Comment 7 for bug 1707238

Reviewed: https://review.openstack.org/491625
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=539d3bbb8aced7703914bb7ef0b72ac3a471c54e
Submitter: Jenkins
Branch: stable/ocata

commit 539d3bbb8aced7703914bb7ef0b72ac3a471c54e
Author: melanie witt <email address hidden>
Date: Fri Jul 28 17:06:53 2017 +0000

    Detach device from live domain even if not found on persistent

    In a past attempt to fix a bug [1], we started raising DeviceNotFound
    if a device wasn't found on the persistent domain. This was to address
    a scenario where the guest ignored the detach from the live domain
    because it was busy and we wanted to avoid failing a later detach
    request to the user (compute handles DeviceNotFound).

    Unfortunately, in the above case, a later detach request won't fail to
    the user but it also won't detach from the live domain. It sees the
    device already detached from the persistent domain and doesn't attempt
    to detach from the live domain.

    This is a serious problem because it's possible for a volume to be
    attached to two live domains and data corruption can occur.

    This adds an attempt to detach from the live domain even if we had
    already detached from the persistent domain in the past.

    Closes-Bug: #1707238

    [1] https://review.openstack.org/386257

    Change-Id: I8cd056fa17184a98c31547add0e9fb2d363d0908
    (cherry picked from commit d39934ad6afb7e2729bb45235f363ada86012d15)