wapbl_circ_write
error = wapbl_circ_write(wl, wc, blocklen, &off);
error = wapbl_circ_write(wl, bp->b_data,
error = wapbl_circ_write(wl, zero, padding, &off);
error = wapbl_circ_write(wl, wc, blocklen, &off);
error = wapbl_circ_write(wl, wc, blocklen, &off);