Comment 7 for bug 1796737

Reviewed: https://review.openstack.org/608777
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=a99722bb854d2ba99c3abc2d2738ba281148fde4
Submitter: Zuul
Branch: master

commit a99722bb854d2ba99c3abc2d2738ba281148fde4
Author: Matt Riedemann <email address hidden>
Date: Mon Oct 8 17:33:49 2018 -0400

    Properly track local root disk usage during moves

    Change I0839470c4bcfb16590a0d87b306d683b059bf8a9 fixed
    root disk usage tracking for volume-backed instances
    when performing an instance_claim which happens during
    the initial server create and unshelve. However, root
    disk reporting is still wrong for volume-backed instances
    during move claims (resize and evacuate) because a move
    claim calls _update_usage_from_migration which passes a
    Flavor object to ResourceTracker._get_usage_dict() and
    that method didn't have "is_bfv" logic in that scenario.

    This fixes the bug by always passing the instance object
    to the _get_usage_dict() method so we can determine if
    it's volume-backed and if so report the root_gb usage as 0.

    The related functional regression test is updated
    appropriately to show the bug is fixed for volume-backed
    instances.

    Change-Id: Ia19264ae7c88bb03ed3118795d4011ceb62ef92c
    Closes-Bug: #1796737