From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 22058C43334 for ; Wed, 5 Sep 2018 09:32:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C78B9206BA for ; Wed, 5 Sep 2018 09:32:36 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C78B9206BA Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=lichtvoll.de Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728215AbeIEOB4 convert rfc822-to-8bit (ORCPT ); Wed, 5 Sep 2018 10:01:56 -0400 Received: from mondschein.lichtvoll.de ([194.150.191.11]:40403 "EHLO mail.lichtvoll.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725862AbeIEOBz (ORCPT ); Wed, 5 Sep 2018 10:01:55 -0400 Authentication-Results: auth=pass smtp.auth=martin smtp.mailfrom=martin@lichtvoll.de Received: from 127.0.0.1 (localhost [127.0.0.1]) (using TLSv1 with cipher ECDHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by mail.lichtvoll.de (Postfix) with ESMTPSA id 898793A2CC8; Wed, 5 Sep 2018 11:32:32 +0200 (CEST) From: Martin Steigerwald To: Rogier Wolff Cc: Jeff Layton , =?utf-8?B?54Sm5pmT5Yas?= , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: POSIX violation by writeback error Date: Wed, 05 Sep 2018 11:32:32 +0200 Message-ID: <49555682.rh9yPTYizh@merkaba> In-Reply-To: <20180905080444.GD24519@BitWizard.nl> References: <3805399.0d8HT3LL4o@merkaba> <20180905080444.GD24519@BitWizard.nl> MIME-Version: 1.0 Content-Transfer-Encoding: 8BIT Content-Type: text/plain; charset="iso-8859-1" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Rogier Wolff - 05.09.18, 10:04: > On Wed, Sep 05, 2018 at 09:39:58AM +0200, Martin Steigerwald wrote: > > Rogier Wolff - 05.09.18, 09:08: > > > So when a mail queuer puts mail the mailq files and the mail > > > processor can get them out of there intact, nobody is going to > > > notice. (I know mail queuers should call fsync and report errors > > > when that fails, but there are bound to be applications where > > > calling fsync is not appropriate (*)) > > > > AFAIK at least Postfix MDA only reports mail as being accepted over > > SMTP once fsync() on the mail file completed successfully. And Iīd > > expect every sensible MDA to do this. I donīt know how Dovecot MDA > > which I currently use for sieve support does this tough. > > Yes. That's why I added the remark that mailers will call fsync and > know about it on the write side. I encountered a situation in the > last few days that when a developer runs into this while developing, > would have caused him to write: > /* Calling this fsync causes unacceptable performance */ > // fsync (fd); Hey, I still have # KDE Sync # Re: zero size file after power failure with kernel 2.6.30.5 # http://permalink.gmane.org/gmane.comp.file-systems.xfs.general/30512 export KDE_EXTRA_FSYNC=1 in my ~/.zshrc. One reason KDE developers did this was Ext3 having been so slow with fsync(). See also: Bug 187172 - truncated configuration files on power loss or hard crash https://bugs.kde.org/187172 > But when apt-get upgrade replaces your /bin/sh and gets a write error > returning error on subsequent reads is really bad. I sometimes used eatmydata with apt upgrade / dist-upgrade, but yeah, this asks for trouble on write interruptions. > It is more difficult than you think. Heh. :) Thanks, -- Martin