Return BadRequest for invalid Unicode names

If the database fails to insert values due to them
containing Unicode that the database can't support (or other
similar errors that fall under DBDataError), return an
HTTP 400 Bad Request rather than HTTP 500.

this patch give fix for

1. backup-create Creates a volume backup.
2. cgsnapshot-create Creates a cgsnapshot.
3. consisgroup-create Creates a consistency group.
4. encryption-type-create Creates encryption-type
5. qos-create Creates a qos specs.
6. snapshot-create Creates a snapshot.
7. type-create Creates a volume type.
8. update/edit of entities mentioned in step1-7 update/edit name.
 ( is already taken care)

 this patch also fix volume create as is taken care by

 https://review.openstack.org/#/c/266036

 by the new mechanism

Change-Id: I0990fdbcda7ef58331503489a51e7f870683f22b
Closes-bug: #1531400

cinder/db/sqlalchemy/api.py

@@ -240,6 +240,18 @@ def _retry_on_deadlock(f):
     return wrapped
 
 
+def handle_db_data_error(f):
+    def wrapper(*args, **kwargs):
+        try:
+            return f(*args, **kwargs)
+        except db_exc.DBDataError:
+            msg = _('Error writing field to database')
+            LOG.exception(msg)
+            raise exception.Invalid(msg)
+
+    return wrapper
+
+
 def model_query(context, *args, **kwargs):
     """Query helper that accounts for context's `read_deleted` field.
 
@@ -1146,6 +1158,7 @@ def volume_attached(context, attachment_id, instance_uuid, host_name,
         return volume_ref
 
 
+@handle_db_data_error
 @require_context
 def volume_create(context, values):
     values['volume_metadata'] = _metadata_refs(values.get('metadata'),
@@ -1163,11 +1176,8 @@ def volume_create(context, values):
     volume_ref.update(values)
 
     session = get_session()
-    try:
-        with session.begin():
-            session.add(volume_ref)
-    except db_exc.DBDataError:
-        raise exception.Invalid()
+    with session.begin():
+        session.add(volume_ref)
 
     return _volume_get(context, values['id'], session=session)
 
@@ -1762,6 +1772,7 @@ def process_sort_params(sort_keys, sort_dirs, default_keys=None,
     return result_keys, result_dirs
 
 
+@handle_db_data_error
 @require_context
 def volume_update(context, volume_id, values):
     session = get_session()
@@ -2060,6 +2071,7 @@ def volume_admin_metadata_update(context, volume_id, metadata, delete,
 ###################
 
 
+@handle_db_data_error
 @require_context
 def snapshot_create(context, values):
     values['snapshot_metadata'] = _metadata_refs(values.get('metadata'),
@@ -2299,6 +2311,7 @@ def snapshot_get_active_by_window(context, begin, end=None, project_id=None):
     return query.all()
 
 
+@handle_db_data_error
 @require_context
 def snapshot_update(context, snapshot_id, values):
     session = get_session()
@@ -2399,6 +2412,7 @@ def snapshot_metadata_update(context, snapshot_id, metadata, delete):
 ###################
 
 
+@handle_db_data_error
 @require_admin_context
 def volume_type_create(context, values, projects=None):
     """Create a new volume type.
@@ -2498,6 +2512,7 @@ def _process_volume_types_filters(query, filters):
     return query
 
 
+@handle_db_data_error
 @require_admin_context
 def volume_type_update(context, volume_type_id, values):
     session = get_session()
@@ -3233,6 +3248,7 @@ def _qos_specs_get_item(context, qos_specs_id, key, session=None):
     return result
 
 
+@handle_db_data_error
 @require_admin_context
 def qos_specs_update(context, qos_specs_id, specs):
     """Make updates to an existing qos specs.
@@ -3290,6 +3306,7 @@ def volume_type_encryption_delete(context, volume_type_id):
                            'updated_at': literal_column('updated_at')})
 
 
+@handle_db_data_error
 @require_admin_context
 def volume_type_encryption_create(context, volume_type_id, values):
     session = get_session()
@@ -3308,6 +3325,7 @@ def volume_type_encryption_create(context, volume_type_id, values):
         return encryption
 
 
+@handle_db_data_error
 @require_admin_context
 def volume_type_encryption_update(context, volume_type_id, values):
     session = get_session()
@@ -3673,6 +3691,7 @@ def backup_get_all_by_volume(context, volume_id, filters=None):
     return _backup_get_all(context, filters)
 
 
+@handle_db_data_error
 @require_context
 def backup_create(context, values):
     backup = models.Backup()
@@ -3686,6 +3705,7 @@ def backup_create(context, values):
         return backup
 
 
+@handle_db_data_error
 @require_context
 def backup_update(context, backup_id, values):
     session = get_session()
@@ -3979,6 +3999,7 @@ def consistencygroup_get_all_by_project(context, project_id, filters=None,
                                      sort_keys, sort_dirs)
 
 
+@handle_db_data_error
 @require_context
 def consistencygroup_create(context, values):
     consistencygroup = models.ConsistencyGroup()
@@ -3993,6 +4014,7 @@ def consistencygroup_create(context, values):
         return _consistencygroup_get(context, values['id'], session=session)
 
 
+@handle_db_data_error
 @require_context
 def consistencygroup_update(context, consistencygroup_id, values):
     session = get_session()
@@ -4092,6 +4114,7 @@ def cgsnapshot_get_all_by_project(context, project_id, filters=None):
     return _cgsnapshot_get_all(context, project_id=project_id, filters=filters)
 
 
+@handle_db_data_error
 @require_context
 def cgsnapshot_create(context, values):
     cgsnapshot = models.Cgsnapshot()
@@ -4106,6 +4129,7 @@ def cgsnapshot_create(context, values):
         return _cgsnapshot_get(context, values['id'], session=session)
 
 
+@handle_db_data_error
 @require_context
 def cgsnapshot_update(context, cgsnapshot_id, values):
     session = get_session()