From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753152AbZHJU2Z (ORCPT ); Mon, 10 Aug 2009 16:28:25 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752579AbZHJU2Y (ORCPT ); Mon, 10 Aug 2009 16:28:24 -0400 Received: from cantor.suse.de ([195.135.220.2]:43485 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752482AbZHJU2X (ORCPT ); Mon, 10 Aug 2009 16:28:23 -0400 Date: Mon, 10 Aug 2009 22:28:22 +0200 From: Jan Kara To: "Theodore Ts'o" Cc: Jan Kara , Linux Kernel Developers List , linux-ext4@vger.kernel.org Subject: Re: [PATCH, RFC] ext3: Update Kconfig description of EXT3_DEFAULTS_TO_ORDERED Message-ID: <20090810202822.GA11979@duck.suse.cz> References: <1249934623-15939-1-git-send-email-tytso@mit.edu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1249934623-15939-1-git-send-email-tytso@mit.edu> User-Agent: Mutt/1.5.17 (2007-11-01) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon 10-08-09 16:03:43, Theodore Ts'o wrote: > The old description for this configuration option was perhaps not > completely balanced in terms of describing the tradeoffs of using a > default of data=writeback vs. data=ordered. Despite the fact that old > description very strongly recomended disabling this feature, all of > the major distributions have elected to preserve the existing 'legacy' > default, which is a strong hint that it perhaps wasn't telling the > whole story. > > This revised description has been vetted by a number of ext3 > developers as being better at informing the user about the tradeoffs > of enabling or disabling this configuration feature. Thanks. Merged to my tree. I plan to push it to Linus in the next merge window. Honza > Signed-off-by: "Theodore Ts'o" > Cc: linux-ext4@vger.kernel.org > --- > fs/ext3/Kconfig | 32 +++++++++++++++++--------------- > 1 files changed, 17 insertions(+), 15 deletions(-) > > diff --git a/fs/ext3/Kconfig b/fs/ext3/Kconfig > index fb3c1a2..522b154 100644 > --- a/fs/ext3/Kconfig > +++ b/fs/ext3/Kconfig > @@ -29,23 +29,25 @@ config EXT3_FS > module will be called ext3. > > config EXT3_DEFAULTS_TO_ORDERED > - bool "Default to 'data=ordered' in ext3 (legacy option)" > + bool "Default to 'data=ordered' in ext3" > depends on EXT3_FS > help > - If a filesystem does not explicitly specify a data ordering > - mode, and the journal capability allowed it, ext3 used to > - historically default to 'data=ordered'. > - > - That was a rather unfortunate choice, because it leads to all > - kinds of latency problems, and the 'data=writeback' mode is more > - appropriate these days. > - > - You should probably always answer 'n' here, and if you really > - want to use 'data=ordered' mode, set it in the filesystem itself > - with 'tune2fs -o journal_data_ordered'. > - > - But if you really want to enable the legacy default, you can do > - so by answering 'y' to this question. > + The journal mode options for ext3 have different tradeoffs > + between when data is guaranteed to be on disk and > + performance. The use of "data=writeback" can cause > + unwritten data to appear in files after an system crash or > + power failure, which can be a security issue. However, > + "data=ordered" mode can also result in major performance > + problems, including seconds-long delays before an fsync() > + call returns. For details, see: > + > + http://ext4.wiki.kernel.org/index.php/Ext3_data_mode_tradeoffs > + > + If you have been historically happy with ext3's performance, > + data=ordered mode will be a safe choice and you should > + answer 'y' here. If you understand the reliability and data > + privacy issues of data=writeback and are willing to make > + that trade off, answer 'n'. > > config EXT3_FS_XATTR > bool "Ext3 extended attributes" > -- > 1.6.3.2.1.gb9f7d.dirty > -- Jan Kara SUSE Labs, CR