md/raid5: Fix livelock when array is both resyncing and degraded.

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commit 26ac107378 upstream.

Commit a7854487cd:
  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: a7854487cd
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>

...

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NeilBrown 2015-02-18 11:35:14 +11:00 • committed by Luis Henriques

parent b4fe5e2d8a

commit dae27fb6ff

1 changed files with 2 additions and 1 deletions

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drivers/md/raid5.c

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