sf_bavail
sbp->f_bavail = (int32_t)sfp->sf_bavail;
sbp->sf_bavail = fxdr_unsigned(u_int32_t, *tl);
sfp->sf_bavail = txdr_unsigned(NFS_V2CLAMP32(sf->f_bavail));
sbp->f_bavail = fxdr_unsigned(int32_t, sfp->sf_bavail);