Prevent create volume from snapshot with bad size

Prevent to create a volume from a snapshot with a volume size less
than the snapshot size.

Check if a volume size is specified that it is less than
the snapshot size.

Raise a exception if it's lesser.

Fixes bug 1161841

Change-Id: Ic1afbfb025ce0b3906c35c6c50a71734d74a9851

cinder/tests/test_volume.py

@@ -253,6 +253,20 @@ def test_create_volume_from_snapshot(self):
         self.volume.delete_snapshot(self.context, snapshot_id)
         self.volume.delete_volume(self.context, volume_src['id'])
 
+    def test_create_volume_from_snapshot_fail_bad_size(self):
+        """Test volume can't be created from snapshot with bad volume size."""
+        volume_api = cinder.volume.api.API()
+        snapshot = dict(id=1234,
+                        status='available',
+                        volume_size=10)
+        self.assertRaises(exception.InvalidInput,
+                          volume_api.create,
+                          self.context,
+                          size=1,
+                          name='fake_name',
+                          description='fake_desc',
+                          snapshot=snapshot)
+
     def test_create_volume_with_invalid_exclusive_options(self):
         """Test volume create with multiple exclusive options fails."""
         volume_api = cinder.volume.api.API()

cinder/volume/api.py

@@ -104,7 +104,10 @@ def create(self, context, size, name, description, snapshot=None,
                 raise exception.InvalidSnapshot(reason=msg)
             if not size:
                 size = snapshot['volume_size']
-
+            elif size < snapshot['volume_size']:
+                msg = _("Volume size cannot be lesser than"
+                        " the Snapshot size")
+                raise exception.InvalidInput(reason=msg)
             snapshot_id = snapshot['id']
         else:
             snapshot_id = None