Comment 20 for bug 1821594

Reviewed: https://review.openstack.org/652146
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=37ac54a42ec91821d62864d63c486c002608491b
Submitter: Zuul
Branch: stable/rocky

commit 37ac54a42ec91821d62864d63c486c002608491b
Author: Matt Riedemann <email address hidden>
Date: Mon Mar 25 14:02:17 2019 -0400

    Delete allocations even if _confirm_resize raises

    When we are confirming a resize, the guest is on the dest
    host and the instance host/node values in the database
    are pointing at the dest host, so the _confirm_resize method
    on the source is really best effort. If something fails, we
    should not leak allocations in placement for the source compute
    node resource provider since the instance is not actually
    consuming the source node provider resources.

    This change refactors the error handling around the _confirm_resize
    call so the big nesting for _error_out_instance_on_exception is
    moved to confirm_resize and then a try/finally is added around
    _confirm_resize so we can be sure to try and cleanup the allocations
    even if _confirm_resize fails in some obscure way. If _confirm_resize
    does fail, the error gets re-raised along with logging a traceback
    and hint about how to correct the instance state in the DB by hard
    rebooting the server on the dest host.

    Conflicts:
          nova/compute/manager.py
          nova/tests/unit/compute/test_compute_mgr.py

    NOTE(mriedem): The manager.py conflict is due to not having change
    Ibb8c12fb2799bb5ceb9e3d72a2b86dbb4f14451e in Rocky. In addition,
    since change I0851e2d54a1fdc82fe3291fb7e286e790f121e92 is not in
    Rocky the _delete_allocation_after_move signature needs to be
    handled a bit different in this backport. The test_compute_mgr.py
    conflict and source_node addition in the setUp is due to the same
    two changes.

    Change-Id: I29c5f491ec20a71283190a1599e7732541de736f
    Closes-Bug: #1821594
    (cherry picked from commit 03a6d26691c1f182224d59190b79f48df278099e)
    (cherry picked from commit 5f515060f6c79f113f7b8107596e41056445c79f)