Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S269400AbTHKP4N (ORCPT ); Mon, 11 Aug 2003 11:56:13 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S269423AbTHKP4N (ORCPT ); Mon, 11 Aug 2003 11:56:13 -0400 Received: from h68-147-142-75.cg.shawcable.net ([68.147.142.75]:38650 "EHLO schatzie.adilger.int") by vger.kernel.org with ESMTP id S269400AbTHKP4H (ORCPT ); Mon, 11 Aug 2003 11:56:07 -0400 Date: Mon, 11 Aug 2003 09:55:18 -0600 From: Andreas Dilger To: Jeff Garzik Cc: Alex Tomas , linux-kernel@vger.kernel.org, ext2-devel@lists.sourceforge.net Subject: Re: [RFC] file extents for EXT3 Message-ID: <20030811095518.T7752@schatzie.adilger.int> Mail-Followup-To: Jeff Garzik , Alex Tomas , linux-kernel@vger.kernel.org, ext2-devel@lists.sourceforge.net References: <3F3791C8.4090903@pobox.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2.5.1i In-Reply-To: <3F3791C8.4090903@pobox.com>; from jgarzik@pobox.com on Mon, Aug 11, 2003 at 08:53:28AM -0400 X-GPG-Key: 1024D/0D35BED6 X-GPG-Fingerprint: 7A37 5D79 BF1B CECA D44F 8A29 A488 39F5 0D35 BED6 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1562 Lines: 36 On Aug 11, 2003 08:53 -0400, Jeff Garzik wrote: > Changing the underlying disk format without bumping the filesystem > revision is a hugely bad idea. I disagreed with merging htree (even > though its backward compat) without bumping the filesystem version, too. > > Vendors, distributors, OEMs, etc. all test against existing on-disk > formats, when they release their products. When the filesystem format > for an existing filesystem, in production, changes underneath them, they > tend to get worried and annoyed. So, to all ext developers, > > Please add to ext4 not ext3! Ext2/3 uses feature flags instead of version numbers to indicate such changes. Version numbers are a poor way of indicating whether a change is compatible or not compared to feature flags. For example, if you bump the minor number to indicate a "compatible" change it means that any code that pretends to support version x.y features also needs to support all features <= y and all features <= x. If you really want to have a feature number to be happy, just think of s.feature_incompat.s_feature_ro_compat.s_feature_compat as something like a version number and you will nearly be happy. Cheers, Andreas -- Andreas Dilger http://sourceforge.net/projects/ext2resize/ http://www-mddsp.enel.ucalgary.ca/People/adilger/ - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/