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Commit 42382b70 authored by Alex Elder's avatar Alex Elder
Browse files

rbd: do not allow remove of mounted-on image 



There is no check in rbd_remove() to see if anybody holds open the
image being removed.  That's not cool.

Add a simple open count that goes up and down with opens and closes
(releases) of the device, and don't allow an rbd image to be removed
if the count is non-zero.

Protect the updates of the open count value with ctl_mutex to ensure
the underlying rbd device doesn't get removed while concurrently
being opened.

Signed-off-by: default avatarAlex Elder <elder@inktank.com>
Reviewed-by: default avatarSage Weil <sage@inktank.com>
parent 8884d53d

drivers/block/rbd.c

+13 −0
Original line number Diff line number Diff line
@@ -235,6 +235,7 @@ struct rbd_device { 


	/* sysfs related */

	struct device		dev;

	unsigned long		open_count;

};



static DEFINE_MUTEX(ctl_mutex);	  /* Serialize open/close/setup/teardown */
@@ -309,8 +310,11 @@ static int rbd_open(struct block_device *bdev, fmode_t mode) 
	if ((mode & FMODE_WRITE) && rbd_dev->mapping.read_only)

		return -EROFS;



	mutex_lock_nested(&ctl_mutex, SINGLE_DEPTH_NESTING);

	rbd_get_dev(rbd_dev);

	set_device_ro(bdev, rbd_dev->mapping.read_only);

	rbd_dev->open_count++;

	mutex_unlock(&ctl_mutex);



	return 0;

}
@@ -319,7 +323,11 @@ static int rbd_release(struct gendisk *disk, fmode_t mode) 
{

	struct rbd_device *rbd_dev = disk->private_data;



	mutex_lock_nested(&ctl_mutex, SINGLE_DEPTH_NESTING);

	rbd_assert(rbd_dev->open_count > 0);

	rbd_dev->open_count--;

	rbd_put_dev(rbd_dev);

	mutex_unlock(&ctl_mutex);



	return 0;

}
@@ -3745,6 +3753,11 @@ static ssize_t rbd_remove(struct bus_type *bus, 
		goto done;

	}



	if (rbd_dev->open_count) {

		ret = -EBUSY;

		goto done;

	}



	rbd_remove_all_snaps(rbd_dev);

	rbd_bus_del_dev(rbd_dev);