Cinder: Add support to extend attached volumes

While creating an image, if we want to extend the volume
(to accomodate the image), we need to first detach the volume,
perform the extend and attach it again. This is inefficient
for backends that support extending attached volumes since we
are performing 3 cinder operations (the attachment call
includes 3 API calls which sum to a total of 5 API calls for 3
operations) instead of directly extending it which requires only
1 API call to cinder.
The support for extending attached volumes was added in cinder
microversion 3.42.

This patch adds a new boolean config option
``cinder_do_extend_attached`` which allows operators to specify
if the cinder backend they are using supports extending
attached (in-use) volumes. By default this will be ``false``.
Based on the parameter, we will perform the extend operation,
online (if cinder_do_extend_attached is true) and offline otherwise.

Spec: https://review.opendev.org/c/openstack/glance-specs/+/868901

Depends-On: https://review.opendev.org/c/openstack/glance/+/869021
Depends-On: https://review.opendev.org/c/openstack/cinder/+/869051

Change-Id: I5e70824e9abc5277ea25ba95704b358fe3686037

1 files changed, 18 insertions, 0 deletions

diff --git a/glance_store/common/cinder_utils.py b/glance_store/common/cinder_utils.py
index b14aa23..c1c4186 100644
--- a/glance_store/common/cinder_utils.py
+++ b/glance_store/common/cinder_utils.py
@@ -208,3 +208,21 @@ class API(object):
                           {'id': attachment_id,
                            'msg': str(ex),
                            'code': getattr(ex, 'code', None)})
+
+    @handle_exceptions
+    def extend_volume(self, client, volume, new_size):
+        """Extend volume
+
+        :param client: cinderclient object
+        :param volume: UUID of the volume to extend
+        :param new_size: new size of the volume after extend
+        """
+        try:
+            client.volumes.extend(volume, new_size)
+        except cinder_exception.ClientException as ex:
+            with excutils.save_and_reraise_exception():
+                LOG.error(_LE('Extend volume failed for volume '
+                              '%(id)s. Error: %(msg)s Code: %(code)s'),
+                          {'id': volume.id,
+                           'msg': str(ex),
+                           'code': getattr(ex, 'code', None)})