PG_BUSY
{ BIT(PG_BUSY), "BUSY" }, \
clear_bit_unlock(PG_BUSY, &req->wb_flags);
wake_up_bit(&req->wb_flags, PG_BUSY);
if (!test_bit(PG_BUSY, &req->wb_flags))
return wait_on_bit_io(&req->wb_flags, PG_BUSY,
return !test_and_set_bit(PG_BUSY, &req->wb_flags);