na_btime
nap->na_btime.tv_sec = -1;
nap->na_btime.tv_nsec = 0;
if (!NFS_CMPTIME(temptime, nap->na_btime))
nap->na_btime = temptime;
nap->na_btime.tv_sec = -1;
nap->na_btime.tv_nsec = 0;
nap->na_btime.tv_sec = -1;
nap->na_btime.tv_nsec = 0;
np->n_vattr.na_btime = nap->na_btime;
fxdr_nfsv4time(tl, &nvap->na_btime);
NFSVNO_SETATTRVAL(&nva2, btime, nva.na_btime);