From f7af85dd7431eea61cdd2b1723a5dbcc3d9471ed Mon Sep 17 00:00:00 2001
From: Pierre LIBEAU <pierre.libeau@corp.ovh.com>
Date: Mon, 6 Dec 2021 15:48:57 +0100
Subject: [PATCH] Nova resize don't extend disk in one specific case

Nova resize not apply extend virtual size of the instance if the image
is not accessible by the customer (public image use to build the
instance is now private image because this image is deprecated) and the
source compute of the resize don't have anymore the base image.

Related-Bug: #1558880
Change-Id: I4d6dfca1efe10caebb017b6ec96820979018203f
---
 nova/tests/unit/virt/libvirt/test_driver.py | 61 +++++++++++++++++++++
 nova/virt/libvirt/imagebackend.py           | 12 +++-
 2 files changed, 70 insertions(+), 3 deletions(-)

diff --git a/nova/tests/unit/virt/libvirt/test_driver.py b/nova/tests/unit/virt/libvirt/test_driver.py
index 71b8f7274f..21b0dea799 100644
--- a/nova/tests/unit/virt/libvirt/test_driver.py
+++ b/nova/tests/unit/virt/libvirt/test_driver.py
@@ -13618,6 +13618,67 @@ class LibvirtConnTestCase(test.NoDBTestCase,
         mock_create_cow_image.assert_called_once_with(
             backfile_path, '/fake/instance/dir/disk_path')
 
+    @mock.patch('nova.virt.libvirt.imagebackend.Image.exists',
+        new=mock.Mock(return_value=True))
+    def test_create_images_backing_images_and_fallback_not_exist(self):
+        self.flags(images_type='raw', group='libvirt')
+        conn = libvirt_driver.LibvirtDriver(fake.FakeVirtAPI(), False)
+
+        base_dir = os.path.join(CONF.instances_path,
+                                CONF.image_cache.subdirectory_name)
+        self.test_instance.update({
+            'user_id': 'fake-user',
+            'os_type': None,
+            'kernel_id': uuids.kernel_id,
+            'ramdisk_id': uuids.ramdisk_id,
+            'project_id': 'fake-project'
+        })
+        instance = objects.Instance(**self.test_instance)
+
+        backing_file = imagecache.get_cache_fname(instance.image_ref)
+        backfile_path = os.path.join(base_dir, backing_file)
+        disk_size = 10747904
+        virt_disk_size = 25165824
+        disk_info = [{
+            'backing_file': backing_file,
+            'disk_size': disk_size,
+            'path': 'disk_path',
+            'type': 'raw',
+            'virt_disk_size': virt_disk_size
+        }]
+
+        with test.nested(
+            mock.patch.object(libvirt_driver.libvirt_utils, 'copy_image'),
+            mock.patch.object(libvirt_driver.libvirt_utils, 'fetch_image',
+                side_effect=exception.ImageNotFound(
+                    image_id=uuids.fake_id)),
+            mock.patch.object(imagebackend.Flat, 'resize_image'),
+        ) as (copy_image_mock, fetch_image_mock, resize_image_mock):
+            conn._create_images_and_backing(
+                self.context, instance, "/fake/instance/dir", disk_info,
+                fallback_from_host="fake_host")
+            kernel_path = os.path.join(CONF.instances_path,
+                self.test_instance['uuid'], 'kernel')
+            ramdisk_path = os.path.join(CONF.instances_path,
+                self.test_instance['uuid'], 'ramdisk')
+            copy_image_mock.assert_has_calls([
+                mock.call(dest=kernel_path, src=kernel_path,
+                          host='fake_host', receive=True),
+                mock.call(dest=ramdisk_path, src=ramdisk_path,
+                          host='fake_host', receive=True)
+            ])
+            fetch_image_mock.assert_has_calls([
+                mock.call(context=self.context,
+                          target=backfile_path,
+                          image_id=self.test_instance['image_ref'],
+                          trusted_certs=None),
+                mock.call(self.context, kernel_path, instance.kernel_id,
+                          None),
+                mock.call(self.context, ramdisk_path, instance.ramdisk_id,
+                          None)
+            ])
+            resize_image_mock.assert_called_once_with(virt_disk_size)
+
     @mock.patch('nova.virt.libvirt.utils.create_image',
                 new=mock.NonCallableMock())
     @mock.patch.object(libvirt_driver.libvirt_utils, 'fetch_image')
diff --git a/nova/virt/libvirt/imagebackend.py b/nova/virt/libvirt/imagebackend.py
index 05b3a8069a..1a0d30a023 100644
--- a/nova/virt/libvirt/imagebackend.py
+++ b/nova/virt/libvirt/imagebackend.py
@@ -568,15 +568,21 @@ class Flat(Image):
         def copy_raw_image(base, target, size):
             libvirt_utils.copy_image(base, target)
             if size:
-                image = imgmodel.LocalFileImage(target,
-                                                self.driver_format)
-                disk.extend(image, size)
+                self.resize_image(size)
 
         generating = 'image_id' not in kwargs
         if generating:
             if not self.exists():
                 # Generating image in place
                 prepare_template(target=self.path, *args, **kwargs)
+
+            # NOTE(plibeau): extend the disk in the case of image is not
+            # accessible anymore by the customer and the base image is
+            # available on source compute during the resize of the
+            # instance.
+            else:
+                if size:
+                    self.resize_image(size)
         else:
             if not os.path.exists(base):
                 prepare_template(target=base, *args, **kwargs)