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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: Alex Elder <elder@inktank.com>
Reviewed-by: Sage Weil <sage@inktank.com>
This commit is contained in:
Alex Elder 2012-11-16 09:29:16 -06:00
parent 8884d53dd6
commit 42382b709b
1 changed files with 13 additions and 0 deletions
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13
drivers/block/rbd.c
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@ -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);