RBD Namespaces are not supported

Ceph Nautilus (v14.2.0) introduced the Namespaces concept for RADOS Block Devices. This provides a logical separation within a RADOS Pool for RBD images which enables granular access control. See https://docs.ceph.com/docs/nautilus/releases/nautilus/ for additional details.

librados and librbd support this, however qemu does not. The rbd man page defines how rbd images within a namespace can be referenced. https://docs.ceph.com/docs/nautilus/man/8/rbd/#image-snap-group-and-journal-specs

Adding support for RBD namespaces would be beneficial for security and reducing the impact of a hypervisor being compromised and putting an entire Ceph pool or cluster at risk.