diff options
| author | Paul Clements <paul.clements@steeleye.com> | 2009-02-11 13:04:45 -0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2009-02-17 09:46:15 -0800 |
| commit | 492fb0dddd7b3d6cec9a82d86cf1ad9ec918f81a (patch) | |
| tree | 8cb4894e0b9d9794f11f6c8ffcce69355dc22dd6 | |
| parent | 59e8c6c4a6c95d6cc4667ad5c14199d53c529936 (diff) | |
nbd: fix I/O hang on disconnected nbds
commit 4d48a542b42747c36a5937447d9c3de7c897ea50 upstream.
Fix a problem that causes I/O to a disconnected (or partially initialized)
nbd device to hang indefinitely. To reproduce:
# ioctl NBD_SET_SIZE_BLOCKS /dev/nbd23 514048
# dd if=/dev/nbd23 of=/dev/null bs=4096 count=1
...hangs...
This can also occur when an nbd device loses its nbd-client/server
connection. Although we clear the queue of any outstanding I/Os after the
client/server connection fails, any additional I/Os that get queued later
will hang.
This bug may also be the problem reported in this bug report:
http://bugzilla.kernel.org/show_bug.cgi?id=12277
Testing would need to be performed to determine if the two issues are the
same.
This problem was introduced by the new request handling thread code ("NBD:
allow nbd to be used locally", 3/2008), which entered into mainline around
2.6.25.
The fix, which is fairly simple, is to restore the check for lo->sock
being NULL in do_nbd_request. This causes I/O to an uninitialized nbd to
immediately fail with an I/O error, as it did prior to the introduction of
this bug.
Signed-off-by: Paul Clements <paul.clements@steeleye.com>
Reported-by: Jon Nelson <jnelson-kernel-bugzilla@jamponi.net>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
| -rw-r--r-- | drivers/block/nbd.c | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c index 1778e4a2c672..814ffd9f1cb4 100644 --- a/drivers/block/nbd.c +++ b/drivers/block/nbd.c @@ -547,6 +547,15 @@ static void do_nbd_request(struct request_queue * q) BUG_ON(lo->magic != LO_MAGIC); + if (unlikely(!lo->sock)) { + printk(KERN_ERR "%s: Attempted send on closed socket\n", + lo->disk->disk_name); + req->errors++; + nbd_end_request(req); + spin_lock_irq(q->queue_lock); + continue; + } + spin_lock_irq(&lo->queue_lock); list_add_tail(&req->queuelist, &lo->waiting_queue); spin_unlock_irq(&lo->queue_lock); |