Merge remote branch 'gh/master' into wip-backfill

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

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

diff --cc src/osd/OSD.cc
Simple merge

diff --cc src/osd/PG.h
Simple merge

diff --cc src/osd/ReplicatedPG.cc
Simple merge