swap_getphysname
err = swap_getphysname(vp, off, &pvp, &poff);
if (swap_getphysname(vp, off, &pvp, &poff)) {
err = swap_getphysname(vp, off, &pvp, &poff);
err = swap_getphysname(vp, off, &pvp, &poff);
extern int swap_getphysname(struct vnode *vp, u_offset_t off,
error = swap_getphysname(vp, off, &pvp, &poff);