[PATCH 4.1 072/123] md/raid1: fix test for was read error from last working device.

[Greg Kroah-Hartman]

4.1-stable review patch.  If anyone has any objections, please let me know.

------------------

From: NeilBrown <neilb@xxxxxxxx>

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

Reported-and-tested-by: Alexander Lyakas <alex.bolshoy@xxxxxxxxx>
Fixes: 76073054c95b ("md/raid1: clean up read_balance.")
Signed-off-by: NeilBrown <neilb@xxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

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

--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -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);
 	}


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