         if (!capable(CAP_SYS_ADMIN))
497                 return -EPERM;
498
499         BUG_ON(lo->magic != LO_MAGIC);
500
501         /* Anyone capable of this syscall can do *real bad* things */
502         dprintk(DBG_IOCTL, "%s: nbd_ioctl cmd=%s(0x%x) arg=%lu\n",
503                         lo->disk->disk_name, ioctl_cmd_to_ascii(cmd), cmd, arg);
504
505         switch (cmd) {
506         case NBD_DISCONNECT:
507                 printk(KERN_INFO "%s: NBD_DISCONNECT\n", lo->disk->disk_name);
508                 sreq.cmd_type = REQ_TYPE_SPECIAL;
509                 nbd_cmd(&sreq) = NBD_CMD_DISC;
510                 /*
511                  * Set these to sane values in case server implementation
512                  * fails to check the request type first and also to keep
513                  * debugging output cleaner.
514                  */
515                 sreq.sector = 0;
516                 sreq.nr_sectors = 0;
517                 if (!lo->sock)
518                         return -EINVAL;
519                 nbd_send_req(lo, &sreq);
520                 return 0;
521  
522         case NBD_CLEAR_SOCK:
523                 error = 0;
524                 mutex_lock(&lo->tx_lock);
525                 lo->sock = NULL;
526                 mutex_unlock(&lo->tx_lock);
527                 file = lo->file;
528                 lo->file = NULL;
529                 nbd_clear_que(lo);
530                 BUG_ON(!list_empty(&lo->queue_head));
531                 if (file)
532                         fput(file);
533                 return error;
534         case NBD_SET_SOCK:
535                 if (lo->file)
536                         return -EBUSY;
537                 error = -EINVAL;
538                 file = fget(arg);
539                 if (file) {
540                         inode = file->f_path.dentry->d_inode;
541                         if (S_ISSOCK(inode->i_mode)) {
542                                 lo->file = file;
543                                 lo->sock = SOCKET_I(inode);
544                                 error = 0;
545                         } else {
546                                 fput(file);
547                         }
548                 }
549                 return error;
550         case NBD_SET_BLKSIZE:
551                 lo->blksize = arg;
552                 lo->bytesize &= ~(lo->blksize-1);
553                 inode->i_bdev->bd_inode->i_size = lo->bytesize;
554                 set_blocksize(inode->i_bdev, lo->blksize);
555                 set_capacity(lo->disk, lo->bytesize >> 9);
556                 return 0;
557         case NBD_SET_SIZE:
558                 lo->bytesize = arg & ~(lo->blksize-1);
559                 inode->i_bdev->bd_inode->i_size = lo->bytesize;
560                 set_blocksize(inode->i_bdev, lo->blksize);
561                 set_capacity(lo->disk, lo->bytesize >> 9);
562                 return 0;
563         case NBD_SET_SIZE_BLOCKS:
564                 lo->bytesize = ((u64) arg) * lo->blksize;
565                 inode->i_bdev->bd_inode->i_size = lo->bytesize;
566                 set_blocksize(inode->i_bdev, lo->blksize);
567                 set_capacity(lo->disk, lo->bytesize >> 9);
568                 return 0;
569         case NBD_DO_IT:
570                 if (!lo->file)
571                         return -EINVAL;
572                 nbd_do_it(lo);
573                 /* on return tidy up in case we have a signal */
574                 /* Forcibly shutdown the socket causing all listeners
575                  * to error
576                  *
577                  * FIXME: This code is duplicated from sys_shutdown, but
578                  * there should be a more generic interface rather than
579                  * calling socket ops directly here */
580                 mutex_lock(&lo->tx_lock);
581                 if (lo->sock) {
582                         printk(KERN_WARNING "%s: shutting down socket\n",
583                                 lo->disk->disk_name);
584                         lo->sock->ops->shutdown(lo->sock,
585                                 SEND_SHUTDOWN|RCV_SHUTDOWN);
586                         lo->sock = NULL;
587                 }
588                 mutex_unlock(&lo->tx_lock);
589                 file = lo->file;
590                 lo->file = NULL;
591                 nbd_clear_que(lo);
592                 printk(KERN_WARNING "%s: queue cleared\n", lo->disk->disk_name);
593                 if (file)
594                         fput(file);
595                 return lo->harderror;
596         case NBD_CLEAR_QUE:
597                 /*
598                  * This is for compatibility only.  The queue is always cleared
599                  * by NBD_DO_IT or NBD_CLEAR_SOCK.
600                  */
601                 BUG_ON(!lo->sock && !list_empty(&lo->queue_head));
602                 return 0;
603         case NBD_PRINT_DEBUG:
604                 printk(KERN_INFO "%s: next = %p, prev = %p, head = %p\n",
605                         inode->i_bdev->bd_disk->disk_name,
606                         lo->queue_head.next, lo->queue_head.prev,
607                         &lo->queue_head);
608                 return 0;
609         }
610         return -EINVAL;
611 }
612
613 static struct block_device_operations nbd_fops =
614 {
615         .owner =        THIS_MODULE,
616         .ioctl =        nbd_ioctl,
617 };
618
619 /*
620  * And here should be modules and kernel interface 
621  *  (Just smiley confuses emacs :-)
622  */
623
624 static int __init nbd_init(void)
625 {
626         int err = -ENOMEM;
627         int i;
628
629         BUILD_BUG_ON(sizeof(struct nbd_request) != 28);
630
631         if (nbds_max > MAX_NBD) {
632                 printk(KERN_CRIT "nbd: cannot allocate more than %u nbds; %u requested.\n", MAX_NBD,
633                                 nbds_max);
634                 return -EINVAL;
635         }
636
637         for (i = 0; i < nbds_max; i++) {
638                 struct gendisk *disk = alloc_disk(1);
639                 if (!disk)
640                         goto out;
641                 nbd_dev[i].disk = disk;
642                 /*
643                  * The new linux 2.5 block layer implementation requires
644                  * every gendisk to have its very own request_queue struct.
645                  * These structs are big so we dynamically allocate them.
646                  */
647                 disk->queue = blk_init_queue(do_nbd_request, &nbd_lock);
648                 if (!disk->queue) {
649                         put_disk(disk);
650                         goto out;
651                 }
652         }
653
654         if (register_blkdev(NBD_MAJOR, "nbd")) {
655                 err = -EIO;
656                 goto out;
657         }
658
659         printk(KERN_INFO "nbd: registered device at major %d\n", NBD_MAJOR);
660         dprintk(DBG_INIT, "nbd: debugflags=0x%x\n", debugflags);
661
662         for (i = 0; i < nbds_max; i++) {
663                 struct gendisk *disk = nbd_dev[i].disk;
664                 nbd_dev[i].file = NULL;
665                 nbd_dev[i].magic = LO_MAGIC;
666                 nbd_dev[i].flags = 0;
667                 spin_lock_init(&nbd_dev[i].queue_lock);
668                 INIT_LIST_HEAD(&nbd_dev[i].queue_head);
669                 mutex_init(&nbd_dev[i].tx_lock);
670                 init_waitqueue_head(&nbd_dev[i].active_wq);
671                 nbd_dev[i].blksize = 1024;
672                 nbd_dev[i].bytesize = 0x7ffffc00ULL << 10; /* 2TB */
673                 disk->major = NBD_MAJOR;
674                 disk->first_minor = i;
675                 disk->fops = &nbd_fops;
676                 disk->private_data = &nbd_dev[i];
677                 disk->flags |= GENHD_FL_SUPPRESS_PARTITION_INFO;
678                 sprintf(disk->disk_name, "nbd%d", i);
679                 set_capacity(disk, 0x7ffffc00ULL << 1); /* 2 TB */
680                 add_disk(disk);
681         }
682
683         return 0;
684 out:
685         while (i--) {
686                 blk_cleanup_queue(nbd_dev[i].disk->queue);
687                 put_disk(nbd_dev[i].disk);
688         }
689         return err;
690 }
691
692 static void __exit nbd_cleanup(void)
693 {
694         int i;
695         for (i = 0; i < nbds_max; i++) {
696                 struct gendisk *disk = nbd_dev[i].disk;
697                 nbd_dev[i].magic = 0;
698                 if (disk) {
699                         del_gendisk(disk);
700                         blk_cleanup_queue(disk->queue);
701                         put_disk(disk);
702                 }
703         }
704         unregister_blkdev(NBD_MAJOR, "nbd");
705         printk(KERN_INFO "nbd: unregistered device at major %d\n", NBD_MAJOR);
706 }
707
708 module_init(nbd_init);
709 module_exit(nbd_cleanup);
710
711 MODULE_DESCRIPTION("Network Block Device");
712 MODULE_LICENSE("GPL");
713
714 module_param(nbds_max, int, 0444);
715 MODULE_PARM_DESC(nbds_max, "How many network block devices to initialize.");
716 #ifndef NDEBUG
717 module_param(debugflags, int, 0644);
718 MODULE_PARM_DESC(debugflags, "flags for controlling debug output");
719 #endif