Ceph » rbd

The umount(8) command has a very useful feature that allows
one to specify either the device or the directory that
device is mounted on to indicate which file system you'd
like to unmount.

I think the rbd CLI should offer a similar feature. That
is, if I map an image like this:

rbd map image1    (suppose it maps to /dev/rbd4)

I should be able to unmap it like this:

rbd unmap image1   (equivalent to "rbd unmap /dev/rbd4")