---
fixes:
  - |
    RBD driver `bug #1907964
    <https://bugs.launchpad.net/cinder/+bug/1907964>`_: Add support
    for fast-diff on backup images stored in Ceph.
    Provided fast-diff is supported by the backend it will automatically be
    enabled and used.
    With fast-diff enabled, the generation of diffs between images and
    snapshots as well as determining the actual data usage of a snapshot
    is speed up significantly.