count_iov
total = count_iov(iov, niov);
iob->ib_remain = count_iov(iov, niov);
size_t count_iov(const struct iovec *, size_t);
size_t c = count_iov(riov, n);
info[n_chains].len = (uint32_t)count_iov(riov, n);
ext_data_len = count_iov(req->vsr_data_iov_in,
ext_data_len = count_iov(req->vsr_data_iov_out,
ext_data_len = count_iov(req->vsr_data_iov_out,