Merge "Fix remotefs clone volume locking"

cinder/volume/drivers/remotefs.py

@@ -1654,6 +1654,7 @@ class RemoteFSSnapDriver(RemoteFSSnapDriverBase):
     def create_volume_from_snapshot(self, volume, snapshot):
         return self._create_volume_from_snapshot(volume, snapshot)
 
+    # TODO: should be locking on src_vref id -- bug #1852449
     @locked_volume_id_operation
     def create_cloned_volume(self, volume, src_vref):
         """Creates a clone of the specified volume."""
@@ -1696,6 +1697,8 @@ class RemoteFSSnapDriverDistributed(RemoteFSSnapDriverBase):
     def create_volume_from_snapshot(self, volume, snapshot):
         return self._create_volume_from_snapshot(volume, snapshot)
 
+    # lock the source volume id first
+    @coordination.synchronized('{self.driver_prefix}-{src_vref.id}')
     @coordination.synchronized('{self.driver_prefix}-{volume.id}')
     def create_cloned_volume(self, volume, src_vref):
         """Creates a clone of the specified volume."""

releasenotes/notes/fix-remotefs-clone-volume-locking-385e740d4a5a813b.yaml

@@ -0,0 +1,12 @@
+---
+fixes:
+  - |
+    An incorrect lock in the remotefs code, which is used for the NFS driver,
+    and other similar drivers, resulted in concurrent clone volume operations
+    failing.  create_cloned_volume now locks on the source volume id, meaning
+    multiple clone operations from the same source volume are serialized.
+
+    A lock in the volume manager flow generally prevents this on normal clone
+    volume operations, but this clone method in the driver is called for
+    operations such as cloning from the cinder image-volume cache or cloning
+    from a cinder backend used as a glance store.