nbd: prevent sock_xmit from attempting to use a NULL socket
[sfrench/cifs-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;
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 error = req->errors ? -EIO : 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, error ? "failed" : "done");
109
110         spin_lock_irqsave(q->queue_lock, flags);
111         __blk_end_request(req, error, req->nr_sectors << 9);
112         spin_unlock_irqrestore(q->queue_lock, flags);
113 }
114
115 static void sock_shutdown(struct nbd_device *lo, int lock)
116 {
117         /* Forcibly shutdown the socket causing all listeners
118          * to error
119          *
120          * FIXME: This code is duplicated from sys_shutdown, but
121          * there should be a more generic interface rather than
122          * calling socket ops directly here */
123         if (lock)
124                 mutex_lock(&lo->tx_lock);
125         if (lo->sock) {
126                 printk(KERN_WARNING "%s: shutting down socket\n",
127                         lo->disk->disk_name);
128                 kernel_sock_shutdown(lo->sock, SHUT_RDWR);
129                 lo->sock = NULL;
130         }
131         if (lock)
132                 mutex_unlock(&lo->tx_lock);
133 }
134
135 static void nbd_xmit_timeout(unsigned long arg)
136 {
137         struct task_struct *task = (struct task_struct *)arg;
138
139         printk(KERN_WARNING "nbd: killing hung xmit (%s, pid: %d)\n",
140                 task->comm, task->pid);
141         force_sig(SIGKILL, task);
142 }
143
144 /*
145  *  Send or receive packet.
146  */
147 static int sock_xmit(struct nbd_device *lo, int send, void *buf, int size,
148                 int msg_flags)
149 {
150         struct socket *sock = lo->sock;
151         int result;
152         struct msghdr msg;
153         struct kvec iov;
154         sigset_t blocked, oldset;
155
156         if (unlikely(!sock)) {
157                 printk(KERN_ERR "%s: Attempted %s on closed socket in sock_xmit\n",
158                        lo->disk->disk_name, (send ? "send" : "recv"));
159                 return -EINVAL;
160         }
161
162         /* Allow interception of SIGKILL only
163          * Don't allow other signals to interrupt the transmission */
164         siginitsetinv(&blocked, sigmask(SIGKILL));
165         sigprocmask(SIG_SETMASK, &blocked, &oldset);
166
167         do {
168                 sock->sk->sk_allocation = GFP_NOIO;
169                 iov.iov_base = buf;
170                 iov.iov_len = size;
171                 msg.msg_name = NULL;
172                 msg.msg_namelen = 0;
173                 msg.msg_control = NULL;
174                 msg.msg_controllen = 0;
175                 msg.msg_flags = msg_flags | MSG_NOSIGNAL;
176
177                 if (send) {
178                         struct timer_list ti;
179
180                         if (lo->xmit_timeout) {
181                                 init_timer(&ti);
182                                 ti.function = nbd_xmit_timeout;
183                                 ti.data = (unsigned long)current;
184                                 ti.expires = jiffies + lo->xmit_timeout;
185                                 add_timer(&ti);
186                         }
187                         result = kernel_sendmsg(sock, &msg, &iov, 1, size);
188                         if (lo->xmit_timeout)
189                                 del_timer_sync(&ti);
190                 } else
191                         result = kernel_recvmsg(sock, &msg, &iov, 1, size, 0);
192
193                 if (signal_pending(current)) {
194                         siginfo_t info;
195                         printk(KERN_WARNING "nbd (pid %d: %s) got signal %d\n",
196                                 task_pid_nr(current), current->comm,
197                                 dequeue_signal_lock(current, &current->blocked, &info));
198                         result = -EINTR;
199                         sock_shutdown(lo, !send);
200                         break;
201                 }
202
203                 if (result <= 0) {
204                         if (result == 0)
205                                 result = -EPIPE; /* short read */
206                         break;
207                 }
208                 size -= result;
209                 buf += result;
210         } while (size > 0);
211
212         sigprocmask(SIG_SETMASK, &oldset, NULL);
213
214         return result;
215 }
216
217 static inline int sock_send_bvec(struct nbd_device *lo, struct bio_vec *bvec,
218                 int flags)
219 {
220         int result;
221         void *kaddr = kmap(bvec->bv_page);
222         result = sock_xmit(lo, 1, kaddr + bvec->bv_offset, bvec->bv_len, flags);
223         kunmap(bvec->bv_page);
224         return result;
225 }
226
227 /* always call with the tx_lock held */
228 static int nbd_send_req(struct nbd_device *lo, struct request *req)
229 {
230         int result, flags;
231         struct nbd_request request;
232         unsigned long size = req->nr_sectors << 9;
233
234         request.magic = htonl(NBD_REQUEST_MAGIC);
235         request.type = htonl(nbd_cmd(req));
236         request.from = cpu_to_be64((u64) req->sector << 9);
237         request.len = htonl(size);
238         memcpy(request.handle, &req, sizeof(req));
239
240         dprintk(DBG_TX, "%s: request %p: sending control (%s@%llu,%luB)\n",
241                         lo->disk->disk_name, req,
242                         nbdcmd_to_ascii(nbd_cmd(req)),
243                         (unsigned long long)req->sector << 9,
244                         req->nr_sectors << 9);
245         result = sock_xmit(lo, 1, &request, sizeof(request),
246                         (nbd_cmd(req) == NBD_CMD_WRITE) ? MSG_MORE : 0);
247         if (result <= 0) {
248                 printk(KERN_ERR "%s: Send control failed (result %d)\n",
249                                 lo->disk->disk_name, result);
250                 goto error_out;
251         }
252
253         if (nbd_cmd(req) == NBD_CMD_WRITE) {
254                 struct req_iterator iter;
255                 struct bio_vec *bvec;
256                 /*
257                  * we are really probing at internals to determine
258                  * whether to set MSG_MORE or not...
259                  */
260                 rq_for_each_segment(bvec, req, iter) {
261                         flags = 0;
262                         if (!rq_iter_last(req, iter))
263                                 flags = MSG_MORE;
264                         dprintk(DBG_TX, "%s: request %p: sending %d bytes data\n",
265                                         lo->disk->disk_name, req, bvec->bv_len);
266                         result = sock_send_bvec(lo, bvec, flags);
267                         if (result <= 0) {
268                                 printk(KERN_ERR "%s: Send data failed (result %d)\n",
269                                                 lo->disk->disk_name, result);
270                                 goto error_out;
271                         }
272                 }
273         }
274         return 0;
275
276 error_out:
277         return 1;
278 }
279
280 static struct request *nbd_find_request(struct nbd_device *lo,
281                                         struct request *xreq)
282 {
283         struct request *req, *tmp;
284         int err;
285
286         err = wait_event_interruptible(lo->active_wq, lo->active_req != xreq);
287         if (unlikely(err))
288                 goto out;
289
290         spin_lock(&lo->queue_lock);
291         list_for_each_entry_safe(req, tmp, &lo->queue_head, queuelist) {
292                 if (req != xreq)
293                         continue;
294                 list_del_init(&req->queuelist);
295                 spin_unlock(&lo->queue_lock);
296                 return req;
297         }
298         spin_unlock(&lo->queue_lock);
299
300         err = -ENOENT;
301
302 out:
303         return ERR_PTR(err);
304 }
305
306 static inline int sock_recv_bvec(struct nbd_device *lo, struct bio_vec *bvec)
307 {
308         int result;
309         void *kaddr = kmap(bvec->bv_page);
310         result = sock_xmit(lo, 0, kaddr + bvec->bv_offset, bvec->bv_len,
311                         MSG_WAITALL);
312         kunmap(bvec->bv_page);
313         return result;
314 }
315
316 /* NULL returned = something went wrong, inform userspace */
317 static struct request *nbd_read_stat(struct nbd_device *lo)
318 {
319         int result;
320         struct nbd_reply reply;
321         struct request *req;
322
323         reply.magic = 0;
324         result = sock_xmit(lo, 0, &reply, sizeof(reply), MSG_WAITALL);
325         if (result <= 0) {
326                 printk(KERN_ERR "%s: Receive control failed (result %d)\n",
327                                 lo->disk->disk_name, result);
328                 goto harderror;
329         }
330
331         if (ntohl(reply.magic) != NBD_REPLY_MAGIC) {
332                 printk(KERN_ERR "%s: Wrong magic (0x%lx)\n",
333                                 lo->disk->disk_name,
334                                 (unsigned long)ntohl(reply.magic));
335                 result = -EPROTO;
336                 goto harderror;
337         }
338
339         req = nbd_find_request(lo, *(struct request **)reply.handle);
340         if (unlikely(IS_ERR(req))) {
341                 result = PTR_ERR(req);
342                 if (result != -ENOENT)
343                         goto harderror;
344
345                 printk(KERN_ERR "%s: Unexpected reply (%p)\n",
346                                 lo->disk->disk_name, reply.handle);
347                 result = -EBADR;
348                 goto harderror;
349         }
350
351         if (ntohl(reply.error)) {
352                 printk(KERN_ERR "%s: Other side returned error (%d)\n",
353                                 lo->disk->disk_name, ntohl(reply.error));
354                 req->errors++;
355                 return req;
356         }
357
358         dprintk(DBG_RX, "%s: request %p: got reply\n",
359                         lo->disk->disk_name, req);
360         if (nbd_cmd(req) == NBD_CMD_READ) {
361                 struct req_iterator iter;
362                 struct bio_vec *bvec;
363
364                 rq_for_each_segment(bvec, req, iter) {
365                         result = sock_recv_bvec(lo, bvec);
366                         if (result <= 0) {
367                                 printk(KERN_ERR "%s: Receive data failed (result %d)\n",
368                                                 lo->disk->disk_name, result);
369                                 req->errors++;
370                                 return req;
371                         }
372                         dprintk(DBG_RX, "%s: request %p: got %d bytes data\n",
373                                 lo->disk->disk_name, req, bvec->bv_len);
374                 }
375         }
376         return req;
377 harderror:
378         lo->harderror = result;
379         return NULL;
380 }
381
382 static ssize_t pid_show(struct device *dev,
383                         struct device_attribute *attr, char *buf)
384 {
385         struct gendisk *disk = dev_to_disk(dev);
386
387         return sprintf(buf, "%ld\n",
388                 (long) ((struct nbd_device *)disk->private_data)->pid);
389 }
390
391 static struct device_attribute pid_attr = {
392         .attr = { .name = "pid", .mode = S_IRUGO, .owner = THIS_MODULE },
393         .show = pid_show,
394 };
395
396 static int nbd_do_it(struct nbd_device *lo)
397 {
398         struct request *req;
399         int ret;
400
401         BUG_ON(lo->magic != LO_MAGIC);
402
403         lo->pid = current->pid;
404         ret = sysfs_create_file(&lo->disk->dev.kobj, &pid_attr.attr);
405         if (ret) {
406                 printk(KERN_ERR "nbd: sysfs_create_file failed!");
407                 return ret;
408         }
409
410         while ((req = nbd_read_stat(lo)) != NULL)
411                 nbd_end_request(req);
412
413         sysfs_remove_file(&lo->disk->dev.kobj, &pid_attr.attr);
414         return 0;
415 }
416
417 static void nbd_clear_que(struct nbd_device *lo)
418 {
419         struct request *req;
420
421         BUG_ON(lo->magic != LO_MAGIC);
422
423         /*
424          * Because we have set lo->sock to NULL under the tx_lock, all
425          * modifications to the list must have completed by now.  For
426          * the same reason, the active_req must be NULL.
427          *
428          * As a consequence, we don't need to take the spin lock while
429          * purging the list here.
430          */
431         BUG_ON(lo->sock);
432         BUG_ON(lo->active_req);
433
434         while (!list_empty(&lo->queue_head)) {
435                 req = list_entry(lo->queue_head.next, struct request,
436                                  queuelist);
437                 list_del_init(&req->queuelist);
438                 req->errors++;
439                 nbd_end_request(req);
440         }
441 }
442
443
444 /*
445  * We always wait for result of write, for now. It would be nice to make it optional
446  * in future
447  * if ((rq_data_dir(req) == WRITE) && (lo->flags & NBD_WRITE_NOCHK))
448  *   { printk( "Warning: Ignoring result!\n"); nbd_end_request( req ); }
449  */
450
451 static void do_nbd_request(struct request_queue * q)
452 {
453         struct request *req;
454         
455         while ((req = elv_next_request(q)) != NULL) {
456                 struct nbd_device *lo;
457
458                 blkdev_dequeue_request(req);
459                 dprintk(DBG_BLKDEV, "%s: request %p: dequeued (flags=%x)\n",
460                                 req->rq_disk->disk_name, req, req->cmd_type);
461
462                 if (!blk_fs_request(req))
463                         goto error_out;
464
465                 lo = req->rq_disk->private_data;
466
467                 BUG_ON(lo->magic != LO_MAGIC);
468
469                 nbd_cmd(req) = NBD_CMD_READ;
470                 if (rq_data_dir(req) == WRITE) {
471                         nbd_cmd(req) = NBD_CMD_WRITE;
472                         if (lo->flags & NBD_READ_ONLY) {
473                                 printk(KERN_ERR "%s: Write on read-only\n",
474                                                 lo->disk->disk_name);
475                                 goto error_out;
476                         }
477                 }
478
479                 req->errors = 0;
480                 spin_unlock_irq(q->queue_lock);
481
482                 mutex_lock(&lo->tx_lock);
483                 if (unlikely(!lo->sock)) {
484                         mutex_unlock(&lo->tx_lock);
485                         printk(KERN_ERR "%s: Attempted send on closed socket\n",
486                                lo->disk->disk_name);
487                         req->errors++;
488                         nbd_end_request(req);
489                         spin_lock_irq(q->queue_lock);
490                         continue;
491                 }
492
493                 lo->active_req = req;
494
495                 if (nbd_send_req(lo, req) != 0) {
496                         printk(KERN_ERR "%s: Request send failed\n",
497                                         lo->disk->disk_name);
498                         req->errors++;
499                         nbd_end_request(req);
500                 } else {
501                         spin_lock(&lo->queue_lock);
502                         list_add(&req->queuelist, &lo->queue_head);
503                         spin_unlock(&lo->queue_lock);
504                 }
505
506                 lo->active_req = NULL;
507                 mutex_unlock(&lo->tx_lock);
508                 wake_up_all(&lo->active_wq);
509
510                 spin_lock_irq(q->queue_lock);
511                 continue;
512
513 error_out:
514                 req->errors++;
515                 spin_unlock(q->queue_lock);
516                 nbd_end_request(req);
517                 spin_lock(q->queue_lock);
518         }
519 }
520
521 static int nbd_ioctl(struct inode *inode, struct file *file,
522                      unsigned int cmd, unsigned long arg)
523 {
524         struct nbd_device *lo = inode->i_bdev->bd_disk->private_data;
525         int error;
526         struct request sreq ;
527
528         if (!capable(CAP_SYS_ADMIN))
529                 return -EPERM;
530
531         BUG_ON(lo->magic != LO_MAGIC);
532
533         /* Anyone capable of this syscall can do *real bad* things */
534         dprintk(DBG_IOCTL, "%s: nbd_ioctl cmd=%s(0x%x) arg=%lu\n",
535                         lo->disk->disk_name, ioctl_cmd_to_ascii(cmd), cmd, arg);
536
537         switch (cmd) {
538         case NBD_DISCONNECT:
539                 printk(KERN_INFO "%s: NBD_DISCONNECT\n", lo->disk->disk_name);
540                 sreq.cmd_type = REQ_TYPE_SPECIAL;
541                 nbd_cmd(&sreq) = NBD_CMD_DISC;
542                 /*
543                  * Set these to sane values in case server implementation
544                  * fails to check the request type first and also to keep
545                  * debugging output cleaner.
546                  */
547                 sreq.sector = 0;
548                 sreq.nr_sectors = 0;
549                 if (!lo->sock)
550                         return -EINVAL;
551                 mutex_lock(&lo->tx_lock);
552                 nbd_send_req(lo, &sreq);
553                 mutex_unlock(&lo->tx_lock);
554                 return 0;
555  
556         case NBD_CLEAR_SOCK:
557                 error = 0;
558                 mutex_lock(&lo->tx_lock);
559                 lo->sock = NULL;
560                 mutex_unlock(&lo->tx_lock);
561                 file = lo->file;
562                 lo->file = NULL;
563                 nbd_clear_que(lo);
564                 BUG_ON(!list_empty(&lo->queue_head));
565                 if (file)
566                         fput(file);
567                 return error;
568         case NBD_SET_SOCK:
569                 if (lo->file)
570                         return -EBUSY;
571                 error = -EINVAL;
572                 file = fget(arg);
573                 if (file) {
574                         inode = file->f_path.dentry->d_inode;
575                         if (S_ISSOCK(inode->i_mode)) {
576                                 lo->file = file;
577                                 lo->sock = SOCKET_I(inode);
578                                 error = 0;
579                         } else {
580                                 fput(file);
581                         }
582                 }
583                 return error;
584         case NBD_SET_BLKSIZE:
585                 lo->blksize = arg;
586                 lo->bytesize &= ~(lo->blksize-1);
587                 inode->i_bdev->bd_inode->i_size = lo->bytesize;
588                 set_blocksize(inode->i_bdev, lo->blksize);
589                 set_capacity(lo->disk, lo->bytesize >> 9);
590                 return 0;
591         case NBD_SET_SIZE:
592                 lo->bytesize = arg & ~(lo->blksize-1);
593                 inode->i_bdev->bd_inode->i_size = lo->bytesize;
594                 set_blocksize(inode->i_bdev, lo->blksize);
595                 set_capacity(lo->disk, lo->bytesize >> 9);
596                 return 0;
597         case NBD_SET_TIMEOUT:
598                 lo->xmit_timeout = arg * HZ;
599                 return 0;
600         case NBD_SET_SIZE_BLOCKS:
601                 lo->bytesize = ((u64) arg) * lo->blksize;
602                 inode->i_bdev->bd_inode->i_size = lo->bytesize;
603                 set_blocksize(inode->i_bdev, lo->blksize);
604                 set_capacity(lo->disk, lo->bytesize >> 9);
605                 return 0;
606         case NBD_DO_IT:
607                 if (!lo->file)
608                         return -EINVAL;
609                 error = nbd_do_it(lo);
610                 if (error)
611                         return error;
612                 sock_shutdown(lo, 1);
613                 file = lo->file;
614                 lo->file = NULL;
615                 nbd_clear_que(lo);
616                 printk(KERN_WARNING "%s: queue cleared\n", lo->disk->disk_name);
617                 if (file)
618                         fput(file);
619                 lo->bytesize = 0;
620                 inode->i_bdev->bd_inode->i_size = 0;
621                 set_capacity(lo->disk, 0);
622                 return lo->harderror;
623         case NBD_CLEAR_QUE:
624                 /*
625                  * This is for compatibility only.  The queue is always cleared
626                  * by NBD_DO_IT or NBD_CLEAR_SOCK.
627                  */
628                 BUG_ON(!lo->sock && !list_empty(&lo->queue_head));
629                 return 0;
630         case NBD_PRINT_DEBUG:
631                 printk(KERN_INFO "%s: next = %p, prev = %p, head = %p\n",
632                         inode->i_bdev->bd_disk->disk_name,
633                         lo->queue_head.next, lo->queue_head.prev,
634                         &lo->queue_head);
635                 return 0;
636         }
637         return -EINVAL;
638 }
639
640 static struct block_device_operations nbd_fops =
641 {
642         .owner =        THIS_MODULE,
643         .ioctl =        nbd_ioctl,
644 };
645
646 /*
647  * And here should be modules and kernel interface 
648  *  (Just smiley confuses emacs :-)
649  */
650
651 static int __init nbd_init(void)
652 {
653         int err = -ENOMEM;
654         int i;
655
656         BUILD_BUG_ON(sizeof(struct nbd_request) != 28);
657
658         nbd_dev = kcalloc(nbds_max, sizeof(*nbd_dev), GFP_KERNEL);
659         if (!nbd_dev)
660                 return -ENOMEM;
661
662         for (i = 0; i < nbds_max; i++) {
663                 struct gendisk *disk = alloc_disk(1);
664                 elevator_t *old_e;
665                 if (!disk)
666                         goto out;
667                 nbd_dev[i].disk = disk;
668                 /*
669                  * The new linux 2.5 block layer implementation requires
670                  * every gendisk to have its very own request_queue struct.
671                  * These structs are big so we dynamically allocate them.
672                  */
673                 disk->queue = blk_init_queue(do_nbd_request, &nbd_lock);
674                 if (!disk->queue) {
675                         put_disk(disk);
676                         goto out;
677                 }
678                 old_e = disk->queue->elevator;
679                 if (elevator_init(disk->queue, "deadline") == 0 ||
680                         elevator_init(disk->queue, "noop") == 0) {
681                                 elevator_exit(old_e);
682                 }
683         }
684
685         if (register_blkdev(NBD_MAJOR, "nbd")) {
686                 err = -EIO;
687                 goto out;
688         }
689
690         printk(KERN_INFO "nbd: registered device at major %d\n", NBD_MAJOR);
691         dprintk(DBG_INIT, "nbd: debugflags=0x%x\n", debugflags);
692
693         for (i = 0; i < nbds_max; i++) {
694                 struct gendisk *disk = nbd_dev[i].disk;
695                 nbd_dev[i].file = NULL;
696                 nbd_dev[i].magic = LO_MAGIC;
697                 nbd_dev[i].flags = 0;
698                 spin_lock_init(&nbd_dev[i].queue_lock);
699                 INIT_LIST_HEAD(&nbd_dev[i].queue_head);
700                 mutex_init(&nbd_dev[i].tx_lock);
701                 init_waitqueue_head(&nbd_dev[i].active_wq);
702                 nbd_dev[i].blksize = 1024;
703                 nbd_dev[i].bytesize = 0;
704                 disk->major = NBD_MAJOR;
705                 disk->first_minor = i;
706                 disk->fops = &nbd_fops;
707                 disk->private_data = &nbd_dev[i];
708                 disk->flags |= GENHD_FL_SUPPRESS_PARTITION_INFO;
709                 sprintf(disk->disk_name, "nbd%d", i);
710                 set_capacity(disk, 0);
711                 add_disk(disk);
712         }
713
714         return 0;
715 out:
716         while (i--) {
717                 blk_cleanup_queue(nbd_dev[i].disk->queue);
718                 put_disk(nbd_dev[i].disk);
719         }
720         return err;
721 }
722
723 static void __exit nbd_cleanup(void)
724 {
725         int i;
726         for (i = 0; i < nbds_max; i++) {
727                 struct gendisk *disk = nbd_dev[i].disk;
728                 nbd_dev[i].magic = 0;
729                 if (disk) {
730                         del_gendisk(disk);
731                         blk_cleanup_queue(disk->queue);
732                         put_disk(disk);
733                 }
734         }
735         unregister_blkdev(NBD_MAJOR, "nbd");
736         printk(KERN_INFO "nbd: unregistered device at major %d\n", NBD_MAJOR);
737 }
738
739 module_init(nbd_init);
740 module_exit(nbd_cleanup);
741
742 MODULE_DESCRIPTION("Network Block Device");
743 MODULE_LICENSE("GPL");
744
745 module_param(nbds_max, int, 0444);
746 MODULE_PARM_DESC(nbds_max, "How many network block devices to initialize.");
747 #ifndef NDEBUG
748 module_param(debugflags, int, 0644);
749 MODULE_PARM_DESC(debugflags, "flags for controlling debug output");
750 #endif