From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx2.suse.de ([195.135.220.15]:53702 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1754256AbdHYBUE (ORCPT ); Thu, 24 Aug 2017 21:20:04 -0400 Date: Fri, 25 Aug 2017 03:20:01 +0200 From: "Luis R. Rodriguez" Subject: Re: Filesystem configuration parsers - (was: Re: [RESEND][PATCH] xfs: add online uevent for mount operation) Message-ID: <20170825012001.GY27873@wotan.suse.de> References: <1503582115-37220-1-git-send-email-houtao1@huawei.com> <20170824171028.GF4796@magnolia> <20170824180441.GL27873@wotan.suse.de> <20170825010155.GK21024@dastard> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170825010155.GK21024@dastard> Sender: linux-xfs-owner@vger.kernel.org List-ID: List-Id: xfs To: Dave Chinner Cc: "Luis R. Rodriguez" , "Darrick J. Wong" , Hou Tao , linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, Jeff Mahoney , NeilBrown , Tso Ted , Dmitri Pal On Fri, Aug 25, 2017 at 11:01:55AM +1000, Dave Chinner wrote: > On Thu, Aug 24, 2017 at 08:04:41PM +0200, Luis R. Rodriguez wrote: > > While all this is nice, I'm sure we're all aware of the dangers of setting > > things in stone through sysfs, its likely already decided for the above > > tunables, but adding a uevent *is* yet another layer of user interface > > which userspace can *expect* and we should be certain we want this so > > we won't regress userspace later. > > > > Just saying, we better damn be sure this is the way we want to go. > > I'm not sure what you are trying to warn us about? :/ > > These are events on an XFS specific kobj, it's not a generic VFS > filesystem event we are generating here. It's no different from a > hardware device generating it's own uevents to tell userspace > something changed in the device. I meant that once its sent even if it is XFS specific, it will be something that some userspace can expect and then we'd always have to send it later. > A quick grep would have told you that GFS2 already has it's own > online/offline uevents (e.g. gfs2_online_uevent()), as does the > DLM code. Orangefs seems to use quite a few of uevent notifications, > too. So it's not like we're doing something controversial or unique > here, nor something that locks us out of a non-existent VFS event > notification mechanism. I don't think its controversial *at all*. Just that a mount uevent, with uuid, sounds like something we could at least agree is pretty generic. Regardless of what we end up doing with it or how. Luis