Merge git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty-2.6
[firefly-linux-kernel-4.4.55.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, 2008 Pavel Machek <pavel@suse.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 <linux/slab.h>
31 #include <net/sock.h>
32 #include <linux/net.h>
33 #include <linux/kthread.h>
34
35 #include <asm/uaccess.h>
36 #include <asm/system.h>
37 #include <asm/types.h>
38
39 #include <linux/nbd.h>
40
41 #define LO_MAGIC 0x68797548
42
43 #ifdef NDEBUG
44 #define dprintk(flags, fmt...)
45 #else /* NDEBUG */
46 #define dprintk(flags, fmt...) do { \
47         if (debugflags & (flags)) printk(KERN_DEBUG fmt); \
48 } while (0)
49 #define DBG_IOCTL       0x0004
50 #define DBG_INIT        0x0010
51 #define DBG_EXIT        0x0020
52 #define DBG_BLKDEV      0x0100
53 #define DBG_RX          0x0200
54 #define DBG_TX          0x0400
55 static unsigned int debugflags;
56 #endif /* NDEBUG */
57
58 static unsigned int nbds_max = 16;
59 static struct nbd_device *nbd_dev;
60 static int max_part;
61
62 /*
63  * Use just one lock (or at most 1 per NIC). Two arguments for this:
64  * 1. Each NIC is essentially a synchronization point for all servers
65  *    accessed through that NIC so there's no need to have more locks
66  *    than NICs anyway.
67  * 2. More locks lead to more "Dirty cache line bouncing" which will slow
68  *    down each lock to the point where they're actually slower than just
69  *    a single lock.
70  * Thanks go to Jens Axboe and Al Viro for their LKML emails explaining this!
71  */
72 static DEFINE_SPINLOCK(nbd_lock);
73
74 #ifndef NDEBUG
75 static const char *ioctl_cmd_to_ascii(int cmd)
76 {
77         switch (cmd) {
78         case NBD_SET_SOCK: return "set-sock";
79         case NBD_SET_BLKSIZE: return "set-blksize";
80         case NBD_SET_SIZE: return "set-size";
81         case NBD_DO_IT: return "do-it";
82         case NBD_CLEAR_SOCK: return "clear-sock";
83         case NBD_CLEAR_QUE: return "clear-que";
84         case NBD_PRINT_DEBUG: return "print-debug";
85         case NBD_SET_SIZE_BLOCKS: return "set-size-blocks";
86         case NBD_DISCONNECT: return "disconnect";
87         case BLKROSET: return "set-read-only";
88         case BLKFLSBUF: return "flush-buffer-cache";
89         }
90         return "unknown";
91 }
92
93 static const char *nbdcmd_to_ascii(int cmd)
94 {
95         switch (cmd) {
96         case  NBD_CMD_READ: return "read";
97         case NBD_CMD_WRITE: return "write";
98         case  NBD_CMD_DISC: return "disconnect";
99         }
100         return "invalid";
101 }
102 #endif /* NDEBUG */
103
104 static void nbd_end_request(struct request *req)
105 {
106         int error = req->errors ? -EIO : 0;
107         struct request_queue *q = req->q;
108         unsigned long flags;
109
110         dprintk(DBG_BLKDEV, "%s: request %p: %s\n", req->rq_disk->disk_name,
111                         req, error ? "failed" : "done");
112
113         spin_lock_irqsave(q->queue_lock, flags);
114         __blk_end_request_all(req, error);
115         spin_unlock_irqrestore(q->queue_lock, flags);
116 }
117
118 static void sock_shutdown(struct nbd_device *lo, int lock)
119 {
120         /* Forcibly shutdown the socket causing all listeners
121          * to error
122          *
123          * FIXME: This code is duplicated from sys_shutdown, but
124          * there should be a more generic interface rather than
125          * calling socket ops directly here */
126         if (lock)
127                 mutex_lock(&lo->tx_lock);
128         if (lo->sock) {
129                 printk(KERN_WARNING "%s: shutting down socket\n",
130                         lo->disk->disk_name);
131                 kernel_sock_shutdown(lo->sock, SHUT_RDWR);
132                 lo->sock = NULL;
133         }
134         if (lock)
135                 mutex_unlock(&lo->tx_lock);
136 }
137
138 static void nbd_xmit_timeout(unsigned long arg)
139 {
140         struct task_struct *task = (struct task_struct *)arg;
141
142         printk(KERN_WARNING "nbd: killing hung xmit (%s, pid: %d)\n",
143                 task->comm, task->pid);
144         force_sig(SIGKILL, task);
145 }
146
147 /*
148  *  Send or receive packet.
149  */
150 static int sock_xmit(struct nbd_device *lo, int send, void *buf, int size,
151                 int msg_flags)
152 {
153         struct socket *sock = lo->sock;
154         int result;
155         struct msghdr msg;
156         struct kvec iov;
157         sigset_t blocked, oldset;
158
159         if (unlikely(!sock)) {
160                 printk(KERN_ERR "%s: Attempted %s on closed socket in sock_xmit\n",
161                        lo->disk->disk_name, (send ? "send" : "recv"));
162                 return -EINVAL;
163         }
164
165         /* Allow interception of SIGKILL only
166          * Don't allow other signals to interrupt the transmission */
167         siginitsetinv(&blocked, sigmask(SIGKILL));
168         sigprocmask(SIG_SETMASK, &blocked, &oldset);
169
170         do {
171                 sock->sk->sk_allocation = GFP_NOIO;
172                 iov.iov_base = buf;
173                 iov.iov_len = size;
174                 msg.msg_name = NULL;
175                 msg.msg_namelen = 0;
176                 msg.msg_control = NULL;
177                 msg.msg_controllen = 0;
178                 msg.msg_flags = msg_flags | MSG_NOSIGNAL;
179
180                 if (send) {
181                         struct timer_list ti;
182
183                         if (lo->xmit_timeout) {
184                                 init_timer(&ti);
185                                 ti.function = nbd_xmit_timeout;
186                                 ti.data = (unsigned long)current;
187                                 ti.expires = jiffies + lo->xmit_timeout;
188                                 add_timer(&ti);
189                         }
190                         result = kernel_sendmsg(sock, &msg, &iov, 1, size);
191                         if (lo->xmit_timeout)
192                                 del_timer_sync(&ti);
193                 } else
194                         result = kernel_recvmsg(sock, &msg, &iov, 1, size, 0);
195
196                 if (signal_pending(current)) {
197                         siginfo_t info;
198                         printk(KERN_WARNING "nbd (pid %d: %s) got signal %d\n",
199                                 task_pid_nr(current), current->comm,
200                                 dequeue_signal_lock(current, &current->blocked, &info));
201                         result = -EINTR;
202                         sock_shutdown(lo, !send);
203                         break;
204                 }
205
206                 if (result <= 0) {
207                         if (result == 0)
208                                 result = -EPIPE; /* short read */
209                         break;
210                 }
211                 size -= result;
212                 buf += result;
213         } while (size > 0);
214
215         sigprocmask(SIG_SETMASK, &oldset, NULL);
216
217         return result;
218 }
219
220 static inline int sock_send_bvec(struct nbd_device *lo, struct bio_vec *bvec,
221                 int flags)
222 {
223         int result;
224         void *kaddr = kmap(bvec->bv_page);
225         result = sock_xmit(lo, 1, kaddr + bvec->bv_offset, bvec->bv_len, flags);
226         kunmap(bvec->bv_page);
227         return result;
228 }
229
230 /* always call with the tx_lock held */
231 static int nbd_send_req(struct nbd_device *lo, struct request *req)
232 {
233         int result, flags;
234         struct nbd_request request;
235         unsigned long size = blk_rq_bytes(req);
236
237         request.magic = htonl(NBD_REQUEST_MAGIC);
238         request.type = htonl(nbd_cmd(req));
239         request.from = cpu_to_be64((u64)blk_rq_pos(req) << 9);
240         request.len = htonl(size);
241         memcpy(request.handle, &req, sizeof(req));
242
243         dprintk(DBG_TX, "%s: request %p: sending control (%s@%llu,%uB)\n",
244                         lo->disk->disk_name, req,
245                         nbdcmd_to_ascii(nbd_cmd(req)),
246                         (unsigned long long)blk_rq_pos(req) << 9,
247                         blk_rq_bytes(req));
248         result = sock_xmit(lo, 1, &request, sizeof(request),
249                         (nbd_cmd(req) == NBD_CMD_WRITE) ? MSG_MORE : 0);
250         if (result <= 0) {
251                 printk(KERN_ERR "%s: Send control failed (result %d)\n",
252                                 lo->disk->disk_name, result);
253                 goto error_out;
254         }
255
256         if (nbd_cmd(req) == NBD_CMD_WRITE) {
257                 struct req_iterator iter;
258                 struct bio_vec *bvec;
259                 /*
260                  * we are really probing at internals to determine
261                  * whether to set MSG_MORE or not...
262                  */
263                 rq_for_each_segment(bvec, req, iter) {
264                         flags = 0;
265                         if (!rq_iter_last(req, iter))
266                                 flags = MSG_MORE;
267                         dprintk(DBG_TX, "%s: request %p: sending %d bytes data\n",
268                                         lo->disk->disk_name, req, bvec->bv_len);
269                         result = sock_send_bvec(lo, bvec, flags);
270                         if (result <= 0) {
271                                 printk(KERN_ERR "%s: Send data failed (result %d)\n",
272                                                 lo->disk->disk_name, result);
273                                 goto error_out;
274                         }
275                 }
276         }
277         return 0;
278
279 error_out:
280         return -EIO;
281 }
282
283 static struct request *nbd_find_request(struct nbd_device *lo,
284                                         struct request *xreq)
285 {
286         struct request *req, *tmp;
287         int err;
288
289         err = wait_event_interruptible(lo->active_wq, lo->active_req != xreq);
290         if (unlikely(err))
291                 goto out;
292
293         spin_lock(&lo->queue_lock);
294         list_for_each_entry_safe(req, tmp, &lo->queue_head, queuelist) {
295                 if (req != xreq)
296                         continue;
297                 list_del_init(&req->queuelist);
298                 spin_unlock(&lo->queue_lock);
299                 return req;
300         }
301         spin_unlock(&lo->queue_lock);
302
303         err = -ENOENT;
304
305 out:
306         return ERR_PTR(err);
307 }
308
309 static inline int sock_recv_bvec(struct nbd_device *lo, struct bio_vec *bvec)
310 {
311         int result;
312         void *kaddr = kmap(bvec->bv_page);
313         result = sock_xmit(lo, 0, kaddr + bvec->bv_offset, bvec->bv_len,
314                         MSG_WAITALL);
315         kunmap(bvec->bv_page);
316         return result;
317 }
318
319 /* NULL returned = something went wrong, inform userspace */
320 static struct request *nbd_read_stat(struct nbd_device *lo)
321 {
322         int result;
323         struct nbd_reply reply;
324         struct request *req;
325
326         reply.magic = 0;
327         result = sock_xmit(lo, 0, &reply, sizeof(reply), MSG_WAITALL);
328         if (result <= 0) {
329                 printk(KERN_ERR "%s: Receive control failed (result %d)\n",
330                                 lo->disk->disk_name, result);
331                 goto harderror;
332         }
333
334         if (ntohl(reply.magic) != NBD_REPLY_MAGIC) {
335                 printk(KERN_ERR "%s: Wrong magic (0x%lx)\n",
336                                 lo->disk->disk_name,
337                                 (unsigned long)ntohl(reply.magic));
338                 result = -EPROTO;
339                 goto harderror;
340         }
341
342         req = nbd_find_request(lo, *(struct request **)reply.handle);
343         if (IS_ERR(req)) {
344                 result = PTR_ERR(req);
345                 if (result != -ENOENT)
346                         goto harderror;
347
348                 printk(KERN_ERR "%s: Unexpected reply (%p)\n",
349                                 lo->disk->disk_name, reply.handle);
350                 result = -EBADR;
351                 goto harderror;
352         }
353
354         if (ntohl(reply.error)) {
355                 printk(KERN_ERR "%s: Other side returned error (%d)\n",
356                                 lo->disk->disk_name, ntohl(reply.error));
357                 req->errors++;
358                 return req;
359         }
360
361         dprintk(DBG_RX, "%s: request %p: got reply\n",
362                         lo->disk->disk_name, req);
363         if (nbd_cmd(req) == NBD_CMD_READ) {
364                 struct req_iterator iter;
365                 struct bio_vec *bvec;
366
367                 rq_for_each_segment(bvec, req, iter) {
368                         result = sock_recv_bvec(lo, bvec);
369                         if (result <= 0) {
370                                 printk(KERN_ERR "%s: Receive data failed (result %d)\n",
371                                                 lo->disk->disk_name, result);
372                                 req->errors++;
373                                 return req;
374                         }
375                         dprintk(DBG_RX, "%s: request %p: got %d bytes data\n",
376                                 lo->disk->disk_name, req, bvec->bv_len);
377                 }
378         }
379         return req;
380 harderror:
381         lo->harderror = result;
382         return NULL;
383 }
384
385 static ssize_t pid_show(struct device *dev,
386                         struct device_attribute *attr, char *buf)
387 {
388         struct gendisk *disk = dev_to_disk(dev);
389
390         return sprintf(buf, "%ld\n",
391                 (long) ((struct nbd_device *)disk->private_data)->pid);
392 }
393
394 static struct device_attribute pid_attr = {
395         .attr = { .name = "pid", .mode = S_IRUGO},
396         .show = pid_show,
397 };
398
399 static int nbd_do_it(struct nbd_device *lo)
400 {
401         struct request *req;
402         int ret;
403
404         BUG_ON(lo->magic != LO_MAGIC);
405
406         lo->pid = current->pid;
407         ret = sysfs_create_file(&disk_to_dev(lo->disk)->kobj, &pid_attr.attr);
408         if (ret) {
409                 printk(KERN_ERR "nbd: sysfs_create_file failed!");
410                 lo->pid = 0;
411                 return ret;
412         }
413
414         while ((req = nbd_read_stat(lo)) != NULL)
415                 nbd_end_request(req);
416
417         sysfs_remove_file(&disk_to_dev(lo->disk)->kobj, &pid_attr.attr);
418         lo->pid = 0;
419         return 0;
420 }
421
422 static void nbd_clear_que(struct nbd_device *lo)
423 {
424         struct request *req;
425
426         BUG_ON(lo->magic != LO_MAGIC);
427
428         /*
429          * Because we have set lo->sock to NULL under the tx_lock, all
430          * modifications to the list must have completed by now.  For
431          * the same reason, the active_req must be NULL.
432          *
433          * As a consequence, we don't need to take the spin lock while
434          * purging the list here.
435          */
436         BUG_ON(lo->sock);
437         BUG_ON(lo->active_req);
438
439         while (!list_empty(&lo->queue_head)) {
440                 req = list_entry(lo->queue_head.next, struct request,
441                                  queuelist);
442                 list_del_init(&req->queuelist);
443                 req->errors++;
444                 nbd_end_request(req);
445         }
446 }
447
448
449 static void nbd_handle_req(struct nbd_device *lo, struct request *req)
450 {
451         if (!blk_fs_request(req))
452                 goto error_out;
453
454         nbd_cmd(req) = NBD_CMD_READ;
455         if (rq_data_dir(req) == WRITE) {
456                 nbd_cmd(req) = NBD_CMD_WRITE;
457                 if (lo->flags & NBD_READ_ONLY) {
458                         printk(KERN_ERR "%s: Write on read-only\n",
459                                         lo->disk->disk_name);
460                         goto error_out;
461                 }
462         }
463
464         req->errors = 0;
465
466         mutex_lock(&lo->tx_lock);
467         if (unlikely(!lo->sock)) {
468                 mutex_unlock(&lo->tx_lock);
469                 printk(KERN_ERR "%s: Attempted send on closed socket\n",
470                        lo->disk->disk_name);
471                 goto error_out;
472         }
473
474         lo->active_req = req;
475
476         if (nbd_send_req(lo, req) != 0) {
477                 printk(KERN_ERR "%s: Request send failed\n",
478                                 lo->disk->disk_name);
479                 req->errors++;
480                 nbd_end_request(req);
481         } else {
482                 spin_lock(&lo->queue_lock);
483                 list_add(&req->queuelist, &lo->queue_head);
484                 spin_unlock(&lo->queue_lock);
485         }
486
487         lo->active_req = NULL;
488         mutex_unlock(&lo->tx_lock);
489         wake_up_all(&lo->active_wq);
490
491         return;
492
493 error_out:
494         req->errors++;
495         nbd_end_request(req);
496 }
497
498 static int nbd_thread(void *data)
499 {
500         struct nbd_device *lo = data;
501         struct request *req;
502
503         set_user_nice(current, -20);
504         while (!kthread_should_stop() || !list_empty(&lo->waiting_queue)) {
505                 /* wait for something to do */
506                 wait_event_interruptible(lo->waiting_wq,
507                                          kthread_should_stop() ||
508                                          !list_empty(&lo->waiting_queue));
509
510                 /* extract request */
511                 if (list_empty(&lo->waiting_queue))
512                         continue;
513
514                 spin_lock_irq(&lo->queue_lock);
515                 req = list_entry(lo->waiting_queue.next, struct request,
516                                  queuelist);
517                 list_del_init(&req->queuelist);
518                 spin_unlock_irq(&lo->queue_lock);
519
520                 /* handle request */
521                 nbd_handle_req(lo, req);
522         }
523         return 0;
524 }
525
526 /*
527  * We always wait for result of write, for now. It would be nice to make it optional
528  * in future
529  * if ((rq_data_dir(req) == WRITE) && (lo->flags & NBD_WRITE_NOCHK))
530  *   { printk( "Warning: Ignoring result!\n"); nbd_end_request( req ); }
531  */
532
533 static void do_nbd_request(struct request_queue *q)
534 {
535         struct request *req;
536         
537         while ((req = blk_fetch_request(q)) != NULL) {
538                 struct nbd_device *lo;
539
540                 spin_unlock_irq(q->queue_lock);
541
542                 dprintk(DBG_BLKDEV, "%s: request %p: dequeued (flags=%x)\n",
543                                 req->rq_disk->disk_name, req, req->cmd_type);
544
545                 lo = req->rq_disk->private_data;
546
547                 BUG_ON(lo->magic != LO_MAGIC);
548
549                 if (unlikely(!lo->sock)) {
550                         printk(KERN_ERR "%s: Attempted send on closed socket\n",
551                                 lo->disk->disk_name);
552                         req->errors++;
553                         nbd_end_request(req);
554                         spin_lock_irq(q->queue_lock);
555                         continue;
556                 }
557
558                 spin_lock_irq(&lo->queue_lock);
559                 list_add_tail(&req->queuelist, &lo->waiting_queue);
560                 spin_unlock_irq(&lo->queue_lock);
561
562                 wake_up(&lo->waiting_wq);
563
564                 spin_lock_irq(q->queue_lock);
565         }
566 }
567
568 /* Must be called with tx_lock held */
569
570 static int __nbd_ioctl(struct block_device *bdev, struct nbd_device *lo,
571                        unsigned int cmd, unsigned long arg)
572 {
573         switch (cmd) {
574         case NBD_DISCONNECT: {
575                 struct request sreq;
576
577                 printk(KERN_INFO "%s: NBD_DISCONNECT\n", lo->disk->disk_name);
578
579                 blk_rq_init(NULL, &sreq);
580                 sreq.cmd_type = REQ_TYPE_SPECIAL;
581                 nbd_cmd(&sreq) = NBD_CMD_DISC;
582                 if (!lo->sock)
583                         return -EINVAL;
584                 nbd_send_req(lo, &sreq);
585                 return 0;
586         }
587  
588         case NBD_CLEAR_SOCK: {
589                 struct file *file;
590
591                 lo->sock = NULL;
592                 file = lo->file;
593                 lo->file = NULL;
594                 nbd_clear_que(lo);
595                 BUG_ON(!list_empty(&lo->queue_head));
596                 if (file)
597                         fput(file);
598                 return 0;
599         }
600
601         case NBD_SET_SOCK: {
602                 struct file *file;
603                 if (lo->file)
604                         return -EBUSY;
605                 file = fget(arg);
606                 if (file) {
607                         struct inode *inode = file->f_path.dentry->d_inode;
608                         if (S_ISSOCK(inode->i_mode)) {
609                                 lo->file = file;
610                                 lo->sock = SOCKET_I(inode);
611                                 if (max_part > 0)
612                                         bdev->bd_invalidated = 1;
613                                 return 0;
614                         } else {
615                                 fput(file);
616                         }
617                 }
618                 return -EINVAL;
619         }
620
621         case NBD_SET_BLKSIZE:
622                 lo->blksize = arg;
623                 lo->bytesize &= ~(lo->blksize-1);
624                 bdev->bd_inode->i_size = lo->bytesize;
625                 set_blocksize(bdev, lo->blksize);
626                 set_capacity(lo->disk, lo->bytesize >> 9);
627                 return 0;
628
629         case NBD_SET_SIZE:
630                 lo->bytesize = arg & ~(lo->blksize-1);
631                 bdev->bd_inode->i_size = lo->bytesize;
632                 set_blocksize(bdev, lo->blksize);
633                 set_capacity(lo->disk, lo->bytesize >> 9);
634                 return 0;
635
636         case NBD_SET_TIMEOUT:
637                 lo->xmit_timeout = arg * HZ;
638                 return 0;
639
640         case NBD_SET_SIZE_BLOCKS:
641                 lo->bytesize = ((u64) arg) * lo->blksize;
642                 bdev->bd_inode->i_size = lo->bytesize;
643                 set_blocksize(bdev, lo->blksize);
644                 set_capacity(lo->disk, lo->bytesize >> 9);
645                 return 0;
646
647         case NBD_DO_IT: {
648                 struct task_struct *thread;
649                 struct file *file;
650                 int error;
651
652                 if (lo->pid)
653                         return -EBUSY;
654                 if (!lo->file)
655                         return -EINVAL;
656
657                 mutex_unlock(&lo->tx_lock);
658
659                 thread = kthread_create(nbd_thread, lo, lo->disk->disk_name);
660                 if (IS_ERR(thread)) {
661                         mutex_lock(&lo->tx_lock);
662                         return PTR_ERR(thread);
663                 }
664                 wake_up_process(thread);
665                 error = nbd_do_it(lo);
666                 kthread_stop(thread);
667
668                 mutex_lock(&lo->tx_lock);
669                 if (error)
670                         return error;
671                 sock_shutdown(lo, 0);
672                 file = lo->file;
673                 lo->file = NULL;
674                 nbd_clear_que(lo);
675                 printk(KERN_WARNING "%s: queue cleared\n", lo->disk->disk_name);
676                 if (file)
677                         fput(file);
678                 lo->bytesize = 0;
679                 bdev->bd_inode->i_size = 0;
680                 set_capacity(lo->disk, 0);
681                 if (max_part > 0)
682                         ioctl_by_bdev(bdev, BLKRRPART, 0);
683                 return lo->harderror;
684         }
685
686         case NBD_CLEAR_QUE:
687                 /*
688                  * This is for compatibility only.  The queue is always cleared
689                  * by NBD_DO_IT or NBD_CLEAR_SOCK.
690                  */
691                 BUG_ON(!lo->sock && !list_empty(&lo->queue_head));
692                 return 0;
693
694         case NBD_PRINT_DEBUG:
695                 printk(KERN_INFO "%s: next = %p, prev = %p, head = %p\n",
696                         bdev->bd_disk->disk_name,
697                         lo->queue_head.next, lo->queue_head.prev,
698                         &lo->queue_head);
699                 return 0;
700         }
701         return -ENOTTY;
702 }
703
704 static int nbd_ioctl(struct block_device *bdev, fmode_t mode,
705                      unsigned int cmd, unsigned long arg)
706 {
707         struct nbd_device *lo = bdev->bd_disk->private_data;
708         int error;
709
710         if (!capable(CAP_SYS_ADMIN))
711                 return -EPERM;
712
713         BUG_ON(lo->magic != LO_MAGIC);
714
715         /* Anyone capable of this syscall can do *real bad* things */
716         dprintk(DBG_IOCTL, "%s: nbd_ioctl cmd=%s(0x%x) arg=%lu\n",
717                         lo->disk->disk_name, ioctl_cmd_to_ascii(cmd), cmd, arg);
718
719         mutex_lock(&lo->tx_lock);
720         error = __nbd_ioctl(bdev, lo, cmd, arg);
721         mutex_unlock(&lo->tx_lock);
722
723         return error;
724 }
725
726 static const struct block_device_operations nbd_fops =
727 {
728         .owner =        THIS_MODULE,
729         .locked_ioctl = nbd_ioctl,
730 };
731
732 /*
733  * And here should be modules and kernel interface 
734  *  (Just smiley confuses emacs :-)
735  */
736
737 static int __init nbd_init(void)
738 {
739         int err = -ENOMEM;
740         int i;
741         int part_shift;
742
743         BUILD_BUG_ON(sizeof(struct nbd_request) != 28);
744
745         if (max_part < 0) {
746                 printk(KERN_CRIT "nbd: max_part must be >= 0\n");
747                 return -EINVAL;
748         }
749
750         nbd_dev = kcalloc(nbds_max, sizeof(*nbd_dev), GFP_KERNEL);
751         if (!nbd_dev)
752                 return -ENOMEM;
753
754         part_shift = 0;
755         if (max_part > 0)
756                 part_shift = fls(max_part);
757
758         for (i = 0; i < nbds_max; i++) {
759                 struct gendisk *disk = alloc_disk(1 << part_shift);
760                 if (!disk)
761                         goto out;
762                 nbd_dev[i].disk = disk;
763                 /*
764                  * The new linux 2.5 block layer implementation requires
765                  * every gendisk to have its very own request_queue struct.
766                  * These structs are big so we dynamically allocate them.
767                  */
768                 disk->queue = blk_init_queue(do_nbd_request, &nbd_lock);
769                 if (!disk->queue) {
770                         put_disk(disk);
771                         goto out;
772                 }
773                 /*
774                  * Tell the block layer that we are not a rotational device
775                  */
776                 queue_flag_set_unlocked(QUEUE_FLAG_NONROT, disk->queue);
777         }
778
779         if (register_blkdev(NBD_MAJOR, "nbd")) {
780                 err = -EIO;
781                 goto out;
782         }
783
784         printk(KERN_INFO "nbd: registered device at major %d\n", NBD_MAJOR);
785         dprintk(DBG_INIT, "nbd: debugflags=0x%x\n", debugflags);
786
787         for (i = 0; i < nbds_max; i++) {
788                 struct gendisk *disk = nbd_dev[i].disk;
789                 nbd_dev[i].file = NULL;
790                 nbd_dev[i].magic = LO_MAGIC;
791                 nbd_dev[i].flags = 0;
792                 INIT_LIST_HEAD(&nbd_dev[i].waiting_queue);
793                 spin_lock_init(&nbd_dev[i].queue_lock);
794                 INIT_LIST_HEAD(&nbd_dev[i].queue_head);
795                 mutex_init(&nbd_dev[i].tx_lock);
796                 init_waitqueue_head(&nbd_dev[i].active_wq);
797                 init_waitqueue_head(&nbd_dev[i].waiting_wq);
798                 nbd_dev[i].blksize = 1024;
799                 nbd_dev[i].bytesize = 0;
800                 disk->major = NBD_MAJOR;
801                 disk->first_minor = i << part_shift;
802                 disk->fops = &nbd_fops;
803                 disk->private_data = &nbd_dev[i];
804                 sprintf(disk->disk_name, "nbd%d", i);
805                 set_capacity(disk, 0);
806                 add_disk(disk);
807         }
808
809         return 0;
810 out:
811         while (i--) {
812                 blk_cleanup_queue(nbd_dev[i].disk->queue);
813                 put_disk(nbd_dev[i].disk);
814         }
815         kfree(nbd_dev);
816         return err;
817 }
818
819 static void __exit nbd_cleanup(void)
820 {
821         int i;
822         for (i = 0; i < nbds_max; i++) {
823                 struct gendisk *disk = nbd_dev[i].disk;
824                 nbd_dev[i].magic = 0;
825                 if (disk) {
826                         del_gendisk(disk);
827                         blk_cleanup_queue(disk->queue);
828                         put_disk(disk);
829                 }
830         }
831         unregister_blkdev(NBD_MAJOR, "nbd");
832         kfree(nbd_dev);
833         printk(KERN_INFO "nbd: unregistered device at major %d\n", NBD_MAJOR);
834 }
835
836 module_init(nbd_init);
837 module_exit(nbd_cleanup);
838
839 MODULE_DESCRIPTION("Network Block Device");
840 MODULE_LICENSE("GPL");
841
842 module_param(nbds_max, int, 0444);
843 MODULE_PARM_DESC(nbds_max, "number of network block devices to initialize (default: 16)");
844 module_param(max_part, int, 0444);
845 MODULE_PARM_DESC(max_part, "number of partitions per device (default: 0)");
846 #ifndef NDEBUG
847 module_param(debugflags, int, 0644);
848 MODULE_PARM_DESC(debugflags, "flags for controlling debug output");
849 #endif