Comment 40 for bug 1628606

Reviewed: https://review.opendev.org/c/openstack/nova/+/861872
Committed: https://opendev.org/openstack/nova/commit/17ae907569e45cc0f5c7da9511bb668a877b7b2e
Submitter: "Zuul (22348)"
Branch: stable/yoga

commit 17ae907569e45cc0f5c7da9511bb668a877b7b2e
Author: Sean Mooney <email address hidden>
Date: Thu May 13 12:48:21 2021 +0100

    [compute] always set instance.host in post_livemigration

    This change add a new _post_live_migration_update_host
    function that wraps _post_live_migration and just ensures
    that if we exit due to an exception instance.host is set
    to the destination host.

    when we are in _post_live_migration the guest has already
    started running on the destination host and we cannot revert.
    Sometimes admins or users will hard reboot the instance expecting
    that to fix everything when the vm enters the error state after
    the failed migrations. Previously this would end up recreating the
    instance on the source node leading to possible data corruption if
    the instance used shared storage.

    Change-Id: Ibc4bc7edf1c8d1e841c72c9188a0a62836e9f153
    Partial-Bug: #1628606
    (cherry picked from commit 8449b7caefa4a5c0728e11380a088525f15ad6f5)
    (cherry picked from commit 643b0c7d35752b214eee19b8d7298a19a8493f6b)