rr_count
uint32_t count = rr->rr_count;
rr->rr_count = 0;
rr->rr_count = (uint32_t)(ra->ra_count - uio.uio_resid);
count -= rr.rr_count;
base += rr.rr_count;
offset += rr.rr_count;
rr.rr_count;
} while (!error && count && rr.rr_count == tsize);