Re: [PATCH] md: move revalidate_disk() back outside open_mutex
From: Neil Brown <hidden>
Date: 2010-08-08 23:56:07
On Fri, 06 Aug 2010 18:01:59 -0700 Dan Williams [off-list ref] 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
quoted hunk ↗ jump to hunk
Cc: <stable@kernel.org> Reported-by: Przemyslaw Czarnowski <redacted> Signed-off-by: Dan Williams <redacted> --- 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; /* --To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html