| From | Luis Henriques <> | Subject | [PATCH 3.16.y-ckt 130/183] md/raid5: Fix livelock when array is both resyncing and degraded. | Date | Fri, 6 Mar 2015 09:57:01 +0000 |
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3.16.7-ckt8 -stable review patch. If anyone has any objections, please let me know.
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From: NeilBrown <neilb@suse.de>
commit 26ac107378c4742978216be1005b7291b799c7b2 upstream.
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 <pmanibalan@amiindia.co.in> Bisected-by: Jes Sorensen <Jes.Sorensen@redhat.com> Tested-by: Jes Sorensen <Jes.Sorensen@redhat.com> Signed-off-by: NeilBrown <neilb@suse.de> Fixes: a7854487cd7128a30a7f4f5259de9f67d5efb95f Signed-off-by: Luis Henriques <luis.henriques@canonical.com> --- drivers/md/raid5.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c index 68a03d7f25ee..b1b9efb5359f 100644 --- a/drivers/md/raid5.c +++ b/drivers/md/raid5.c @@ -3111,7 +3111,8 @@ 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 */
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