sf_bfree
sbp->f_bfree = (int32_t)sfp->sf_bfree;
sbp->sf_bfree = fxdr_unsigned(u_int32_t, *tl++);
sfp->sf_bfree = txdr_unsigned(NFS_V2CLAMP32(sf->f_bfree));
sbp->f_bfree = fxdr_unsigned(int32_t, sfp->sf_bfree);