Quota: Add backup related default limits

Logs show deprecation warning in the logs when creating backups.

Warnings are related to the "backups" and "backup_gigabytes" quota
resources:

  Deprecated: Default quota for resource: backups is set by the default
  quota flag: quota_backups, it is now deprecated. Please use the
  default quota class for default quota.

  Deprecated: Default quota for resource: backup_gigabytes is set by the
  default quota flag: quota_backup_gigabytes, it is now deprecated.
  Please use the default quota class for default quota.

This warning is shown because the ``quota_classes`` table doesn't have
entries for these 2 resources for the "default" quota class.

This patch adds a database migration to create the ``backups`` and
``backup_gigabytes`` entries in the ``quota_classes`` table like we have
for the other standard resources, such as ``volumes``, ``gigabytes``,
etc.

Closes-Bug: #1952420
Change-Id: I2a83e9b23f40a8ef4a734b456e4b7afb1ad65f94

cinder/db/migrations/versions/9c74c1c6971f_quota_add_backup_defaults_in_quota_class.py

@@ -0,0 +1,64 @@
+# Licensed under the Apache License, Version 2.0 (the "License"); you may
+# not use this file except in compliance with the License. You may obtain
+# a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+# License for the specific language governing permissions and limitations
+# under the License.
+
+"""Quota: Add backup defaults in quota class
+
+Revision ID: 9c74c1c6971f
+Revises: b7b88f50aab5
+Create Date: 2021-11-10 12:17:06.713239
+"""
+
+from datetime import datetime
+
+from alembic import op
+from oslo_config import cfg
+import sqlalchemy as sa
+
+from cinder.db.sqlalchemy import models
+
+# revision identifiers, used by Alembic.
+revision = '9c74c1c6971f'
+down_revision = 'b7b88f50aab5'
+branch_labels = None
+depends_on = None
+
+
+def _create_default(bind, resource, hard_limit):
+    session = sa.orm.Session(bind=bind)
+
+    class_name = 'default'
+    created_at = datetime.now()  # noqa
+
+    with session.begin():
+        if session.query(sa.sql.exists()
+                         .where(
+                             sa.and_(
+                                 ~models.QuotaClass.deleted,
+                                 models.QuotaClass.class_name == class_name,
+                                 models.QuotaClass.resource == resource)))\
+                .scalar():
+            return
+
+        quota_class = models.QuotaClass(created_at=created_at,
+                                        class_name=class_name,
+                                        resource=resource,
+                                        hard_limit=hard_limit,
+                                        deleted=False)
+
+        session.add(quota_class)
+
+
+def upgrade():
+    bind = op.get_bind()
+
+    _create_default(bind, 'backups', cfg.CONF.quota_backups)
+    _create_default(bind, 'backup_gigabytes', cfg.CONF.quota_backup_gigabytes)

cinder/tests/unit/db/test_migrations.py

@@ -381,6 +381,21 @@ class MigrationsWalk(
             )).all()
         self.assertListEqual([], res)
 
+    def _check_9c74c1c6971f(self, connection):
+        """Test backup related quota was added."""
+        quota_classes = db_utils.get_table(connection, 'quota_classes')
+        res = connection.execute(
+            sqlalchemy.select(quota_classes.c.resource).where(
+                sqlalchemy.and_(
+                    quota_classes.c.resource.startswith('backup'),
+                    ~quota_classes.c.deleted,
+                    quota_classes.c.class_name == 'default')
+            )).all()
+
+        self.assertEqual(2, len(res))
+        self.assertEqual({'backups', 'backup_gigabytes'},
+                         {r[0] for r in res})
+
     # TODO: (D Release) Uncomment method _check_afd7494d43b7 and create a
     # migration with hash afd7494d43b7 using the following command:
     #   $ tox -e venv -- alembic -c cinder/db/alembic.ini revision \

releasenotes/notes/quota-backup-resources-fc4e0795f520c4ab.yaml

@@ -0,0 +1,6 @@
+---
+fixes:
+  - |
+    `Bug #1952420 <https://bugs.launchpad.net/cinder/+bug/1952420>`_: Fixed
+    quota warnings about ``backups`` and ``backup_gigabytes`` when creating
+    backups.