Comment 22 for bug 1469179

Reviewed: https://review.openstack.org/270482
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=d6210a4d0cdaf8a71d2516bf44f04789cbe89d0c
Submitter: Jenkins
Branch: master

commit d6210a4d0cdaf8a71d2516bf44f04789cbe89d0c
Author: Tobias Urdin <email address hidden>
Date: Wed Jan 20 21:55:33 2016 +0100

    Move is_volume_backed_instance to compute.utils

    This function is a method of ComputeAPI, so its callers must have an
    instance of the class. This make the usage difficult in modules which
    do not need to call ComputeAPI by other reason.

    Besides this function does not use any of the class members. So there is
    no reason for it to be the class method.

    This patch moves this function to compute.utils because it does not use
    anything of the class members.

    This patch also adds support for the _get_root_bdm and
    is_volume_backed_instance to read from a dictionary instead of an
    Instance object. Because of this we can call is_volume_backed_instance
    from build_request_spec and fix bug #1469179.

    Change-Id: I6d446088faf500ed39a4504794d09d0f86e2bbc3
    Co-Authored-By: Feodor Tersin <email address hidden>
    Co-Authored-By: Ankit Agrawal <email address hidden>
    Related-Bug: #1469179
    Related-Bug: #1334974
    Related-Bug: #1358566