F_REQUIRE_OPEN
F_REQUIRE_DIR | F_REQUIRE_OPEN, &req->lr_fid);
F_REQUIRE_OPEN, &req->lr_fid);
F_REQUIRE_OPEN, &req->lr_fid);
F_REQUIRE_OPEN, &req->lr_fid);
if ((flags & F_REQUIRE_OPEN) && !l9p_fid_isopen(file))