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/types.h>
38
39 #include <linux/nbd.h>
40
41 #define NBD_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
ioctl_cmd_to_ascii(int cmd)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_SET_TIMEOUT: return "set-timeout";
82 case NBD_SET_FLAGS: return "set-flags";
83 case NBD_DO_IT: return "do-it";
84 case NBD_CLEAR_SOCK: return "clear-sock";
85 case NBD_CLEAR_QUE: return "clear-que";
86 case NBD_PRINT_DEBUG: return "print-debug";
87 case NBD_SET_SIZE_BLOCKS: return "set-size-blocks";
88 case NBD_DISCONNECT: return "disconnect";
89 case BLKROSET: return "set-read-only";
90 case BLKFLSBUF: return "flush-buffer-cache";
91 }
92 return "unknown";
93 }
94
nbdcmd_to_ascii(int cmd)95 static const char *nbdcmd_to_ascii(int cmd)
96 {
97 switch (cmd) {
98 case NBD_CMD_READ: return "read";
99 case NBD_CMD_WRITE: return "write";
100 case NBD_CMD_DISC: return "disconnect";
101 case NBD_CMD_FLUSH: return "flush";
102 case NBD_CMD_TRIM: return "trim/discard";
103 }
104 return "invalid";
105 }
106 #endif /* NDEBUG */
107
nbd_end_request(struct request * req)108 static void nbd_end_request(struct request *req)
109 {
110 int error = req->errors ? -EIO : 0;
111 struct request_queue *q = req->q;
112 unsigned long flags;
113
114 dprintk(DBG_BLKDEV, "%s: request %p: %s\n", req->rq_disk->disk_name,
115 req, error ? "failed" : "done");
116
117 spin_lock_irqsave(q->queue_lock, flags);
118 __blk_end_request_all(req, error);
119 spin_unlock_irqrestore(q->queue_lock, flags);
120 }
121
sock_shutdown(struct nbd_device * nbd,int lock)122 static void sock_shutdown(struct nbd_device *nbd, int lock)
123 {
124 /* Forcibly shutdown the socket causing all listeners
125 * to error
126 *
127 * FIXME: This code is duplicated from sys_shutdown, but
128 * there should be a more generic interface rather than
129 * calling socket ops directly here */
130 if (lock)
131 mutex_lock(&nbd->tx_lock);
132 if (nbd->sock) {
133 dev_warn(disk_to_dev(nbd->disk), "shutting down socket\n");
134 kernel_sock_shutdown(nbd->sock, SHUT_RDWR);
135 nbd->sock = NULL;
136 }
137 if (lock)
138 mutex_unlock(&nbd->tx_lock);
139 }
140
nbd_xmit_timeout(unsigned long arg)141 static void nbd_xmit_timeout(unsigned long arg)
142 {
143 struct task_struct *task = (struct task_struct *)arg;
144
145 printk(KERN_WARNING "nbd: killing hung xmit (%s, pid: %d)\n",
146 task->comm, task->pid);
147 force_sig(SIGKILL, task);
148 }
149
150 /*
151 * Send or receive packet.
152 */
sock_xmit(struct nbd_device * nbd,int send,void * buf,int size,int msg_flags)153 static int sock_xmit(struct nbd_device *nbd, int send, void *buf, int size,
154 int msg_flags)
155 {
156 struct socket *sock = nbd->sock;
157 int result;
158 struct msghdr msg;
159 struct kvec iov;
160 sigset_t blocked, oldset;
161 unsigned long pflags = current->flags;
162
163 if (unlikely(!sock)) {
164 dev_err(disk_to_dev(nbd->disk),
165 "Attempted %s on closed socket in sock_xmit\n",
166 (send ? "send" : "recv"));
167 return -EINVAL;
168 }
169
170 /* Allow interception of SIGKILL only
171 * Don't allow other signals to interrupt the transmission */
172 siginitsetinv(&blocked, sigmask(SIGKILL));
173 sigprocmask(SIG_SETMASK, &blocked, &oldset);
174
175 current->flags |= PF_MEMALLOC;
176 do {
177 sock->sk->sk_allocation = GFP_NOIO | __GFP_MEMALLOC;
178 iov.iov_base = buf;
179 iov.iov_len = size;
180 msg.msg_name = NULL;
181 msg.msg_namelen = 0;
182 msg.msg_control = NULL;
183 msg.msg_controllen = 0;
184 msg.msg_flags = msg_flags | MSG_NOSIGNAL;
185
186 if (send) {
187 struct timer_list ti;
188
189 if (nbd->xmit_timeout) {
190 init_timer(&ti);
191 ti.function = nbd_xmit_timeout;
192 ti.data = (unsigned long)current;
193 ti.expires = jiffies + nbd->xmit_timeout;
194 add_timer(&ti);
195 }
196 result = kernel_sendmsg(sock, &msg, &iov, 1, size);
197 if (nbd->xmit_timeout)
198 del_timer_sync(&ti);
199 } else
200 result = kernel_recvmsg(sock, &msg, &iov, 1, size,
201 msg.msg_flags);
202
203 if (signal_pending(current)) {
204 siginfo_t info;
205 printk(KERN_WARNING "nbd (pid %d: %s) got signal %d\n",
206 task_pid_nr(current), current->comm,
207 dequeue_signal_lock(current, ¤t->blocked, &info));
208 result = -EINTR;
209 sock_shutdown(nbd, !send);
210 break;
211 }
212
213 if (result <= 0) {
214 if (result == 0)
215 result = -EPIPE; /* short read */
216 break;
217 }
218 size -= result;
219 buf += result;
220 } while (size > 0);
221
222 sigprocmask(SIG_SETMASK, &oldset, NULL);
223 tsk_restore_flags(current, pflags, PF_MEMALLOC);
224
225 return result;
226 }
227
sock_send_bvec(struct nbd_device * nbd,struct bio_vec * bvec,int flags)228 static inline int sock_send_bvec(struct nbd_device *nbd, struct bio_vec *bvec,
229 int flags)
230 {
231 int result;
232 void *kaddr = kmap(bvec->bv_page);
233 result = sock_xmit(nbd, 1, kaddr + bvec->bv_offset,
234 bvec->bv_len, flags);
235 kunmap(bvec->bv_page);
236 return result;
237 }
238
239 /* always call with the tx_lock held */
nbd_send_req(struct nbd_device * nbd,struct request * req)240 static int nbd_send_req(struct nbd_device *nbd, struct request *req)
241 {
242 int result, flags;
243 struct nbd_request request;
244 unsigned long size = blk_rq_bytes(req);
245
246 memset(&request, 0, sizeof(request));
247 request.magic = htonl(NBD_REQUEST_MAGIC);
248 request.type = htonl(nbd_cmd(req));
249
250 if (nbd_cmd(req) != NBD_CMD_FLUSH && nbd_cmd(req) != NBD_CMD_DISC) {
251 request.from = cpu_to_be64((u64)blk_rq_pos(req) << 9);
252 request.len = htonl(size);
253 }
254 memcpy(request.handle, &req, sizeof(req));
255
256 dprintk(DBG_TX, "%s: request %p: sending control (%s@%llu,%uB)\n",
257 nbd->disk->disk_name, req,
258 nbdcmd_to_ascii(nbd_cmd(req)),
259 (unsigned long long)blk_rq_pos(req) << 9,
260 blk_rq_bytes(req));
261 result = sock_xmit(nbd, 1, &request, sizeof(request),
262 (nbd_cmd(req) == NBD_CMD_WRITE) ? MSG_MORE : 0);
263 if (result <= 0) {
264 dev_err(disk_to_dev(nbd->disk),
265 "Send control failed (result %d)\n", result);
266 goto error_out;
267 }
268
269 if (nbd_cmd(req) == NBD_CMD_WRITE) {
270 struct req_iterator iter;
271 struct bio_vec bvec;
272 /*
273 * we are really probing at internals to determine
274 * whether to set MSG_MORE or not...
275 */
276 rq_for_each_segment(bvec, req, iter) {
277 flags = 0;
278 if (!rq_iter_last(bvec, iter))
279 flags = MSG_MORE;
280 dprintk(DBG_TX, "%s: request %p: sending %d bytes data\n",
281 nbd->disk->disk_name, req, bvec.bv_len);
282 result = sock_send_bvec(nbd, &bvec, flags);
283 if (result <= 0) {
284 dev_err(disk_to_dev(nbd->disk),
285 "Send data failed (result %d)\n",
286 result);
287 goto error_out;
288 }
289 }
290 }
291 return 0;
292
293 error_out:
294 return -EIO;
295 }
296
nbd_find_request(struct nbd_device * nbd,struct request * xreq)297 static struct request *nbd_find_request(struct nbd_device *nbd,
298 struct request *xreq)
299 {
300 struct request *req, *tmp;
301 int err;
302
303 err = wait_event_interruptible(nbd->active_wq, nbd->active_req != xreq);
304 if (unlikely(err))
305 goto out;
306
307 spin_lock(&nbd->queue_lock);
308 list_for_each_entry_safe(req, tmp, &nbd->queue_head, queuelist) {
309 if (req != xreq)
310 continue;
311 list_del_init(&req->queuelist);
312 spin_unlock(&nbd->queue_lock);
313 return req;
314 }
315 spin_unlock(&nbd->queue_lock);
316
317 err = -ENOENT;
318
319 out:
320 return ERR_PTR(err);
321 }
322
sock_recv_bvec(struct nbd_device * nbd,struct bio_vec * bvec)323 static inline int sock_recv_bvec(struct nbd_device *nbd, struct bio_vec *bvec)
324 {
325 int result;
326 void *kaddr = kmap(bvec->bv_page);
327 result = sock_xmit(nbd, 0, kaddr + bvec->bv_offset, bvec->bv_len,
328 MSG_WAITALL);
329 kunmap(bvec->bv_page);
330 return result;
331 }
332
333 /* NULL returned = something went wrong, inform userspace */
nbd_read_stat(struct nbd_device * nbd)334 static struct request *nbd_read_stat(struct nbd_device *nbd)
335 {
336 int result;
337 struct nbd_reply reply;
338 struct request *req;
339
340 reply.magic = 0;
341 result = sock_xmit(nbd, 0, &reply, sizeof(reply), MSG_WAITALL);
342 if (result <= 0) {
343 dev_err(disk_to_dev(nbd->disk),
344 "Receive control failed (result %d)\n", result);
345 goto harderror;
346 }
347
348 if (ntohl(reply.magic) != NBD_REPLY_MAGIC) {
349 dev_err(disk_to_dev(nbd->disk), "Wrong magic (0x%lx)\n",
350 (unsigned long)ntohl(reply.magic));
351 result = -EPROTO;
352 goto harderror;
353 }
354
355 req = nbd_find_request(nbd, *(struct request **)reply.handle);
356 if (IS_ERR(req)) {
357 result = PTR_ERR(req);
358 if (result != -ENOENT)
359 goto harderror;
360
361 dev_err(disk_to_dev(nbd->disk), "Unexpected reply (%p)\n",
362 reply.handle);
363 result = -EBADR;
364 goto harderror;
365 }
366
367 if (ntohl(reply.error)) {
368 dev_err(disk_to_dev(nbd->disk), "Other side returned error (%d)\n",
369 ntohl(reply.error));
370 req->errors++;
371 return req;
372 }
373
374 dprintk(DBG_RX, "%s: request %p: got reply\n",
375 nbd->disk->disk_name, req);
376 if (nbd_cmd(req) == NBD_CMD_READ) {
377 struct req_iterator iter;
378 struct bio_vec bvec;
379
380 rq_for_each_segment(bvec, req, iter) {
381 result = sock_recv_bvec(nbd, &bvec);
382 if (result <= 0) {
383 dev_err(disk_to_dev(nbd->disk), "Receive data failed (result %d)\n",
384 result);
385 req->errors++;
386 return req;
387 }
388 dprintk(DBG_RX, "%s: request %p: got %d bytes data\n",
389 nbd->disk->disk_name, req, bvec.bv_len);
390 }
391 }
392 return req;
393 harderror:
394 nbd->harderror = result;
395 return NULL;
396 }
397
pid_show(struct device * dev,struct device_attribute * attr,char * buf)398 static ssize_t pid_show(struct device *dev,
399 struct device_attribute *attr, char *buf)
400 {
401 struct gendisk *disk = dev_to_disk(dev);
402
403 return sprintf(buf, "%ld\n",
404 (long) ((struct nbd_device *)disk->private_data)->pid);
405 }
406
407 static struct device_attribute pid_attr = {
408 .attr = { .name = "pid", .mode = S_IRUGO},
409 .show = pid_show,
410 };
411
nbd_do_it(struct nbd_device * nbd)412 static int nbd_do_it(struct nbd_device *nbd)
413 {
414 struct request *req;
415 int ret;
416
417 BUG_ON(nbd->magic != NBD_MAGIC);
418
419 sk_set_memalloc(nbd->sock->sk);
420 nbd->pid = task_pid_nr(current);
421 ret = device_create_file(disk_to_dev(nbd->disk), &pid_attr);
422 if (ret) {
423 dev_err(disk_to_dev(nbd->disk), "device_create_file failed!\n");
424 nbd->pid = 0;
425 return ret;
426 }
427
428 while ((req = nbd_read_stat(nbd)) != NULL)
429 nbd_end_request(req);
430
431 device_remove_file(disk_to_dev(nbd->disk), &pid_attr);
432 nbd->pid = 0;
433 return 0;
434 }
435
nbd_clear_que(struct nbd_device * nbd)436 static void nbd_clear_que(struct nbd_device *nbd)
437 {
438 struct request *req;
439
440 BUG_ON(nbd->magic != NBD_MAGIC);
441
442 /*
443 * Because we have set nbd->sock to NULL under the tx_lock, all
444 * modifications to the list must have completed by now. For
445 * the same reason, the active_req must be NULL.
446 *
447 * As a consequence, we don't need to take the spin lock while
448 * purging the list here.
449 */
450 BUG_ON(nbd->sock);
451 BUG_ON(nbd->active_req);
452
453 while (!list_empty(&nbd->queue_head)) {
454 req = list_entry(nbd->queue_head.next, struct request,
455 queuelist);
456 list_del_init(&req->queuelist);
457 req->errors++;
458 nbd_end_request(req);
459 }
460
461 while (!list_empty(&nbd->waiting_queue)) {
462 req = list_entry(nbd->waiting_queue.next, struct request,
463 queuelist);
464 list_del_init(&req->queuelist);
465 req->errors++;
466 nbd_end_request(req);
467 }
468 }
469
470
nbd_handle_req(struct nbd_device * nbd,struct request * req)471 static void nbd_handle_req(struct nbd_device *nbd, struct request *req)
472 {
473 if (req->cmd_type != REQ_TYPE_FS)
474 goto error_out;
475
476 nbd_cmd(req) = NBD_CMD_READ;
477 if (rq_data_dir(req) == WRITE) {
478 if ((req->cmd_flags & REQ_DISCARD)) {
479 WARN_ON(!(nbd->flags & NBD_FLAG_SEND_TRIM));
480 nbd_cmd(req) = NBD_CMD_TRIM;
481 } else
482 nbd_cmd(req) = NBD_CMD_WRITE;
483 if (nbd->flags & NBD_FLAG_READ_ONLY) {
484 dev_err(disk_to_dev(nbd->disk),
485 "Write on read-only\n");
486 goto error_out;
487 }
488 }
489
490 if (req->cmd_flags & REQ_FLUSH) {
491 BUG_ON(unlikely(blk_rq_sectors(req)));
492 nbd_cmd(req) = NBD_CMD_FLUSH;
493 }
494
495 req->errors = 0;
496
497 mutex_lock(&nbd->tx_lock);
498 if (unlikely(!nbd->sock)) {
499 mutex_unlock(&nbd->tx_lock);
500 dev_err(disk_to_dev(nbd->disk),
501 "Attempted send on closed socket\n");
502 goto error_out;
503 }
504
505 nbd->active_req = req;
506
507 if (nbd_send_req(nbd, req) != 0) {
508 dev_err(disk_to_dev(nbd->disk), "Request send failed\n");
509 req->errors++;
510 nbd_end_request(req);
511 } else {
512 spin_lock(&nbd->queue_lock);
513 list_add_tail(&req->queuelist, &nbd->queue_head);
514 spin_unlock(&nbd->queue_lock);
515 }
516
517 nbd->active_req = NULL;
518 mutex_unlock(&nbd->tx_lock);
519 wake_up_all(&nbd->active_wq);
520
521 return;
522
523 error_out:
524 req->errors++;
525 nbd_end_request(req);
526 }
527
nbd_thread(void * data)528 static int nbd_thread(void *data)
529 {
530 struct nbd_device *nbd = data;
531 struct request *req;
532
533 set_user_nice(current, MIN_NICE);
534 while (!kthread_should_stop() || !list_empty(&nbd->waiting_queue)) {
535 /* wait for something to do */
536 wait_event_interruptible(nbd->waiting_wq,
537 kthread_should_stop() ||
538 !list_empty(&nbd->waiting_queue));
539
540 /* extract request */
541 if (list_empty(&nbd->waiting_queue))
542 continue;
543
544 spin_lock_irq(&nbd->queue_lock);
545 req = list_entry(nbd->waiting_queue.next, struct request,
546 queuelist);
547 list_del_init(&req->queuelist);
548 spin_unlock_irq(&nbd->queue_lock);
549
550 /* handle request */
551 nbd_handle_req(nbd, req);
552 }
553 return 0;
554 }
555
556 /*
557 * We always wait for result of write, for now. It would be nice to make it optional
558 * in future
559 * if ((rq_data_dir(req) == WRITE) && (nbd->flags & NBD_WRITE_NOCHK))
560 * { printk( "Warning: Ignoring result!\n"); nbd_end_request( req ); }
561 */
562
do_nbd_request(struct request_queue * q)563 static void do_nbd_request(struct request_queue *q)
564 __releases(q->queue_lock) __acquires(q->queue_lock)
565 {
566 struct request *req;
567
568 while ((req = blk_fetch_request(q)) != NULL) {
569 struct nbd_device *nbd;
570
571 spin_unlock_irq(q->queue_lock);
572
573 dprintk(DBG_BLKDEV, "%s: request %p: dequeued (flags=%x)\n",
574 req->rq_disk->disk_name, req, req->cmd_type);
575
576 nbd = req->rq_disk->private_data;
577
578 BUG_ON(nbd->magic != NBD_MAGIC);
579
580 if (unlikely(!nbd->sock)) {
581 dev_err_ratelimited(disk_to_dev(nbd->disk),
582 "Attempted send on closed socket\n");
583 req->errors++;
584 nbd_end_request(req);
585 spin_lock_irq(q->queue_lock);
586 continue;
587 }
588
589 spin_lock_irq(&nbd->queue_lock);
590 list_add_tail(&req->queuelist, &nbd->waiting_queue);
591 spin_unlock_irq(&nbd->queue_lock);
592
593 wake_up(&nbd->waiting_wq);
594
595 spin_lock_irq(q->queue_lock);
596 }
597 }
598
599 /* Must be called with tx_lock held */
600
__nbd_ioctl(struct block_device * bdev,struct nbd_device * nbd,unsigned int cmd,unsigned long arg)601 static int __nbd_ioctl(struct block_device *bdev, struct nbd_device *nbd,
602 unsigned int cmd, unsigned long arg)
603 {
604 switch (cmd) {
605 case NBD_DISCONNECT: {
606 struct request sreq;
607
608 dev_info(disk_to_dev(nbd->disk), "NBD_DISCONNECT\n");
609 if (!nbd->sock)
610 return -EINVAL;
611
612 mutex_unlock(&nbd->tx_lock);
613 fsync_bdev(bdev);
614 mutex_lock(&nbd->tx_lock);
615 blk_rq_init(NULL, &sreq);
616 sreq.cmd_type = REQ_TYPE_SPECIAL;
617 nbd_cmd(&sreq) = NBD_CMD_DISC;
618
619 /* Check again after getting mutex back. */
620 if (!nbd->sock)
621 return -EINVAL;
622
623 nbd->disconnect = 1;
624
625 nbd_send_req(nbd, &sreq);
626 return 0;
627 }
628
629 case NBD_CLEAR_SOCK: {
630 struct socket *sock = nbd->sock;
631 nbd->sock = NULL;
632 nbd_clear_que(nbd);
633 BUG_ON(!list_empty(&nbd->queue_head));
634 BUG_ON(!list_empty(&nbd->waiting_queue));
635 kill_bdev(bdev);
636 if (sock)
637 sockfd_put(sock);
638 return 0;
639 }
640
641 case NBD_SET_SOCK: {
642 struct socket *sock;
643 int err;
644 if (nbd->sock)
645 return -EBUSY;
646 sock = sockfd_lookup(arg, &err);
647 if (sock) {
648 nbd->sock = sock;
649 if (max_part > 0)
650 bdev->bd_invalidated = 1;
651 nbd->disconnect = 0; /* we're connected now */
652 return 0;
653 }
654 return -EINVAL;
655 }
656
657 case NBD_SET_BLKSIZE:
658 nbd->blksize = arg;
659 nbd->bytesize &= ~(nbd->blksize-1);
660 bdev->bd_inode->i_size = nbd->bytesize;
661 set_blocksize(bdev, nbd->blksize);
662 set_capacity(nbd->disk, nbd->bytesize >> 9);
663 return 0;
664
665 case NBD_SET_SIZE:
666 nbd->bytesize = arg & ~(nbd->blksize-1);
667 bdev->bd_inode->i_size = nbd->bytesize;
668 set_blocksize(bdev, nbd->blksize);
669 set_capacity(nbd->disk, nbd->bytesize >> 9);
670 return 0;
671
672 case NBD_SET_TIMEOUT:
673 nbd->xmit_timeout = arg * HZ;
674 return 0;
675
676 case NBD_SET_FLAGS:
677 nbd->flags = arg;
678 return 0;
679
680 case NBD_SET_SIZE_BLOCKS:
681 nbd->bytesize = ((u64) arg) * nbd->blksize;
682 bdev->bd_inode->i_size = nbd->bytesize;
683 set_blocksize(bdev, nbd->blksize);
684 set_capacity(nbd->disk, nbd->bytesize >> 9);
685 return 0;
686
687 case NBD_DO_IT: {
688 struct task_struct *thread;
689 struct socket *sock;
690 int error;
691
692 if (nbd->pid)
693 return -EBUSY;
694 if (!nbd->sock)
695 return -EINVAL;
696
697 mutex_unlock(&nbd->tx_lock);
698
699 if (nbd->flags & NBD_FLAG_READ_ONLY)
700 set_device_ro(bdev, true);
701 if (nbd->flags & NBD_FLAG_SEND_TRIM)
702 queue_flag_set_unlocked(QUEUE_FLAG_DISCARD,
703 nbd->disk->queue);
704 if (nbd->flags & NBD_FLAG_SEND_FLUSH)
705 blk_queue_flush(nbd->disk->queue, REQ_FLUSH);
706 else
707 blk_queue_flush(nbd->disk->queue, 0);
708
709 thread = kthread_create(nbd_thread, nbd, "%s",
710 nbd->disk->disk_name);
711 if (IS_ERR(thread)) {
712 mutex_lock(&nbd->tx_lock);
713 return PTR_ERR(thread);
714 }
715 wake_up_process(thread);
716 error = nbd_do_it(nbd);
717 kthread_stop(thread);
718
719 mutex_lock(&nbd->tx_lock);
720 if (error)
721 return error;
722 sock_shutdown(nbd, 0);
723 sock = nbd->sock;
724 nbd->sock = NULL;
725 nbd_clear_que(nbd);
726 dev_warn(disk_to_dev(nbd->disk), "queue cleared\n");
727 kill_bdev(bdev);
728 queue_flag_clear_unlocked(QUEUE_FLAG_DISCARD, nbd->disk->queue);
729 set_device_ro(bdev, false);
730 if (sock)
731 sockfd_put(sock);
732 nbd->flags = 0;
733 nbd->bytesize = 0;
734 bdev->bd_inode->i_size = 0;
735 set_capacity(nbd->disk, 0);
736 if (max_part > 0)
737 ioctl_by_bdev(bdev, BLKRRPART, 0);
738 if (nbd->disconnect) /* user requested, ignore socket errors */
739 return 0;
740 return nbd->harderror;
741 }
742
743 case NBD_CLEAR_QUE:
744 /*
745 * This is for compatibility only. The queue is always cleared
746 * by NBD_DO_IT or NBD_CLEAR_SOCK.
747 */
748 return 0;
749
750 case NBD_PRINT_DEBUG:
751 dev_info(disk_to_dev(nbd->disk),
752 "next = %p, prev = %p, head = %p\n",
753 nbd->queue_head.next, nbd->queue_head.prev,
754 &nbd->queue_head);
755 return 0;
756 }
757 return -ENOTTY;
758 }
759
nbd_ioctl(struct block_device * bdev,fmode_t mode,unsigned int cmd,unsigned long arg)760 static int nbd_ioctl(struct block_device *bdev, fmode_t mode,
761 unsigned int cmd, unsigned long arg)
762 {
763 struct nbd_device *nbd = bdev->bd_disk->private_data;
764 int error;
765
766 if (!capable(CAP_SYS_ADMIN))
767 return -EPERM;
768
769 BUG_ON(nbd->magic != NBD_MAGIC);
770
771 /* Anyone capable of this syscall can do *real bad* things */
772 dprintk(DBG_IOCTL, "%s: nbd_ioctl cmd=%s(0x%x) arg=%lu\n",
773 nbd->disk->disk_name, ioctl_cmd_to_ascii(cmd), cmd, arg);
774
775 mutex_lock(&nbd->tx_lock);
776 error = __nbd_ioctl(bdev, nbd, cmd, arg);
777 mutex_unlock(&nbd->tx_lock);
778
779 return error;
780 }
781
782 static const struct block_device_operations nbd_fops =
783 {
784 .owner = THIS_MODULE,
785 .ioctl = nbd_ioctl,
786 };
787
788 /*
789 * And here should be modules and kernel interface
790 * (Just smiley confuses emacs :-)
791 */
792
nbd_init(void)793 static int __init nbd_init(void)
794 {
795 int err = -ENOMEM;
796 int i;
797 int part_shift;
798
799 BUILD_BUG_ON(sizeof(struct nbd_request) != 28);
800
801 if (max_part < 0) {
802 printk(KERN_ERR "nbd: max_part must be >= 0\n");
803 return -EINVAL;
804 }
805
806 part_shift = 0;
807 if (max_part > 0) {
808 part_shift = fls(max_part);
809
810 /*
811 * Adjust max_part according to part_shift as it is exported
812 * to user space so that user can know the max number of
813 * partition kernel should be able to manage.
814 *
815 * Note that -1 is required because partition 0 is reserved
816 * for the whole disk.
817 */
818 max_part = (1UL << part_shift) - 1;
819 }
820
821 if ((1UL << part_shift) > DISK_MAX_PARTS)
822 return -EINVAL;
823
824 if (nbds_max > 1UL << (MINORBITS - part_shift))
825 return -EINVAL;
826
827 nbd_dev = kcalloc(nbds_max, sizeof(*nbd_dev), GFP_KERNEL);
828 if (!nbd_dev)
829 return -ENOMEM;
830
831 for (i = 0; i < nbds_max; i++) {
832 struct gendisk *disk = alloc_disk(1 << part_shift);
833 if (!disk)
834 goto out;
835 nbd_dev[i].disk = disk;
836 /*
837 * The new linux 2.5 block layer implementation requires
838 * every gendisk to have its very own request_queue struct.
839 * These structs are big so we dynamically allocate them.
840 */
841 disk->queue = blk_init_queue(do_nbd_request, &nbd_lock);
842 if (!disk->queue) {
843 put_disk(disk);
844 goto out;
845 }
846 /*
847 * Tell the block layer that we are not a rotational device
848 */
849 queue_flag_set_unlocked(QUEUE_FLAG_NONROT, disk->queue);
850 queue_flag_clear_unlocked(QUEUE_FLAG_ADD_RANDOM, disk->queue);
851 disk->queue->limits.discard_granularity = 512;
852 disk->queue->limits.max_discard_sectors = UINT_MAX;
853 disk->queue->limits.discard_zeroes_data = 0;
854 blk_queue_max_hw_sectors(disk->queue, 65536);
855 disk->queue->limits.max_sectors = 256;
856 }
857
858 if (register_blkdev(NBD_MAJOR, "nbd")) {
859 err = -EIO;
860 goto out;
861 }
862
863 printk(KERN_INFO "nbd: registered device at major %d\n", NBD_MAJOR);
864 dprintk(DBG_INIT, "nbd: debugflags=0x%x\n", debugflags);
865
866 for (i = 0; i < nbds_max; i++) {
867 struct gendisk *disk = nbd_dev[i].disk;
868 nbd_dev[i].magic = NBD_MAGIC;
869 INIT_LIST_HEAD(&nbd_dev[i].waiting_queue);
870 spin_lock_init(&nbd_dev[i].queue_lock);
871 INIT_LIST_HEAD(&nbd_dev[i].queue_head);
872 mutex_init(&nbd_dev[i].tx_lock);
873 init_waitqueue_head(&nbd_dev[i].active_wq);
874 init_waitqueue_head(&nbd_dev[i].waiting_wq);
875 nbd_dev[i].blksize = 1024;
876 nbd_dev[i].bytesize = 0;
877 disk->major = NBD_MAJOR;
878 disk->first_minor = i << part_shift;
879 disk->fops = &nbd_fops;
880 disk->private_data = &nbd_dev[i];
881 sprintf(disk->disk_name, "nbd%d", i);
882 set_capacity(disk, 0);
883 add_disk(disk);
884 }
885
886 return 0;
887 out:
888 while (i--) {
889 blk_cleanup_queue(nbd_dev[i].disk->queue);
890 put_disk(nbd_dev[i].disk);
891 }
892 kfree(nbd_dev);
893 return err;
894 }
895
nbd_cleanup(void)896 static void __exit nbd_cleanup(void)
897 {
898 int i;
899 for (i = 0; i < nbds_max; i++) {
900 struct gendisk *disk = nbd_dev[i].disk;
901 nbd_dev[i].magic = 0;
902 if (disk) {
903 del_gendisk(disk);
904 blk_cleanup_queue(disk->queue);
905 put_disk(disk);
906 }
907 }
908 unregister_blkdev(NBD_MAJOR, "nbd");
909 kfree(nbd_dev);
910 printk(KERN_INFO "nbd: unregistered device at major %d\n", NBD_MAJOR);
911 }
912
913 module_init(nbd_init);
914 module_exit(nbd_cleanup);
915
916 MODULE_DESCRIPTION("Network Block Device");
917 MODULE_LICENSE("GPL");
918
919 module_param(nbds_max, int, 0444);
920 MODULE_PARM_DESC(nbds_max, "number of network block devices to initialize (default: 16)");
921 module_param(max_part, int, 0444);
922 MODULE_PARM_DESC(max_part, "number of partitions per device (default: 0)");
923 #ifndef NDEBUG
924 module_param(debugflags, int, 0644);
925 MODULE_PARM_DESC(debugflags, "flags for controlling debug output");
926 #endif
927