From 42382b709bd1d143b9f0fa93e0a3a1f2f4210707 Mon Sep 17 00:00:00 2001 From: Alex Elder Date: Fri, 16 Nov 2012 09:29:16 -0600 Subject: [PATCH] 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 Reviewed-by: Sage Weil --- drivers/block/rbd.c | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c index 842caf4aab47..c7bf9613ad40 100644 --- a/drivers/block/rbd.c +++ b/drivers/block/rbd.c @@ -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); -- 2.20.1