blockVolume: check parent tag and meta match

blockVolume getParent method uses the volume tag
PU_<id> to obtain the parent. However, this tag
could be outdated. For example, when the host
syncs a volume chain after removing a volume,
it only updates the metadata. Afterwards,
the SPM will update the volume tag once the
volume is deleted.

To ensure we do not return outdated parent UUID,
we need to ensure that the parent UUID obtained
from the parent tag, and the UUID in the volume
metadata match, and log a warning and update
the volume otherwise.

Bug-Url: https://bugzilla.redhat.com/2103582
Signed-off-by: Albert Esteve <aesteve@redhat.com>

lib/vdsm/storage/blockVolume.py

@@ -164,6 +164,13 @@ def getParent(self):
         """
         Return parent volume UUID
         """
+        parent_tag = self.getParentTag()
+        parent_meta = self.getParentMeta()
+        if parent_tag != parent_meta:
+            self.log.warning(
+                "volUUID=%s parent in tag (%s) and metadata (%s) differ",
+                self.volUUID, parent_tag, parent_meta)
+            self.refreshVolume()
         return self.getParentTag()
 
     def getChildren(self):