From: NeilBrown Date: Tue, 12 Aug 2014 23:57:07 +0000 (+1000) Subject: md/raid6: avoid data corruption during recovery of double-degraded RAID6 X-Git-Tag: v4.9.8~5849^2~4 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=9c4bdf697c39805078392d5ddbbba5ae5680e0dd;p=platform%2Fkernel%2Flinux-rpi3.git md/raid6: avoid data corruption during recovery of double-degraded RAID6 During recovery of a double-degraded RAID6 it is possible for some blocks not to be recovered properly, leading to corruption. If a write happens to one block in a stripe that would be written to a missing device, and at the same time that stripe is recovering data to the other missing device, then that recovered data may not be written. This patch skips, in the double-degraded case, an optimisation that is only safe for single-degraded arrays. Bug was introduced in 2.6.32 and fix is suitable for any kernel since then. In an older kernel with separate handle_stripe5() and handle_stripe6() functions the patch must change handle_stripe6(). Cc: stable@vger.kernel.org (2.6.32+) Fixes: 6c0069c0ae9659e3a91b68eaed06a5c6c37f45c8 Cc: Yuri Tikhonov Cc: Dan Williams Reported-by: "Manibalan P" Tested-by: "Manibalan P" Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1090423 Signed-off-by: NeilBrown Acked-by: Dan Williams --- diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c index 6b2d615..183588b 100644 --- a/drivers/md/raid5.c +++ b/drivers/md/raid5.c @@ -3817,6 +3817,8 @@ static void handle_stripe(struct stripe_head *sh) set_bit(R5_Wantwrite, &dev->flags); if (prexor) continue; + if (s.failed > 1) + continue; if (!test_bit(R5_Insync, &dev->flags) || ((i == sh->pd_idx || i == sh->qd_idx) && s.failed == 0))