From: NeilBrown Date: Wed, 18 Feb 2015 00:35:14 +0000 (+1100) Subject: md/raid5: Fix livelock when array is both resyncing and degraded. X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=26ac107378c4742978216be1005b7291b799c7b2;p=linux-beck.git md/raid5: Fix livelock when array is both resyncing and degraded. Commit a7854487cd7128a30a7f4f5259de9f67d5efb95f: md: When RAID5 is dirty, force reconstruct-write instead of read-modify-write. Causes an RCW cycle to be forced even when the array is degraded. A degraded array cannot support RCW as that requires reading all data blocks, and one may be missing. Forcing an RCW when it is not possible causes a live-lock and the code spins, repeatedly deciding to do something that cannot succeed. So change the condition to only force RCW on non-degraded arrays. Reported-by: Manibalan P Bisected-by: Jes Sorensen Tested-by: Jes Sorensen Signed-off-by: NeilBrown Fixes: a7854487cd7128a30a7f4f5259de9f67d5efb95f Cc: stable@vger.kernel.org (v3.7+) --- diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c index aa76865b804b..e75d48c0421a 100644 --- a/drivers/md/raid5.c +++ b/drivers/md/raid5.c @@ -3170,7 +3170,8 @@ static void handle_stripe_dirtying(struct r5conf *conf, * generate correct data from the parity. */ if (conf->max_degraded == 2 || - (recovery_cp < MaxSector && sh->sector >= recovery_cp)) { + (recovery_cp < MaxSector && sh->sector >= recovery_cp && + s->failed == 0)) { /* Calculate the real rcw later - for now make it * look like rcw is cheaper */