add: TRACE("dec_vnode(): id = %Ld, rcnt = %d (after decreasing)\n", vn->vnid, vn->rcnt);
context: dec_vnode(vnode *vn, char r){    vnode       *ovn;    LOCK(vnlock);    vn->rcnt--;    if (vn->rcnt == 0) {        if (vn->remove) {            vn->busy = TRUE;            move_vnode(vn, LOCKED_LIST);            UNLOCK(vnlock);            (*vn->ns->fs->ops.remove_vnode)(vn->ns->data, vn->data, r);            LOCK(vnlock);            clear_vnode(vn);            move_vnode(vn, FREE_LIST);        } else {            move_vnode(vn, USED_LIST);            if (lists[USED_LIST].num > usdvnnum) {                ovn = steal_vnode(USED_LIST);                flush_vnode(ovn, r);                move_vnode(ovn, FREE_LIST);            }        }	}    UNLOCK(vnlock);    return;}