Patch "md/raid1: fix test for 'was read error from last working device'." has been added to the 4.1-stable tree

This is a note to let you know that I've just added the patch titled

md/raid1: fix test for 'was read error from last working device'.

to the 4.1-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
md-raid1-fix-test-for-was-read-error-from-last-working-device.patch
and it can be found in the queue-4.1 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: NeilBrown <[email protected]>
Date: Fri, 24 Jul 2015 09:22:16 +1000
Subject: md/raid1: fix test for 'was read error from last working device'.

From: NeilBrown <[email protected]>

commit 34cab6f42003cb06f48f86a86652984dec338ae9 upstream.

When we get a read error from the last working device, we don't try to repair it, and don't fail the device. We simple report a read error to the caller.

However the current test for 'is this the last working device' is wrong.
When there is only one fully working device, it assumes that a non-faulty device is that device. However a spare which is rebuilding would be non-faulty but so not the only working device.

So change the test from "!Faulty" to "In_sync". If ->degraded says there is only one fully working device and this device is in_sync, this must be the one.

This bug has existed since we allowed read_balance to read from a recovering spare in v3.0

---
 drivers/md/raid1.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

@@ -336,7 +336,7 @@ static void raid1_end_read_request(struc
 		spin_lock_irqsave(&conf->device_lock, flags);
 		if (r1_bio->mddev->degraded == conf->raid_disks ||
 		    (r1_bio->mddev->degraded == conf->raid_disks-1 &&
-		     !test_bit(Faulty, &conf->mirrors[mirror].rdev->flags)))
+		     test_bit(In_sync, &conf->mirrors[mirror].rdev->flags)))
 			uptodate = 1;
 		spin_unlock_irqrestore(&conf->device_lock, flags);
 	}

Patches currently in stable-queue which might be from [email protected] are

queue-4.1/md-raid1-fix-test-for-was-read-error-from-last-working-device.patch