2 * Network block device - make block devices work over TCP
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.
7 * Copyright 1997-2000 Pavel Machek <pavel@ucw.cz>
8 * Parts copyright 2001 Steven Whitehouse <steve@chygwyn.com>
10 * This file is released under GPLv2 or later.
12 * (part of code stolen from loop.c)
15 #include <linux/major.h>
17 #include <linux/blkdev.h>
18 #include <linux/module.h>
19 #include <linux/init.h>
20 #include <linux/sched.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>
32 #include <asm/uaccess.h>
33 #include <asm/system.h>
34 #include <asm/types.h>
36 #include <linux/nbd.h>
38 #define LO_MAGIC 0x68797548
41 #define dprintk(flags, fmt...)
43 #define dprintk(flags, fmt...) do { \
44 if (debugflags & (flags)) printk(KERN_DEBUG fmt); \
46 #define DBG_IOCTL 0x0004
47 #define DBG_INIT 0x0010
48 #define DBG_EXIT 0x0020
49 #define DBG_BLKDEV 0x0100
52 static unsigned int debugflags
;
55 static unsigned int nbds_max
= 16;
56 static struct nbd_device nbd_dev
[MAX_NBD
];
59 * Use just one lock (or at most 1 per NIC). Two arguments for this:
60 * 1. Each NIC is essentially a synchronization point for all servers
61 * accessed through that NIC so there's no need to have more locks
63 * 2. More locks lead to more "Dirty cache line bouncing" which will slow
64 * down each lock to the point where they're actually slower than just
66 * Thanks go to Jens Axboe and Al Viro for their LKML emails explaining this!
68 static DEFINE_SPINLOCK(nbd_lock
);
71 static const char *ioctl_cmd_to_ascii(int cmd
)
74 case NBD_SET_SOCK
: return "set-sock";
75 case NBD_SET_BLKSIZE
: return "set-blksize";
76 case NBD_SET_SIZE
: return "set-size";
77 case NBD_DO_IT
: return "do-it";
78 case NBD_CLEAR_SOCK
: return "clear-sock";
79 case NBD_CLEAR_QUE
: return "clear-que";
80 case NBD_PRINT_DEBUG
: return "print-debug";
81 case NBD_SET_SIZE_BLOCKS
: return "set-size-blocks";
82 case NBD_DISCONNECT
: return "disconnect";
83 case BLKROSET
: return "set-read-only";
84 case BLKFLSBUF
: return "flush-buffer-cache";
89 static const char *nbdcmd_to_ascii(int cmd
)
92 case NBD_CMD_READ
: return "read";
93 case NBD_CMD_WRITE
: return "write";
94 case NBD_CMD_DISC
: return "disconnect";
100 static void nbd_end_request(struct request
*req
)
102 int uptodate
= (req
->errors
== 0) ? 1 : 0;
103 struct request_queue
*q
= req
->q
;
106 dprintk(DBG_BLKDEV
, "%s: request %p: %s\n", req
->rq_disk
->disk_name
,
107 req
, uptodate
? "done": "failed");
109 spin_lock_irqsave(q
->queue_lock
, flags
);
110 if (!end_that_request_first(req
, uptodate
, req
->nr_sectors
)) {
111 end_that_request_last(req
, uptodate
);
113 spin_unlock_irqrestore(q
->queue_lock
, flags
);
116 static void sock_shutdown(struct nbd_device
*lo
, int lock
)
118 /* Forcibly shutdown the socket causing all listeners
121 * FIXME: This code is duplicated from sys_shutdown, but
122 * there should be a more generic interface rather than
123 * calling socket ops directly here */
125 mutex_lock(&lo
->tx_lock
);
127 printk(KERN_WARNING
"%s: shutting down socket\n",
128 lo
->disk
->disk_name
);
129 lo
->sock
->ops
->shutdown(lo
->sock
, SEND_SHUTDOWN
|RCV_SHUTDOWN
);
133 mutex_unlock(&lo
->tx_lock
);
136 static void nbd_xmit_timeout(unsigned long arg
)
138 struct task_struct
*task
= (struct task_struct
*)arg
;
140 printk(KERN_WARNING
"nbd: killing hung xmit (%s, pid: %d)\n",
141 task
->comm
, task
->pid
);
142 force_sig(SIGKILL
, task
);
146 * Send or receive packet.
148 static int sock_xmit(struct nbd_device
*lo
, int send
, void *buf
, int size
,
151 struct socket
*sock
= lo
->sock
;
155 sigset_t blocked
, oldset
;
157 /* Allow interception of SIGKILL only
158 * Don't allow other signals to interrupt the transmission */
159 siginitsetinv(&blocked
, sigmask(SIGKILL
));
160 sigprocmask(SIG_SETMASK
, &blocked
, &oldset
);
163 sock
->sk
->sk_allocation
= GFP_NOIO
;
168 msg
.msg_control
= NULL
;
169 msg
.msg_controllen
= 0;
170 msg
.msg_flags
= msg_flags
| MSG_NOSIGNAL
;
173 struct timer_list ti
;
175 if (lo
->xmit_timeout
) {
177 ti
.function
= nbd_xmit_timeout
;
178 ti
.data
= (unsigned long)current
;
179 ti
.expires
= jiffies
+ lo
->xmit_timeout
;
182 result
= kernel_sendmsg(sock
, &msg
, &iov
, 1, size
);
183 if (lo
->xmit_timeout
)
186 result
= kernel_recvmsg(sock
, &msg
, &iov
, 1, size
, 0);
188 if (signal_pending(current
)) {
190 printk(KERN_WARNING
"nbd (pid %d: %s) got signal %d\n",
191 current
->pid
, current
->comm
,
192 dequeue_signal_lock(current
, ¤t
->blocked
, &info
));
194 sock_shutdown(lo
, !send
);
200 result
= -EPIPE
; /* short read */
207 sigprocmask(SIG_SETMASK
, &oldset
, NULL
);
212 static inline int sock_send_bvec(struct nbd_device
*lo
, struct bio_vec
*bvec
,
216 void *kaddr
= kmap(bvec
->bv_page
);
217 result
= sock_xmit(lo
, 1, kaddr
+ bvec
->bv_offset
, bvec
->bv_len
, flags
);
218 kunmap(bvec
->bv_page
);
222 /* always call with the tx_lock held */
223 static int nbd_send_req(struct nbd_device
*lo
, struct request
*req
)
226 struct nbd_request request
;
227 unsigned long size
= req
->nr_sectors
<< 9;
229 request
.magic
= htonl(NBD_REQUEST_MAGIC
);
230 request
.type
= htonl(nbd_cmd(req
));
231 request
.from
= cpu_to_be64((u64
) req
->sector
<< 9);
232 request
.len
= htonl(size
);
233 memcpy(request
.handle
, &req
, sizeof(req
));
235 dprintk(DBG_TX
, "%s: request %p: sending control (%s@%llu,%luB)\n",
236 lo
->disk
->disk_name
, req
,
237 nbdcmd_to_ascii(nbd_cmd(req
)),
238 (unsigned long long)req
->sector
<< 9,
239 req
->nr_sectors
<< 9);
240 result
= sock_xmit(lo
, 1, &request
, sizeof(request
),
241 (nbd_cmd(req
) == NBD_CMD_WRITE
) ? MSG_MORE
: 0);
243 printk(KERN_ERR
"%s: Send control failed (result %d)\n",
244 lo
->disk
->disk_name
, result
);
248 if (nbd_cmd(req
) == NBD_CMD_WRITE
) {
249 struct req_iterator iter
;
250 struct bio_vec
*bvec
;
252 * we are really probing at internals to determine
253 * whether to set MSG_MORE or not...
255 rq_for_each_segment(bvec
, req
, iter
) {
257 if (!rq_iter_last(req
, iter
))
259 dprintk(DBG_TX
, "%s: request %p: sending %d bytes data\n",
260 lo
->disk
->disk_name
, req
, bvec
->bv_len
);
261 result
= sock_send_bvec(lo
, bvec
, flags
);
263 printk(KERN_ERR
"%s: Send data failed (result %d)\n",
264 lo
->disk
->disk_name
, result
);
275 static struct request
*nbd_find_request(struct nbd_device
*lo
,
276 struct request
*xreq
)
278 struct request
*req
, *tmp
;
281 err
= wait_event_interruptible(lo
->active_wq
, lo
->active_req
!= xreq
);
285 spin_lock(&lo
->queue_lock
);
286 list_for_each_entry_safe(req
, tmp
, &lo
->queue_head
, queuelist
) {
289 list_del_init(&req
->queuelist
);
290 spin_unlock(&lo
->queue_lock
);
293 spin_unlock(&lo
->queue_lock
);
301 static inline int sock_recv_bvec(struct nbd_device
*lo
, struct bio_vec
*bvec
)
304 void *kaddr
= kmap(bvec
->bv_page
);
305 result
= sock_xmit(lo
, 0, kaddr
+ bvec
->bv_offset
, bvec
->bv_len
,
307 kunmap(bvec
->bv_page
);
311 /* NULL returned = something went wrong, inform userspace */
312 static struct request
*nbd_read_stat(struct nbd_device
*lo
)
315 struct nbd_reply reply
;
319 result
= sock_xmit(lo
, 0, &reply
, sizeof(reply
), MSG_WAITALL
);
321 printk(KERN_ERR
"%s: Receive control failed (result %d)\n",
322 lo
->disk
->disk_name
, result
);
326 if (ntohl(reply
.magic
) != NBD_REPLY_MAGIC
) {
327 printk(KERN_ERR
"%s: Wrong magic (0x%lx)\n",
329 (unsigned long)ntohl(reply
.magic
));
334 req
= nbd_find_request(lo
, *(struct request
**)reply
.handle
);
335 if (unlikely(IS_ERR(req
))) {
336 result
= PTR_ERR(req
);
337 if (result
!= -ENOENT
)
340 printk(KERN_ERR
"%s: Unexpected reply (%p)\n",
341 lo
->disk
->disk_name
, reply
.handle
);
346 if (ntohl(reply
.error
)) {
347 printk(KERN_ERR
"%s: Other side returned error (%d)\n",
348 lo
->disk
->disk_name
, ntohl(reply
.error
));
353 dprintk(DBG_RX
, "%s: request %p: got reply\n",
354 lo
->disk
->disk_name
, req
);
355 if (nbd_cmd(req
) == NBD_CMD_READ
) {
356 struct req_iterator iter
;
357 struct bio_vec
*bvec
;
359 rq_for_each_segment(bvec
, req
, iter
) {
360 result
= sock_recv_bvec(lo
, bvec
);
362 printk(KERN_ERR
"%s: Receive data failed (result %d)\n",
363 lo
->disk
->disk_name
, result
);
367 dprintk(DBG_RX
, "%s: request %p: got %d bytes data\n",
368 lo
->disk
->disk_name
, req
, bvec
->bv_len
);
373 lo
->harderror
= result
;
377 static ssize_t
pid_show(struct gendisk
*disk
, char *page
)
379 return sprintf(page
, "%ld\n",
380 (long) ((struct nbd_device
*)disk
->private_data
)->pid
);
383 static struct disk_attribute pid_attr
= {
384 .attr
= { .name
= "pid", .mode
= S_IRUGO
},
388 static int nbd_do_it(struct nbd_device
*lo
)
393 BUG_ON(lo
->magic
!= LO_MAGIC
);
395 lo
->pid
= current
->pid
;
396 ret
= sysfs_create_file(&lo
->disk
->kobj
, &pid_attr
.attr
);
398 printk(KERN_ERR
"nbd: sysfs_create_file failed!");
402 while ((req
= nbd_read_stat(lo
)) != NULL
)
403 nbd_end_request(req
);
405 sysfs_remove_file(&lo
->disk
->kobj
, &pid_attr
.attr
);
409 static void nbd_clear_que(struct nbd_device
*lo
)
413 BUG_ON(lo
->magic
!= LO_MAGIC
);
416 * Because we have set lo->sock to NULL under the tx_lock, all
417 * modifications to the list must have completed by now. For
418 * the same reason, the active_req must be NULL.
420 * As a consequence, we don't need to take the spin lock while
421 * purging the list here.
424 BUG_ON(lo
->active_req
);
426 while (!list_empty(&lo
->queue_head
)) {
427 req
= list_entry(lo
->queue_head
.next
, struct request
,
429 list_del_init(&req
->queuelist
);
431 nbd_end_request(req
);
437 * We always wait for result of write, for now. It would be nice to make it optional
439 * if ((rq_data_dir(req) == WRITE) && (lo->flags & NBD_WRITE_NOCHK))
440 * { printk( "Warning: Ignoring result!\n"); nbd_end_request( req ); }
443 static void do_nbd_request(struct request_queue
* q
)
447 while ((req
= elv_next_request(q
)) != NULL
) {
448 struct nbd_device
*lo
;
450 blkdev_dequeue_request(req
);
451 dprintk(DBG_BLKDEV
, "%s: request %p: dequeued (flags=%x)\n",
452 req
->rq_disk
->disk_name
, req
, req
->cmd_type
);
454 if (!blk_fs_request(req
))
457 lo
= req
->rq_disk
->private_data
;
459 BUG_ON(lo
->magic
!= LO_MAGIC
);
461 nbd_cmd(req
) = NBD_CMD_READ
;
462 if (rq_data_dir(req
) == WRITE
) {
463 nbd_cmd(req
) = NBD_CMD_WRITE
;
464 if (lo
->flags
& NBD_READ_ONLY
) {
465 printk(KERN_ERR
"%s: Write on read-only\n",
466 lo
->disk
->disk_name
);
472 spin_unlock_irq(q
->queue_lock
);
474 mutex_lock(&lo
->tx_lock
);
475 if (unlikely(!lo
->sock
)) {
476 mutex_unlock(&lo
->tx_lock
);
477 printk(KERN_ERR
"%s: Attempted send on closed socket\n",
478 lo
->disk
->disk_name
);
480 nbd_end_request(req
);
481 spin_lock_irq(q
->queue_lock
);
485 lo
->active_req
= req
;
487 if (nbd_send_req(lo
, req
) != 0) {
488 printk(KERN_ERR
"%s: Request send failed\n",
489 lo
->disk
->disk_name
);
491 nbd_end_request(req
);
493 spin_lock(&lo
->queue_lock
);
494 list_add(&req
->queuelist
, &lo
->queue_head
);
495 spin_unlock(&lo
->queue_lock
);
498 lo
->active_req
= NULL
;
499 mutex_unlock(&lo
->tx_lock
);
500 wake_up_all(&lo
->active_wq
);
502 spin_lock_irq(q
->queue_lock
);
507 spin_unlock(q
->queue_lock
);
508 nbd_end_request(req
);
509 spin_lock(q
->queue_lock
);
514 static int nbd_ioctl(struct inode
*inode
, struct file
*file
,
515 unsigned int cmd
, unsigned long arg
)
517 struct nbd_device
*lo
= inode
->i_bdev
->bd_disk
->private_data
;
519 struct request sreq
;
521 if (!capable(CAP_SYS_ADMIN
))
524 BUG_ON(lo
->magic
!= LO_MAGIC
);
526 /* Anyone capable of this syscall can do *real bad* things */
527 dprintk(DBG_IOCTL
, "%s: nbd_ioctl cmd=%s(0x%x) arg=%lu\n",
528 lo
->disk
->disk_name
, ioctl_cmd_to_ascii(cmd
), cmd
, arg
);
532 printk(KERN_INFO
"%s: NBD_DISCONNECT\n", lo
->disk
->disk_name
);
533 sreq
.cmd_type
= REQ_TYPE_SPECIAL
;
534 nbd_cmd(&sreq
) = NBD_CMD_DISC
;
536 * Set these to sane values in case server implementation
537 * fails to check the request type first and also to keep
538 * debugging output cleaner.
544 mutex_lock(&lo
->tx_lock
);
545 nbd_send_req(lo
, &sreq
);
546 mutex_unlock(&lo
->tx_lock
);
551 mutex_lock(&lo
->tx_lock
);
553 mutex_unlock(&lo
->tx_lock
);
557 BUG_ON(!list_empty(&lo
->queue_head
));
567 inode
= file
->f_path
.dentry
->d_inode
;
568 if (S_ISSOCK(inode
->i_mode
)) {
570 lo
->sock
= SOCKET_I(inode
);
577 case NBD_SET_BLKSIZE
:
579 lo
->bytesize
&= ~(lo
->blksize
-1);
580 inode
->i_bdev
->bd_inode
->i_size
= lo
->bytesize
;
581 set_blocksize(inode
->i_bdev
, lo
->blksize
);
582 set_capacity(lo
->disk
, lo
->bytesize
>> 9);
585 lo
->bytesize
= arg
& ~(lo
->blksize
-1);
586 inode
->i_bdev
->bd_inode
->i_size
= lo
->bytesize
;
587 set_blocksize(inode
->i_bdev
, lo
->blksize
);
588 set_capacity(lo
->disk
, lo
->bytesize
>> 9);
590 case NBD_SET_TIMEOUT
:
591 lo
->xmit_timeout
= arg
* HZ
;
593 case NBD_SET_SIZE_BLOCKS
:
594 lo
->bytesize
= ((u64
) arg
) * lo
->blksize
;
595 inode
->i_bdev
->bd_inode
->i_size
= lo
->bytesize
;
596 set_blocksize(inode
->i_bdev
, lo
->blksize
);
597 set_capacity(lo
->disk
, lo
->bytesize
>> 9);
602 error
= nbd_do_it(lo
);
605 sock_shutdown(lo
, 1);
609 printk(KERN_WARNING
"%s: queue cleared\n", lo
->disk
->disk_name
);
613 inode
->i_bdev
->bd_inode
->i_size
= 0;
614 set_capacity(lo
->disk
, 0);
615 return lo
->harderror
;
618 * This is for compatibility only. The queue is always cleared
619 * by NBD_DO_IT or NBD_CLEAR_SOCK.
621 BUG_ON(!lo
->sock
&& !list_empty(&lo
->queue_head
));
623 case NBD_PRINT_DEBUG
:
624 printk(KERN_INFO
"%s: next = %p, prev = %p, head = %p\n",
625 inode
->i_bdev
->bd_disk
->disk_name
,
626 lo
->queue_head
.next
, lo
->queue_head
.prev
,
633 static struct block_device_operations nbd_fops
=
635 .owner
= THIS_MODULE
,
640 * And here should be modules and kernel interface
641 * (Just smiley confuses emacs :-)
644 static int __init
nbd_init(void)
649 BUILD_BUG_ON(sizeof(struct nbd_request
) != 28);
651 if (nbds_max
> MAX_NBD
) {
652 printk(KERN_CRIT
"nbd: cannot allocate more than %u nbds; %u requested.\n", MAX_NBD
,
657 for (i
= 0; i
< nbds_max
; i
++) {
658 struct gendisk
*disk
= alloc_disk(1);
661 nbd_dev
[i
].disk
= disk
;
663 * The new linux 2.5 block layer implementation requires
664 * every gendisk to have its very own request_queue struct.
665 * These structs are big so we dynamically allocate them.
667 disk
->queue
= blk_init_queue(do_nbd_request
, &nbd_lock
);
674 if (register_blkdev(NBD_MAJOR
, "nbd")) {
679 printk(KERN_INFO
"nbd: registered device at major %d\n", NBD_MAJOR
);
680 dprintk(DBG_INIT
, "nbd: debugflags=0x%x\n", debugflags
);
682 for (i
= 0; i
< nbds_max
; i
++) {
683 struct gendisk
*disk
= nbd_dev
[i
].disk
;
684 nbd_dev
[i
].file
= NULL
;
685 nbd_dev
[i
].magic
= LO_MAGIC
;
686 nbd_dev
[i
].flags
= 0;
687 spin_lock_init(&nbd_dev
[i
].queue_lock
);
688 INIT_LIST_HEAD(&nbd_dev
[i
].queue_head
);
689 mutex_init(&nbd_dev
[i
].tx_lock
);
690 init_waitqueue_head(&nbd_dev
[i
].active_wq
);
691 nbd_dev
[i
].blksize
= 1024;
692 nbd_dev
[i
].bytesize
= 0;
693 disk
->major
= NBD_MAJOR
;
694 disk
->first_minor
= i
;
695 disk
->fops
= &nbd_fops
;
696 disk
->private_data
= &nbd_dev
[i
];
697 disk
->flags
|= GENHD_FL_SUPPRESS_PARTITION_INFO
;
698 sprintf(disk
->disk_name
, "nbd%d", i
);
699 set_capacity(disk
, 0);
706 blk_cleanup_queue(nbd_dev
[i
].disk
->queue
);
707 put_disk(nbd_dev
[i
].disk
);
712 static void __exit
nbd_cleanup(void)
715 for (i
= 0; i
< nbds_max
; i
++) {
716 struct gendisk
*disk
= nbd_dev
[i
].disk
;
717 nbd_dev
[i
].magic
= 0;
720 blk_cleanup_queue(disk
->queue
);
724 unregister_blkdev(NBD_MAJOR
, "nbd");
725 printk(KERN_INFO
"nbd: unregistered device at major %d\n", NBD_MAJOR
);
728 module_init(nbd_init
);
729 module_exit(nbd_cleanup
);
731 MODULE_DESCRIPTION("Network Block Device");
732 MODULE_LICENSE("GPL");
734 module_param(nbds_max
, int, 0444);
735 MODULE_PARM_DESC(nbds_max
, "How many network block devices to initialize.");
737 module_param(debugflags
, int, 0644);
738 MODULE_PARM_DESC(debugflags
, "flags for controlling debug output");