xfs_trans_get_buf_map
error = xfs_trans_get_buf_map(tp, mp->m_ddev_targp, mapp, nmap, 0, &bp);
int xfs_trans_get_buf_map(struct xfs_trans *tp, struct xfs_buftarg *target,
return xfs_trans_get_buf_map(tp, target, &map, 1, flags, bpp);