Merge pull request #5662 from ceph/wip-scrub-basic

ScrubStack and "tag path" command

Reviewed-by: John Spray <john.spray@redhat.com>
Reviewed-by: Yan, Zheng <zyan@redhat.com>

diff --cc src/CMakeLists.txt
Simple merge

diff --cc src/common/config_opts.h
Simple merge

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

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

diff --cc src/mds/Makefile.am
Simple merge