From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750930AbWGUStQ (ORCPT ); Fri, 21 Jul 2006 14:49:16 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750983AbWGUStQ (ORCPT ); Fri, 21 Jul 2006 14:49:16 -0400 Received: from inti.inf.utfsm.cl ([200.1.21.155]:59849 "EHLO inti.inf.utfsm.cl") by vger.kernel.org with ESMTP id S1750885AbWGUStP (ORCPT ); Fri, 21 Jul 2006 14:49:15 -0400 Message-Id: <200607211849.k6LInCi8011368@laptop13.inf.utfsm.cl> To: "Joshua Hudson" Cc: Linux Kernel Mailing List Subject: Re: what is necessary for directory hard links In-Reply-To: Your message of "Thu, 20 Jul 2006 18:04:49 MST." X-Mailer: MH-E 7.4.2; nmh 1.1; XEmacs 21.4 (patch 19) Date: Fri, 21 Jul 2006 14:49:12 -0400 From: "Horst H. von Brand" X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-2.0.2 (inti.inf.utfsm.cl [200.1.21.155]); Fri, 21 Jul 2006 14:49:12 -0400 (CLT) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Joshua Hudson wrote: > This patch is the sum total of all that I had to change in the kernel > VFS layer to support hard links to directories Can't be done, as it creates the possibility of loops. The "only files can be hardlinked" idea makes garbage collection (== deleting of unreachable objects) simple: Just check the number of references. Detecting unconnected subgraphs uses a /lot/ of memory; and much worse, you have to stop (almost) all filesystem activity while doing it. Besides, the flow "root down through directories" gives a natural order in which to go locking stuff when needed; if there can be loops, the system could easily deadlock. -- Dr. Horst H. von Brand User #22616 counter.li.org Departamento de Informatica Fono: +56 32 654431 Universidad Tecnica Federico Santa Maria +56 32 654239 Casilla 110-V, Valparaiso, Chile Fax: +56 32 797513