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Commit f2ea68cf authored by NeilBrown's avatar NeilBrown
Browse files

md: only count actual openers as access which prevent a 'stop' 



Open isn't the only thing that increments ->active.  e.g. reading
/proc/mdstat will increment it briefly.  So to avoid false positives
in testing for concurrent access, introduce a new counter that counts
just the number of times the md device it open.

Signed-off-by: default avatarNeilBrown <neilb@suse.de>
parent d6e22150

drivers/md/md.c

+6 −3
Original line number Original line Diff line number Diff line
@@ -273,6 +273,7 @@ static mddev_t * mddev_find(dev_t unit) 
	INIT_LIST_HEAD(&new->all_mddevs);

	INIT_LIST_HEAD(&new->all_mddevs);

	init_timer(&new->safemode_timer);

	init_timer(&new->safemode_timer);

	atomic_set(&new->active, 1);

	atomic_set(&new->active, 1);

	atomic_set(&new->openers, 0);

	spin_lock_init(&new->write_lock);

	spin_lock_init(&new->write_lock);

	init_waitqueue_head(&new->sb_wait);

	init_waitqueue_head(&new->sb_wait);

	init_waitqueue_head(&new->recovery_wait);

	init_waitqueue_head(&new->recovery_wait);
@@ -2695,14 +2696,14 @@ array_state_store(mddev_t *mddev, const char *buf, size_t len) 
		break;

		break;

	case clear:

	case clear:

		/* stopping an active array */

		/* stopping an active array */

		if (atomic_read(&mddev->active) > 1)

		if (atomic_read(&mddev->openers) > 0)

			return -EBUSY;

			return -EBUSY;

		err = do_md_stop(mddev, 0, 0);

		err = do_md_stop(mddev, 0, 0);

		break;

		break;

	case inactive:

	case inactive:

		/* stopping an active array */

		/* stopping an active array */

		if (mddev->pers) {

		if (mddev->pers) {

			if (atomic_read(&mddev->active) > 1)

			if (atomic_read(&mddev->openers) > 0)

				return -EBUSY;

				return -EBUSY;

			err = do_md_stop(mddev, 2, 0);

			err = do_md_stop(mddev, 2, 0);

		} else

		} else
@@ -3816,7 +3817,7 @@ static int do_md_stop(mddev_t * mddev, int mode, int is_open) 
	int err = 0;

	int err = 0;

	struct gendisk *disk = mddev->gendisk;

	struct gendisk *disk = mddev->gendisk;





	if (atomic_read(&mddev->active) > 1 + is_open) {

	if (atomic_read(&mddev->openers) > is_open) {

		printk("md: %s still in use.\n",mdname(mddev));

		printk("md: %s still in use.\n",mdname(mddev));

		return -EBUSY;

		return -EBUSY;

	}

	}
@@ -5014,6 +5015,7 @@ static int md_open(struct inode *inode, struct file *file) 




	err = 0;

	err = 0;

	mddev_get(mddev);

	mddev_get(mddev);

	atomic_inc(&mddev->openers);

	mddev_unlock(mddev);

	mddev_unlock(mddev);





	check_disk_change(inode->i_bdev);

	check_disk_change(inode->i_bdev);
@@ -5026,6 +5028,7 @@ static int md_release(struct inode *inode, struct file * file) 
 	mddev_t *mddev = inode->i_bdev->bd_disk->private_data;

 	mddev_t *mddev = inode->i_bdev->bd_disk->private_data;





	BUG_ON(!mddev);

	BUG_ON(!mddev);

	atomic_dec(&mddev->openers);

	mddev_put(mddev);

	mddev_put(mddev);





	return 0;

	return 0;

include/linux/raid/md_k.h

+2 −1
Original line number Original line Diff line number Diff line
@@ -215,7 +215,8 @@ struct mddev_s 




	int				in_sync;	/* know to not need resync */

	int				in_sync;	/* know to not need resync */

	struct mutex			reconfig_mutex;

	struct mutex			reconfig_mutex;

	atomic_t			active;

	atomic_t			active;		/* general refcount */

	atomic_t			openers;	/* number of active opens */





	int				changed;	/* true if we might need to reread partition info */

	int				changed;	/* true if we might need to reread partition info */

	int				degraded;	/* whether md should consider

	int				degraded;	/* whether md should consider