DMTC_BUF_SIZE
(2 * DMTC_BUF_SIZE) + 1;
explicit_bzero(buffer, DMTC_BUF_SIZE);
mpipe_init(&priv->read_mpipe, M_DMCRYPT, DMTC_BUF_SIZE,
mpipe_init(&priv->write_mpipe, M_DMCRYPT, DMTC_BUF_SIZE,
dmtc_bio_read_decrypt(bio, data_buf, DMTC_BUF_SIZE);
dmtc_bio_write_encrypt(bio, data_buf, DMTC_BUF_SIZE);