i_e2fs_gen
if (ip->i_e2fs_gen == 0) {
ip->i_e2fs_gen = ext2gennumber;
ip->i_e2fs_gen = ext2gennumber;
ip->i_e2fs_gen != ufh.ufid_gen) {
ufh.ufid_gen = ip->i_e2fs_gen;
vap->va_gen = ip->i_e2fs_gen;