From: NeilBrown <neilb@suse.de>
Date: Wed, 18 Feb 2015 00:35:14 +0000 (+1100)
Subject: md/raid5: Fix livelock when array is both resyncing and degraded.
X-Git-Tag: fixes-v4.0-rc1~69^2
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=26ac107378c4742978216be1005b7291b799c7b2;p=pandora-kernel.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 <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
Cc: stable@vger.kernel.org (v3.7+)
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