rmk-nova-improve_resize_efficiency.patch

diff --git a/nova/virt/libvirt/driver.py b/nova/virt/libvirt/driver.py
index 9b8ced7..59b088f 100755
--- a/nova/virt/libvirt/driver.py
+++ b/nova/virt/libvirt/driver.py
@@ -3473,8 +3473,8 @@ class LibvirtDriver(driver.ComputeDriver):
         return shared_storage

     def migrate_disk_and_power_off(self, context, instance, dest,
-                                   instance_type, network_info,
-                                   block_device_info=None):
+                               instance_type, network_info,
+                               block_device_info=None):
         LOG.debug(_("Starting migrate_disk_and_power_off"),
                    instance=instance)
         disk_info_text = self.get_instance_disk_info(instance['name'])
@@ -3512,9 +3512,11 @@ class LibvirtDriver(driver.ComputeDriver):
                 from_path = os.path.join(inst_base_resize, fname)
                 if info['type'] == 'qcow2' and info['backing_file']:
                     tmp_path = from_path + "_rbase"
-                    # merge backing file
-                    utils.execute('qemu-img', 'convert', '-f', 'qcow2',
-                                  '-O', 'qcow2', from_path, tmp_path)
+                    # NOTE(rmk): Simply copy the existing backing-file
+                    # based qcow2 file and rely on the remote server to
+                    # properly grab the necessary backing files from
+                    # Glance.
+                    utils.execute('cp', '-a', from_path, tmp_path)

                     if shared_storage:
                         utils.execute('mv', tmp_path, img_path)
@@ -3529,7 +3531,6 @@ class LibvirtDriver(driver.ComputeDriver):
                 self._cleanup_remote_migration(dest, inst_base,
                                                inst_base_resize,
                                                shared_storage)
-
         return disk_info_text

     def _wait_for_running(self, instance):
@@ -3544,44 +3545,12 @@ class LibvirtDriver(driver.ComputeDriver):
                          block_device_info=None):
         LOG.debug(_("Starting finish_migration"), instance=instance)

-        # resize disks. only "disk" and "disk.local" are necessary.
-        disk_info = jsonutils.loads(disk_info)
-        for info in disk_info:
-            fname = os.path.basename(info['path'])
-            if fname == 'disk':
-                size = instance['root_gb']
-            elif fname == 'disk.local':
-                size = instance['ephemeral_gb']
-            else:
-                size = 0
-            size *= 1024 * 1024 * 1024
-
-            # If we have a non partitioned image that we can extend
-            # then ensure we're in 'raw' format so we can extend file system.
-            fmt = info['type']
-            if (size and fmt == 'qcow2' and
-                disk.can_resize_fs(info['path'], size, use_cow=True)):
-                path_raw = info['path'] + '_raw'
-                utils.execute('qemu-img', 'convert', '-f', 'qcow2',
-                              '-O', 'raw', info['path'], path_raw)
-                utils.execute('mv', path_raw, info['path'])
-                fmt = 'raw'
-
-            if size:
-                disk.extend(info['path'], size)
-
-            if fmt == 'raw' and CONF.use_cow_images:
-                # back to qcow2 (no backing_file though) so that snapshot
-                # will be available
-                path_qcow = info['path'] + '_qcow'
-                utils.execute('qemu-img', 'convert', '-f', 'raw',
-                              '-O', 'qcow2', info['path'], path_qcow)
-                utils.execute('mv', path_qcow, info['path'])
-
+        disk_info_json = jsonutils.loads(disk_info)
         disk_info = blockinfo.get_disk_info(CONF.libvirt_type,
                                             instance,
                                             block_device_info,
                                             image_meta)
+
         # assume _create_image do nothing if a target file exists.
         # TODO(oda): injecting files is not necessary
         self._create_image(context, instance,
@@ -3591,6 +3560,21 @@ class LibvirtDriver(driver.ComputeDriver):
         xml = self.to_xml(instance, network_info, disk_info,
                           block_device_info=block_device_info,
                           write_to_disk=True)
+
+        # resize disks. only "disk" and "disk.local" are necessary.
+        for info in disk_info_json:
+            fname = os.path.basename(info['path'])
+            if fname == 'disk':
+                size = instance['root_gb']
+            elif fname == 'disk.local':
+                size = instance['ephemeral_gb']
+            else:
+                size = 0
+            size *= 1024 * 1024 * 1024
+
+            if size:
+                disk.extend(info['path'], size)
+
         self._create_domain_and_network(xml, instance, network_info,
                                         block_device_info)
         timer = utils.FixedIntervalLoopingCall(self._wait_for_running,