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@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/mutex.h>
28 #include <linux/compiler.h>
29 #include <linux/err.h>
30 #include <linux/kernel.h>
31 #include <linux/slab.h>
32 #include <net/sock.h>
33 #include <linux/net.h>
34 #include <linux/kthread.h>
35
36 #include <asm/uaccess.h>
37 #include <asm/system.h>
38 #include <asm/types.h>
39
40 #include <linux/nbd.h>
41
42 #define LO_MAGIC 0x68797548
43
44 #ifdef NDEBUG
45 #define dprintk(flags, fmt...)
46 #else /* NDEBUG */
47 #define dprintk(flags, fmt...) do { \
48 if (debugflags & (flags)) printk(KERN_DEBUG fmt); \
49 } while (0)
50 #define DBG_IOCTL 0x0004
51 #define DBG_INIT 0x0010
52 #define DBG_EXIT 0x0020
53 #define DBG_BLKDEV 0x0100
54 #define DBG_RX 0x0200
55 #define DBG_TX 0x0400
56 static unsigned int debugflags;
57 #endif /* NDEBUG */
58
59 static unsigned int nbds_max = 16;
60 static struct nbd_device *nbd_dev;
61 static int max_part;
62
63 /*
64 * Use just one lock (or at most 1 per NIC). Two arguments for this:
65 * 1. Each NIC is essentially a synchronization point for all servers
66 * accessed through that NIC so there's no need to have more locks
67 * than NICs anyway.
68 * 2. More locks lead to more "Dirty cache line bouncing" which will slow
69 * down each lock to the point where they're actually slower than just
70 * a single lock.
71 * Thanks go to Jens Axboe and Al Viro for their LKML emails explaining this!
72 */
73 static DEFINE_SPINLOCK(nbd_lock);
74
75 #ifndef NDEBUG
ioctl_cmd_to_ascii(int cmd)76 static const char *ioctl_cmd_to_ascii(int cmd)
77 {
78 switch (cmd) {
79 case NBD_SET_SOCK: return "set-sock";
80 case NBD_SET_BLKSIZE: return "set-blksize";
81 case NBD_SET_SIZE: return "set-size";
82 case NBD_DO_IT: return "do-it";
83 case NBD_CLEAR_SOCK: return "clear-sock";
84 case NBD_CLEAR_QUE: return "clear-que";
85 case NBD_PRINT_DEBUG: return "print-debug";
86 case NBD_SET_SIZE_BLOCKS: return "set-size-blocks";
87 case NBD_DISCONNECT: return "disconnect";
88 case BLKROSET: return "set-read-only";
89 case BLKFLSBUF: return "flush-buffer-cache";
90 }
91 return "unknown";
92 }
93
nbdcmd_to_ascii(int cmd)94 static const char *nbdcmd_to_ascii(int cmd)
95 {
96 switch (cmd) {
97 case NBD_CMD_READ: return "read";
98 case NBD_CMD_WRITE: return "write";
99 case NBD_CMD_DISC: return "disconnect";
100 }
101 return "invalid";
102 }
103 #endif /* NDEBUG */
104
nbd_end_request(struct request * req)105 static void nbd_end_request(struct request *req)
106 {
107 int error = req->errors ? -EIO : 0;
108 struct request_queue *q = req->q;
109 unsigned long flags;
110
111 dprintk(DBG_BLKDEV, "%s: request %p: %s\n", req->rq_disk->disk_name,
112 req, error ? "failed" : "done");
113
114 spin_lock_irqsave(q->queue_lock, flags);
115 __blk_end_request_all(req, error);
116 spin_unlock_irqrestore(q->queue_lock, flags);
117 }
118
sock_shutdown(struct nbd_device * lo,int lock)119 static void sock_shutdown(struct nbd_device *lo, int lock)
120 {
121 /* Forcibly shutdown the socket causing all listeners
122 * to error
123 *
124 * FIXME: This code is duplicated from sys_shutdown, but
125 * there should be a more generic interface rather than
126 * calling socket ops directly here */
127 if (lock)
128 mutex_lock(&lo->tx_lock);
129 if (lo->sock) {
130 printk(KERN_WARNING "%s: shutting down socket\n",
131 lo->disk->disk_name);
132 kernel_sock_shutdown(lo->sock, SHUT_RDWR);
133 lo->sock = NULL;
134 }
135 if (lock)
136 mutex_unlock(&lo->tx_lock);
137 }
138
nbd_xmit_timeout(unsigned long arg)139 static void nbd_xmit_timeout(unsigned long arg)
140 {
141 struct task_struct *task = (struct task_struct *)arg;
142
143 printk(KERN_WARNING "nbd: killing hung xmit (%s, pid: %d)\n",
144 task->comm, task->pid);
145 force_sig(SIGKILL, task);
146 }
147
148 /*
149 * Send or receive packet.
150 */
sock_xmit(struct nbd_device * lo,int send,void * buf,int size,int msg_flags)151 static int sock_xmit(struct nbd_device *lo, int send, void *buf, int size,
152 int msg_flags)
153 {
154 struct socket *sock = lo->sock;
155 int result;
156 struct msghdr msg;
157 struct kvec iov;
158 sigset_t blocked, oldset;
159
160 if (unlikely(!sock)) {
161 printk(KERN_ERR "%s: Attempted %s on closed socket in sock_xmit\n",
162 lo->disk->disk_name, (send ? "send" : "recv"));
163 return -EINVAL;
164 }
165
166 /* Allow interception of SIGKILL only
167 * Don't allow other signals to interrupt the transmission */
168 siginitsetinv(&blocked, sigmask(SIGKILL));
169 sigprocmask(SIG_SETMASK, &blocked, &oldset);
170
171 do {
172 sock->sk->sk_allocation = GFP_NOIO;
173 iov.iov_base = buf;
174 iov.iov_len = size;
175 msg.msg_name = NULL;
176 msg.msg_namelen = 0;
177 msg.msg_control = NULL;
178 msg.msg_controllen = 0;
179 msg.msg_flags = msg_flags | MSG_NOSIGNAL;
180
181 if (send) {
182 struct timer_list ti;
183
184 if (lo->xmit_timeout) {
185 init_timer(&ti);
186 ti.function = nbd_xmit_timeout;
187 ti.data = (unsigned long)current;
188 ti.expires = jiffies + lo->xmit_timeout;
189 add_timer(&ti);
190 }
191 result = kernel_sendmsg(sock, &msg, &iov, 1, size);
192 if (lo->xmit_timeout)
193 del_timer_sync(&ti);
194 } else
195 result = kernel_recvmsg(sock, &msg, &iov, 1, size, 0);
196
197 if (signal_pending(current)) {
198 siginfo_t info;
199 printk(KERN_WARNING "nbd (pid %d: %s) got signal %d\n",
200 task_pid_nr(current), current->comm,
201 dequeue_signal_lock(current, ¤t->blocked, &info));
202 result = -EINTR;
203 sock_shutdown(lo, !send);
204 break;
205 }
206
207 if (result <= 0) {
208 if (result == 0)
209 result = -EPIPE; /* short read */
210 break;
211 }
212 size -= result;
213 buf += result;
214 } while (size > 0);
215
216 sigprocmask(SIG_SETMASK, &oldset, NULL);
217
218 return result;
219 }
220
sock_send_bvec(struct nbd_device * lo,struct bio_vec * bvec,int flags)221 static inline int sock_send_bvec(struct nbd_device *lo, struct bio_vec *bvec,
222 int flags)
223 {
224 int result;
225 void *kaddr = kmap(bvec->bv_page);
226 result = sock_xmit(lo, 1, kaddr + bvec->bv_offset, bvec->bv_len, flags);
227 kunmap(bvec->bv_page);
228 return result;
229 }
230
231 /* always call with the tx_lock held */
nbd_send_req(struct nbd_device * lo,struct request * req)232 static int nbd_send_req(struct nbd_device *lo, struct request *req)
233 {
234 int result, flags;
235 struct nbd_request request;
236 unsigned long size = blk_rq_bytes(req);
237
238 request.magic = htonl(NBD_REQUEST_MAGIC);
239 request.type = htonl(nbd_cmd(req));
240 request.from = cpu_to_be64((u64)blk_rq_pos(req) << 9);
241 request.len = htonl(size);
242 memcpy(request.handle, &req, sizeof(req));
243
244 dprintk(DBG_TX, "%s: request %p: sending control (%s@%llu,%uB)\n",
245 lo->disk->disk_name, req,
246 nbdcmd_to_ascii(nbd_cmd(req)),
247 (unsigned long long)blk_rq_pos(req) << 9,
248 blk_rq_bytes(req));
249 result = sock_xmit(lo, 1, &request, sizeof(request),
250 (nbd_cmd(req) == NBD_CMD_WRITE) ? MSG_MORE : 0);
251 if (result <= 0) {
252 printk(KERN_ERR "%s: Send control failed (result %d)\n",
253 lo->disk->disk_name, result);
254 goto error_out;
255 }
256
257 if (nbd_cmd(req) == NBD_CMD_WRITE) {
258 struct req_iterator iter;
259 struct bio_vec *bvec;
260 /*
261 * we are really probing at internals to determine
262 * whether to set MSG_MORE or not...
263 */
264 rq_for_each_segment(bvec, req, iter) {
265 flags = 0;
266 if (!rq_iter_last(req, iter))
267 flags = MSG_MORE;
268 dprintk(DBG_TX, "%s: request %p: sending %d bytes data\n",
269 lo->disk->disk_name, req, bvec->bv_len);
270 result = sock_send_bvec(lo, bvec, flags);
271 if (result <= 0) {
272 printk(KERN_ERR "%s: Send data failed (result %d)\n",
273 lo->disk->disk_name, result);
274 goto error_out;
275 }
276 }
277 }
278 return 0;
279
280 error_out:
281 return -EIO;
282 }
283
nbd_find_request(struct nbd_device * lo,struct request * xreq)284 static struct request *nbd_find_request(struct nbd_device *lo,
285 struct request *xreq)
286 {
287 struct request *req, *tmp;
288 int err;
289
290 err = wait_event_interruptible(lo->active_wq, lo->active_req != xreq);
291 if (unlikely(err))
292 goto out;
293
294 spin_lock(&lo->queue_lock);
295 list_for_each_entry_safe(req, tmp, &lo->queue_head, queuelist) {
296 if (req != xreq)
297 continue;
298 list_del_init(&req->queuelist);
299 spin_unlock(&lo->queue_lock);
300 return req;
301 }
302 spin_unlock(&lo->queue_lock);
303
304 err = -ENOENT;
305
306 out:
307 return ERR_PTR(err);
308 }
309
sock_recv_bvec(struct nbd_device * lo,struct bio_vec * bvec)310 static inline int sock_recv_bvec(struct nbd_device *lo, struct bio_vec *bvec)
311 {
312 int result;
313 void *kaddr = kmap(bvec->bv_page);
314 result = sock_xmit(lo, 0, kaddr + bvec->bv_offset, bvec->bv_len,
315 MSG_WAITALL);
316 kunmap(bvec->bv_page);
317 return result;
318 }
319
320 /* NULL returned = something went wrong, inform userspace */
nbd_read_stat(struct nbd_device * lo)321 static struct request *nbd_read_stat(struct nbd_device *lo)
322 {
323 int result;
324 struct nbd_reply reply;
325 struct request *req;
326
327 reply.magic = 0;
328 result = sock_xmit(lo, 0, &reply, sizeof(reply), MSG_WAITALL);
329 if (result <= 0) {
330 printk(KERN_ERR "%s: Receive control failed (result %d)\n",
331 lo->disk->disk_name, result);
332 goto harderror;
333 }
334
335 if (ntohl(reply.magic) != NBD_REPLY_MAGIC) {
336 printk(KERN_ERR "%s: Wrong magic (0x%lx)\n",
337 lo->disk->disk_name,
338 (unsigned long)ntohl(reply.magic));
339 result = -EPROTO;
340 goto harderror;
341 }
342
343 req = nbd_find_request(lo, *(struct request **)reply.handle);
344 if (IS_ERR(req)) {
345 result = PTR_ERR(req);
346 if (result != -ENOENT)
347 goto harderror;
348
349 printk(KERN_ERR "%s: Unexpected reply (%p)\n",
350 lo->disk->disk_name, reply.handle);
351 result = -EBADR;
352 goto harderror;
353 }
354
355 if (ntohl(reply.error)) {
356 printk(KERN_ERR "%s: Other side returned error (%d)\n",
357 lo->disk->disk_name, ntohl(reply.error));
358 req->errors++;
359 return req;
360 }
361
362 dprintk(DBG_RX, "%s: request %p: got reply\n",
363 lo->disk->disk_name, req);
364 if (nbd_cmd(req) == NBD_CMD_READ) {
365 struct req_iterator iter;
366 struct bio_vec *bvec;
367
368 rq_for_each_segment(bvec, req, iter) {
369 result = sock_recv_bvec(lo, bvec);
370 if (result <= 0) {
371 printk(KERN_ERR "%s: Receive data failed (result %d)\n",
372 lo->disk->disk_name, result);
373 req->errors++;
374 return req;
375 }
376 dprintk(DBG_RX, "%s: request %p: got %d bytes data\n",
377 lo->disk->disk_name, req, bvec->bv_len);
378 }
379 }
380 return req;
381 harderror:
382 lo->harderror = result;
383 return NULL;
384 }
385
pid_show(struct device * dev,struct device_attribute * attr,char * buf)386 static ssize_t pid_show(struct device *dev,
387 struct device_attribute *attr, char *buf)
388 {
389 struct gendisk *disk = dev_to_disk(dev);
390
391 return sprintf(buf, "%ld\n",
392 (long) ((struct nbd_device *)disk->private_data)->pid);
393 }
394
395 static struct device_attribute pid_attr = {
396 .attr = { .name = "pid", .mode = S_IRUGO},
397 .show = pid_show,
398 };
399
nbd_do_it(struct nbd_device * lo)400 static int nbd_do_it(struct nbd_device *lo)
401 {
402 struct request *req;
403 int ret;
404
405 BUG_ON(lo->magic != LO_MAGIC);
406
407 lo->pid = current->pid;
408 ret = sysfs_create_file(&disk_to_dev(lo->disk)->kobj, &pid_attr.attr);
409 if (ret) {
410 printk(KERN_ERR "nbd: sysfs_create_file failed!");
411 lo->pid = 0;
412 return ret;
413 }
414
415 while ((req = nbd_read_stat(lo)) != NULL)
416 nbd_end_request(req);
417
418 sysfs_remove_file(&disk_to_dev(lo->disk)->kobj, &pid_attr.attr);
419 lo->pid = 0;
420 return 0;
421 }
422
nbd_clear_que(struct nbd_device * lo)423 static void nbd_clear_que(struct nbd_device *lo)
424 {
425 struct request *req;
426
427 BUG_ON(lo->magic != LO_MAGIC);
428
429 /*
430 * Because we have set lo->sock to NULL under the tx_lock, all
431 * modifications to the list must have completed by now. For
432 * the same reason, the active_req must be NULL.
433 *
434 * As a consequence, we don't need to take the spin lock while
435 * purging the list here.
436 */
437 BUG_ON(lo->sock);
438 BUG_ON(lo->active_req);
439
440 while (!list_empty(&lo->queue_head)) {
441 req = list_entry(lo->queue_head.next, struct request,
442 queuelist);
443 list_del_init(&req->queuelist);
444 req->errors++;
445 nbd_end_request(req);
446 }
447 }
448
449
nbd_handle_req(struct nbd_device * lo,struct request * req)450 static void nbd_handle_req(struct nbd_device *lo, struct request *req)
451 {
452 if (req->cmd_type != REQ_TYPE_FS)
453 goto error_out;
454
455 nbd_cmd(req) = NBD_CMD_READ;
456 if (rq_data_dir(req) == WRITE) {
457 nbd_cmd(req) = NBD_CMD_WRITE;
458 if (lo->flags & NBD_READ_ONLY) {
459 printk(KERN_ERR "%s: Write on read-only\n",
460 lo->disk->disk_name);
461 goto error_out;
462 }
463 }
464
465 req->errors = 0;
466
467 mutex_lock(&lo->tx_lock);
468 if (unlikely(!lo->sock)) {
469 mutex_unlock(&lo->tx_lock);
470 printk(KERN_ERR "%s: Attempted send on closed socket\n",
471 lo->disk->disk_name);
472 goto error_out;
473 }
474
475 lo->active_req = req;
476
477 if (nbd_send_req(lo, req) != 0) {
478 printk(KERN_ERR "%s: Request send failed\n",
479 lo->disk->disk_name);
480 req->errors++;
481 nbd_end_request(req);
482 } else {
483 spin_lock(&lo->queue_lock);
484 list_add(&req->queuelist, &lo->queue_head);
485 spin_unlock(&lo->queue_lock);
486 }
487
488 lo->active_req = NULL;
489 mutex_unlock(&lo->tx_lock);
490 wake_up_all(&lo->active_wq);
491
492 return;
493
494 error_out:
495 req->errors++;
496 nbd_end_request(req);
497 }
498
nbd_thread(void * data)499 static int nbd_thread(void *data)
500 {
501 struct nbd_device *lo = data;
502 struct request *req;
503
504 set_user_nice(current, -20);
505 while (!kthread_should_stop() || !list_empty(&lo->waiting_queue)) {
506 /* wait for something to do */
507 wait_event_interruptible(lo->waiting_wq,
508 kthread_should_stop() ||
509 !list_empty(&lo->waiting_queue));
510
511 /* extract request */
512 if (list_empty(&lo->waiting_queue))
513 continue;
514
515 spin_lock_irq(&lo->queue_lock);
516 req = list_entry(lo->waiting_queue.next, struct request,
517 queuelist);
518 list_del_init(&req->queuelist);
519 spin_unlock_irq(&lo->queue_lock);
520
521 /* handle request */
522 nbd_handle_req(lo, req);
523 }
524 return 0;
525 }
526
527 /*
528 * We always wait for result of write, for now. It would be nice to make it optional
529 * in future
530 * if ((rq_data_dir(req) == WRITE) && (lo->flags & NBD_WRITE_NOCHK))
531 * { printk( "Warning: Ignoring result!\n"); nbd_end_request( req ); }
532 */
533
do_nbd_request(struct request_queue * q)534 static void do_nbd_request(struct request_queue *q)
535 {
536 struct request *req;
537
538 while ((req = blk_fetch_request(q)) != NULL) {
539 struct nbd_device *lo;
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 if (unlikely(!lo->sock)) {
551 printk(KERN_ERR "%s: Attempted send on closed socket\n",
552 lo->disk->disk_name);
553 req->errors++;
554 nbd_end_request(req);
555 spin_lock_irq(q->queue_lock);
556 continue;
557 }
558
559 spin_lock_irq(&lo->queue_lock);
560 list_add_tail(&req->queuelist, &lo->waiting_queue);
561 spin_unlock_irq(&lo->queue_lock);
562
563 wake_up(&lo->waiting_wq);
564
565 spin_lock_irq(q->queue_lock);
566 }
567 }
568
569 /* Must be called with tx_lock held */
570
__nbd_ioctl(struct block_device * bdev,struct nbd_device * lo,unsigned int cmd,unsigned long arg)571 static int __nbd_ioctl(struct block_device *bdev, struct nbd_device *lo,
572 unsigned int cmd, unsigned long arg)
573 {
574 switch (cmd) {
575 case NBD_DISCONNECT: {
576 struct request sreq;
577
578 printk(KERN_INFO "%s: NBD_DISCONNECT\n", lo->disk->disk_name);
579
580 blk_rq_init(NULL, &sreq);
581 sreq.cmd_type = REQ_TYPE_SPECIAL;
582 nbd_cmd(&sreq) = NBD_CMD_DISC;
583 if (!lo->sock)
584 return -EINVAL;
585 nbd_send_req(lo, &sreq);
586 return 0;
587 }
588
589 case NBD_CLEAR_SOCK: {
590 struct file *file;
591
592 lo->sock = NULL;
593 file = lo->file;
594 lo->file = NULL;
595 nbd_clear_que(lo);
596 BUG_ON(!list_empty(&lo->queue_head));
597 if (file)
598 fput(file);
599 return 0;
600 }
601
602 case NBD_SET_SOCK: {
603 struct file *file;
604 if (lo->file)
605 return -EBUSY;
606 file = fget(arg);
607 if (file) {
608 struct inode *inode = file->f_path.dentry->d_inode;
609 if (S_ISSOCK(inode->i_mode)) {
610 lo->file = file;
611 lo->sock = SOCKET_I(inode);
612 if (max_part > 0)
613 bdev->bd_invalidated = 1;
614 return 0;
615 } else {
616 fput(file);
617 }
618 }
619 return -EINVAL;
620 }
621
622 case NBD_SET_BLKSIZE:
623 lo->blksize = arg;
624 lo->bytesize &= ~(lo->blksize-1);
625 bdev->bd_inode->i_size = lo->bytesize;
626 set_blocksize(bdev, lo->blksize);
627 set_capacity(lo->disk, lo->bytesize >> 9);
628 return 0;
629
630 case NBD_SET_SIZE:
631 lo->bytesize = arg & ~(lo->blksize-1);
632 bdev->bd_inode->i_size = lo->bytesize;
633 set_blocksize(bdev, lo->blksize);
634 set_capacity(lo->disk, lo->bytesize >> 9);
635 return 0;
636
637 case NBD_SET_TIMEOUT:
638 lo->xmit_timeout = arg * HZ;
639 return 0;
640
641 case NBD_SET_SIZE_BLOCKS:
642 lo->bytesize = ((u64) arg) * lo->blksize;
643 bdev->bd_inode->i_size = lo->bytesize;
644 set_blocksize(bdev, lo->blksize);
645 set_capacity(lo->disk, lo->bytesize >> 9);
646 return 0;
647
648 case NBD_DO_IT: {
649 struct task_struct *thread;
650 struct file *file;
651 int error;
652
653 if (lo->pid)
654 return -EBUSY;
655 if (!lo->file)
656 return -EINVAL;
657
658 mutex_unlock(&lo->tx_lock);
659
660 thread = kthread_create(nbd_thread, lo, lo->disk->disk_name);
661 if (IS_ERR(thread)) {
662 mutex_lock(&lo->tx_lock);
663 return PTR_ERR(thread);
664 }
665 wake_up_process(thread);
666 error = nbd_do_it(lo);
667 kthread_stop(thread);
668
669 mutex_lock(&lo->tx_lock);
670 if (error)
671 return error;
672 sock_shutdown(lo, 0);
673 file = lo->file;
674 lo->file = NULL;
675 nbd_clear_que(lo);
676 printk(KERN_WARNING "%s: queue cleared\n", lo->disk->disk_name);
677 if (file)
678 fput(file);
679 lo->bytesize = 0;
680 bdev->bd_inode->i_size = 0;
681 set_capacity(lo->disk, 0);
682 if (max_part > 0)
683 ioctl_by_bdev(bdev, BLKRRPART, 0);
684 return lo->harderror;
685 }
686
687 case NBD_CLEAR_QUE:
688 /*
689 * This is for compatibility only. The queue is always cleared
690 * by NBD_DO_IT or NBD_CLEAR_SOCK.
691 */
692 BUG_ON(!lo->sock && !list_empty(&lo->queue_head));
693 return 0;
694
695 case NBD_PRINT_DEBUG:
696 printk(KERN_INFO "%s: next = %p, prev = %p, head = %p\n",
697 bdev->bd_disk->disk_name,
698 lo->queue_head.next, lo->queue_head.prev,
699 &lo->queue_head);
700 return 0;
701 }
702 return -ENOTTY;
703 }
704
nbd_ioctl(struct block_device * bdev,fmode_t mode,unsigned int cmd,unsigned long arg)705 static int nbd_ioctl(struct block_device *bdev, fmode_t mode,
706 unsigned int cmd, unsigned long arg)
707 {
708 struct nbd_device *lo = bdev->bd_disk->private_data;
709 int error;
710
711 if (!capable(CAP_SYS_ADMIN))
712 return -EPERM;
713
714 BUG_ON(lo->magic != LO_MAGIC);
715
716 /* Anyone capable of this syscall can do *real bad* things */
717 dprintk(DBG_IOCTL, "%s: nbd_ioctl cmd=%s(0x%x) arg=%lu\n",
718 lo->disk->disk_name, ioctl_cmd_to_ascii(cmd), cmd, arg);
719
720 mutex_lock(&lo->tx_lock);
721 error = __nbd_ioctl(bdev, lo, cmd, arg);
722 mutex_unlock(&lo->tx_lock);
723
724 return error;
725 }
726
727 static const struct block_device_operations nbd_fops =
728 {
729 .owner = THIS_MODULE,
730 .ioctl = nbd_ioctl,
731 };
732
733 /*
734 * And here should be modules and kernel interface
735 * (Just smiley confuses emacs :-)
736 */
737
nbd_init(void)738 static int __init nbd_init(void)
739 {
740 int err = -ENOMEM;
741 int i;
742 int part_shift;
743
744 BUILD_BUG_ON(sizeof(struct nbd_request) != 28);
745
746 if (max_part < 0) {
747 printk(KERN_CRIT "nbd: max_part must be >= 0\n");
748 return -EINVAL;
749 }
750
751 nbd_dev = kcalloc(nbds_max, sizeof(*nbd_dev), GFP_KERNEL);
752 if (!nbd_dev)
753 return -ENOMEM;
754
755 part_shift = 0;
756 if (max_part > 0)
757 part_shift = fls(max_part);
758
759 for (i = 0; i < nbds_max; i++) {
760 struct gendisk *disk = alloc_disk(1 << part_shift);
761 if (!disk)
762 goto out;
763 nbd_dev[i].disk = disk;
764 /*
765 * The new linux 2.5 block layer implementation requires
766 * every gendisk to have its very own request_queue struct.
767 * These structs are big so we dynamically allocate them.
768 */
769 disk->queue = blk_init_queue(do_nbd_request, &nbd_lock);
770 if (!disk->queue) {
771 put_disk(disk);
772 goto out;
773 }
774 /*
775 * Tell the block layer that we are not a rotational device
776 */
777 queue_flag_set_unlocked(QUEUE_FLAG_NONROT, disk->queue);
778 }
779
780 if (register_blkdev(NBD_MAJOR, "nbd")) {
781 err = -EIO;
782 goto out;
783 }
784
785 printk(KERN_INFO "nbd: registered device at major %d\n", NBD_MAJOR);
786 dprintk(DBG_INIT, "nbd: debugflags=0x%x\n", debugflags);
787
788 for (i = 0; i < nbds_max; i++) {
789 struct gendisk *disk = nbd_dev[i].disk;
790 nbd_dev[i].file = NULL;
791 nbd_dev[i].magic = LO_MAGIC;
792 nbd_dev[i].flags = 0;
793 INIT_LIST_HEAD(&nbd_dev[i].waiting_queue);
794 spin_lock_init(&nbd_dev[i].queue_lock);
795 INIT_LIST_HEAD(&nbd_dev[i].queue_head);
796 mutex_init(&nbd_dev[i].tx_lock);
797 init_waitqueue_head(&nbd_dev[i].active_wq);
798 init_waitqueue_head(&nbd_dev[i].waiting_wq);
799 nbd_dev[i].blksize = 1024;
800 nbd_dev[i].bytesize = 0;
801 disk->major = NBD_MAJOR;
802 disk->first_minor = i << part_shift;
803 disk->fops = &nbd_fops;
804 disk->private_data = &nbd_dev[i];
805 sprintf(disk->disk_name, "nbd%d", i);
806 set_capacity(disk, 0);
807 add_disk(disk);
808 }
809
810 return 0;
811 out:
812 while (i--) {
813 blk_cleanup_queue(nbd_dev[i].disk->queue);
814 put_disk(nbd_dev[i].disk);
815 }
816 kfree(nbd_dev);
817 return err;
818 }
819
nbd_cleanup(void)820 static void __exit nbd_cleanup(void)
821 {
822 int i;
823 for (i = 0; i < nbds_max; i++) {
824 struct gendisk *disk = nbd_dev[i].disk;
825 nbd_dev[i].magic = 0;
826 if (disk) {
827 del_gendisk(disk);
828 blk_cleanup_queue(disk->queue);
829 put_disk(disk);
830 }
831 }
832 unregister_blkdev(NBD_MAJOR, "nbd");
833 kfree(nbd_dev);
834 printk(KERN_INFO "nbd: unregistered device at major %d\n", NBD_MAJOR);
835 }
836
837 module_init(nbd_init);
838 module_exit(nbd_cleanup);
839
840 MODULE_DESCRIPTION("Network Block Device");
841 MODULE_LICENSE("GPL");
842
843 module_param(nbds_max, int, 0444);
844 MODULE_PARM_DESC(nbds_max, "number of network block devices to initialize (default: 16)");
845 module_param(max_part, int, 0444);
846 MODULE_PARM_DESC(max_part, "number of partitions per device (default: 0)");
847 #ifndef NDEBUG
848 module_param(debugflags, int, 0644);
849 MODULE_PARM_DESC(debugflags, "flags for controlling debug output");
850 #endif
851