From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from ipmail07.adl2.internode.on.net ([150.101.137.131]:52024 "EHLO ipmail07.adl2.internode.on.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752405AbdKTU0K (ORCPT ); Mon, 20 Nov 2017 15:26:10 -0500 Date: Tue, 21 Nov 2017 07:26:06 +1100 From: Dave Chinner Subject: Re: [PATCH v2] iomap: report collisions between directio and buffered writes to userspace Message-ID: <20171120202606.GN5858@dastard> References: <20171117193925.GM5119@magnolia> <20171120161829.GA25991@bombadil.infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20171120161829.GA25991@bombadil.infradead.org> Sender: linux-xfs-owner@vger.kernel.org List-ID: List-Id: xfs To: Matthew Wilcox Cc: "Darrick J. Wong" , xfs , Ilya Dryomov , linux-fsdevel , Brian Foster , holger@applied-asynchrony.com, linux-ext4 , linux-btrfs On Mon, Nov 20, 2017 at 08:18:29AM -0800, Matthew Wilcox wrote: > On Fri, Nov 17, 2017 at 11:39:25AM -0800, Darrick J. Wong wrote: > > If two programs simultaneously try to write to the same part of a file > > via direct IO and buffered IO, there's a chance that the post-diowrite > > pagecache invalidation will fail on the dirty page. When this happens, > > the dio write succeeded, which means that the page cache is no longer > > coherent with the disk! > > This seems like a good opportunity to talk about what I've been working > on for solving this problem. The XArray is going to introduce a set > of entries which can be stored to locations in the page cache that I'm > calling 'wait entries'. What's this XArray thing you speak of? Cheers, Dave. -- Dave Chinner david@fromorbit.com