Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Thu, 26 Jul 2001 09:58:53 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Thu, 26 Jul 2001 09:58:43 -0400 Received: from pD951F257.dip.t-dialin.net ([217.81.242.87]:13188 "EHLO emma1.emma.line.org") by vger.kernel.org with ESMTP id ; Thu, 26 Jul 2001 09:58:27 -0400 Date: Thu, 26 Jul 2001 15:58:33 +0200 From: Matthias Andree To: Rik van Riel Cc: Matthias Andree , Andrew Morton , lkml , "ext3-users@redhat.com" Subject: Re: ext3-2.4-0.9.4 Message-ID: <20010726155833.P17244@emma1.emma.line.org> Mail-Followup-To: Rik van Riel , Andrew Morton , lkml , "ext3-users@redhat.com" In-Reply-To: <20010726151749.M17244@emma1.emma.line.org> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.3.19i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Original-Recipient: rfc822;linux-kernel-outgoing On Thu, 26 Jul 2001, Rik van Riel wrote: > On Thu, 26 Jul 2001, Matthias Andree wrote: > > On Thu, 26 Jul 2001, Rik van Riel wrote: > > > > > In fact, knowing how hard disks work mechanically, only > > > journaling filesystems could have an extention to make > > > this work. Ie. this is NOT something you can rely on ;) > > > > This is not about failing hard disks. It is about premature > > acknowledgment of something which has not happened at that time. > > So you didn't read what I was writing. Sorry. > Let me explain it to you slowly: > > Disks. Write. One. Write. At. A. Time. > > A rename often needs as many as 4 or 5 writes, > ergo, you CANNOT do a rename atomically without > journaling and transactions. You're missing the point, with this as the previous mail. The MTA is not going to change from one unsupported/incompatible interface (that only Linux suffers from) and if it did, it would still do the wrong thing. MTAs often run multiple processes, and if these all open the same directory and sync it while others have changes open that don't need a sync at that time and will sync later, you're getting no further than with chattr +S or mount -o sync. It's not about atomicity itself, but about first. write. all. required. blocks. for. a. certain. change. physically. to. disc. and. only. after. this. do. return. from. rename, link, unlink. function. calls. I'm aware of phase-tree concepts ("single block write switches from one consistent state to another") and I'm aware that ext3fs and reiserfs do feature atomic renames (after crash recovery). That a drive might fall over or the power might fail before all writes of a certain rename operation have completed is harmless UNLESS you lied to someone that the operation was already complete (when it wasn't). > > The competition is there and it has names: BSD + ufs + softupdates, > > Solaris + logging ufs. Read MTA mailing lists before obstructing. > > BSD + softupdates is physically incapable of doing what > you suggest it does. This can be proven from the lack > of transactions and the way hard disks work physically. You misunderstood me. I'm not talking about atomicity. -- Matthias Andree - 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/