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md: move revalidate_disk() back outside open_mutex

PATCH In review Dan Williams 2 participants 2 messages Aug 7, 2010 – Aug 8, 2010 MD RAID

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Dan Williams

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#0 lore raw

PATCH 1/1 md: move revalidate_disk() back outside open_mutex

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.

Cc <[email protected]>
Reported-by Przemyslaw Czarnowski <[email protected]>
Signed-off-by Dan Williams <[email protected]>
---
 drivers/md/md.c |    6 ++++--
 1 files changed, 4 insertions(+), 2 deletions(-)
drivers/md/md.c +4 -2
index cb20d0b..9743554 100644
@@ -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;
 	/*
#1 lore raw
Quoted 9 lines · On Fri, 06 Aug 2010 18:01:59 -0700 Dan Williams <[email protected]>…

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

Quoted 4 lines

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 44 lines
Cc <[email protected]>
Reported-by Przemyslaw Czarnowski <[email protected]>
Signed-off-by Dan Williams <[email protected]>
---
 drivers/md/md.c |    6 ++++--
 1 files changed, 4 insertions(+), 2 deletions(-)
drivers/md/md.c +4 -3
index cb20d0b..9743554 100644
@@ -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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