[ 024/167] [PATCH] md: dont call ->add_disk unless there is good reason.

From: Ben Hutchings
Date: Wed May 09 2012 - 02:34:01 EST

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


From: NeilBrown <neilb@xxxxxxx>

commit ed209584c38fb74b7eecc03e5b1bfe674e591bd8 upstream.

Commit 7bfec5f35c68121e7b18

md/raid5: If there is a spare and a want_replacement device, start replacement.

cause md_check_recovery to call ->add_disk much more often.
Instead of only when the array is degraded, it is now called whenever
md_check_recovery finds anything useful to do, which includes
updating the metadata for clean<->dirty transition.
This causes unnecessary work, and causes info messages from ->add_disk
to be reported much too often.

So refine md_check_recovery to only do any actual recovery checking
(including ->add_disk) if MD_RECOVERY_NEEDED is set.

This fix is suitable for 3.3.y:

Reported-by: Jan Ceuleers <jan.ceuleers@xxxxxxxxxxxx>
Signed-off-by: NeilBrown <neilb@xxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
drivers/md/md.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/md/md.c b/drivers/md/md.c
index b572e1e..8beb19c 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -7560,14 +7560,14 @@ void md_check_recovery(struct mddev *mddev)
* any transients in the value of "sync_action".
set_bit(MD_RECOVERY_RUNNING, &mddev->recovery);
- clear_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
/* Clear some bits that don't mean anything, but
* might be left set
clear_bit(MD_RECOVERY_INTR, &mddev->recovery);
clear_bit(MD_RECOVERY_DONE, &mddev->recovery);

- if (test_bit(MD_RECOVERY_FROZEN, &mddev->recovery))
+ if (!test_and_clear_bit(MD_RECOVERY_NEEDED, &mddev->recovery) ||
+ test_bit(MD_RECOVERY_FROZEN, &mddev->recovery))
goto unlock;
/* no recovery is running.
* remove any failed drives, then

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