Comment 21 for bug 1578036

Hi, we meet this problem too.
Openstack: Newton
os-brick:1.13.2
ceph:10.2.5

With patch in comment #18, the volumes in availabel status can do rbd incremental backup. But it doesn't work for "in-use" status volumes and raise this problem:
https://bugs.launchpad.net/oslo.privsep/+bug/1593743