From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932490AbcBCUMZ (ORCPT ); Wed, 3 Feb 2016 15:12:25 -0500 Received: from userp1040.oracle.com ([156.151.31.81]:51897 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932264AbcBCUMU (ORCPT ); Wed, 3 Feb 2016 15:12:20 -0500 Date: Wed, 3 Feb 2016 12:07:06 -0800 From: "Darrick J. Wong" To: Joe Perches Cc: Huaitong Han , tytso@mit.edu, adilger.kernel@dilger.ca, linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] ext4: add a line break for proc mb_groups display Message-ID: <20160203200706.GG22352@birch.djwong.org> References: <1454505546-4875-1-git-send-email-huaitong.han@intel.com> <20160203181356.GA5842@birch.djwong.org> <1454524232.7291.105.camel@perches.com> <20160203193233.GB5842@birch.djwong.org> <1454528313.7291.115.camel@perches.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <1454528313.7291.115.camel@perches.com> User-Agent: Mutt/1.5.21 (2010-09-15) X-Source-IP: userv0022.oracle.com [156.151.31.74] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Feb 03, 2016 at 11:38:33AM -0800, Joe Perches wrote: > On Wed, 2016-02-03 at 11:32 -0800, Darrick J. Wong wrote: > > On Wed, Feb 03, 2016 at 10:30:32AM -0800, Joe Perches wrote: > > > On Wed, 2016-02-03 at 10:13 -0800, Darrick J. Wong wrote: > > > > On Wed, Feb 03, 2016 at 09:19:06PM +0800, Huaitong Han wrote: > > > > > This patch adds a line break for proc mb_groups display. > > > > > > Using 2 lines for output might break any existing users. > > > > > > Are there any? > > > > It's a multiline file if you have more than one blockgroup; this just makes it > > so that you don't have to special-case BG 0. > > And existing scripts might do that now and might fail > to do properly after this change. Or they might have sed -e 's/]#0/]\n#0/g' in which case they won't be affected. > > IOW: mb_groups scripts already had to parse multiple lines, and most likely any > > script parsing it would inject a newline after the header. > > I've no dog in this fight really.  I just wanted to make > it clear that this could cause existing scripts to fail. > > proc output is supposed to be unchanging except maybe > adding new fields to existing lines. > > Your choice. Ted's, really. I have no idea which scripts do with various per-fs /proc files. Usually poking in mb_groups is only done as part of failure report data collection to see what's mucked up the fs this time. Anyway, I'll defer to the maintainer. :) --D > > cheers, Joe