NeilBrown [off-list ref] wrote:
Hi,
thanks for the report and the patch.

However I don't think the patch really does what you want.

The two tests are already mutually exclusive as one begins with
raid_disk >= 0
and the other with
raid_disk < 0
and neither change raid_disk.

The reason the patch has an effect is the 'break' that has been added.
i.e. as soon as you find a normal working device you break out of the
loop
and stop looking for spares.

I think the correct fix is simply:

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 4332fc2..91e31e2 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c

@@ -7088,6 +7088,7 @@ static int remove_and_add_spares(mddev_t *mddev)

list_for_each_entry(rdev, &mddev->disks, same_set) {
if (rdev->raid_disk >= 0 &&
!test_bit(In_sync, &rdev->flags) &&
+ !test_bit(Faulty, &rdev->flags) &&
!test_bit(Blocked, &rdev->flags))
spares++;
if (rdev->raid_disk < 0


i.e. never consider a Faulty device to be a spare.

It looks like this bug was introduced by commit dfc70645000616777
in 2.6.26 when we allowed partially recovered devices to remain in the
array
when a different device fails.

Can you please conform that this patch removes your symptom?

Thanks,
NeilBrown