Disk filter should not filter for boot volume

[Jay Lee]

Diskfilter shouldn't be filtered a host when create a VM with boot volume.

Diskfilter based on host disk usage, it check between usable host disk size and requested vm disk size.
But when create a VM with boot volume, Diskfilter has filtered a host although a VM doesn't use host disk. (Usually ISCSI volume could be attached)

[Sean Dague (sdague)]

The core issue here is that remove volumes are filtered against for placement, seems like an issue that should be fixed.

[Luo Gangyi (luogangyi)]

Guys, I have submit a patch, please review it .

https://review.openstack.org/#/c/194059/

[OpenStack Infra (hudson-openstack)]

Related fix proposed to branch: master
Review: https://review.openstack.org/203766

[OpenStack Infra (hudson-openstack)]

Change abandoned by Feodor Tersin (<email address hidden>) on branch: master
Review: https://review.openstack.org/203766
Reason: This was a preparation step to fix bug #1334974 and bug #1358566. The idea was to call is_volume_backed_instance from nova.scheduler.utils.build_request_spec to set root_gb=0 for volume-backed instances.

But since an object refactoring is doing now under https://blueprints.launchpad.net/nova/+spec/request-spec-object , i prefer to wait the result of it.

[OpenStack Infra (hudson-openstack)]

Change abandoned by Michael Still (<email address hidden>) on branch: master
Review: https://review.openstack.org/194059
Reason: This change has stalled. Please restore if when its ready for further review.

[OpenStack Infra (hudson-openstack)]

Related fix proposed to branch: master
Review: https://review.openstack.org/270482

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/270482
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=d6210a4d0cdaf8a71d2516bf44f04789cbe89d0c
Submitter: Jenkins
Branch: master

commit d6210a4d0cdaf8a71d2516bf44f04789cbe89d0c
Author: Tobias Urdin <email address hidden>
Date: Wed Jan 20 21:55:33 2016 +0100

    Move is_volume_backed_instance to compute.utils

    This function is a method of ComputeAPI, so its callers must have an
    instance of the class. This make the usage difficult in modules which
    do not need to call ComputeAPI by other reason.

    Besides this function does not use any of the class members. So there is
    no reason for it to be the class method.

    This patch moves this function to compute.utils because it does not use
    anything of the class members.

    This patch also adds support for the _get_root_bdm and
    is_volume_backed_instance to read from a dictionary instead of an
    Instance object. Because of this we can call is_volume_backed_instance
    from build_request_spec and fix bug #1469179.

    Change-Id: I6d446088faf500ed39a4504794d09d0f86e2bbc3
    Co-Authored-By: Feodor Tersin <email address hidden>
    Co-Authored-By: Ankit Agrawal <email address hidden>
    Related-Bug: #1469179
    Related-Bug: #1334974
    Related-Bug: #1358566