target_power_state should be cleared on conductor start up

[Zhenguo Niu]

when nova issuing a power action request to ironic, it will wait until the node target_power_state change to NOSTATE, but if there are something wrong with ironic during the waiting power state change process, and we reboot ironic conductor to recover, the nova instance's power state can't become complete any more, such as 'rebooting'.

so this proposes to clear the tartget_power_state during conductor startup, and it doesn't make sense to set the target state in a new started ironic.

[Dmitry Tantsur (divius)]

It makes sense, but it's not as simple as just clear the field in database. The power request might be in progress, so we should first wait for the target state. On timeout we should clean it and properly set the error.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/310090

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/310090
Committed: https://git.openstack.org/cgit/openstack/ironic/commit/?id=d52077f4fe8c668b258702e8298a4beaa19476d8
Submitter: Jenkins
Branch: master

commit d52077f4fe8c668b258702e8298a4beaa19476d8
Author: Zhenguo Niu <email address hidden>
Date: Tue Apr 26 10:19:04 2016 +0800

    Clear target_power_state on conductor startup

    During clearing locks, also clear target_power_state. As nodes
    may locked in powering process, sync_power_state task will sync
    the power_state field, but nobody handles target_power_state.

    Change-Id: I2293e03c05e13c716f78533680d128ba45ccda02
    Closes-Bug: #1567255

[Davanum Srinivas (DIMS) (dims-v)]

This issue was fixed in the openstack/ironic 6.1.0 release.