Comment 12 for bug 1750666

Reviewed: https://review.openstack.org/546275
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=e5a055d2c6f04330cb83b33f8ddd4c9875fdb1b7
Submitter: Zuul
Branch: stable/pike

commit e5a055d2c6f04330cb83b33f8ddd4c9875fdb1b7
Author: Mohammed Naser <email address hidden>
Date: Tue Feb 20 17:11:37 2018 -0500

    Ensure attachment_id always exists for block device mapping

    If an instance is deleted before it is scheduled, the BDM
    clean-up code uses the mappings from the build request as
    they don't exist in the database yet.

    When using the older attachment flow with reserve_volume,
    there is no attachment_id bound to the block device mapping
    and because it is not loaded from database but rather from
    the build request, accessing the attachment_id field raises
    an exception with 'attachment_id not lazy-loadable'

    If we did a new style attach, _validate_bdm will add the
    attachment_id from Cinder. If we did not, then this patch
    will make sure to set it to 'None' to avoid raising an
    exception when checking if we have an attachment_id set in
    the BDM clean-up code

    Conflicts:
          nova/tests/functional/wsgi/test_servers.py

    Change-Id: I3cc775fc7dafe691b97a15e50ae2e93c92f355be
    Closes-Bug: #1750666
    (cherry picked from commit 16c2c8b3ee9d70e928a61ceb1ef5931d40e509a4)

    Detach volumes when deleting a BFV server pre-scheduling

    If the user creates a volume-backed server from an existing
    volume, the API reserves the volume by creating an attachment
    against it. This puts the volume into 'attaching' status.

    If the user then deletes the server before it's created in a
    cell, by deleting the build request, the attached volume is
    orphaned and requires admin intervention in the block storage
    service.

    This change simply pulls the BDMs off the BuildRequest when
    we delete the server via the build request and does the same
    local cleanup of those volumes as we would in a "normal" local
    delete scenario that the instance was created in a cell but
    doesn't have a host.

    We don't have to worry about ports in this scenario since
    ports are created on the compute, in a cell, and if we're
    deleting a build request then we never got far enough to
    create ports.

    Conflicts:
          nova/tests/functional/wsgi/test_servers.py

    Change-Id: I1a576bdb16befabe06a9728d7adf008fc0667077
    Partial-Bug: #1404867
    (cherry picked from commit 0652e4ab3d506ea21f1bd80b6802c6df5e7b523e)