libvirt: Nova volume driver for volumes backed by a local file for OpenStack Compute (nova)

Currently there is a class in https://github.com/openstack/nova/blob/master/nova/virt/libvirt/volume.py, line 159, "Class for volumes backed by local file." but the actual implementation is of a block device (is_block_dev=True, conf.source_type = "block"). We have a storage solution (and a cinder volume driver) th...