reproduce (this is a W=1 build):
        # https://github.com/ceph/ceph-client/commit/310aa14b5bf4d5ecd1abf6a00782e044f7d76940
        git remote add ceph-client https://github.com/ceph/ceph-client.git
        git fetch --no-tags ceph-client tls-tracing-only
        git checkout 310aa14b5bf4d5ecd1abf6a00782e044f7d76940
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        make W=1 O=build_dir ARCH=i386 olddefconfig
        make W=1 O=build_dir ARCH=i386 SHELL=/bin/bash fs/ceph/