Merge PR #16608 into master

* refs/pull/16608/head:
	qa: whitelist mds down wrn during cephfs testing
	mds: add config to disable fragmentation
	qa: add max_mds thrash test
	qa: mds_thrash updates for new max_mds behavior
	doc: update upgrade procedure and release notes
	qa: add test for cluster resizing
	qa: remove use of mds deactivate
	cephfs: add new down/joinable fs flags
	mds: evict all clients if last mds shutting down
	cephfs: deprecate ceph mds deactivate
	cephfs: kill allow_dirfrags
	cephfs: Kill allow_multimds
	cephfs: Change behavior of cluster_down flag
	mon/FSCommands: Set extra MDS to standby
	cephfs: Health check changes
	mon/MDSMonitor: Remove command support for legacy syntax

Reviewed-by: Patrick Donnelly <pdonnell@redhat.com>

diff --cc PendingReleaseNotes
Simple merge

diff --cc qa/workunits/cephtool/test.sh
Simple merge

diff --cc src/common/options.cc
Simple merge

diff --cc src/mds/FSMap.cc
Simple merge

diff --cc src/mon/MDSMonitor.cc
Simple merge

diff --cc src/mon/MonCommands.h
Simple merge

diff --cc src/vstart.sh
Simple merge