mapped_fsgid
mapped_fsgid(req->r_mnt_idmap,
fsgid = no_idmap ? current_fsgid() : mapped_fsgid(idmap, fc->user_ns);
gid = mapped_fsgid(args->idmap, i_user_ns(dir));
inode->i_gid = mapped_fsgid(idmap, i_user_ns(inode));
kgid = mapped_fsgid(idmap, fs_userns);