Comment 8 for bug 1845146

Reviewed: https://review.opendev.org/684409
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=6ec686c26b2c8b18bcff522633bfe9715e0feec3
Submitter: Zuul
Branch: master

commit 6ec686c26b2c8b18bcff522633bfe9715e0feec3
Author: Artom Lifshitz <email address hidden>
Date: Tue Sep 24 13:22:23 2019 -0400

    Stop filtering out 'accepted' for in-progress migrations

    Live migrations are created with an 'accepted' status. Resource claims
    on the destination are done with the migration in 'accepted' status.
    The status is set to 'preparing' a bit later, right before running
    pre_live_migration(). Migrations with status 'accepted' are filtered
    out by the database layer when getting in-progress migrations. Thus,
    there's a time window after resource claims but before 'preparing'
    during which resources have been claimed but the migration is not
    considered in-progress by the database layer. During that window, the
    instance's host is the source - that's only updated once the live
    migration finishes. If the update available resources periodic task
    runs during that window, it'll free the instance's resource from the
    destination because neither the instance nor any of its in-progress
    migrations are associated with the destination. This means that other
    incoming instances are able to consume resources that should not be
    available. This patch stops filtering out the 'accepted' status in the
    database layer when retrieving in-progress migrations.

    Change-Id: I4c56925ed35bc3275ca1ac6c30d7fd641ad84260
    Closes-bug: 1845146