From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755334AbaENLjt (ORCPT ); Wed, 14 May 2014 07:39:49 -0400 Received: from cantor2.suse.de ([195.135.220.15]:50135 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755131AbaENLjs (ORCPT ); Wed, 14 May 2014 07:39:48 -0400 Date: Wed, 14 May 2014 13:39:45 +0200 From: Jan Kara To: Mateusz Guzik Cc: Jan Kara , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, Josef Bacik , Al Viro , Eric Sandeen , Joe Perches Subject: Re: [PATCH V2 2/2] fs: print a message when freezing/unfreezing filesystems Message-ID: <20140514113945.GC5824@quack.suse.cz> References: <1400018683-5565-1-git-send-email-mguzik@redhat.com> <1400018683-5565-2-git-send-email-mguzik@redhat.com> <20140514111449.GB5824@quack.suse.cz> <20140514112619.GA10637@mguzik.redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20140514112619.GA10637@mguzik.redhat.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed 14-05-14 13:26:21, Mateusz Guzik wrote: > On Wed, May 14, 2014 at 01:14:49PM +0200, Jan Kara wrote: > > On Wed 14-05-14 00:04:43, Mateusz Guzik wrote: > > > This helps hang troubleshooting efforts when only dmesg is available. > > > > > > While here remove code duplication with MS_RDONLY case and fix a > > > whitespace nit. > > I'm somewhat undecided here I have to say. On one hand I don't like > > printing to kernel log when everything is fine and kernel is operating > > normally. On the other hand I've seen quite a few cases where people have > > shot themselves in the foot with filesystem freezing so having some trace > > of this in the log doesn't seem like a completely bad thing either. What do > > other people think? > > > > I would like to note that the kernel already prints messages when e.g. > filesystems get mounted. Yeah, that's a fair point. > And yes, situations where I/O is frozen and hung task detector comes into > play happen more often than you may think. I can hide these behind a > sysctl if this helps. No, I don't think hiding behind sysctl is really needed. > Finally, somewhat related to the first mail, my preferred message format > (which I was somewhat reluctant to propose earlier) would be: > > VFS (%s): Filesystem frozen by %s:%d > > with device, process and pid respectively. More common seems to be "%s (%d)" for process & pid but whatever. I like the format change. Honza -- Jan Kara SUSE Labs, CR