Merge PR #24794 into master

* refs/pull/24794/head:
	mds: move BatchOp to separate translation unit
	mds: use auto ref during iteration
	mds: answering all pending getattr/lookups targeting the same inode in one go

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

diff --cc src/mds/CDentry.h
Simple merge

diff --cc src/mds/CInode.h
Simple merge

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

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

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

diff --cc src/mds/Server.h
Simple merge