On Fri, 06 Aug 2010 18:01:59 -0700
Dan Williams <dan.j.williams@xxxxxxxxx> wrote:
> Commit b821eaa5 "md: remove ->changed and related code" moved
> revalidate_disk() under open_mutex, and lockdep noticed.
>
> [ INFO: possible circular locking dependency detected ]
> 2.6.32-mdadm-locking #1
> -------------------------------------------------------
> mdadm/3640 is trying to acquire lock:
> (&bdev->bd_mutex){+.+.+.}, at: [<ffffffff811acecb>] revalidate_disk+0x5b/0x90
>
> but task is already holding lock:
> (&mddev->open_mutex){+.+...}, at: [<ffffffffa055e07a>] do_md_stop+0x4a/0x4d0 [md_mod]
>
> which lock already depends on the new lock.
Thanks! applied and sent to Linus - as you might have noticed.
I didn't really like the 'revalidate' variable, and realised that the 'err'
variable wasn't really needed either so added a patch to restructure the
function a little bit.
Thanks,
NeilBrown
>
> Cc: <stable@xxxxxxxxxx>
> Reported-by: Przemyslaw Czarnowski <przemyslaw.hawrylewicz.czarnowski@xxxxxxxxx>
> Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
> ---
> drivers/md/md.c | 6 ++++--
> 1 files changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/md/md.c b/drivers/md/md.c
> index cb20d0b..9743554 100644
> --- a/drivers/md/md.c
> +++ b/drivers/md/md.c
> @@ -4711,7 +4711,7 @@ out:
> */
> static int do_md_stop(mddev_t * mddev, int mode, int is_open)
> {
> - int err = 0;
> + int err = 0, revalidate = 0;
> struct gendisk *disk = mddev->gendisk;
> mdk_rdev_t *rdev;
>
> @@ -4740,7 +4740,7 @@ static int do_md_stop(mddev_t * mddev, int mode, int is_open)
> }
>
> set_capacity(disk, 0);
> - revalidate_disk(disk);
> + revalidate = 1;
>
> if (mddev->ro)
> mddev->ro = 0;
> @@ -4748,6 +4748,8 @@ static int do_md_stop(mddev_t * mddev, int mode, int is_open)
> err = 0;
> }
> mutex_unlock(&mddev->open_mutex);
> + if (revalidate)
> + revalidate_disk(disk);
> if (err)
> return err;
> /*
>
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