Right now, we still ask placement for a disk allocation covering
swap, ephemeral, and root disks for the instance even if the instance
is going to be volume-backed. This patch makes us not include the
root size in that calculation for placement, avoiding a false
failure because the volume size is counted against the compute's
available space.
To do this, we need another flag in request_spec to track the
BFV-ness of the instance. Right now, this patch just sets that on
new builds and the scheduler client assumes a lack of said flag
as "I don't know, so assume not-BFV" for compatibility. A
subsequent patch can calculate that flag for existing instances
so that we will be able to heal over time by migrating instances
or re-writing their allocations to reflect reality.
Partial-Bug: #1469179
Change-Id: I9c2111f7377df65c1fc3c72323f85483b3295989
Dan Smith
03c596a9f4