From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mga04.intel.com ([192.55.52.120]:62151 "EHLO mga04.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727108AbeHHSIE (ORCPT ); Wed, 8 Aug 2018 14:08:04 -0400 Subject: Re: [PATCH 2/2] [PATCH] xfs: Close race between direct IO and xfs_break_layouts() To: Jan Kara Cc: tytso@mit.edu, darrick.wong@oracle.com, zwisler@kernel.org, linux-nvdimm@lists.01.org, david@fromorbit.com, linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, lczerner@redhat.com, linux-ext4@vger.kernel.org, hch@lst.de References: <153367989755.37314.6889218648604435494.stgit@djiang5-desk3.ch.intel.com> <153367990333.37314.16218849614019392916.stgit@djiang5-desk3.ch.intel.com> <20180808085339.GD15413@quack2.suse.cz> From: Dave Jiang Message-ID: <97fcc79a-2d2e-b2ba-562a-76533fe3696f@intel.com> Date: Wed, 8 Aug 2018 08:47:39 -0700 MIME-Version: 1.0 In-Reply-To: <20180808085339.GD15413@quack2.suse.cz> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-fsdevel-owner@vger.kernel.org List-ID: On 08/08/2018 01:53 AM, Jan Kara wrote: > On Tue 07-08-18 15:11:43, Dave Jiang wrote: >> This patch is the duplicate of ross's fix for ext4 for xfs. >> >> If the refcount of a page is lowered between the time that it is returned >> by dax_busy_page() and when the refcount is again checked in >> xfs_break_layouts() => ___wait_var_event(), the waiting function >> xfs_wait_dax_page() will never be called. This means that >> xfs_break_layouts() will still have 'retry' set to false, so we'll stop >> looping and never check the refcount of other pages in this inode. >> >> Instead, always continue looping as long as dax_layout_busy_page() gives us >> a page which it found with an elevated refcount. >> >> Signed-off-by: Dave Jiang > > The patch looks good to me. You can add: > > Reviewed-by: Jan Kara > > Just one minor nit below: > >> @@ -746,9 +744,10 @@ xfs_break_dax_layouts( >> if (!page) >> return 0; >> >> + *did_unlock = true; > > I think it would be more understandable to name the argument of > xfs_break_dax_layouts() as 'retry' instead of 'did_unlock' as it's not > about unlocking anymore. Thanks for the review Jan! I will change. I was trying to decide between less code change vs more clear definition. :) > > Honza >