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authorNeilBrown <neilb@suse.de>2014-12-03 16:07:58 +1100
committerNeilBrown <neilb@suse.de>2014-12-03 16:07:58 +1100
commit108cef3aa41669610e1836fe638812dd067d72de (patch)
tree65d0fe1bbfbfbaf5bee3eff388e89c6cd420b360
parent3a18ca061311f2f1ee9c44012f89c7436d392117 (diff)
md/raid5: fetch_block must fetch all the blocks handle_stripe_dirtying wants.
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>
-rw-r--r--drivers/md/raid5.c7
1 files changed, 5 insertions, 2 deletions
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 9c66e5997fc8..c1b0d52bfcb0 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -2917,8 +2917,11 @@ static int fetch_block(struct stripe_head *sh, struct stripe_head_state *s,
(sh->raid_conf->level <= 5 && s->failed && fdev[0]->towrite &&
(!test_bit(R5_Insync, &dev->flags) || test_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) &&
!test_bit(R5_OVERWRITE, &fdev[0]->flags)) ||
- (sh->raid_conf->level == 6 && s->failed && s->to_write &&
- s->to_write - s->non_overwrite < sh->raid_conf->raid_disks - 2 &&
+ ((sh->raid_conf->level == 6 ||
+ sh->sector >= sh->raid_conf->mddev->recovery_cp)
+ && s->failed && s->to_write &&
+ (s->to_write - s->non_overwrite <
+ sh->raid_conf->raid_disks - sh->raid_conf->max_degraded) &&
(!test_bit(R5_Insync, &dev->flags) || test_bit(STRIPE_PREREAD_ACTIVE, &sh->state))))) {
/* we would like to get this block, possibly by computing it,
* otherwise read it if the backing disk is insync