Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 1c830532 authored by NeilBrown's avatar NeilBrown Committed by Linus Torvalds
Browse files

md: fix possible raid1/raid10 deadlock on read error during resync 



Thanks to K.Tanaka and the scsi fault injection framework, here is a fix for
another possible deadlock in raid1/raid10 error handing.

If a read request returns an error while a resync is happening and a resync
request is pending, the attempt to fix the error will block until the resync
progresses, and the resync will block until the read request completes.  Thus
a deadlock.

This patch fixes the problem.

Cc: "K.Tanaka" <k-tanaka@ce.jp.nec.com>
Signed-off-by: default avatarNeil Brown <neilb@suse.de>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 8ed3a195

drivers/md/raid1.c

+9 −2
Original line number Diff line number Diff line
@@ -704,13 +704,20 @@ static void freeze_array(conf_t *conf) 
	/* stop syncio and normal IO and wait for everything to

	 * go quite.

	 * We increment barrier and nr_waiting, and then

	 * wait until barrier+nr_pending match nr_queued+2

	 * wait until nr_pending match nr_queued+1

	 * This is called in the context of one normal IO request

	 * that has failed. Thus any sync request that might be pending

	 * will be blocked by nr_pending, and we need to wait for

	 * pending IO requests to complete or be queued for re-try.

	 * Thus the number queued (nr_queued) plus this request (1)

	 * must match the number of pending IOs (nr_pending) before

	 * we continue.

	 */

	spin_lock_irq(&conf->resync_lock);

	conf->barrier++;

	conf->nr_waiting++;

	wait_event_lock_irq(conf->wait_barrier,

			    conf->barrier+conf->nr_pending == conf->nr_queued+2,

			    conf->nr_pending == conf->nr_queued+1,

			    conf->resync_lock,

			    ({ flush_pending_writes(conf);

			       raid1_unplug(conf->mddev->queue); }));

drivers/md/raid10.c

+9 −2
Original line number Diff line number Diff line
@@ -747,13 +747,20 @@ static void freeze_array(conf_t *conf) 
	/* stop syncio and normal IO and wait for everything to

	 * go quiet.

	 * We increment barrier and nr_waiting, and then

	 * wait until barrier+nr_pending match nr_queued+2

	 * wait until nr_pending match nr_queued+1

	 * This is called in the context of one normal IO request

	 * that has failed. Thus any sync request that might be pending

	 * will be blocked by nr_pending, and we need to wait for

	 * pending IO requests to complete or be queued for re-try.

	 * Thus the number queued (nr_queued) plus this request (1)

	 * must match the number of pending IOs (nr_pending) before

	 * we continue.

	 */

	spin_lock_irq(&conf->resync_lock);

	conf->barrier++;

	conf->nr_waiting++;

	wait_event_lock_irq(conf->wait_barrier,

			    conf->barrier+conf->nr_pending == conf->nr_queued+2,

			    conf->nr_pending == conf->nr_queued+1,

			    conf->resync_lock,

			    ({ flush_pending_writes(conf);

			       raid10_unplug(conf->mddev->queue); }));