Comment 2 for bug 1596957

Reviewed: https://review.openstack.org/382024
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=ed994bb4d72b5f93cfb76a5f726264e4896ad4ed
Submitter: Jenkins
Branch: master

commit ed994bb4d72b5f93cfb76a5f726264e4896ad4ed
Author: Feodor Tersin <email address hidden>
Date: Tue Oct 4 20:17:17 2016 +0300

    libvirt: Improve _is_booted_from_volume implementation

    Currently this method cannot be used widely due to its parameters. It
    requires device_info - the dict which can not be easily obtained in many
    cases. Since it is often needed to figure out if an instance is booted
    from volume, and the method name is "appropriate", this sometimes leads
    to errors (when string result of get_instance_disk_info is passed as an
    argument to _is_booted_from_volume; see also Id5901254).

    This patch makes _is_booted_from_volume to use standard
    block_device_info structure, which is accessible in almost any driver
    method.

    Closes-bug: 1596957
    Closes-bug: 1587802
    Change-Id: Ie424d172ac9d6aeb42d83e512f2a18713134be3b