Merge PR #24991 into master

* refs/pull/24991/head:
	mds: disallow dumping huge caches to formatter

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

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

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

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