Creating image-volume cache on NFS backend fails

snapshot.id doesn't have `tmp-snap` in it as id
is not passed as a option while creating snapshot
object. This should be change to
`snapshot.display_name` at same location

Closes-Bug: #1875570
Change-Id: I66da0212a61d778fe9795d382b3af5b225a8aa54

cinder/tests/unit/volume/drivers/test_remotefs.py

@@ -280,7 +280,9 @@ class RemoteFsSnapDriverTestCase(test.TestCase):
         exp_acceptable_states = ['available', 'in-use', 'backing-up']
         if tmp_snap:
             exp_acceptable_states.append('downloading')
-            self._fake_snapshot.id = 'tmp-snap-%s' % self._fake_snapshot.id
+            self._fake_snapshot.volume.status = 'downloading'
+            display_name = 'tmp-snap-%s' % self._fake_snapshot.id
+            self._fake_snapshot.display_name = display_name
 
         if volume_in_use:
             self._fake_snapshot.volume.status = 'backing-up'
@@ -315,6 +317,9 @@ class RemoteFsSnapDriverTestCase(test.TestCase):
                           self._driver._create_snapshot,
                           self._fake_snapshot)
 
+    def test_create_snapshot_w_image_caching(self):
+        self._test_create_snapshot(tmp_snap=True)
+
     @mock.patch('cinder.db.snapshot_get')
     @mock.patch('time.sleep')
     def test_create_snapshot_online_with_concurrent_delete(

cinder/volume/drivers/remotefs.py

@@ -1440,7 +1440,7 @@ class RemoteFSSnapDriverBase(RemoteFSDriver):
         status = snapshot.volume.status
 
         acceptable_states = ['available', 'in-use', 'backing-up']
-        if snapshot.id.startswith('tmp-snap-'):
+        if snapshot.display_name.startswith('tmp-snap-'):
             # This is an internal volume snapshot. In order to support
             # image caching, we'll allow creating/deleting such snapshots
             # while having volumes in 'downloading' state.

releasenotes/notes/bug-1875570-nfs-image-volume-cache-c45e840a6ec2a702.yaml

@@ -0,0 +1,6 @@
+---
+fixes:
+  - |
+    `Bug #1875570 <https://bugs.launchpad.net/cinder/+bug/1875570>`:
+    Fixed issue with NFS backend where the image-volume cache was
+    never used to create a volume, even when the cache was enabled.