Merge PR #16378 into master

Merge PR #16378 into master

* refs/remotes/upstream/pull/16378/head:
	doc: remove accidental additions to release notes
	qa/cephfs: Fix race in test_volume_client
	qa/cephfs: Test filtered df
	PendingReleaseNotes: add note about df filtering
	client: Support new, filtered MStatfs
	objecter: Support new, filtered MStatfs
	mon/PGMap stats: Support new, filtered MStatfs
	messages: Add optional data pool to MStatfs

Reviewed-by: John Spray <john.spray@redhat.com>
Reviewed-by: Patrick Donnelly <pdonnell@redhat.com>
Reviewed-by: Sage Weil <sage@redhat.com>