Description of problem:
When converting a large qcow2 image to upload to Ceph-backed cinder, the root disk of a controller can become full without warning.
Version-Release number of selected component (if applicable):
Consistently with large images and limited disk space
Steps to Reproduce:
1. Deploy RHOSP 10 with Ceph
2. Attempt to create a cinder volume from a large qcow2 image
The root disk does not have enough free space for the conversion to complete properly and the disk becomes full.
A check is performed on available disk space before beginning the conversion.
This was addressed upstream by https://bugs.launchpad.net/cinder/+bug/1653225 and https://review.openstack.org/#/c/415868/ and has already been included in OSP 11+. Can we backport this to OSP 10?