From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1946296AbXBIKKg (ORCPT ); Fri, 9 Feb 2007 05:10:36 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1946265AbXBIKKb (ORCPT ); Fri, 9 Feb 2007 05:10:31 -0500 Received: from smtp.osdl.org ([65.172.181.24]:40985 "EHLO smtp.osdl.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1946294AbXBIKJ7 (ORCPT ); Fri, 9 Feb 2007 05:09:59 -0500 Date: Fri, 9 Feb 2007 02:09:54 -0800 From: Andrew Morton To: Nick Piggin Cc: Linux Filesystems , Linux Kernel , Linus Torvalds Subject: Re: [rfc][patch 0/3] a faster buffered write deadlock fix? Message-Id: <20070209020954.4951256e.akpm@linux-foundation.org> In-Reply-To: <20070209095405.GA14398@wotan.suse.de> References: <20070208105437.26443.35653.sendpatchset@linux.site> <20070209004101.3e4a88fc.akpm@linux-foundation.org> <20070209095405.GA14398@wotan.suse.de> X-Mailer: Sylpheed version 2.2.7 (GTK+ 2.8.17; x86_64-unknown-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 9 Feb 2007 10:54:05 +0100 Nick Piggin wrote: > On Fri, Feb 09, 2007 at 12:41:01AM -0800, Andrew Morton wrote: > > On Thu, 8 Feb 2007 14:07:15 +0100 (CET) Nick Piggin wrote: > > > > > So I have finally finished a first slightly-working draft of my new aops > > > op (perform_write) proposal. I would be interested to hear comments about > > > it. Most of my issues and concerns are in the patch headers themselves, > > > so reply to them. > > > > > > The patches are against my latest buffered-write-fix patchset. > > > > What happened with Linus's proposal to instantiate the page as pinned, > > non-uptodate, unlocked and in pagecache while we poke the user address? > > That's still got a deadlock, It does? > and also it doesn't work if we want to lock > the page when performing a minor fault (which I want to fix fault vs > invalidate), It's hard to discuss this without a description of what you want to fix there, and a description of how you plan to fix it. > and also assumes nobody's ->nopage locks the page or > requires any resources that are held by prepare_write (something not > immediately clear to me with the cluster filesystems, at least). The nopage handler is filemap_nopage(). Are there any exceptions to that? > But that all becomes legacy path, so do we really care? Supposing fs > maintainers like perform_write, then after the main ones have implementations > we could switch over to the slow-but-correct prepare_write legacy path. > Or we could leave it, or we could use Linus's slightly-less-buggy scheme... > by that point I expect I'd be sick of arguing about it ;) It's worth "arguing" about. This is write(). What matters more??