From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756214Ab0ITLNR (ORCPT ); Mon, 20 Sep 2010 07:13:17 -0400 Received: from moutng.kundenserver.de ([212.227.17.10]:64558 "EHLO moutng.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755984Ab0ITLNQ (ORCPT ); Mon, 20 Sep 2010 07:13:16 -0400 From: Arnd Bergmann To: Jan Kara Subject: Re: [PATCH] BKL: Remove BKL from isofs Date: Mon, 20 Sep 2010 13:13:11 +0200 User-Agent: KMail/1.12.2 (Linux/2.6.35-16-generic; KDE/4.3.2; x86_64; ; ) Cc: Christoph Hellwig , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org References: <201009161632.59210.arnd@arndb.de> <201009172100.06598.arnd@arndb.de> <20100920105811.GC3390@quack.suse.cz> In-Reply-To: <20100920105811.GC3390@quack.suse.cz> MIME-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Message-Id: <201009201313.11526.arnd@arndb.de> X-Provags-ID: V02:K0:dlBIRXWsEoQboA+vznq/PdDbUhDn9/ROMhGaFqzTtaT bklV2TeKet0A4qn/bQHCHNWE8JMnLXbmOw//Zzxk6pMC7kfAT3 MGsmmn919M2pq9FkzN2TtfxYmx9ywtKUBn9rvZuXb5dXzr9IHu cBbhlcNoXXa3ESgLQkZIofL0ezZR4p+JTCwvoYEoh6EjnU+uWX IX7CON/YZEpFSPcXVr7Fg== Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Monday 20 September 2010, Jan Kara wrote: > Hmm, looking through the code, I actually don't see a reason > why we should need any per-sb lock at all. The filesystem is always > read-only and we don't seem to have any global data structures that > change. But that needs some testing I guess - I'll try to do that. Ok, great! The BKL was basically as wrong as the global mutex protecting the operations anyway, because it does not document what data is actually getting protected in any of all the drivers that I'm converting to a private mutex. Given more time for code inspection and some testing, you can probably come up with a good explanation why the BKL is not needed in all those places, but since nobody ever bothered to do this for the last decade for all these drivers, my approach was to simply prove (in a rather lose sense) that I can't make it worse by converting to a mutex. Arnd