From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754846AbZHFKLJ (ORCPT ); Thu, 6 Aug 2009 06:11:09 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753816AbZHFKLI (ORCPT ); Thu, 6 Aug 2009 06:11:08 -0400 Received: from atrey.karlin.mff.cuni.cz ([195.113.26.193]:48966 "EHLO atrey.karlin.mff.cuni.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753567AbZHFKLH (ORCPT ); Thu, 6 Aug 2009 06:11:07 -0400 Date: Thu, 6 Aug 2009 12:10:59 +0200 From: Pavel Machek To: Tvrtko Ursulin Cc: Eric Paris , "linux-kernel@vger.kernel.org" , "linux-fsdevel@vger.kernel.org" , "malware-list@dmesg.printk.net" , "Valdis.Kletnieks@vt.edu" , "greg@kroah.com" , "jcm@redhat.com" , Douglas Leeder , "tytso@mit.edu" , "arjan@infradead.org" , "david@lang.hm" , "jengelh@medozas.de" , "aviro@redhat.com" , "mrkafk@gmail.com" , "alexl@redhat.com" , "jack@suse.cz" , "a.p.zijlstra@chello.nl" , "hch@infradead.org" , "alan@lxorguk.ukuu.org.uk" , "mmorley@hcl.in" Subject: Re: fanotify - overall design before I start sending patches Message-ID: <20090806101059.GD31370@elf.ucw.cz> References: <1248466429.3567.82.camel@localhost> <20090805020534.GB1354@ucw.cz> <200908051746.17903.tvrtko.ursulin@sophos.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <200908051746.17903.tvrtko.ursulin@sophos.com> X-Warning: Reading this can be dangerous to your mental health. User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed 2009-08-05 17:46:16, Tvrtko Ursulin wrote: > On Wednesday 05 August 2009 03:05:34 Pavel Machek wrote: > > BTW my -@suse.cz address no longer works. pavel@ucw.cz should be ok. > > > > > If a FAN_ACCESS_PERM or FAN_OPEN_PERM event is received the listener > > > must send a response before the 5 second timeout. If no response is > > > sent before the 5 second timeout the original operation is allowed. If > > > this happens too many times (10 in a row) the fanotify group is evicted > > > from the kernel and will not get any new events. Sending a response is > > > done using the setsockopt() call with the socket options set to > > > FANOTIFY_ACCESS_RESPONSE. The buffer should contain a structure like: > > > > The timeout part of interface is very ugly. Will fanotify users have > > to be realtime/mlocked? > > Why do you think it is very ugly? Do I need to explain? > Just to make sure you haven't missed this - it is not that they have to > complete the whole operation before the timeout period (since you mention > realtime/mlock I suspect this is what you think?), but _during_ the operation > they have to show that they are active by sending something like keep alive > messages. > > Or you are worried about failing to meet even that on a loaded system? There > has to be something like this otherwise hung userspace client would kill the > whole system. Of course, I'm worried about failing to meet this on loaded system. And the fact that I _have_ to worry about that means that interface is ugly/broken. Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html