LK_UPGRADE
case LK_UPGRADE:
vn_lock(vp, LK_UPGRADE | LK_RETRY); /* safety */
vn_lock(vp, LK_UPGRADE | LK_RETRY);
vn_lock(vp, LK_UPGRADE | LK_RETRY);
vn_lock(vp, LK_UPGRADE | LK_RETRY); /* XXX */
vn_lock(vp, LK_UPGRADE | LK_RETRY); /* XXX */
vn_lock(ap->a_vp, LK_UPGRADE | LK_RETRY);
vn_lock(vp, LK_UPGRADE | LK_RETRY);
vn_lock(vp, LK_UPGRADE | LK_RETRY);