From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752792AbaIYIaV (ORCPT ); Thu, 25 Sep 2014 04:30:21 -0400 Received: from cantor2.suse.de ([195.135.220.15]:60612 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750977AbaIYIaQ (ORCPT ); Thu, 25 Sep 2014 04:30:16 -0400 Date: Thu, 25 Sep 2014 10:30:10 +0200 From: Jan Kara To: Andrew Morton Cc: Jan Kara , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, Heinrich Schuchardt , "Michael Kerrisk (man-pages)" , Alexander Viro , John McCutchan , Robert Love , Eric Paris , Cyrill Gorcunov , Pavel Emelyanov , Andrey Vagin Subject: Re: [PATCH] fs: don't remove inotify watchers from alive inode-s (v2) Message-ID: <20140925083010.GA3096@quack.suse.cz> References: <1411141516-1918-1-git-send-email-avagin@openvz.org> <20140924105155.GA24411@quack.suse.cz> <20140924131947.bc083e7f34981bbf73a364f1@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20140924131947.bc083e7f34981bbf73a364f1@linux-foundation.org> 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 24-09-14 13:19:47, Andrew Morton wrote: > On Wed, 24 Sep 2014 12:51:55 +0200 Jan Kara wrote: > > > Hello, > > > > Andrew, what do you think about the patch below? Al objected that it > > changes userspace visible behavior some time ago and then he didn't react > > to our explanations... > > Difficult situation. There's some really important information missing > from the changelog: > > - Who cares? Is there some real application which is hurting from > the current situation? If so, who, what, how and why. If not, then > why change anything? I believe Openvz guys hit this in their application but I'll defer to them for more details. > - A description of the userspace API change impact. How did the > interface change? What is the risk of this change causing damage to > real applications? I believe this was covered in the changelog. Without the patch depending on the order of unlinks for hardlinked file you sometimes get events: 4 (IN_ATTRIB) 400 (IN_DELETE_SELF) 8000 (IN_IGNORED) and sometimes you get events: 4 (IN_ATTRIB) 8 (IN_CLOSE_WRITE) 400 (IN_DELETE_SELF) 8000 (IN_IGNORED) With the patch you'll always have the second case. So without the patch you don't receive some events if the file has at least 2 hardlinks and then gets unlinked. I think the risk that some application relies on *not* getting those events is pretty low (especially since in the common case of file without hardlinks you will get all those events). Honza -- Jan Kara SUSE Labs, CR