Commit 26ac1073 authored by NeilBrown's avatar NeilBrown
Browse files

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

Commit a7854487

  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: default avatarManibalan P <>
Bisected-by: default avatarJes Sorensen <>
Tested-by: default avatarJes Sorensen <>
Signed-off-by: default avatarNeilBrown <>
Fixes: a7854487
Cc: (v3.7+)
parent f04ebb0b
......@@ -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
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