Comment 2 for bug 1713857

Reviewed: https://review.openstack.org/498983
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=5b008c6540f948d28dc50a0ef84095ebd96d198d
Submitter: Zuul
Branch: master

commit 5b008c6540f948d28dc50a0ef84095ebd96d198d
Author: melanie witt <email address hidden>
Date: Tue Aug 29 22:53:44 2017 +0000

    Save updated libvirt domain XML after swapping volume

    When a user calls the volume-update API, we swap_volume in the libvirt
    driver from the old volume attachment to the new volume attachment.
    Currently, we're saving the domain XML with the old configuration prior
    to updating the volume and upon a soft-reboot request, it results in an
    error:

      Instance soft reboot failed: Cannot access storage file <old path>

    and falls back to a hard reboot, which is like pulling the power cord,
    possibly resulting in file system inconsistencies.

    This changes to saving the new, updated domain XML after the volume
    swap.

    Closes-Bug: #1713857

    Change-Id: I166cde5ad8b00699e4ec02609f0d7b69236d855d