Description of problem: Current glance can set its quota for all tenants. A user requests us to implement quota mechanism for per tenant. An upsptream blueprint is https://blueprints.launchpad.net/glance/+spec/enhance-quota-mechanism
See https://specs.openstack.org/openstack/glance-specs/specs/xena/approved/glance/glance-unified-quotas.html .
*** This bug has been marked as a duplicate of bug 1957666 ***