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authorNeilBrown <neilb@suse.de>2014-12-03 16:07:58 +1100
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2015-01-29 17:40:53 -0800
commit50606f9a4cdba0499ae76a3111b3a7acfdb4a9d0 (patch)
treed9f0a8f986bccb28db2515643dd5750859bc02d5
parent525f2d01368852ed91d220e0106bbfcefe5f1450 (diff)
md/raid5: fetch_block must fetch all the blocks handle_stripe_dirtying wants.
commit 108cef3aa41669610e1836fe638812dd067d72de upstream. It is critical that fetch_block() and handle_stripe_dirtying() are consistent in their analysis of what needs to be loaded. Otherwise raid5 can wait forever for a block that won't be loaded. Currently when writing to a RAID5 that is resyncing, to a location beyond the resync offset, handle_stripe_dirtying chooses a reconstruct-write cycle, but fetch_block() assumes a read-modify-write, and a lockup can happen. So treat that case just like RAID6, just as we do in handle_stripe_dirtying. RAID6 always does reconstruct-write. This bug was introduced when the behaviour of handle_stripe_dirtying was changed in 3.7, so the patch is suitable for any kernel since, though it will need careful merging for some versions. Cc: stable@vger.kernel.org (v3.7+) Fixes: a7854487cd7128a30a7f4f5259de9f67d5efb95f Reported-by: Henry Cai <henryplusplus@gmail.com> Signed-off-by: NeilBrown <neilb@suse.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--drivers/md/raid5.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 4913c0690872..175584ad643f 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -2896,7 +2896,8 @@ static int fetch_block(struct stripe_head *sh, struct stripe_head_state *s,
(s->failed >= 2 && fdev[1]->toread) ||
(sh->raid_conf->level <= 5 && s->failed && fdev[0]->towrite &&
!test_bit(R5_OVERWRITE, &fdev[0]->flags)) ||
- (sh->raid_conf->level == 6 && s->failed && s->to_write))) {
+ ((sh->raid_conf->level == 6 || sh->sector >= sh->raid_conf->mddev->recovery_cp)
+ && s->failed && s->to_write))) {
/* we would like to get this block, possibly by computing it,
* otherwise read it if the backing disk is insync
*/