Comment 4 for bug 1939545

Reviewed: https://review.opendev.org/c/openstack/nova/+/804230
Committed: https://opendev.org/openstack/nova/commit/962eda94d52321c3237da870c3d0455c6f0e851b
Submitter: "Zuul (22348)"
Branch: master

commit 962eda94d52321c3237da870c3d0455c6f0e851b
Author: Lee Yarwood <email address hidden>
Date: Wed Aug 11 12:04:11 2021 +0100

    compute: Ensure updates to bdms during pre_live_migration are saved

    When connecting volumes to the underlying host the virt drivers can
    attempt to stash additional metadata returned from os-brick into the
    connection_info associated with a bdm. This pretty janky behaviour
    relies on someone later calling .save() against the underlying
    BlockDeviceMapping object to persist these changes into the database as
    happens in the driver block device layer during a standard volume
    attach.

    However during pre_live_migration no call was made to .save() resulting
    in the changes made to the connection_info being lost. This change
    simply introduces this call at the end of the pre_live_migration method
    on the destination via the driver bdm objects we provide in
    block_device_info.

    Closes-Bug: #1939545
    Change-Id: Iea8896682fc28e3a5cd25afa45238272bee745e1