Merge pull request #3477 from liewegas/wip-noreuse

librados: add NOREUSE fadvise hint

Reviewed-by: Jianpeng Ma <jianpeng.ma@intel.com>

diff --cc src/include/rados/librados.hpp
Simple merge

diff --cc src/librados/librados.cc
Simple merge

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