[dm-devel] dm raid: avoid mddev->suspended access
Mike Snitzer
snitzer at redhat.com
Tue Jul 25 18:29:17 UTC 2017
On Tue, Jul 25 2017 at 2:17pm -0400,
Mike Snitzer <snitzer at redhat.com> wrote:
> On Thu, Jul 13 2017 at 11:34am -0400,
> heinzm at redhat.com <heinzm at redhat.com> wrote:
>
> > From: Heinz Mauelshagen <heinzm at redhat.com>
> >
> > Use runtime flag to ensure that an mddev gets suspended/resumed just once.
> >
> > Signed-off-by: Heinz Mauelshagen <heinzm at redhat.com>
> > ---
> > drivers/md/dm-raid.c | 12 +++++++-----
> > 1 file changed, 7 insertions(+), 5 deletions(-)
> >
> > diff --git a/drivers/md/dm-raid.c b/drivers/md/dm-raid.c
> > index b409015..60c524b 100644
> > --- a/drivers/md/dm-raid.c
> > +++ b/drivers/md/dm-raid.c
> > @@ -3760,7 +3762,7 @@ static int rs_start_reshape(struct raid_set *rs)
> > return r;
> >
> > /* Need to be resumed to be able to start reshape, recovery is frozen until raid_resume() though */
> > - if (mddev->suspended)
> > + if (test_and_clear_bit(RT_FLAG_RS_SUSPENDED, &rs->runtime_flags))
> > mddev_resume(mddev);
> >
> > /*
> > @@ -3787,8 +3789,8 @@ static int rs_start_reshape(struct raid_set *rs)
> > }
> >
> > /* Suspend because a resume will happen in raid_resume() */
> > - if (!mddev->suspended)
> > - mddev_suspend(mddev);
> > + set_bit(RT_FLAG_RS_SUSPENDED, &rs->runtime_flags);
> > + mddev_suspend(mddev);
> >
> > /*
> > * Now reshape got set up, update superblocks to
>
> Shouldn't this be the following?
>
> if (!test_and_set_bit(RT_FLAG_RS_SUSPENDED, &rs->runtime_flags))
> mddev_suspend(mddev);
Looking closer, the preceding test_and_clear_bit() should ensure that
the device is always resumed by the time it gets to the code I called
into question.
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