From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jan Kara Subject: Re: [PATCH] BKL: Remove BKL from isofs Date: Mon, 20 Sep 2010 17:50:15 +0200 Message-ID: <20100920155014.GH3390@quack.suse.cz> References: <201009161632.59210.arnd@arndb.de> <201009172100.06598.arnd@arndb.de> <20100920105811.GC3390@quack.suse.cz> <201009201313.11526.arnd@arndb.de> <20100920151834.GF3390@quack.suse.cz> <4C978087.7060802@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Jan Kara , Arnd Bergmann , Christoph Hellwig , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org To: "Alexander E. Patrakov" Return-path: Received: from cantor2.suse.de ([195.135.220.15]:50699 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756363Ab0ITPvF (ORCPT ); Mon, 20 Sep 2010 11:51:05 -0400 Content-Disposition: inline In-Reply-To: <4C978087.7060802@gmail.com> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: On Mon 20-09-10 21:40:55, Alexander E. Patrakov wrote: > [I know nothing about linux filesystem code, please disregard this > mail if it is stupid] > > 20.09.2010 21:18, Jan Kara wrote: > > >BKL isn't needed for isofs at all so we can just remove it. Generally, since > >isofs is always mounted read-only, filesystem structure cannot change under us. > > Does your statement also cover the case of read errors on scratched > CD-ROMs (i.e., the driver has successfully read a sector with a > directory once after a lot of strugging, and failed the next time), > or ejects of mounted media? Well, BKL definitely won't help in protecting races triggered by such problems. Also if we fail to read some data, we just bail out with error so data appearing later do not bother us. Similarly once we get hold of some buffer with data, it cannot disappear under us while we hold a reference to it so again we are safe... I don't think these case pose any problem. Honza -- Jan Kara SUSE Labs, CR