The patch titled
nbd: fix I/O hang on disconnected nbds
has been removed from the -mm tree. Its filename was
nbd-fix-i-o-hang-on-disconnected-nbds.patch
This patch was dropped because it was merged into mainline or a subsystem tree
The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/
------------------------------------------------------
Subject: nbd: fix I/O hang on disconnected nbds
From: Paul Clements <paul.clements@xxxxxxxxxxxx>
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@xxxxxxxxxxxx>
Reported-by: Jon Nelson <jnelson-kernel-bugzilla@xxxxxxxxxxx>
Acked-by: Pavel Machek <pavel@xxxxxx>
Cc: <stable@xxxxxxxxxx> [2.6.26.x, 2.6.27.x, 2.6.28.x]
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
drivers/block/nbd.c | 9 +++++++++
1 file changed, 9 insertions(+)
diff -puN drivers/block/nbd.c~nbd-fix-i-o-hang-on-disconnected-nbds drivers/block/nbd.c
--- a/drivers/block/nbd.c~nbd-fix-i-o-hang-on-disconnected-nbds
+++ a/drivers/block/nbd.c
@@ -549,6 +549,15 @@ static void do_nbd_request(struct reques
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);
_
Patches currently in -mm which might be from paul.clements@xxxxxxxxxxxx are
origin.patch
nbd-add-locking-to-nbd_ioctl.patch
nbd-add-locking-to-nbd_ioctl-checkpatch-fixes.patch
nbd-add-locking-to-nbd_ioctl-fix.patch
nbd-trivial-cleanups.patch
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