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