Re-enable -1 child limits for nested quotas

Add back support for -1 limits of child projects. The way that we
support the -1 child limits requires the following changes:
  * Continue quota validation up the hierarchy if the current limit is
    -1 until we hit a hard limit or no more parents, and update the
    any relevant parents' allocated value along the way
  * When updating limits, special care needs to be taken when updating
    child limit to be -1, or when changing from a -1 limit
  * Enable support for creating reservations for "allocated" values
    to support the scenario that:
      - a volume is created on a project with a limit of -1
      - the parent's allocated value has been updated appropriately
      - the volume create fails and the child's in_use quota rolls back
      - now we must also rollback the parent's allocated value

NOTE: There is a race condition between validation the NestedQuotas
and when the driver may be switched into use, and if -1 quotas are used
the validation could be out of date. Will look into better support for
switching on of NestedQuotas on live deployment with -1 limits, which
would likely leverage the "allocated" reservation system.

Closes-Bug: #1548645
Closes-Bug: #1544774
Closes-Bug: #1537189
Change-Id: I2d1dba87baf3595cc8f48574e0281ac17509fe7d

cinder/quota_utils.py

@@ -22,6 +22,7 @@ from keystoneclient import client
 from keystoneclient import exceptions
 from keystoneclient import session
 
+from cinder import db
 from cinder import exception
 from cinder.i18n import _, _LW
 
@@ -102,7 +103,8 @@ def get_volume_type_reservation(ctxt, volume, type_id,
     return reservations
 
 
-def get_project_hierarchy(context, project_id, subtree_as_ids=False):
+def get_project_hierarchy(context, project_id, subtree_as_ids=False,
+                          parents_as_ids=False):
     """A Helper method to get the project hierarchy.
 
     Along with hierarchical multitenancy in keystone API v3, projects can be
@@ -114,10 +116,13 @@ def get_project_hierarchy(context, project_id, subtree_as_ids=False):
         generic_project = GenericProjectInfo(project_id, keystone.version)
         if keystone.version == 'v3':
             project = keystone.projects.get(project_id,
-                                            subtree_as_ids=subtree_as_ids)
+                                            subtree_as_ids=subtree_as_ids,
+                                            parents_as_ids=parents_as_ids)
             generic_project.parent_id = project.parent_id
             generic_project.subtree = (
                 project.subtree if subtree_as_ids else None)
+            generic_project.parents = (
+                project.parents if parents_as_ids else None)
     except exceptions.NotFound:
         msg = (_("Tenant ID: %s does not exist.") % project_id)
         raise webob.exc.HTTPNotFound(explanation=msg)
@@ -145,6 +150,35 @@ def get_all_root_project_ids(context):
     return project_roots
 
 
+def update_alloc_to_next_hard_limit(context, resources, deltas, res,
+                                    expire, project_id):
+    from cinder import quota
+    QUOTAS = quota.QUOTAS
+    reservations = []
+    projects = get_project_hierarchy(context, project_id,
+                                     parents_as_ids=True).parents
+    hard_limit_found = False
+    # Update allocated values up the chain til we hit a hard limit or run out
+    # of parents
+    while projects and not hard_limit_found:
+        cur_proj_id = list(projects)[0]
+        projects = projects[cur_proj_id]
+        cur_quota_lim = QUOTAS.get_by_project_or_default(
+            context, cur_proj_id, res)
+        hard_limit_found = (cur_quota_lim != -1)
+        cur_quota = {res: cur_quota_lim}
+        cur_delta = {res: deltas[res]}
+        try:
+            reservations += db.quota_reserve(
+                context, resources, cur_quota, cur_delta, expire,
+                CONF.until_refresh, CONF.max_age, cur_proj_id,
+                is_allocated_reserve=True)
+        except exception.OverQuota:
+            db.reservation_rollback(context, reservations)
+            raise
+    return reservations
+
+
 def validate_setup_for_nested_quota_use(ctxt, resources,
                                         nested_quota_driver,
                                         fix_allocated_quotas=False):