From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dave Jiang Subject: Re: [PATCH 2/2] [PATCH] xfs: Close race between direct IO and xfs_break_layouts() Date: Wed, 8 Aug 2018 08:47:39 -0700 Message-ID: <97fcc79a-2d2e-b2ba-562a-76533fe3696f@intel.com> References: <153367989755.37314.6889218648604435494.stgit@djiang5-desk3.ch.intel.com> <153367990333.37314.16218849614019392916.stgit@djiang5-desk3.ch.intel.com> <20180808085339.GD15413@quack2.suse.cz> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: tytso-3s7WtUTddSA@public.gmane.org, linux-nvdimm-hn68Rpc1hR1g9hUCZPvPmw@public.gmane.org, darrick.wong-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org, david-FqsqvQoI3Ljby3iVrkZq2A@public.gmane.org, linux-xfs-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, zwisler-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, linux-fsdevel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, lczerner-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, linux-ext4-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, hch-jcswGhMUV9g@public.gmane.org To: Jan Kara Return-path: In-Reply-To: <20180808085339.GD15413-4I4JzKEfoa/jFM9bn6wA6Q@public.gmane.org> Content-Language: en-US List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: linux-nvdimm-bounces-hn68Rpc1hR1g9hUCZPvPmw@public.gmane.org Sender: "Linux-nvdimm" List-Id: linux-ext4.vger.kernel.org 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 >