I wrote a tiny patch to add the Ceph RDB feature of fast-diff to backups created by cinder-backup:

 * https://review.opendev.org/c/openstack/cinder/+/766856/


Could someone please take a peek and let me know of this is sufficient to be merged?

This change was already merged to master and I now created cherry-picks / backports to victoria (https://review.opendev.org/c/openstack/cinder/+/782917) and ussuri (https://review.opendev.org/c/openstack/cinder/+/782929).
Also Andrey Bolgov did create yet another backport of this feaure down to stable/train (https://review.opendev.org/c/openstack/cinder/+/784041).

While the cherry-pick onto the stable/victoria branch does verify fine with Zuul (only need review to be merged), the cinder-plugin-ceph-tempest tests fail for ussuri and also train.

Stdout: 'RBD image feature set mismatch. You can disable features unsupported by the kernel with "rbd feature disable volumes/volume-081e9c22-21f3-4585-a2fe-1caed098052b object-map fast-diff".\nIn some cases useful info is found in syslog - try "dmesg | tail".\n'
Stderr: 'rbd: sysfs write failed\nrbd: map failed: (6) No such device or address\n'

Also is there any other process to follow for backports than to create a cherry-pick from the following release down and wait for review?

Regards

Christian