From mboxrd@z Thu Jan 1 00:00:00 1970 From: =?ISO-8859-15?Q?Luk=E1=A8_Czerner?= Subject: Re: [PATCH v2] ext4: add sysfs entry showing whether the fs contains errors Date: Wed, 7 May 2014 17:35:54 +0200 (CEST) Message-ID: References: <1399464274-16310-1-git-send-email-lczerner@redhat.com> <20140507143646.GB28814@thunk.org> Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Cc: linux-ext4@vger.kernel.org To: "Theodore Ts'o" Return-path: Received: from mx1.redhat.com ([209.132.183.28]:16618 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755443AbaEGPf7 (ORCPT ); Wed, 7 May 2014 11:35:59 -0400 In-Reply-To: <20140507143646.GB28814@thunk.org> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Wed, 7 May 2014, Theodore Ts'o wrote: > Date: Wed, 7 May 2014 10:36:46 -0400 > From: Theodore Ts'o > To: Lukas Czerner > Cc: linux-ext4@vger.kernel.org > Subject: Re: [PATCH v2] ext4: add sysfs entry showing whether the fs contains > errors > > On Wed, May 07, 2014 at 02:04:34PM +0200, Lukas Czerner wrote: > > > > cat /sys/fs/ext4/sda/errors > > > > If the file system is not marked as containing errors then the file > > returns just 0. Otherwise it would print out the following information: > > > > first : \ > > last : > > This goes against the typical way in which information is returned in > sysfs. Personally, I've always preferred the scheme used by, for > example /proc/acpi/battery/BAT0/info, versus needing to read N > different files in /sys/class/power_supply/BAT0/*, but the argument is > that it's easier for programs to parse information if they are in > separate files. What about /sys/class/power_supply/BAT0/uevent ? It it is easily parsable and has all the information in /sys/class/power_supply/BAT0/* Also something like /sys/block/sda/stat seems to differ from the rest. > > It's one of the reasons why I've kept /proc/fs/ext4/sda3/mb_groups, > since trying to convert that file over to the Church of Sysfs's style > guidelines was far more work than it was worth. I tried to find sysfs guidelines but I can not see any in Documentation speaking about the contents of the files. What are the guidelines then ? > > I'm not actually sure it's that important to be able to expose the > error function and error line number via sysfs or procfs. If a > process wants a complete record of all of the various errors, then > dmesg or maybe some netlink socket is really the best interface for > getting this information. Maybe not important, but it seems useful enough. However we might want to restrict read permissions to owner only, since it does not seem like a good idea to expose this information to the world. > > For sysfs, I suspect the primary use will be answering the questions: > "is this file system healthy or not", and "when did it first become > unhealthy". And for questoins like this, the errors_count and > first_error_time and last_error_time is probably the most useful bits > of information to expose. So you're suggesting to have three sysfs files ? errors_count first_error_time last_error_time -Lukas > > Cheers, > > - Ted >