use dirty file instead of clean file

Author: Guiiix

qubes/storage/reflink.py

@@ -176,9 +176,7 @@ def __init__(self, *args, **kwargs):
         self._path_precache = self._path_vid + "-precache.img"
         self._path_dirty = self._path_vid + "-dirty.img"
         self._path_import = self._path_vid + "-import.img"
-        self.path = (
-            self._path_clean if self.snapshots_disabled else self._path_dirty
-        )
+        self.path = self._path_dirty
 
     @contextmanager
     def _update_precache(self):
@@ -270,6 +268,9 @@ def start(self):  # pylint: disable=invalid-overridden-method
         if self.snapshots_disabled:
             self._prune_revisions(keep=0)
             _remove_file(self._path_precache)
+            if not self.is_dirty():
+                _rename_file(self._path_clean, self._path_dirty)
+
             return self
         if not self.is_dirty():
             if self.snap_on_start:
@@ -291,7 +292,9 @@ def start(self):  # pylint: disable=invalid-overridden-method
     @_coroutinized
     def stop(self):  # pylint: disable=invalid-overridden-method
         if self.is_dirty():
-            if not self.snapshots_disabled:
+            if self.snapshots_disabled:
+                _rename_file(self._path_dirty, self._path_clean)
+            else:
                 self._commit(self._path_dirty)
         elif not self.save_on_stop:
             if not self.snap_on_start:

qubes/tests/storage_reflink.py

@@ -364,13 +364,17 @@ def test_120_private_snapshots_disabled(self):
         self.assertEqual(volume.pool, self.pool.name)
         volume._copy_file = unittest.mock.Mock()
         self.loop.run_until_complete(volume.create())
+        self.loop.run_until_complete(volume.start())
         self.assertEqual(
             volume.block_device().path,
-            "/var/tmp/test-reflink-units-on-btrfs/appvms/test-inst-appvm/private.img",
+            "/var/tmp/test-reflink-units-on-btrfs/appvms/test-inst-appvm/private-dirty.img",
         )
-        self.assertFalse(os.path.exists(volume._path_dirty))
+        self.assertFalse(os.path.exists(volume._path_clean))
         self.assertFalse(os.path.exists(volume._path_precache))
         self.loop.run_until_complete(volume.stop())
+        self.assertFalse(os.path.exists(volume._path_dirty))
+        self.assertTrue(os.path.exists(volume._path_clean))
+        self.assertFalse(os.path.exists(volume._path_precache))
         self.loop.run_until_complete(volume.remove())
         volume._copy_file.assert_not_called()