ldm_vnum_get
offset = ldm_vnum_get(p, LDM_VBLK_OID_OFF, &blk->u.id, size);
offset = ldm_vnum_get(p, offset + 16,
offset = ldm_vnum_get(p, offset + 28, &blk->u.part.size, size);
offset = ldm_vnum_get(p, offset, &blk->u.part.comp_id, size);
offset = ldm_vnum_get(p, offset, &blk->u.part.disk_id, size);
offset = ldm_vnum_get(p, offset + 16, &blk->u.vol.size, size);