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

NeilBrown
2012-05-09T07:20:40Z

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On Wed, 9 May 2012 01:57:17 -0500 Jonathan Nieder <jrnieder@gmail.com> wrote:

> 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

Thanks for checking!

Probably not needed then, but it wouldn't be harmful.

NeilBrown

>
> > 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

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