PendingReleaseNotes: add rbd_diff_iterate2 note

Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

diff --git a/PendingReleaseNotes b/PendingReleaseNotes
index b3fa9b9990e292e4d766db6d6550fce45c29a757..0de7e784507bba0f5f5306d3d84a969ccffd36d3 100644 (file)
--- a/PendingReleaseNotes
+++ b/PendingReleaseNotes
@@ -105,6 +105,11 @@ CephFS: Disallow delegating preallocated inode ranges to clients. Config
   See https://docs.ceph.com/en/latest/rados/operations/balancer/ for more information.
 * CephFS: Full support for subvolumes and subvolume groups is now available
   for snap_schedule Manager module.
+* RBD: When diffing against the beginning of time (`fromsnapname == NULL`) in
+  fast-diff mode (`whole_object == true` with `fast-diff` image feature enabled
+  and valid), diff-iterate is now guaranteed to execute locally if exclusive
+  lock is available.  This brings a dramatic performance improvement for QEMU
+  live disk synchronization and backup use cases.
 
 >=18.0.0