From: NeilBrown <redacted>

This patch has been added to the 3.18 stable tree. If you have any
objections, please let us know.

===============

[ Upstream commit 34cab6f42003cb06f48f86a86652984dec338ae9 ]

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

Reported-and-tested-by: Alexander Lyakas <redacted>
Fixes: 76073054c95b ("md/raid1: clean up read_balance.")
Cc: stable@vger.kernel.org (v3.0+)
Signed-off-by: NeilBrown <redacted>
Signed-off-by: Sasha Levin <redacted>
---
 drivers/md/raid1.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
index 8712bc0..d24245c 100644
--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c

@@ -336,7 +336,7 @@ static void raid1_end_read_request(struct bio *bio, int error)
 		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);
 	}

-- 
2.1.4