Teardown replica when replication fails

When disk replication fails during live storage migration, we detect it
properly, fail the operation and remove the disk from the destination
storage domain. However, we didn't tear down the replica on the host
that executes the replication and therefore, if the removal of the
destination disk was done on a different host, we had leftovers
remaining on the host that executed the replication.

This patch changes the diskReplicateFinish function to tear down the
replicate when the corresponding block job doesn't exist in order to
prevent this scenario of having leftovers on the host that could lead to
data corruption later on.

Bug-Url: https://bugzilla.redhat.com/2193392
Signed-off-by: Arik Hadas <ahadas@redhat.com>

lib/vdsm/virt/vm.py

@@ -4443,6 +4443,13 @@ def diskReplicateFinish(self, srcDisk, dstDisk):
                            "srcDisk: %r, job: %r)",
                            drive.name, srcDisk, blkJobInfo)
 
+            # best-effort attempt to tear down the replica
+            try:
+                self.cif.teardownVolumePath(drive.diskReplicate)
+            except Exception as e:
+                self.log.exception("Failed to teardown replica of %s: %s",
+                                   drive, e)
+
             # Making sure that we don't have any stale information
             self._delDiskReplica(drive)
             return response.error('replicaErr')