Comment 7 for bug 1704786

Please take a look of the following patch set which included a lengthy discussion on the exact same
line you are trying to change in this patch. After discussion, we decided it is safer to keep this calculation. Also we decided not to use utils.calculate_virtual_free_capacity() which is used in the weigher. In weigher, we have to use one formula to come up with a number for ranking. In filter, there are multiple steps to filter things out. So they are not exactly the same.

https://review.openstack.org/#/c/189261/3/cinder/scheduler/filters/capacity_filter.py

After discussion, we agreed just to rename the variable to adjusted_free_virtual:
https://review.openstack.org/#/c/214276/ (patch to rename variable name to adjusted_free_virtual)

Here is a list of patches from the past on oversubscription:

Oversubscription in thin provisioning:
https://blueprints.launchpad.net/cinder/+spec/over-subscription-in-thin-provisioning

Initial spec review:
https://review.openstack.org/#/c/129342/

Code in scheduler to introduce oversubscription ratio:
https://review.openstack.org/#/c/142171

Code to add provisioned_capacity:
https://review.openstack.org/147934

Update spec after code is merged:
https://review.openstack.org/153469

Fix capacity filter to allow oversubscription:
https://review.openstack.org/#/c/185764/

Attempt to not to use virtual free capacity but it is abandoned after lengthy discussion:
https://review.openstack.org/#/c/189261/

Patch to rename variable to adjusted_free_virtual following the discussion in https://review.openstack.org/#/c/189261/:
https://review.openstack.org/#/c/214276/1

Differentiate thick and thin provisioning:
https://blueprints.launchpad.net/cinder/+spec/differentiate-thick-thin-in-scheduler
https://review.openstack.org/#/c/315352/