dect
/
linux-2.6
Archived
13
0
Fork 0
Code Releases Activity

md/raid1,raid10: avoid deadlock during resync/recovery. 

If RAID1 or RAID10 is used under LVM or some other stacking
block device, it is possible to enter a deadlock during
resync or recovery.
This can happen if the upper level block device creates
two requests to the RAID1 or RAID10.  The first request gets
processed, blocks recovery and queue requests for underlying
requests in current->bio_list.  A resync request then starts
which will wait for those requests and block new IO.

But then the second request to the RAID1/10 will be attempted
and it cannot progress until the resync request completes,
which cannot progress until the underlying device requests complete,
which are on a queue behind that second request.

So allow that second request to proceed even though there is
a resync request about to start.

This is suitable for any -stable kernel.

Cc: stable@vger.kernel.org
Reported-by: Ray Morris <support@bettercgi.com>
Tested-by: Ray Morris <support@bettercgi.com>
Signed-off-by: NeilBrown <neilb@suse.de>
This commit is contained in:
NeilBrown 2012-03-19 12:46:38 +11:00
parent 4474ca42e2
commit d6b42dcb99
2 changed files with 30 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

17
drivers/md/raid1.c
View File

@ -737,9 +737,22 @@ static void wait_barrier(struct r1conf *conf)
spin_lock_irq(&conf->resync_lock);
if (conf->barrier) {
conf->nr_waiting++;
wait_event_lock_irq(conf->wait_barrier, !conf->barrier,
/* Wait for the barrier to drop.
* However if there are already pending
* requests (preventing the barrier from
* rising completely), and the
* pre-process bio queue isn't empty,
* then don't wait, as we need to empty
* that queue to get the nr_pending
* count down.
*/
wait_event_lock_irq(conf->wait_barrier,
!conf->barrier ||
(conf->nr_pending &&
current->bio_list &&
!bio_list_empty(current->bio_list)),
conf->resync_lock,
);
);
conf->nr_waiting--;
}
conf->nr_pending++;

17
drivers/md/raid10.c
View File

@ -863,9 +863,22 @@ static void wait_barrier(struct r10conf *conf)
spin_lock_irq(&conf->resync_lock);
if (conf->barrier) {
conf->nr_waiting++;
wait_event_lock_irq(conf->wait_barrier, !conf->barrier,
/* Wait for the barrier to drop.
* However if there are already pending
* requests (preventing the barrier from
* rising completely), and the
* pre-process bio queue isn't empty,
* then don't wait, as we need to empty
* that queue to get the nr_pending
* count down.
*/
wait_event_lock_irq(conf->wait_barrier,
!conf->barrier ||
(conf->nr_pending &&
current->bio_list &&
!bio_list_empty(current->bio_list)),
conf->resync_lock,
);
);
conf->nr_waiting--;
}
conf->nr_pending++;