ALQ_WAITOK
if (alq->aq_writetail >= len || flags & ALQ_WAITOK) {
alq_writen(siftr_alq, sbuf_data(s), sbuf_len(s), ALQ_WAITOK);
alq_writen(siftr_alq, sbuf_data(s)+i, bytes_to_write, ALQ_WAITOK);
ALQ_WAITOK);