Remove duplicated unlikely() in IS_ERR()
[linux-3.10.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 #include <linux/kthread.h>
33
34 #include <asm/uaccess.h>
35 #include <asm/system.h>
36 #include <asm/types.h>
37
38 #include <linux/nbd.h>
39
40 #define LO_MAGIC 0x68797548
41
42 #ifdef NDEBUG
43 #define dprintk(flags, fmt...)
44 #else /* NDEBUG */
45 #define dprintk(flags, fmt...) do { \
46         if (debugflags & (flags)) printk(KERN_DEBUG fmt); \
47 } while (0)
48 #define DBG_IOCTL       0x0004
49 #define DBG_INIT        0x0010
50 #define DBG_EXIT        0x0020
51 #define DBG_BLKDEV      0x0100
52 #define DBG_RX          0x0200
53 #define DBG_TX          0x0400
54 static unsigned int debugflags;
55 #endif /* NDEBUG */
56
57 static unsigned int nbds_max = 16;
58 static struct nbd_device *nbd_dev;
59 static int max_part;
60
61 /*
62  * Use just one lock (or at most 1 per NIC). Two arguments for this:
63  * 1. Each NIC is essentially a synchronization point for all servers
64  *    accessed through that NIC so there's no need to have more locks
65  *    than NICs anyway.
66  * 2. More locks lead to more "Dirty cache line bouncing" which will slow
67  *    down each lock to the point where they're actually slower than just
68  *    a single lock.
69  * Thanks go to Jens Axboe and Al Viro for their LKML emails explaining this!
70  */
71 static DEFINE_SPINLOCK(nbd_lock);
72
73 #ifndef NDEBUG
74 static const char *ioctl_cmd_to_ascii(int cmd)
75 {
76         switch (cmd) {
77         case NBD_SET_SOCK: return "set-sock";
78         case NBD_SET_BLKSIZE: return "set-blksize";
79         case NBD_SET_SIZE: return "set-size";
80         case NBD_DO_IT: return "do-it";
81         case NBD_CLEAR_SOCK: return "clear-sock";
82         case NBD_CLEAR_QUE: return "clear-que";
83         case NBD_PRINT_DEBUG: return "print-debug";
84         case NBD_SET_SIZE_BLOCKS: return "set-size-blocks";
85         case NBD_DISCONNECT: return "disconnect";
86         case BLKROSET: return "set-read-only";
87         case BLKFLSBUF: return "flush-buffer-cache";
88         }
89         return "unknown";
90 }
91
92 static const char *nbdcmd_to_ascii(int cmd)
93 {
94         switch (cmd) {
95         case  NBD_CMD_READ: return "read";
96         case NBD_CMD_WRITE: return "write";
97         case  NBD_CMD_DISC: return "disconnect";
98         }
99         return "invalid";
100 }
101 #endif /* NDEBUG */
102
103 static void nbd_end_request(struct request *req)
104 {
105         int error = req->errors ? -EIO : 0;
106         struct request_queue *q = req->q;
107         unsigned long flags;
108
109         dprintk(DBG_BLKDEV, "%s: request %p: %s\n", req->rq_disk->disk_name,
110                         req, error ? "failed" : "done");
111
112         spin_lock_irqsave(q->queue_lock, flags);
113         __blk_end_request(req, error, req->nr_sectors << 9);
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         if (unlikely(!sock)) {
159                 printk(KERN_ERR "%s: Attempted %s on closed socket in sock_xmit\n",
160                        lo->disk->disk_name, (send ? "send" : "recv"));
161                 return -EINVAL;
162         }
163
164         /* Allow interception of SIGKILL only
165          * Don't allow other signals to interrupt the transmission */
166         siginitsetinv(&blocked, sigmask(SIGKILL));
167         sigprocmask(SIG_SETMASK, &blocked, &oldset);
168
169         do {
170                 sock->sk->sk_allocation = GFP_NOIO;
171                 iov.iov_base = buf;
172                 iov.iov_len = size;
173                 msg.msg_name = NULL;
174                 msg.msg_namelen = 0;
175                 msg.msg_control = NULL;
176                 msg.msg_controllen = 0;
177                 msg.msg_flags = msg_flags | MSG_NOSIGNAL;
178
179                 if (send) {
180                         struct timer_list ti;
181
182                         if (lo->xmit_timeout) {
183                                 init_timer(&ti);
184                                 ti.function = nbd_xmit_timeout;
185                                 ti.data = (unsigned long)current;
186                                 ti.expires = jiffies + lo->xmit_timeout;
187                                 add_timer(&ti);
188                         }
189                         result = kernel_sendmsg(sock, &msg, &iov, 1, size);
190                         if (lo->xmit_timeout)
191                                 del_timer_sync(&ti);
192                 } else
193                         result = kernel_recvmsg(sock, &msg, &iov, 1, size, 0);
194
195                 if (signal_pending(current)) {
196                         siginfo_t info;
197                         printk(KERN_WARNING "nbd (pid %d: %s) got signal %d\n",
198                                 task_pid_nr(current), current->comm,
199                                 dequeue_signal_lock(current, &current->blocked, &info));
200                         result = -EINTR;
201                         sock_shutdown(lo, !send);
202                         break;
203                 }
204
205                 if (result <= 0) {
206                         if (result == 0)
207                                 result = -EPIPE; /* short read */
208                         break;
209                 }
210                 size -= result;
211                 buf += result;
212         } while (size > 0);
213
214         sigprocmask(SIG_SETMASK, &oldset, NULL);
215
216         return result;
217 }
218
219 static inline int sock_send_bvec(struct nbd_device *lo, struct bio_vec *bvec,
220                 int flags)
221 {
222         int result;
223         void *kaddr = kmap(bvec->bv_page);
224         result = sock_xmit(lo, 1, kaddr + bvec->bv_offset, bvec->bv_len, flags);
225         kunmap(bvec->bv_page);
226         return result;
227 }
228
229 /* always call with the tx_lock held */
230 static int nbd_send_req(struct nbd_device *lo, struct request *req)
231 {
232         int result, flags;
233         struct nbd_request request;
234         unsigned long size = req->nr_sectors << 9;
235
236         request.magic = htonl(NBD_REQUEST_MAGIC);
237         request.type = htonl(nbd_cmd(req));
238         request.from = cpu_to_be64((u64) req->sector << 9);
239         request.len = htonl(size);
240         memcpy(request.handle, &req, sizeof(req));
241
242         dprintk(DBG_TX, "%s: request %p: sending control (%s@%llu,%luB)\n",
243                         lo->disk->disk_name, req,
244                         nbdcmd_to_ascii(nbd_cmd(req)),
245                         (unsigned long long)req->sector << 9,
246                         req->nr_sectors << 9);
247         result = sock_xmit(lo, 1, &request, sizeof(request),
248                         (nbd_cmd(req) == NBD_CMD_WRITE) ? MSG_MORE : 0);
249         if (result <= 0) {
250                 printk(KERN_ERR "%s: Send control failed (result %d)\n",
251                                 lo->disk->disk_name, result);
252                 goto error_out;
253         }
254
255         if (nbd_cmd(req) == NBD_CMD_WRITE) {
256                 struct req_iterator iter;
257                 struct bio_vec *bvec;
258                 /*
259                  * we are really probing at internals to determine
260                  * whether to set MSG_MORE or not...
261                  */
262                 rq_for_each_segment(bvec, req, iter) {
263                         flags = 0;
264                         if (!rq_iter_last(req, iter))
265                                 flags = MSG_MORE;
266                         dprintk(DBG_TX, "%s: request %p: sending %d bytes data\n",
267                                         lo->disk->disk_name, req, bvec->bv_len);
268                         result = sock_send_bvec(lo, bvec, flags);
269                         if (result <= 0) {
270                                 printk(KERN_ERR "%s: Send data failed (result %d)\n",
271                                                 lo->disk->disk_name, result);
272                                 goto error_out;
273                         }
274                 }
275         }
276         return 0;
277
278 error_out:
279         return 1;
280 }
281
282 static struct request *nbd_find_request(struct nbd_device *lo,
283                                         struct request *xreq)
284 {
285         struct request *req, *tmp;
286         int err;
287
288         err = wait_event_interruptible(lo->active_wq, lo->active_req != xreq);
289         if (unlikely(err))
290                 goto out;
291
292         spin_lock(&lo->queue_lock);
293         list_for_each_entry_safe(req, tmp, &lo->queue_head, queuelist) {
294                 if (req != xreq)
295                         continue;
296                 list_del_init(&req->queuelist);
297                 spin_unlock(&lo->queue_lock);
298                 return req;
299         }
300         spin_unlock(&lo->queue_lock);
301
302         err = -ENOENT;
303
304 out:
305         return ERR_PTR(err);
306 }
307
308 static inline int sock_recv_bvec(struct nbd_device *lo, struct bio_vec *bvec)
309 {
310         int result;
311         void *kaddr = kmap(bvec->bv_page);
312         result = sock_xmit(lo, 0, kaddr + bvec->bv_offset, bvec->bv_len,
313                         MSG_WAITALL);
314         kunmap(bvec->bv_page);
315         return result;
316 }
317
318 /* NULL returned = something went wrong, inform userspace */
319 static struct request *nbd_read_stat(struct nbd_device *lo)
320 {
321         int result;
322         struct nbd_reply reply;
323         struct request *req;
324
325         reply.magic = 0;
326         result = sock_xmit(lo, 0, &reply, sizeof(reply), MSG_WAITALL);
327         if (result <= 0) {
328                 printk(KERN_ERR "%s: Receive control failed (result %d)\n",
329                                 lo->disk->disk_name, result);
330                 goto harderror;
331         }
332
333         if (ntohl(reply.magic) != NBD_REPLY_MAGIC) {
334                 printk(KERN_ERR "%s: Wrong magic (0x%lx)\n",
335                                 lo->disk->disk_name,
336                                 (unsigned long)ntohl(reply.magic));
337                 result = -EPROTO;
338                 goto harderror;
339         }
340
341         req = nbd_find_request(lo, *(struct request **)reply.handle);
342         if (IS_ERR(req)) {
343                 result = PTR_ERR(req);
344                 if (result != -ENOENT)
345                         goto harderror;
346
347                 printk(KERN_ERR "%s: Unexpected reply (%p)\n",
348                                 lo->disk->disk_name, reply.handle);
349                 result = -EBADR;
350                 goto harderror;
351         }
352
353         if (ntohl(reply.error)) {
354                 printk(KERN_ERR "%s: Other side returned error (%d)\n",
355                                 lo->disk->disk_name, ntohl(reply.error));
356                 req->errors++;
357                 return req;
358         }
359
360         dprintk(DBG_RX, "%s: request %p: got reply\n",
361                         lo->disk->disk_name, req);
362         if (nbd_cmd(req) == NBD_CMD_READ) {
363                 struct req_iterator iter;
364                 struct bio_vec *bvec;
365
366                 rq_for_each_segment(bvec, req, iter) {
367                         result = sock_recv_bvec(lo, bvec);
368                         if (result <= 0) {
369                                 printk(KERN_ERR "%s: Receive data failed (result %d)\n",
370                                                 lo->disk->disk_name, result);
371                                 req->errors++;
372                                 return req;
373                         }
374                         dprintk(DBG_RX, "%s: request %p: got %d bytes data\n",
375                                 lo->disk->disk_name, req, bvec->bv_len);
376                 }
377         }
378         return req;
379 harderror:
380         lo->harderror = result;
381         return NULL;
382 }
383
384 static ssize_t pid_show(struct device *dev,
385                         struct device_attribute *attr, char *buf)
386 {
387         struct gendisk *disk = dev_to_disk(dev);
388
389         return sprintf(buf, "%ld\n",
390                 (long) ((struct nbd_device *)disk->private_data)->pid);
391 }
392
393 static struct device_attribute pid_attr = {
394         .attr = { .name = "pid", .mode = S_IRUGO, .owner = THIS_MODULE },
395         .show = pid_show,
396 };
397
398 static int nbd_do_it(struct nbd_device *lo)
399 {
400         struct request *req;
401         int ret;
402
403         BUG_ON(lo->magic != LO_MAGIC);
404
405         lo->pid = current->pid;
406         ret = sysfs_create_file(&lo->disk->dev.kobj, &pid_attr.attr);
407         if (ret) {
408                 printk(KERN_ERR "nbd: sysfs_create_file failed!");
409                 return ret;
410         }
411
412         while ((req = nbd_read_stat(lo)) != NULL)
413                 nbd_end_request(req);
414
415         sysfs_remove_file(&lo->disk->dev.kobj, &pid_attr.attr);
416         return 0;
417 }
418
419 static void nbd_clear_que(struct nbd_device *lo)
420 {
421         struct request *req;
422
423         BUG_ON(lo->magic != LO_MAGIC);
424
425         /*
426          * Because we have set lo->sock to NULL under the tx_lock, all
427          * modifications to the list must have completed by now.  For
428          * the same reason, the active_req must be NULL.
429          *
430          * As a consequence, we don't need to take the spin lock while
431          * purging the list here.
432          */
433         BUG_ON(lo->sock);
434         BUG_ON(lo->active_req);
435
436         while (!list_empty(&lo->queue_head)) {
437                 req = list_entry(lo->queue_head.next, struct request,
438                                  queuelist);
439                 list_del_init(&req->queuelist);
440                 req->errors++;
441                 nbd_end_request(req);
442         }
443 }
444
445
446 static void nbd_handle_req(struct nbd_device *lo, struct request *req)
447 {
448         if (!blk_fs_request(req))
449                 goto error_out;
450
451         nbd_cmd(req) = NBD_CMD_READ;
452         if (rq_data_dir(req) == WRITE) {
453                 nbd_cmd(req) = NBD_CMD_WRITE;
454                 if (lo->flags & NBD_READ_ONLY) {
455                         printk(KERN_ERR "%s: Write on read-only\n",
456                                         lo->disk->disk_name);
457                         goto error_out;
458                 }
459         }
460
461         req->errors = 0;
462
463         mutex_lock(&lo->tx_lock);
464         if (unlikely(!lo->sock)) {
465                 mutex_unlock(&lo->tx_lock);
466                 printk(KERN_ERR "%s: Attempted send on closed socket\n",
467                        lo->disk->disk_name);
468                 req->errors++;
469                 nbd_end_request(req);
470                 return;
471         }
472
473         lo->active_req = req;
474
475         if (nbd_send_req(lo, req) != 0) {
476                 printk(KERN_ERR "%s: Request send failed\n",
477                                 lo->disk->disk_name);
478                 req->errors++;
479                 nbd_end_request(req);
480         } else {
481                 spin_lock(&lo->queue_lock);
482                 list_add(&req->queuelist, &lo->queue_head);
483                 spin_unlock(&lo->queue_lock);
484         }
485
486         lo->active_req = NULL;
487         mutex_unlock(&lo->tx_lock);
488         wake_up_all(&lo->active_wq);
489
490         return;
491
492 error_out:
493         req->errors++;
494         nbd_end_request(req);
495 }
496
497 static int nbd_thread(void *data)
498 {
499         struct nbd_device *lo = data;
500         struct request *req;
501
502         set_user_nice(current, -20);
503         while (!kthread_should_stop() || !list_empty(&lo->waiting_queue)) {
504                 /* wait for something to do */
505                 wait_event_interruptible(lo->waiting_wq,
506                                          kthread_should_stop() ||
507                                          !list_empty(&lo->waiting_queue));
508
509                 /* extract request */
510                 if (list_empty(&lo->waiting_queue))
511                         continue;
512
513                 spin_lock_irq(&lo->queue_lock);
514                 req = list_entry(lo->waiting_queue.next, struct request,
515                                  queuelist);
516                 list_del_init(&req->queuelist);
517                 spin_unlock_irq(&lo->queue_lock);
518
519                 /* handle request */
520                 nbd_handle_req(lo, req);
521         }
522         return 0;
523 }
524
525 /*
526  * We always wait for result of write, for now. It would be nice to make it optional
527  * in future
528  * if ((rq_data_dir(req) == WRITE) && (lo->flags & NBD_WRITE_NOCHK))
529  *   { printk( "Warning: Ignoring result!\n"); nbd_end_request( req ); }
530  */
531
532 static void do_nbd_request(struct request_queue * q)
533 {
534         struct request *req;
535         
536         while ((req = elv_next_request(q)) != NULL) {
537                 struct nbd_device *lo;
538
539                 blkdev_dequeue_request(req);
540
541                 spin_unlock_irq(q->queue_lock);
542
543                 dprintk(DBG_BLKDEV, "%s: request %p: dequeued (flags=%x)\n",
544                                 req->rq_disk->disk_name, req, req->cmd_type);
545
546                 lo = req->rq_disk->private_data;
547
548                 BUG_ON(lo->magic != LO_MAGIC);
549
550                 spin_lock_irq(&lo->queue_lock);
551                 list_add_tail(&req->queuelist, &lo->waiting_queue);
552                 spin_unlock_irq(&lo->queue_lock);
553
554                 wake_up(&lo->waiting_wq);
555
556                 spin_lock_irq(q->queue_lock);
557         }
558 }
559
560 static int nbd_ioctl(struct inode *inode, struct file *file,
561                      unsigned int cmd, unsigned long arg)
562 {
563         struct nbd_device *lo = inode->i_bdev->bd_disk->private_data;
564         int error;
565         struct request sreq ;
566         struct task_struct *thread;
567
568         if (!capable(CAP_SYS_ADMIN))
569                 return -EPERM;
570
571         BUG_ON(lo->magic != LO_MAGIC);
572
573         /* Anyone capable of this syscall can do *real bad* things */
574         dprintk(DBG_IOCTL, "%s: nbd_ioctl cmd=%s(0x%x) arg=%lu\n",
575                         lo->disk->disk_name, ioctl_cmd_to_ascii(cmd), cmd, arg);
576
577         switch (cmd) {
578         case NBD_DISCONNECT:
579                 printk(KERN_INFO "%s: NBD_DISCONNECT\n", lo->disk->disk_name);
580                 sreq.cmd_type = REQ_TYPE_SPECIAL;
581                 nbd_cmd(&sreq) = NBD_CMD_DISC;
582                 /*
583                  * Set these to sane values in case server implementation
584                  * fails to check the request type first and also to keep
585                  * debugging output cleaner.
586                  */
587                 sreq.sector = 0;
588                 sreq.nr_sectors = 0;
589                 if (!lo->sock)
590                         return -EINVAL;
591                 mutex_lock(&lo->tx_lock);
592                 nbd_send_req(lo, &sreq);
593                 mutex_unlock(&lo->tx_lock);
594                 return 0;
595  
596         case NBD_CLEAR_SOCK:
597                 error = 0;
598                 mutex_lock(&lo->tx_lock);
599                 lo->sock = NULL;
600                 mutex_unlock(&lo->tx_lock);
601                 file = lo->file;
602                 lo->file = NULL;
603                 nbd_clear_que(lo);
604                 BUG_ON(!list_empty(&lo->queue_head));
605                 if (file)
606                         fput(file);
607                 return error;
608         case NBD_SET_SOCK:
609                 if (lo->file)
610                         return -EBUSY;
611                 error = -EINVAL;
612                 file = fget(arg);
613                 if (file) {
614                         struct block_device *bdev = inode->i_bdev;
615                         inode = file->f_path.dentry->d_inode;
616                         if (S_ISSOCK(inode->i_mode)) {
617                                 lo->file = file;
618                                 lo->sock = SOCKET_I(inode);
619                                 if (max_part > 0)
620                                         bdev->bd_invalidated = 1;
621                                 error = 0;
622                         } else {
623                                 fput(file);
624                         }
625                 }
626                 return error;
627         case NBD_SET_BLKSIZE:
628                 lo->blksize = arg;
629                 lo->bytesize &= ~(lo->blksize-1);
630                 inode->i_bdev->bd_inode->i_size = lo->bytesize;
631                 set_blocksize(inode->i_bdev, lo->blksize);
632                 set_capacity(lo->disk, lo->bytesize >> 9);
633                 return 0;
634         case NBD_SET_SIZE:
635                 lo->bytesize = arg & ~(lo->blksize-1);
636                 inode->i_bdev->bd_inode->i_size = lo->bytesize;
637                 set_blocksize(inode->i_bdev, lo->blksize);
638                 set_capacity(lo->disk, lo->bytesize >> 9);
639                 return 0;
640         case NBD_SET_TIMEOUT:
641                 lo->xmit_timeout = arg * HZ;
642                 return 0;
643         case NBD_SET_SIZE_BLOCKS:
644                 lo->bytesize = ((u64) arg) * lo->blksize;
645                 inode->i_bdev->bd_inode->i_size = lo->bytesize;
646                 set_blocksize(inode->i_bdev, lo->blksize);
647                 set_capacity(lo->disk, lo->bytesize >> 9);
648                 return 0;
649         case NBD_DO_IT:
650                 if (!lo->file)
651                         return -EINVAL;
652                 thread = kthread_create(nbd_thread, lo, lo->disk->disk_name);
653                 if (IS_ERR(thread))
654                         return PTR_ERR(thread);
655                 wake_up_process(thread);
656                 error = nbd_do_it(lo);
657                 kthread_stop(thread);
658                 if (error)
659                         return error;
660                 sock_shutdown(lo, 1);
661                 file = lo->file;
662                 lo->file = NULL;
663                 nbd_clear_que(lo);
664                 printk(KERN_WARNING "%s: queue cleared\n", lo->disk->disk_name);
665                 if (file)
666                         fput(file);
667                 lo->bytesize = 0;
668                 inode->i_bdev->bd_inode->i_size = 0;
669                 set_capacity(lo->disk, 0);
670                 if (max_part > 0)
671                         ioctl_by_bdev(inode->i_bdev, BLKRRPART, 0);
672                 return lo->harderror;
673         case NBD_CLEAR_QUE:
674                 /*
675                  * This is for compatibility only.  The queue is always cleared
676                  * by NBD_DO_IT or NBD_CLEAR_SOCK.
677                  */
678                 BUG_ON(!lo->sock && !list_empty(&lo->queue_head));
679                 return 0;
680         case NBD_PRINT_DEBUG:
681                 printk(KERN_INFO "%s: next = %p, prev = %p, head = %p\n",
682                         inode->i_bdev->bd_disk->disk_name,
683                         lo->queue_head.next, lo->queue_head.prev,
684                         &lo->queue_head);
685                 return 0;
686         }
687         return -EINVAL;
688 }
689
690 static struct block_device_operations nbd_fops =
691 {
692         .owner =        THIS_MODULE,
693         .ioctl =        nbd_ioctl,
694 };
695
696 /*
697  * And here should be modules and kernel interface 
698  *  (Just smiley confuses emacs :-)
699  */
700
701 static int __init nbd_init(void)
702 {
703         int err = -ENOMEM;
704         int i;
705         int part_shift;
706
707         BUILD_BUG_ON(sizeof(struct nbd_request) != 28);
708
709         nbd_dev = kcalloc(nbds_max, sizeof(*nbd_dev), GFP_KERNEL);
710         if (!nbd_dev)
711                 return -ENOMEM;
712
713         if (max_part < 0) {
714                 printk(KERN_CRIT "nbd: max_part must be >= 0\n");
715                 return -EINVAL;
716         }
717
718         part_shift = 0;
719         if (max_part > 0)
720                 part_shift = fls(max_part);
721
722         for (i = 0; i < nbds_max; i++) {
723                 struct gendisk *disk = alloc_disk(1 << part_shift);
724                 elevator_t *old_e;
725                 if (!disk)
726                         goto out;
727                 nbd_dev[i].disk = disk;
728                 /*
729                  * The new linux 2.5 block layer implementation requires
730                  * every gendisk to have its very own request_queue struct.
731                  * These structs are big so we dynamically allocate them.
732                  */
733                 disk->queue = blk_init_queue(do_nbd_request, &nbd_lock);
734                 if (!disk->queue) {
735                         put_disk(disk);
736                         goto out;
737                 }
738                 old_e = disk->queue->elevator;
739                 if (elevator_init(disk->queue, "deadline") == 0 ||
740                         elevator_init(disk->queue, "noop") == 0) {
741                                 elevator_exit(old_e);
742                 }
743         }
744
745         if (register_blkdev(NBD_MAJOR, "nbd")) {
746                 err = -EIO;
747                 goto out;
748         }
749
750         printk(KERN_INFO "nbd: registered device at major %d\n", NBD_MAJOR);
751         dprintk(DBG_INIT, "nbd: debugflags=0x%x\n", debugflags);
752
753         for (i = 0; i < nbds_max; i++) {
754                 struct gendisk *disk = nbd_dev[i].disk;
755                 nbd_dev[i].file = NULL;
756                 nbd_dev[i].magic = LO_MAGIC;
757                 nbd_dev[i].flags = 0;
758                 INIT_LIST_HEAD(&nbd_dev[i].waiting_queue);
759                 spin_lock_init(&nbd_dev[i].queue_lock);
760                 INIT_LIST_HEAD(&nbd_dev[i].queue_head);
761                 mutex_init(&nbd_dev[i].tx_lock);
762                 init_waitqueue_head(&nbd_dev[i].active_wq);
763                 init_waitqueue_head(&nbd_dev[i].waiting_wq);
764                 nbd_dev[i].blksize = 1024;
765                 nbd_dev[i].bytesize = 0;
766                 disk->major = NBD_MAJOR;
767                 disk->first_minor = i << part_shift;
768                 disk->fops = &nbd_fops;
769                 disk->private_data = &nbd_dev[i];
770                 sprintf(disk->disk_name, "nbd%d", i);
771                 set_capacity(disk, 0);
772                 add_disk(disk);
773         }
774
775         return 0;
776 out:
777         while (i--) {
778                 blk_cleanup_queue(nbd_dev[i].disk->queue);
779                 put_disk(nbd_dev[i].disk);
780         }
781         return err;
782 }
783
784 static void __exit nbd_cleanup(void)
785 {
786         int i;
787         for (i = 0; i < nbds_max; i++) {
788                 struct gendisk *disk = nbd_dev[i].disk;
789                 nbd_dev[i].magic = 0;
790                 if (disk) {
791                         del_gendisk(disk);
792                         blk_cleanup_queue(disk->queue);
793                         put_disk(disk);
794                 }
795         }
796         unregister_blkdev(NBD_MAJOR, "nbd");
797         printk(KERN_INFO "nbd: unregistered device at major %d\n", NBD_MAJOR);
798 }
799
800 module_init(nbd_init);
801 module_exit(nbd_cleanup);
802
803 MODULE_DESCRIPTION("Network Block Device");
804 MODULE_LICENSE("GPL");
805
806 module_param(nbds_max, int, 0444);
807 MODULE_PARM_DESC(nbds_max, "number of network block devices to initialize (default: 16)");
808 module_param(max_part, int, 0444);
809 MODULE_PARM_DESC(max_part, "number of partitions per device (default: 0)");
810 #ifndef NDEBUG
811 module_param(debugflags, int, 0644);
812 MODULE_PARM_DESC(debugflags, "flags for controlling debug output");
813 #endif