Comment 23 for bug 1608934

Reviewed: https://review.openstack.org/368216
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=9146f9d602ae1ee64cd8ccbf6fc371bc3fb36395
Submitter: Jenkins
Branch: stable/mitaka

commit 9146f9d602ae1ee64cd8ccbf6fc371bc3fb36395
Author: Jens Rosenboom <email address hidden>
Date: Mon Aug 15 13:16:58 2016 +0200

    Fix resizing in imagebackend.cache()

    The Raw and Lvm backends do not create a 'base image' (the file in the
    image cache) when creating an ephemeral or swap disk. However, cache()
    expects it to exist when checking if a resize is required.

    This change ignores the resize check if the backing file doesn't exist.
    This happens to be ok, because ephemeral and swap disks are always
    created with the correct target size anyway, and therefore never need
    to be resized.

    NOTE(mriedem): There is a slight change in the commit message and
    test since the Raw image backend was renamed to Flat in Newton. Since
    Flat didn't exist in Mitaka it's better to use Raw here.

    Closes-Bug: 1608934
    Co-Authored-By: Matthew Booth <email address hidden>
    Change-Id: I46b5658efafe558dd6b28c9910fb8fde830adec0
    (cherry picked from commit d0775c50d0c2bd50a62ccd49ea7063948af6c3b3)