Comment 22 for bug 1550400

Reviewed: https://review.openstack.org/362180
Committed: https://git.openstack.org/cgit/openstack/neutron/commit/?id=69d73630301a9c2d55781920c47b3c29a2cd0fc4
Submitter: Jenkins
Branch: master

commit 69d73630301a9c2d55781920c47b3c29a2cd0fc4
Author: Andreas Scheuring <email address hidden>
Date: Mon Aug 29 13:31:17 2016 +0200

    ml2: Add original port to context on _bind_port

    During portbinding a new PortContext with the binding information
    for the new host gets created. This patch adds the original
    port to the newly created context. This has the following effects

    - When the port was not bound before, context.original will be set
      set to None on portbinding.

    - When the port was bound before (also if binding failed before)
      context.original is set to this port dict on portbinding. This
      happens mostly in the following scenarios:

      - Nova triggers a reschedule of an instance
        Nova reschedules an instance to another host, after spawning an
        instance on the first host failed for some reason. In this case,
        context.original is set to the port with the binding information
        as it was on the failed host.

      - Live Migration
        The port is now available on another host. context.original is
        set to the port and binding information of the source host.

    Context.original can now be used in mechanism drivers that need to be
    migration aware. This is the case for the macvtap mechanism driver.
    The corresponding functionality will be added with patch [1].

    [1] https://review.openstack.org/#/c/361301

    Partial-Bug: #1550400

    Change-Id: I2b60243366505f6e6e4c716d627255a56a4ba486