From: NeilBrown Date: Tue, 25 Oct 2011 23:31:04 +0000 (+1100) Subject: md/raid5: fix bug that could result in reads from a failed device. X-Git-Tag: firefly_0821_release~7541^2~2477 X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=a847627709b3402163d99f7c6fda4a77bcd6b51b;p=firefly-linux-kernel-4.4.55.git md/raid5: fix bug that could result in reads from a failed device. commit 355840e7a7e56bb2834fd3b0da64da5465f8aeaa upstream. This bug was introduced in 415e72d034c50520ddb7ff79e7d1792c1306f0c9 which was in 2.6.36. There is a small window of time between when a device fails and when it is removed from the array. During this time we might still read from it, but we won't write to it - so it is possible that we could read stale data. We didn't need the test of 'Faulty' before because the test on In_sync is sufficient. Since we started allowing reads from the early part of non-In_sync devices we need a test on Faulty too. This is suitable for any kernel from 2.6.36 onwards, though the patch might need a bit of tweaking in 3.0 and earlier. Signed-off-by: NeilBrown Signed-off-by: Greg Kroah-Hartman --- diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c index 2581ba127354..e509147318e6 100644 --- a/drivers/md/raid5.c +++ b/drivers/md/raid5.c @@ -3369,7 +3369,7 @@ static void handle_stripe6(struct stripe_head *sh) /* Not in-sync */; else if (test_bit(In_sync, &rdev->flags)) set_bit(R5_Insync, &dev->flags); - else { + else if (!test_bit(Faulty, &rdev->flags)) { /* in sync if before recovery_offset */ if (sh->sector + STRIPE_SECTORS <= rdev->recovery_offset) set_bit(R5_Insync, &dev->flags);