reproduce (this is a W=1 build):
        # https://git.kernel.org/pub/scm/linux/kernel/git/gfs2/linux-gfs2.git/commit/?id=b3cbb48767a2c7a9348b13852b75ea01ed52017b
        git remote add gfs2 https://git.kernel.org/pub/scm/linux/kernel/git/gfs2/linux-gfs2.git
        git fetch --no-tags gfs2 for-next
        git checkout b3cbb48767a2c7a9348b13852b75ea01ed52017b
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        make W=1 O=build_dir ARCH=x86_64 olddefconfig
        make W=1 O=build_dir ARCH=x86_64 SHELL=/bin/bash fs/ocfs2/