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
);
117 * Send or receive packet.
119 static int sock_xmit(struct socket
*sock
, int send
, void *buf
, int size
,
125 sigset_t blocked
, oldset
;
127 /* Allow interception of SIGKILL only
128 * Don't allow other signals to interrupt the transmission */
129 siginitsetinv(&blocked
, sigmask(SIGKILL
));
130 sigprocmask(SIG_SETMASK
, &blocked
, &oldset
);
133 sock
->sk
->sk_allocation
= GFP_NOIO
;
138 msg
.msg_control
= NULL
;
139 msg
.msg_controllen
= 0;
140 msg
.msg_flags
= msg_flags
| MSG_NOSIGNAL
;
143 result
= kernel_sendmsg(sock
, &msg
, &iov
, 1, size
);
145 result
= kernel_recvmsg(sock
, &msg
, &iov
, 1, size
, 0);
147 if (signal_pending(current
)) {
149 printk(KERN_WARNING
"nbd (pid %d: %s) got signal %d\n",
150 current
->pid
, current
->comm
,
151 dequeue_signal_lock(current
, ¤t
->blocked
, &info
));
158 result
= -EPIPE
; /* short read */
165 sigprocmask(SIG_SETMASK
, &oldset
, NULL
);
170 static inline int sock_send_bvec(struct socket
*sock
, struct bio_vec
*bvec
,
174 void *kaddr
= kmap(bvec
->bv_page
);
175 result
= sock_xmit(sock
, 1, kaddr
+ bvec
->bv_offset
, bvec
->bv_len
,
177 kunmap(bvec
->bv_page
);
181 static int nbd_send_req(struct nbd_device
*lo
, struct request
*req
)
184 struct nbd_request request
;
185 unsigned long size
= req
->nr_sectors
<< 9;
186 struct socket
*sock
= lo
->sock
;
188 request
.magic
= htonl(NBD_REQUEST_MAGIC
);
189 request
.type
= htonl(nbd_cmd(req
));
190 request
.from
= cpu_to_be64((u64
) req
->sector
<< 9);
191 request
.len
= htonl(size
);
192 memcpy(request
.handle
, &req
, sizeof(req
));
194 dprintk(DBG_TX
, "%s: request %p: sending control (%s@%llu,%luB)\n",
195 lo
->disk
->disk_name
, req
,
196 nbdcmd_to_ascii(nbd_cmd(req
)),
197 (unsigned long long)req
->sector
<< 9,
198 req
->nr_sectors
<< 9);
199 result
= sock_xmit(sock
, 1, &request
, sizeof(request
),
200 (nbd_cmd(req
) == NBD_CMD_WRITE
)? MSG_MORE
: 0);
202 printk(KERN_ERR
"%s: Send control failed (result %d)\n",
203 lo
->disk
->disk_name
, result
);
207 if (nbd_cmd(req
) == NBD_CMD_WRITE
) {
208 struct req_iterator iter
;
209 struct bio_vec
*bvec
;
211 * we are really probing at internals to determine
212 * whether to set MSG_MORE or not...
214 rq_for_each_segment(bvec
, req
, iter
) {
216 if (!rq_iter_last(req
, iter
))
218 dprintk(DBG_TX
, "%s: request %p: sending %d bytes data\n",
219 lo
->disk
->disk_name
, req
, bvec
->bv_len
);
220 result
= sock_send_bvec(sock
, bvec
, flags
);
222 printk(KERN_ERR
"%s: Send data failed (result %d)\n",
223 lo
->disk
->disk_name
, result
);
234 static struct request
*nbd_find_request(struct nbd_device
*lo
, char *handle
)
237 struct list_head
*tmp
;
238 struct request
*xreq
;
241 memcpy(&xreq
, handle
, sizeof(xreq
));
243 err
= wait_event_interruptible(lo
->active_wq
, lo
->active_req
!= xreq
);
247 spin_lock(&lo
->queue_lock
);
248 list_for_each(tmp
, &lo
->queue_head
) {
249 req
= list_entry(tmp
, struct request
, queuelist
);
252 list_del_init(&req
->queuelist
);
253 spin_unlock(&lo
->queue_lock
);
256 spin_unlock(&lo
->queue_lock
);
264 static inline int sock_recv_bvec(struct socket
*sock
, struct bio_vec
*bvec
)
267 void *kaddr
= kmap(bvec
->bv_page
);
268 result
= sock_xmit(sock
, 0, kaddr
+ bvec
->bv_offset
, bvec
->bv_len
,
270 kunmap(bvec
->bv_page
);
274 /* NULL returned = something went wrong, inform userspace */
275 static struct request
*nbd_read_stat(struct nbd_device
*lo
)
278 struct nbd_reply reply
;
280 struct socket
*sock
= lo
->sock
;
283 result
= sock_xmit(sock
, 0, &reply
, sizeof(reply
), MSG_WAITALL
);
285 printk(KERN_ERR
"%s: Receive control failed (result %d)\n",
286 lo
->disk
->disk_name
, result
);
290 if (ntohl(reply
.magic
) != NBD_REPLY_MAGIC
) {
291 printk(KERN_ERR
"%s: Wrong magic (0x%lx)\n",
293 (unsigned long)ntohl(reply
.magic
));
298 req
= nbd_find_request(lo
, reply
.handle
);
299 if (unlikely(IS_ERR(req
))) {
300 result
= PTR_ERR(req
);
301 if (result
!= -ENOENT
)
304 printk(KERN_ERR
"%s: Unexpected reply (%p)\n",
305 lo
->disk
->disk_name
, reply
.handle
);
310 if (ntohl(reply
.error
)) {
311 printk(KERN_ERR
"%s: Other side returned error (%d)\n",
312 lo
->disk
->disk_name
, ntohl(reply
.error
));
317 dprintk(DBG_RX
, "%s: request %p: got reply\n",
318 lo
->disk
->disk_name
, req
);
319 if (nbd_cmd(req
) == NBD_CMD_READ
) {
320 struct req_iterator iter
;
321 struct bio_vec
*bvec
;
323 rq_for_each_segment(bvec
, req
, iter
) {
324 result
= sock_recv_bvec(sock
, bvec
);
326 printk(KERN_ERR
"%s: Receive data failed (result %d)\n",
327 lo
->disk
->disk_name
, result
);
331 dprintk(DBG_RX
, "%s: request %p: got %d bytes data\n",
332 lo
->disk
->disk_name
, req
, bvec
->bv_len
);
337 lo
->harderror
= result
;
341 static ssize_t
pid_show(struct gendisk
*disk
, char *page
)
343 return sprintf(page
, "%ld\n",
344 (long) ((struct nbd_device
*)disk
->private_data
)->pid
);
347 static struct disk_attribute pid_attr
= {
348 .attr
= { .name
= "pid", .mode
= S_IRUGO
},
352 static int nbd_do_it(struct nbd_device
*lo
)
357 BUG_ON(lo
->magic
!= LO_MAGIC
);
359 lo
->pid
= current
->pid
;
360 ret
= sysfs_create_file(&lo
->disk
->kobj
, &pid_attr
.attr
);
362 printk(KERN_ERR
"nbd: sysfs_create_file failed!");
366 while ((req
= nbd_read_stat(lo
)) != NULL
)
367 nbd_end_request(req
);
369 sysfs_remove_file(&lo
->disk
->kobj
, &pid_attr
.attr
);
373 static void nbd_clear_que(struct nbd_device
*lo
)
377 BUG_ON(lo
->magic
!= LO_MAGIC
);
380 * Because we have set lo->sock to NULL under the tx_lock, all
381 * modifications to the list must have completed by now. For
382 * the same reason, the active_req must be NULL.
384 * As a consequence, we don't need to take the spin lock while
385 * purging the list here.
388 BUG_ON(lo
->active_req
);
390 while (!list_empty(&lo
->queue_head
)) {
391 req
= list_entry(lo
->queue_head
.next
, struct request
,
393 list_del_init(&req
->queuelist
);
395 nbd_end_request(req
);
400 * We always wait for result of write, for now. It would be nice to make it optional
402 * if ((rq_data_dir(req) == WRITE) && (lo->flags & NBD_WRITE_NOCHK))
403 * { printk( "Warning: Ignoring result!\n"); nbd_end_request( req ); }
406 static void do_nbd_request(struct request_queue
* q
)
410 while ((req
= elv_next_request(q
)) != NULL
) {
411 struct nbd_device
*lo
;
413 blkdev_dequeue_request(req
);
414 dprintk(DBG_BLKDEV
, "%s: request %p: dequeued (flags=%x)\n",
415 req
->rq_disk
->disk_name
, req
, req
->cmd_type
);
417 if (!blk_fs_request(req
))
420 lo
= req
->rq_disk
->private_data
;
422 BUG_ON(lo
->magic
!= LO_MAGIC
);
424 nbd_cmd(req
) = NBD_CMD_READ
;
425 if (rq_data_dir(req
) == WRITE
) {
426 nbd_cmd(req
) = NBD_CMD_WRITE
;
427 if (lo
->flags
& NBD_READ_ONLY
) {
428 printk(KERN_ERR
"%s: Write on read-only\n",
429 lo
->disk
->disk_name
);
435 spin_unlock_irq(q
->queue_lock
);
437 mutex_lock(&lo
->tx_lock
);
438 if (unlikely(!lo
->sock
)) {
439 mutex_unlock(&lo
->tx_lock
);
440 printk(KERN_ERR
"%s: Attempted send on closed socket\n",
441 lo
->disk
->disk_name
);
443 nbd_end_request(req
);
444 spin_lock_irq(q
->queue_lock
);
448 lo
->active_req
= req
;
450 if (nbd_send_req(lo
, req
) != 0) {
451 printk(KERN_ERR
"%s: Request send failed\n",
452 lo
->disk
->disk_name
);
454 nbd_end_request(req
);
456 spin_lock(&lo
->queue_lock
);
457 list_add(&req
->queuelist
, &lo
->queue_head
);
458 spin_unlock(&lo
->queue_lock
);
461 lo
->active_req
= NULL
;
462 mutex_unlock(&lo
->tx_lock
);
463 wake_up_all(&lo
->active_wq
);
465 spin_lock_irq(q
->queue_lock
);
470 spin_unlock(q
->queue_lock
);
471 nbd_end_request(req
);
472 spin_lock(q
->queue_lock
);
477 static int nbd_ioctl(struct inode
*inode
, struct file
*file
,
478 unsigned int cmd
, unsigned long arg
)
480 struct nbd_device
*lo
= inode
->i_bdev
->bd_disk
->private_data
;
482 struct request sreq
;
484 if (!capable(CAP_SYS_ADMIN
))
487 BUG_ON(lo
->magic
!= LO_MAGIC
);
489 /* Anyone capable of this syscall can do *real bad* things */
490 dprintk(DBG_IOCTL
, "%s: nbd_ioctl cmd=%s(0x%x) arg=%lu\n",
491 lo
->disk
->disk_name
, ioctl_cmd_to_ascii(cmd
), cmd
, arg
);
495 printk(KERN_INFO
"%s: NBD_DISCONNECT\n", lo
->disk
->disk_name
);
496 sreq
.cmd_type
= REQ_TYPE_SPECIAL
;
497 nbd_cmd(&sreq
) = NBD_CMD_DISC
;
499 * Set these to sane values in case server implementation
500 * fails to check the request type first and also to keep
501 * debugging output cleaner.
507 nbd_send_req(lo
, &sreq
);
512 mutex_lock(&lo
->tx_lock
);
514 mutex_unlock(&lo
->tx_lock
);
518 BUG_ON(!list_empty(&lo
->queue_head
));
528 inode
= file
->f_path
.dentry
->d_inode
;
529 if (S_ISSOCK(inode
->i_mode
)) {
531 lo
->sock
= SOCKET_I(inode
);
538 case NBD_SET_BLKSIZE
:
540 lo
->bytesize
&= ~(lo
->blksize
-1);
541 inode
->i_bdev
->bd_inode
->i_size
= lo
->bytesize
;
542 set_blocksize(inode
->i_bdev
, lo
->blksize
);
543 set_capacity(lo
->disk
, lo
->bytesize
>> 9);
546 lo
->bytesize
= arg
& ~(lo
->blksize
-1);
547 inode
->i_bdev
->bd_inode
->i_size
= lo
->bytesize
;
548 set_blocksize(inode
->i_bdev
, lo
->blksize
);
549 set_capacity(lo
->disk
, lo
->bytesize
>> 9);
551 case NBD_SET_SIZE_BLOCKS
:
552 lo
->bytesize
= ((u64
) arg
) * lo
->blksize
;
553 inode
->i_bdev
->bd_inode
->i_size
= lo
->bytesize
;
554 set_blocksize(inode
->i_bdev
, lo
->blksize
);
555 set_capacity(lo
->disk
, lo
->bytesize
>> 9);
560 error
= nbd_do_it(lo
);
563 /* on return tidy up in case we have a signal */
564 /* Forcibly shutdown the socket causing all listeners
567 * FIXME: This code is duplicated from sys_shutdown, but
568 * there should be a more generic interface rather than
569 * calling socket ops directly here */
570 mutex_lock(&lo
->tx_lock
);
572 printk(KERN_WARNING
"%s: shutting down socket\n",
573 lo
->disk
->disk_name
);
574 lo
->sock
->ops
->shutdown(lo
->sock
,
575 SEND_SHUTDOWN
|RCV_SHUTDOWN
);
578 mutex_unlock(&lo
->tx_lock
);
582 printk(KERN_WARNING
"%s: queue cleared\n", lo
->disk
->disk_name
);
585 return lo
->harderror
;
588 * This is for compatibility only. The queue is always cleared
589 * by NBD_DO_IT or NBD_CLEAR_SOCK.
591 BUG_ON(!lo
->sock
&& !list_empty(&lo
->queue_head
));
593 case NBD_PRINT_DEBUG
:
594 printk(KERN_INFO
"%s: next = %p, prev = %p, head = %p\n",
595 inode
->i_bdev
->bd_disk
->disk_name
,
596 lo
->queue_head
.next
, lo
->queue_head
.prev
,
603 static struct block_device_operations nbd_fops
=
605 .owner
= THIS_MODULE
,
610 * And here should be modules and kernel interface
611 * (Just smiley confuses emacs :-)
614 static int __init
nbd_init(void)
619 BUILD_BUG_ON(sizeof(struct nbd_request
) != 28);
621 if (nbds_max
> MAX_NBD
) {
622 printk(KERN_CRIT
"nbd: cannot allocate more than %u nbds; %u requested.\n", MAX_NBD
,
627 for (i
= 0; i
< nbds_max
; i
++) {
628 struct gendisk
*disk
= alloc_disk(1);
631 nbd_dev
[i
].disk
= disk
;
633 * The new linux 2.5 block layer implementation requires
634 * every gendisk to have its very own request_queue struct.
635 * These structs are big so we dynamically allocate them.
637 disk
->queue
= blk_init_queue(do_nbd_request
, &nbd_lock
);
644 if (register_blkdev(NBD_MAJOR
, "nbd")) {
649 printk(KERN_INFO
"nbd: registered device at major %d\n", NBD_MAJOR
);
650 dprintk(DBG_INIT
, "nbd: debugflags=0x%x\n", debugflags
);
652 for (i
= 0; i
< nbds_max
; i
++) {
653 struct gendisk
*disk
= nbd_dev
[i
].disk
;
654 nbd_dev
[i
].file
= NULL
;
655 nbd_dev
[i
].magic
= LO_MAGIC
;
656 nbd_dev
[i
].flags
= 0;
657 spin_lock_init(&nbd_dev
[i
].queue_lock
);
658 INIT_LIST_HEAD(&nbd_dev
[i
].queue_head
);
659 mutex_init(&nbd_dev
[i
].tx_lock
);
660 init_waitqueue_head(&nbd_dev
[i
].active_wq
);
661 nbd_dev
[i
].blksize
= 1024;
662 nbd_dev
[i
].bytesize
= 0x7ffffc00ULL
<< 10; /* 2TB */
663 disk
->major
= NBD_MAJOR
;
664 disk
->first_minor
= i
;
665 disk
->fops
= &nbd_fops
;
666 disk
->private_data
= &nbd_dev
[i
];
667 disk
->flags
|= GENHD_FL_SUPPRESS_PARTITION_INFO
;
668 sprintf(disk
->disk_name
, "nbd%d", i
);
669 set_capacity(disk
, 0x7ffffc00ULL
<< 1); /* 2 TB */
676 blk_cleanup_queue(nbd_dev
[i
].disk
->queue
);
677 put_disk(nbd_dev
[i
].disk
);
682 static void __exit
nbd_cleanup(void)
685 for (i
= 0; i
< nbds_max
; i
++) {
686 struct gendisk
*disk
= nbd_dev
[i
].disk
;
687 nbd_dev
[i
].magic
= 0;
690 blk_cleanup_queue(disk
->queue
);
694 unregister_blkdev(NBD_MAJOR
, "nbd");
695 printk(KERN_INFO
"nbd: unregistered device at major %d\n", NBD_MAJOR
);
698 module_init(nbd_init
);
699 module_exit(nbd_cleanup
);
701 MODULE_DESCRIPTION("Network Block Device");
702 MODULE_LICENSE("GPL");
704 module_param(nbds_max
, int, 0444);
705 MODULE_PARM_DESC(nbds_max
, "How many network block devices to initialize.");
707 module_param(debugflags
, int, 0644);
708 MODULE_PARM_DESC(debugflags
, "flags for controlling debug output");