From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S268077AbUHZJZ5 (ORCPT ); Thu, 26 Aug 2004 05:25:57 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S268020AbUHZJXn (ORCPT ); Thu, 26 Aug 2004 05:23:43 -0400 Received: from omx3-ext.sgi.com ([192.48.171.20]:43684 "EHLO omx3.sgi.com") by vger.kernel.org with ESMTP id S266626AbUHZJWK (ORCPT ); Thu, 26 Aug 2004 05:22:10 -0400 Date: Thu, 26 Aug 2004 02:21:37 -0700 From: Paul Jackson To: Helge Hafting Cc: riel@redhat.com, mikulas@artax.karlin.mff.cuni.cz, torvalds@osdl.org, hch@lst.de, reiser@namesys.com, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, flx@namesys.com, reiserfs-list@namesys.com Subject: Re: silent semantic changes with reiser4 Message-Id: <20040826022137.1504ffb7.pj@sgi.com> In-Reply-To: <412D968B.9030107@hist.no> References: <412D968B.9030107@hist.no> Organization: SGI X-Mailer: Sylpheed version 0.9.12 (GTK+ 1.2.10; i686-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Helge wrote: > So an old "tar" won't get this right as it will assume that an object > is either file or directory. There are many backup apps, not just one. I've written a few myself, none of which will ever be worthy of notice. The sourceforge Topic.System.Archiving.Backup lists 335 projects at present. I find the idea that most backup tools and scripts will silently stop working correctly to be pretty scary. And then there's archiving, installation, distribution, administration, emulation, file system and partition managers, and on and on. === I wonder if we can make this "modal" somehow. The one consistency I see is that apps that want the "enhanced" view need to ask for it, somehow. It is the new views of the data that are being added - let the app announce to the kernel (usually via specialized code in some shared library that the app is using to get the alternate views) that either per-task, or per-file descriptor, it is to see the "enhanced" view, as a side affect of trying to access it. Old stuff, or even new stuff that is content to work with the "classic" view that a file is a single data stream, and that directories only have pathnames, not data, would by default see that view, and see _all_ the data, presented somehow in that view, perhaps as additional files with magic names. This still leaves the breakage that such tools don't know, and don't preserve, the magic linkage between such magic files. But that is much less of an issue, in my view. Programs such as backups that are manipulating the files of apps they know nothing about already have to presume that all the files are important in inscrutable ways, and just be careful to preserve or copy or backup all of them. Yeah - I realize that there will be a few followups denouncing modal architectures. I might even agree with some of them. If this were easy, it would have been done years ago. The onus should be on the new stuff to request the enhanced view, rather than on the old dogs to learn new tricks. -- I won't rest till it's the best ... Programmer, Linux Scalability Paul Jackson 1.650.933.1373