Merge pull request #3904 from yuyuyu101/wip-librbd-metadata

Wip librbd metadata

Reviewed-by: Josh Durgin <jdurgin@redhat.com>

diff --cc src/cls/rbd/cls_rbd.cc
Simple merge

diff --cc src/cls/rbd/cls_rbd_client.cc
Simple merge

diff --cc src/cls/rbd/cls_rbd_client.h
Simple merge

diff --cc src/librbd/internal.cc
Simple merge

diff --cc src/librbd/internal.h
Simple merge

diff --cc src/test/cls_rbd/test_cls_rbd.cc
Simple merge

diff --cc src/test/librbd/test_librbd.cc
Simple merge