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

Jonathan Nieder
2012-05-09T06:57:28Z

Hi,

Ben Hutchings wrote:

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

Does 3.2.y need this? Commit 7bfec5f35c68121e7b18 (aka v3.3-rc3~3^2~22)
does not seem to be part of the 3.2-stable tree.

Jonathan

> 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@computer.org>
> Signed-off-by: NeilBrown <neilb@suse.de>
> Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
> ---
> 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