diff options
| author | NeilBrown <neilb@suse.de> | 2008-03-04 14:29:35 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@woody.linux-foundation.org> | 2008-03-04 16:35:18 -0800 |
| commit | 1c830532f6b44d10a1743ccd00e990c6b83396f5 (patch) | |
| tree | 506c8fef4d84f54e76b533756cff86c45bb61746 /drivers/md | |
| parent | 8ed3a19563b6c05b7625649b1769ddb063d53253 (diff) | |
| download | lwn-1c830532f6b44d10a1743ccd00e990c6b83396f5.tar.gz lwn-1c830532f6b44d10a1743ccd00e990c6b83396f5.zip | |
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: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'drivers/md')
| -rw-r--r-- | drivers/md/raid1.c | 11 | ||||
| -rw-r--r-- | drivers/md/raid10.c | 11 |
2 files changed, 18 insertions, 4 deletions
diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c index 38f076a3400d..ff61b309129a 100644 --- a/drivers/md/raid1.c +++ b/drivers/md/raid1.c @@ -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); })); diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c index 6c486d839c99..8e5671d2f3d3 100644 --- a/drivers/md/raid10.c +++ b/drivers/md/raid10.c @@ -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); })); |