From: Nick Piggin Subject: Re: + fs-introduce-write_begin-write_end-and-perform_write-aops.patch added to -mm tree Date: Thu, 14 Jun 2007 01:28:38 +0200 Message-ID: <20070613232838.GB4015@wotan.suse.de> References: <200705292119.l4TLJtAD011726@shell0.pdx.osdl.net> <20070613134005.GA13815@localhost.sw.ru> <20070613114356.GD17547@wotan.suse.de> <1181776021.21924.87.camel@dyn9047017100.beaverton.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: lkml , mark.fasheh@oracle.com, ext4 , Andrew Morton , cmm@us.ibm.com To: Badari Pulavarty Return-path: Received: from ns1.suse.de ([195.135.220.2]:56255 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755321AbXFMX2o (ORCPT ); Wed, 13 Jun 2007 19:28:44 -0400 Content-Disposition: inline In-Reply-To: <1181776021.21924.87.camel@dyn9047017100.beaverton.ibm.com> Sender: linux-ext4-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org On Wed, Jun 13, 2007 at 04:07:01PM -0700, Badari Pulavarty wrote: > On Wed, 2007-06-13 at 13:43 +0200, Nick Piggin wrote: > .. > > > > > 5) ext3_write_end: > > > Before write_begin/write_end patch set we have folowing locking > > > order: > > > stop_journal(handle); > > > unlock_page(page); > > > But now order is oposite: > > > unlock_page(page); > > > stop_journal(handle); > > > Can we got any race condition now? I'm not sure is it actual problem, > > > may be somebody cant describe this. > > > > Can we just change it to the original order? That would seem to be > > safest unless one of the ext3 devs explicitly acks it. > > It would be nice to go back to original order, but its not that > simple with current structure of the code. With Nick's patches > unlock_page() happens in generic_write_end(). journal_stop() > needs to happen after generic_write_end(). :( Well we could use block_write_end? > Mingming, can you take a look at the current & proposed order ? > I ran into bunch of races when I tried to change the order for > ->writepages() support earlier :( OK, it sounds like we probably want to revert to the original order at least for this patchset. If the new order is proven safe then that could be introduced later to simplify things... Thanks, Nick