From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753219AbaEOKOA (ORCPT ); Thu, 15 May 2014 06:14:00 -0400 Received: from cantor2.suse.de ([195.135.220.15]:44146 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751831AbaEOKN7 (ORCPT ); Thu, 15 May 2014 06:13:59 -0400 Date: Thu, 15 May 2014 12:13:56 +0200 From: Jan Kara To: Dave Chinner Cc: Jan Kara , Mateusz Guzik , 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: <20140515101356.GC27289@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> <20140514113945.GC5824@quack.suse.cz> <20140514220052.GD5421@dastard> <20140514223745.GF5421@dastard> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20140514223745.GF5421@dastard> 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 Thu 15-05-14 08:37:45, Dave Chinner wrote: > On Thu, May 15, 2014 at 08:00:52AM +1000, Dave Chinner wrote: > > On Wed, May 14, 2014 at 01:39:45PM +0200, Jan Kara wrote: > > > 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. > > > > But filesystems choose to output that info, not the VFS. When you do > > a remount,ro there is no output in syslog, because filesystems don't > > need to dump any output - the state change is reflected in > > /proc/self/mounts. IMO frozen should state should be communicated > > the same way so that it is silent when it just works, and the state > > can easily be determined when something goes wrong. > > Say, like this: > > $ grep /mnt/test /proc/mounts > /dev/vda /mnt/test xfs rw,relatime,attr2,inode64,noquota 0 0 > $ sudo xfs_freeze -f /mnt/test > $ grep /mnt/test /proc/mounts > /dev/vda /mnt/test xfs rw,frozen,relatime,attr2,inode64,noquota 0 0 > $ sudo xfs_freeze -u /mnt/test > $ grep /mnt/test /proc/mounts > /dev/vda /mnt/test xfs rw,relatime,attr2,inode64,noquota 0 0 > $ > > Patch below does this. Hum, same as Eric I'm not very enthusiastic about a fake mount option in /proc/mounts. Maybe we could stuff some extra field in /proc/self/mountinfo? Honza -- Jan Kara SUSE Labs, CR