nfs_cookie
if (a->nfs_cookie == b->nfs_cookie) {
if (a->nfs_cookie < b->nfs_cookie)
srdc.nfs_cookie = uiop->uio_offset;
srdc.nfs_cookie = rdc->nfs_ncookie;
rrdc->nfs_cookie = rdc->nfs_ncookie;
nrdc->nfs_cookie = uiop->uio_offset;
rda.rda_offset = rdc->nfs_cookie;
if (rdc->nfs_cookie == (off_t)0) {