Driver core: convert block from raw kobjects to core devices
[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 #include <linux/net.h>
32
33 #include <asm/uaccess.h>
34 #include <asm/system.h>
35 #include <asm/types.h>
36
37 #include <linux/nbd.h>
38
39 #define LO_MAGIC 0x68797548
40
41 #ifdef NDEBUG
42 #define dprintk(flags, fmt...)
43 #else /* NDEBUG */
44 #define dprintk(flags, fmt...) do { \
45         if (debugflags & (flags)) printk(KERN_DEBUG fmt); \
46 } while (0)
47 #define DBG_IOCTL       0x0004
48 #define DBG_INIT        0x0010
49 #define DBG_EXIT        0x0020
50 #define DBG_BLKDEV      0x0100
51 #define DBG_RX          0x0200
52 #define DBG_TX          0x0400
53 static unsigned int debugflags;
54 #endif /* NDEBUG */
55
56 static unsigned int nbds_max = 16;
57 static struct nbd_device nbd_dev[MAX_NBD];
58
59 /*
60  * Use just one lock (or at most 1 per NIC). Two arguments for this:
61  * 1. Each NIC is essentially a synchronization point for all servers
62  *    accessed through that NIC so there's no need to have more locks
63  *    than NICs anyway.
64  * 2. More locks lead to more "Dirty cache line bouncing" which will slow
65  *    down each lock to the point where they're actually slower than just
66  *    a single lock.
67  * Thanks go to Jens Axboe and Al Viro for their LKML emails explaining this!
68  */
69 static DEFINE_SPINLOCK(nbd_lock);
70
71 #ifndef NDEBUG
72 static const char *ioctl_cmd_to_ascii(int cmd)
73 {
74         switch (cmd) {
75         case NBD_SET_SOCK: return "set-sock";
76         case NBD_SET_BLKSIZE: return "set-blksize";
77         case NBD_SET_SIZE: return "set-size";
78         case NBD_DO_IT: return "do-it";
79         case NBD_CLEAR_SOCK: return "clear-sock";
80         case NBD_CLEAR_QUE: return "clear-que";
81         case NBD_PRINT_DEBUG: return "print-debug";
82         case NBD_SET_SIZE_BLOCKS: return "set-size-blocks";
83         case NBD_DISCONNECT: return "disconnect";
84         case BLKROSET: return "set-read-only";
85         case BLKFLSBUF: return "flush-buffer-cache";
86         }
87         return "unknown";
88 }
89
90 static const char *nbdcmd_to_ascii(int cmd)
91 {
92         switch (cmd) {
93         case  NBD_CMD_READ: return "read";
94         case NBD_CMD_WRITE: return "write";
95         case  NBD_CMD_DISC: return "disconnect";
96         }
97         return "invalid";
98 }
99 #endif /* NDEBUG */
100
101 static void nbd_end_request(struct request *req)
102 {
103         int uptodate = (req->errors == 0) ? 1 : 0;
104         struct request_queue *q = req->q;
105         unsigned long flags;
106
107         dprintk(DBG_BLKDEV, "%s: request %p: %s\n", req->rq_disk->disk_name,
108                         req, uptodate? "done": "failed");
109
110         spin_lock_irqsave(q->queue_lock, flags);
111         if (!end_that_request_first(req, uptodate, req->nr_sectors)) {
112                 end_that_request_last(req, uptodate);
113         }
114         spin_unlock_irqrestore(q->queue_lock, flags);
115 }
116
117 static void sock_shutdown(struct nbd_device *lo, int lock)
118 {
119         /* Forcibly shutdown the socket causing all listeners
120          * to error
121          *
122          * FIXME: This code is duplicated from sys_shutdown, but
123          * there should be a more generic interface rather than
124          * calling socket ops directly here */
125         if (lock)
126                 mutex_lock(&lo->tx_lock);
127         if (lo->sock) {
128                 printk(KERN_WARNING "%s: shutting down socket\n",
129                         lo->disk->disk_name);
130                 kernel_sock_shutdown(lo->sock, SHUT_RDWR);
131                 lo->sock = NULL;
132         }
133         if (lock)
134                 mutex_unlock(&lo->tx_lock);
135 }
136
137 static void nbd_xmit_timeout(unsigned long arg)
138 {
139         struct task_struct *task = (struct task_struct *)arg;
140
141         printk(KERN_WARNING "nbd: killing hung xmit (%s, pid: %d)\n",
142                 task->comm, task->pid);
143         force_sig(SIGKILL, task);
144 }
145
146 /*
147  *  Send or receive packet.
148  */
149 static int sock_xmit(struct nbd_device *lo, int send, void *buf, int size,
150                 int msg_flags)
151 {
152         struct socket *sock = lo->sock;
153         int result;
154         struct msghdr msg;
155         struct kvec iov;
156         sigset_t blocked, oldset;
157
158         /* Allow interception of SIGKILL only
159          * Don't allow other signals to interrupt the transmission */
160         siginitsetinv(&blocked, sigmask(SIGKILL));
161         sigprocmask(SIG_SETMASK, &blocked, &oldset);
162
163         do {
164                 sock->sk->sk_allocation = GFP_NOIO;
165                 iov.iov_base = buf;
166                 iov.iov_len = size;
167                 msg.msg_name = NULL;
168                 msg.msg_namelen = 0;
169                 msg.msg_control = NULL;
170                 msg.msg_controllen = 0;
171                 msg.msg_flags = msg_flags | MSG_NOSIGNAL;
172
173                 if (send) {
174                         struct timer_list ti;
175
176                         if (lo->xmit_timeout) {
177                                 init_timer(&ti);
178                                 ti.function = nbd_xmit_timeout;
179                                 ti.data = (unsigned long)current;
180                                 ti.expires = jiffies + lo->xmit_timeout;
181                                 add_timer(&ti);
182                         }
183                         result = kernel_sendmsg(sock, &msg, &iov, 1, size);
184                         if (lo->xmit_timeout)
185                                 del_timer_sync(&ti);
186                 } else
187                         result = kernel_recvmsg(sock, &msg, &iov, 1, size, 0);
188
189                 if (signal_pending(current)) {
190                         siginfo_t info;
191                         printk(KERN_WARNING "nbd (pid %d: %s) got signal %d\n",
192                                 task_pid_nr(current), current->comm,
193                                 dequeue_signal_lock(current, &current->blocked, &info));
194                         result = -EINTR;
195                         sock_shutdown(lo, !send);
196                         break;
197                 }
198
199                 if (result <= 0) {
200                         if (result == 0)
201                                 result = -EPIPE; /* short read */
202                         break;
203                 }
204                 size -= result;
205                 buf += result;
206         } while (size > 0);
207
208         sigprocmask(SIG_SETMASK, &oldset, NULL);
209
210         return result;
211 }
212
213 static inline int sock_send_bvec(struct nbd_device *lo, struct bio_vec *bvec,
214                 int flags)
215 {
216         int result;
217         void *kaddr = kmap(bvec->bv_page);
218         result = sock_xmit(lo, 1, kaddr + bvec->bv_offset, bvec->bv_len, flags);
219         kunmap(bvec->bv_page);
220         return result;
221 }
222
223 /* always call with the tx_lock held */
224 static int nbd_send_req(struct nbd_device *lo, struct request *req)
225 {
226         int result, flags;
227         struct nbd_request request;
228         unsigned long size = req->nr_sectors << 9;
229
230         request.magic = htonl(NBD_REQUEST_MAGIC);
231         request.type = htonl(nbd_cmd(req));
232         request.from = cpu_to_be64((u64) req->sector << 9);
233         request.len = htonl(size);
234         memcpy(request.handle, &req, sizeof(req));
235
236         dprintk(DBG_TX, "%s: request %p: sending control (%s@%llu,%luB)\n",
237                         lo->disk->disk_name, req,
238                         nbdcmd_to_ascii(nbd_cmd(req)),
239                         (unsigned long long)req->sector << 9,
240                         req->nr_sectors << 9);
241         result = sock_xmit(lo, 1, &request, sizeof(request),
242                         (nbd_cmd(req) == NBD_CMD_WRITE) ? MSG_MORE : 0);
243         if (result <= 0) {
244                 printk(KERN_ERR "%s: Send control failed (result %d)\n",
245                                 lo->disk->disk_name, result);
246                 goto error_out;
247         }
248
249         if (nbd_cmd(req) == NBD_CMD_WRITE) {
250                 struct req_iterator iter;
251                 struct bio_vec *bvec;
252                 /*
253                  * we are really probing at internals to determine
254                  * whether to set MSG_MORE or not...
255                  */
256                 rq_for_each_segment(bvec, req, iter) {
257                         flags = 0;
258                         if (!rq_iter_last(req, iter))
259                                 flags = MSG_MORE;
260                         dprintk(DBG_TX, "%s: request %p: sending %d bytes data\n",
261                                         lo->disk->disk_name, req, bvec->bv_len);
262                         result = sock_send_bvec(lo, bvec, flags);
263                         if (result <= 0) {
264                                 printk(KERN_ERR "%s: Send data failed (result %d)\n",
265                                                 lo->disk->disk_name, result);
266                                 goto error_out;
267                         }
268                 }
269         }
270         return 0;
271
272 error_out:
273         return 1;
274 }
275
276 static struct request *nbd_find_request(struct nbd_device *lo,
277                                         struct request *xreq)
278 {
279         struct request *req, *tmp;
280         int err;
281
282         err = wait_event_interruptible(lo->active_wq, lo->active_req != xreq);
283         if (unlikely(err))
284                 goto out;
285
286         spin_lock(&lo->queue_lock);
287         list_for_each_entry_safe(req, tmp, &lo->queue_head, queuelist) {
288                 if (req != xreq)
289                         continue;
290                 list_del_init(&req->queuelist);
291                 spin_unlock(&lo->queue_lock);
292                 return req;
293         }
294         spin_unlock(&lo->queue_lock);
295
296         err = -ENOENT;
297
298 out:
299         return ERR_PTR(err);
300 }
301
302 static inline int sock_recv_bvec(struct nbd_device *lo, struct bio_vec *bvec)
303 {
304         int result;
305         void *kaddr = kmap(bvec->bv_page);
306         result = sock_xmit(lo, 0, kaddr + bvec->bv_offset, bvec->bv_len,
307                         MSG_WAITALL);
308         kunmap(bvec->bv_page);
309         return result;
310 }
311
312 /* NULL returned = something went wrong, inform userspace */
313 static struct request *nbd_read_stat(struct nbd_device *lo)
314 {
315         int result;
316         struct nbd_reply reply;
317         struct request *req;
318
319         reply.magic = 0;
320         result = sock_xmit(lo, 0, &reply, sizeof(reply), MSG_WAITALL);
321         if (result <= 0) {
322                 printk(KERN_ERR "%s: Receive control failed (result %d)\n",
323                                 lo->disk->disk_name, result);
324                 goto harderror;
325         }
326
327         if (ntohl(reply.magic) != NBD_REPLY_MAGIC) {
328                 printk(KERN_ERR "%s: Wrong magic (0x%lx)\n",
329                                 lo->disk->disk_name,
330                                 (unsigned long)ntohl(reply.magic));
331                 result = -EPROTO;
332                 goto harderror;
333         }
334
335         req = nbd_find_request(lo, *(struct request **)reply.handle);
336         if (unlikely(IS_ERR(req))) {
337                 result = PTR_ERR(req);
338                 if (result != -ENOENT)
339                         goto harderror;
340
341                 printk(KERN_ERR "%s: Unexpected reply (%p)\n",
342                                 lo->disk->disk_name, reply.handle);
343                 result = -EBADR;
344                 goto harderror;
345         }
346
347         if (ntohl(reply.error)) {
348                 printk(KERN_ERR "%s: Other side returned error (%d)\n",
349                                 lo->disk->disk_name, ntohl(reply.error));
350                 req->errors++;
351                 return req;
352         }
353
354         dprintk(DBG_RX, "%s: request %p: got reply\n",
355                         lo->disk->disk_name, req);
356         if (nbd_cmd(req) == NBD_CMD_READ) {
357                 struct req_iterator iter;
358                 struct bio_vec *bvec;
359
360                 rq_for_each_segment(bvec, req, iter) {
361                         result = sock_recv_bvec(lo, bvec);
362                         if (result <= 0) {
363                                 printk(KERN_ERR "%s: Receive data failed (result %d)\n",
364                                                 lo->disk->disk_name, result);
365                                 req->errors++;
366                                 return req;
367                         }
368                         dprintk(DBG_RX, "%s: request %p: got %d bytes data\n",
369                                 lo->disk->disk_name, req, bvec->bv_len);
370                 }
371         }
372         return req;
373 harderror:
374         lo->harderror = result;
375         return NULL;
376 }
377
378 static ssize_t pid_show(struct device *dev,
379                         struct device_attribute *attr, char *buf)
380 {
381         struct gendisk *disk = dev_to_disk(dev);
382
383         return sprintf(buf, "%ld\n",
384                 (long) ((struct nbd_device *)disk->private_data)->pid);
385 }
386
387 static struct device_attribute pid_attr = {
388         .attr = { .name = "pid", .mode = S_IRUGO, .owner = THIS_MODULE },
389         .show = pid_show,
390 };
391
392 static int nbd_do_it(struct nbd_device *lo)
393 {
394         struct request *req;
395         int ret;
396
397         BUG_ON(lo->magic != LO_MAGIC);
398
399         lo->pid = current->pid;
400         ret = sysfs_create_file(&lo->disk->dev.kobj, &pid_attr.attr);
401         if (ret) {
402                 printk(KERN_ERR "nbd: sysfs_create_file failed!");
403                 return ret;
404         }
405
406         while ((req = nbd_read_stat(lo)) != NULL)
407                 nbd_end_request(req);
408
409         sysfs_remove_file(&lo->disk->dev.kobj, &pid_attr.attr);
410         return 0;
411 }
412
413 static void nbd_clear_que(struct nbd_device *lo)
414 {
415         struct request *req;
416
417         BUG_ON(lo->magic != LO_MAGIC);
418
419         /*
420          * Because we have set lo->sock to NULL under the tx_lock, all
421          * modifications to the list must have completed by now.  For
422          * the same reason, the active_req must be NULL.
423          *
424          * As a consequence, we don't need to take the spin lock while
425          * purging the list here.
426          */
427         BUG_ON(lo->sock);
428         BUG_ON(lo->active_req);
429
430         while (!list_empty(&lo->queue_head)) {
431                 req = list_entry(lo->queue_head.next, struct request,
432                                  queuelist);
433                 list_del_init(&req->queuelist);
434                 req->errors++;
435                 nbd_end_request(req);
436         }
437 }
438
439
440 /*
441  * We always wait for result of write, for now. It would be nice to make it optional
442  * in future
443  * if ((rq_data_dir(req) == WRITE) && (lo->flags & NBD_WRITE_NOCHK))
444  *   { printk( "Warning: Ignoring result!\n"); nbd_end_request( req ); }
445  */
446
447 static void do_nbd_request(struct request_queue * q)
448 {
449         struct request *req;
450         
451         while ((req = elv_next_request(q)) != NULL) {
452                 struct nbd_device *lo;
453
454                 blkdev_dequeue_request(req);
455                 dprintk(DBG_BLKDEV, "%s: request %p: dequeued (flags=%x)\n",
456                                 req->rq_disk->disk_name, req, req->cmd_type);
457
458                 if (!blk_fs_request(req))
459                         goto error_out;
460
461                 lo = req->rq_disk->private_data;
462
463                 BUG_ON(lo->magic != LO_MAGIC);
464
465                 nbd_cmd(req) = NBD_CMD_READ;
466                 if (rq_data_dir(req) == WRITE) {
467                         nbd_cmd(req) = NBD_CMD_WRITE;
468                         if (lo->flags & NBD_READ_ONLY) {
469                                 printk(KERN_ERR "%s: Write on read-only\n",
470                                                 lo->disk->disk_name);
471                                 goto error_out;
472                         }
473                 }
474
475                 req->errors = 0;
476                 spin_unlock_irq(q->queue_lock);
477
478                 mutex_lock(&lo->tx_lock);
479                 if (unlikely(!lo->sock)) {
480                         mutex_unlock(&lo->tx_lock);
481                         printk(KERN_ERR "%s: Attempted send on closed socket\n",
482                                lo->disk->disk_name);
483                         req->errors++;
484                         nbd_end_request(req);
485                         spin_lock_irq(q->queue_lock);
486                         continue;
487                 }
488
489                 lo->active_req = req;
490
491                 if (nbd_send_req(lo, req) != 0) {
492                         printk(KERN_ERR "%s: Request send failed\n",
493                                         lo->disk->disk_name);
494                         req->errors++;
495                         nbd_end_request(req);
496                 } else {
497                         spin_lock(&lo->queue_lock);
498                         list_add(&req->queuelist, &lo->queue_head);
499                         spin_unlock(&lo->queue_lock);
500                 }
501
502                 lo->active_req = NULL;
503                 mutex_unlock(&lo->tx_lock);
504                 wake_up_all(&lo->active_wq);
505
506                 spin_lock_irq(q->queue_lock);
507                 continue;
508
509 error_out:
510                 req->errors++;
511                 spin_unlock(q->queue_lock);
512                 nbd_end_request(req);
513                 spin_lock(q->queue_lock);
514         }
515 }
516
517 static int nbd_ioctl(struct inode *inode, struct file *file,
518                      unsigned int cmd, unsigned long arg)
519 {
520         struct nbd_device *lo = inode->i_bdev->bd_disk->private_data;
521         int error;
522         struct request sreq ;
523
524         if (!capable(CAP_SYS_ADMIN))
525                 return -EPERM;
526
527         BUG_ON(lo->magic != LO_MAGIC);
528
529         /* Anyone capable of this syscall can do *real bad* things */
530         dprintk(DBG_IOCTL, "%s: nbd_ioctl cmd=%s(0x%x) arg=%lu\n",
531                         lo->disk->disk_name, ioctl_cmd_to_ascii(cmd), cmd, arg);
532
533         switch (cmd) {
534         case NBD_DISCONNECT:
535                 printk(KERN_INFO "%s: NBD_DISCONNECT\n", lo->disk->disk_name);
536                 sreq.cmd_type = REQ_TYPE_SPECIAL;
537                 nbd_cmd(&sreq) = NBD_CMD_DISC;
538                 /*
539                  * Set these to sane values in case server implementation
540                  * fails to check the request type first and also to keep
541                  * debugging output cleaner.
542                  */
543                 sreq.sector = 0;
544                 sreq.nr_sectors = 0;
545                 if (!lo->sock)
546                         return -EINVAL;
547                 mutex_lock(&lo->tx_lock);
548                 nbd_send_req(lo, &sreq);
549                 mutex_unlock(&lo->tx_lock);
550                 return 0;
551  
552         case NBD_CLEAR_SOCK:
553                 error = 0;
554                 mutex_lock(&lo->tx_lock);
555                 lo->sock = NULL;
556                 mutex_unlock(&lo->tx_lock);
557                 file = lo->file;
558                 lo->file = NULL;
559                 nbd_clear_que(lo);
560                 BUG_ON(!list_empty(&lo->queue_head));
561                 if (file)
562                         fput(file);
563                 return error;
564         case NBD_SET_SOCK:
565                 if (lo->file)
566                         return -EBUSY;
567                 error = -EINVAL;
568                 file = fget(arg);
569                 if (file) {
570                         inode = file->f_path.dentry->d_inode;
571                         if (S_ISSOCK(inode->i_mode)) {
572                                 lo->file = file;
573                                 lo->sock = SOCKET_I(inode);
574                                 error = 0;
575                         } else {
576                                 fput(file);
577                         }
578                 }
579                 return error;
580         case NBD_SET_BLKSIZE:
581                 lo->blksize = arg;
582                 lo->bytesize &= ~(lo->blksize-1);
583                 inode->i_bdev->bd_inode->i_size = lo->bytesize;
584                 set_blocksize(inode->i_bdev, lo->blksize);
585                 set_capacity(lo->disk, lo->bytesize >> 9);
586                 return 0;
587         case NBD_SET_SIZE:
588                 lo->bytesize = arg & ~(lo->blksize-1);
589                 inode->i_bdev->bd_inode->i_size = lo->bytesize;
590                 set_blocksize(inode->i_bdev, lo->blksize);
591                 set_capacity(lo->disk, lo->bytesize >> 9);
592                 return 0;
593         case NBD_SET_TIMEOUT:
594                 lo->xmit_timeout = arg * HZ;
595                 return 0;
596         case NBD_SET_SIZE_BLOCKS:
597                 lo->bytesize = ((u64) arg) * lo->blksize;
598                 inode->i_bdev->bd_inode->i_size = lo->bytesize;
599                 set_blocksize(inode->i_bdev, lo->blksize);
600                 set_capacity(lo->disk, lo->bytesize >> 9);
601                 return 0;
602         case NBD_DO_IT:
603                 if (!lo->file)
604                         return -EINVAL;
605                 error = nbd_do_it(lo);
606                 if (error)
607                         return error;
608                 sock_shutdown(lo, 1);
609                 file = lo->file;
610                 lo->file = NULL;
611                 nbd_clear_que(lo);
612                 printk(KERN_WARNING "%s: queue cleared\n", lo->disk->disk_name);
613                 if (file)
614                         fput(file);
615                 lo->bytesize = 0;
616                 inode->i_bdev->bd_inode->i_size = 0;
617                 set_capacity(lo->disk, 0);
618                 return lo->harderror;
619         case NBD_CLEAR_QUE:
620                 /*
621                  * This is for compatibility only.  The queue is always cleared
622                  * by NBD_DO_IT or NBD_CLEAR_SOCK.
623                  */
624                 BUG_ON(!lo->sock && !list_empty(&lo->queue_head));
625                 return 0;
626         case NBD_PRINT_DEBUG:
627                 printk(KERN_INFO "%s: next = %p, prev = %p, head = %p\n",
628                         inode->i_bdev->bd_disk->disk_name,
629                         lo->queue_head.next, lo->queue_head.prev,
630                         &lo->queue_head);
631                 return 0;
632         }
633         return -EINVAL;
634 }
635
636 static struct block_device_operations nbd_fops =
637 {
638         .owner =        THIS_MODULE,
639         .ioctl =        nbd_ioctl,
640 };
641
642 /*
643  * And here should be modules and kernel interface 
644  *  (Just smiley confuses emacs :-)
645  */
646
647 static int __init nbd_init(void)
648 {
649         int err = -ENOMEM;
650         int i;
651
652         BUILD_BUG_ON(sizeof(struct nbd_request) != 28);
653
654         if (nbds_max > MAX_NBD) {
655                 printk(KERN_CRIT "nbd: cannot allocate more than %u nbds; %u requested.\n", MAX_NBD,
656                                 nbds_max);
657                 return -EINVAL;
658         }
659
660         for (i = 0; i < nbds_max; i++) {
661                 struct gendisk *disk = alloc_disk(1);
662                 if (!disk)
663                         goto out;
664                 nbd_dev[i].disk = disk;
665                 /*
666                  * The new linux 2.5 block layer implementation requires
667                  * every gendisk to have its very own request_queue struct.
668                  * These structs are big so we dynamically allocate them.
669                  */
670                 disk->queue = blk_init_queue(do_nbd_request, &nbd_lock);
671                 if (!disk->queue) {
672                         put_disk(disk);
673                         goto out;
674                 }
675         }
676
677         if (register_blkdev(NBD_MAJOR, "nbd")) {
678                 err = -EIO;
679                 goto out;
680         }
681
682         printk(KERN_INFO "nbd: registered device at major %d\n", NBD_MAJOR);
683         dprintk(DBG_INIT, "nbd: debugflags=0x%x\n", debugflags);
684
685         for (i = 0; i < nbds_max; i++) {
686                 struct gendisk *disk = nbd_dev[i].disk;
687                 nbd_dev[i].file = NULL;
688                 nbd_dev[i].magic = LO_MAGIC;
689                 nbd_dev[i].flags = 0;
690                 spin_lock_init(&nbd_dev[i].queue_lock);
691                 INIT_LIST_HEAD(&nbd_dev[i].queue_head);
692                 mutex_init(&nbd_dev[i].tx_lock);
693                 init_waitqueue_head(&nbd_dev[i].active_wq);
694                 nbd_dev[i].blksize = 1024;
695                 nbd_dev[i].bytesize = 0;
696                 disk->major = NBD_MAJOR;
697                 disk->first_minor = i;
698                 disk->fops = &nbd_fops;
699                 disk->private_data = &nbd_dev[i];
700                 disk->flags |= GENHD_FL_SUPPRESS_PARTITION_INFO;
701                 sprintf(disk->disk_name, "nbd%d", i);
702                 set_capacity(disk, 0);
703                 add_disk(disk);
704         }
705
706         return 0;
707 out:
708         while (i--) {
709                 blk_cleanup_queue(nbd_dev[i].disk->queue);
710                 put_disk(nbd_dev[i].disk);
711         }
712         return err;
713 }
714
715 static void __exit nbd_cleanup(void)
716 {
717         int i;
718         for (i = 0; i < nbds_max; i++) {
719                 struct gendisk *disk = nbd_dev[i].disk;
720                 nbd_dev[i].magic = 0;
721                 if (disk) {
722                         del_gendisk(disk);
723                         blk_cleanup_queue(disk->queue);
724                         put_disk(disk);
725                 }
726         }
727         unregister_blkdev(NBD_MAJOR, "nbd");
728         printk(KERN_INFO "nbd: unregistered device at major %d\n", NBD_MAJOR);
729 }
730
731 module_init(nbd_init);
732 module_exit(nbd_cleanup);
733
734 MODULE_DESCRIPTION("Network Block Device");
735 MODULE_LICENSE("GPL");
736
737 module_param(nbds_max, int, 0444);
738 MODULE_PARM_DESC(nbds_max, "How many network block devices to initialize.");
739 #ifndef NDEBUG
740 module_param(debugflags, int, 0644);
741 MODULE_PARM_DESC(debugflags, "flags for controlling debug output");
742 #endif