DB: Set quota resource property length to 300

On change I6c30a6be750f6b9ecff7399dbb0aea66cdc097da we increased the
`resource` column of the quota_usages table from 255 to 300, because its
value is constructed from (prefix + volume_type_name), but the length of
`volume_type_name` can be up to 255 characters, so if we add a prefix
such as 'volumes_' or 'gigabytes_' to it we'll exceed the db length
limit of the `resource` column.

There are other 3 quota related tables (quotas, quota_classes,
reservations) that have a `resource` column, and they are all
referencing the same kind of thing, but they still have a maximum size
of 255 characters, so there will be things that we won't be able to do
when using a volume type with a 255 characters name. Some of the
operations we won't be able to do are setting a default quota limit for
it or migrate volumes using that volume type.

Related-Bug: #1798327
Related-Bug: #1608849
Closes-Bug: #1948962
Change-Id: I40546b20322443dc34556de4aababf33a230db78

cinder/api/validation/parameter_types.py

@@ -269,7 +269,7 @@ quota_class_set = {
     'type': 'object',
     'format': 'quota_class_set',
     'patternProperties': {
-        '^[a-zA-Z0-9-_:. ]{1,255}$': {
+        '^[a-zA-Z0-9-_:. ]{1,300}$': {
             'type': ['integer', 'string'],
             'pattern': '^[0-9]*$', 'minimum': -1, 'minLength': 1,
             'maximum': constants.DB_MAX_INT

cinder/db/migrations/versions/b8660621f1b9_update_reservations_resource.py

@@ -0,0 +1,67 @@
+# 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.
+
+"""Update reservations resource
+
+Revision ID: b8660621f1b9
+Revises: 89aa6f9639f9
+Create Date: 2021-10-27 17:25:16.790525
+"""
+
+from alembic import op
+from oslo_log import log as logging
+import sqlalchemy as sa
+
+
+LOG = logging.getLogger(__name__)
+
+
+# revision identifiers, used by Alembic.
+revision = 'b8660621f1b9'
+down_revision = '89aa6f9639f9'
+branch_labels = None
+depends_on = None
+
+
+def upgrade():
+    connection = op.get_bind()
+
+    for table_name in ('quotas', 'quota_classes', 'reservations'):
+        table = sa.Table(table_name, sa.MetaData(), autoload_with=connection)
+        col = table.c.resource
+        # SQLite doesn't support altering tables, so we use a workaround
+        if connection.engine.name == 'sqlite':
+            with op.batch_alter_table(table_name) as batch_op:
+                batch_op.alter_column('resource',
+                                      existing_type=col.type,
+                                      type_=sa.String(length=300))
+
+        else:
+            # MySQL ALTER needs to have existing_type, existing_server_default,
+            # and existing_nullable or it will do who-knows-what
+            try:
+                op.alter_column(table_name, 'resource',
+                                existing_type=col.type,
+                                existing_nullable=col.nullable,
+                                existing_server_default=col.server_default,
+                                type_=sa.String(length=300))
+            except Exception:
+                # On MariaDB, max length varies depending on the version and
+                # the InnoDB page size [1], so it is possible to have error
+                # 1071 ('Specified key was too long; max key length is 767
+                # bytes").  Since this migration is to resolve a corner case,
+                # deployments with those DB versions won't be covered.
+                # [1]: https://mariadb.com/kb/en/library/innodb-limitations/#page-sizes  # noqa
+                if not connection.engine.name == 'mysql':
+                    raise
+                LOG.warning('Error in migration %s, Cinder still affected by '
+                            'bug #1948962', revision)

cinder/db/sqlalchemy/models.py

@@ -802,7 +802,7 @@ class Quota(BASE, CinderBase):
     # TODO(stephenfin): Add index=True
     project_id = sa.Column(sa.String(255))
 
-    resource = sa.Column(sa.String(255), nullable=False)
+    resource = sa.Column(sa.String(300), nullable=False)
     hard_limit = sa.Column(sa.Integer, nullable=True)
     # TODO: (X release): Remove allocated, belonged to nested quotas
     allocated = sa.Column(sa.Integer, default=0)
@@ -822,7 +822,7 @@ class QuotaClass(BASE, CinderBase):
 
     class_name = sa.Column(sa.String(255), index=True)
 
-    resource = sa.Column(sa.String(255))
+    resource = sa.Column(sa.String(300))
     hard_limit = sa.Column(sa.Integer, nullable=True)
 
 
@@ -886,7 +886,7 @@ class Reservation(BASE, CinderBase):
     )
 
     project_id = sa.Column(sa.String(255), index=True)
-    resource = sa.Column(sa.String(255))
+    resource = sa.Column(sa.String(300))
 
     delta = sa.Column(sa.Integer, nullable=False)
     # TODO(stephenfin): Add nullable=False

cinder/tests/unit/db/test_migrations.py

@@ -183,6 +183,10 @@ class MigrationsWalk(
         'c92a3e68beed',
         # Migration 89aa6f9639f9 doesn't fail because it's for a SQLAlquemy
         # internal table, and we only check Cinder's tables.
+
+        # Increasing resource column max length to 300 is acceptable, since
+        # it's a backward compatible change.
+        'b8660621f1b9',
     ]
     FORBIDDEN_METHODS = ('alembic.operations.Operations.alter_column',
                          'alembic.operations.Operations.drop_column',
@@ -190,6 +194,8 @@ class MigrationsWalk(
                          'alembic.operations.BatchOperations.alter_column',
                          'alembic.operations.BatchOperations.drop_column')
 
+    VARCHAR_TYPE = sqlalchemy.types.VARCHAR
+
     def setUp(self):
         super().setUp()
         self.engine = enginefacade.writer.get_engine()
@@ -284,6 +290,22 @@ class MigrationsWalk(
         # for its removal without creating it first, which is dumb
         pass
 
+    def _pre_upgrade_b8660621f1b9(self, connection):
+        """Test resource columns were limited to 255 chars before."""
+        for table_name in ('quotas', 'quota_classes', 'reservations'):
+            table = db_utils.get_table(connection, table_name)
+            self.assertIn('resource', table.c)
+            self.assertIsInstance(table.c.resource.type, self.VARCHAR_TYPE)
+            self.assertEqual(255, table.c.resource.type.length)
+
+    def _check_b8660621f1b9(self, connection):
+        """Test resource columns can be up to 300 chars."""
+        for table_name in ('quotas', 'quota_classes', 'reservations'):
+            table = db_utils.get_table(connection, table_name)
+            self.assertIn('resource', table.c)
+            self.assertIsInstance(table.c.resource.type, self.VARCHAR_TYPE)
+            self.assertEqual(300, table.c.resource.type.length)
+
 
 class TestMigrationsWalkSQLite(
     MigrationsWalk,

releasenotes/notes/fix-resource-size-76e8ff25f07925f2.yaml

@@ -0,0 +1,6 @@
+---
+fixes:
+  - |
+    `Bug #1948962 <https://bugs.launchpad.net/cinder/+bug/1948962>`_: Fixed
+    operations that failed on volume types with 255 characters names (e.g. set
+    quota limits or volume migrate).