Allowing operations during RESIZE_VERIFY leaks original instance

[Johannes Erdfelt]

Resizing an instance is a two-step process. First the instance is resized and the task_state ends up set to RESIZE_VERIFY. Then a second step is required to confirm or revert the resize, eventually cleaning up one instance and clearing the task_state.

However, a variety of commands are allowed in RESIZE_VERIFY that will end up clearing the task_state without cleaning up one of the instances (the original since the new instance is the one running at that time).

These operations appear to result in this scenario happening:

stop
reboot
rebuild
pause
suspend
rescue
changePassword
createImage

(I've personally seen it and tested it with rescue and changePassword, the others I found from reading the code, there may be more too).

I'm not sure if the API intended for any of these operations to occur when in RESIZE_VERIFY. If not, the simplest fix would be to prevent any of these from executing while in RESIZE_VERIFY.

If it is intended, some redesigning of how states are tracked is necessary to avoid task_state being cleared.

[Rick Harris (rconradharris)]

I'd vote that we prevent any of these actions until the migration is either verified or reverted.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/6391

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/7976

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/7976
Committed: http://github.com/openstack/nova/commit/cc87be923ff83fed349c0da4b285a180d0644db8
Submitter: Jenkins
Branch: master

commit cc87be923ff83fed349c0da4b285a180d0644db8
Author: Dan Prince <email address hidden>
Date: Thu May 31 11:40:27 2012 -0400

    Prevent task_state changes during VERIFY_RESIZE.

    Don't allow operations that cause task_state to change
    when an instance is in VERIFY_RESIZE.

    Fixes LP Bug #965630.

    Change-Id: I7e222985c199d619c5cb248c04e1670c92d5587b