From: Jan Kara Subject: Re: [PATCH 2/2] [PATCH] xfs: Close race between direct IO and xfs_break_layouts() Date: Wed, 8 Aug 2018 10:53:39 +0200 Message-ID: <20180808085339.GD15413@quack2.suse.cz> References: <153367989755.37314.6889218648604435494.stgit@djiang5-desk3.ch.intel.com> <153367990333.37314.16218849614019392916.stgit@djiang5-desk3.ch.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: lczerner-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, jack-AlSwsSmVLrQ@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, tytso-3s7WtUTddSA@public.gmane.org, linux-ext4-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, hch-jcswGhMUV9g@public.gmane.org To: Dave Jiang Return-path: Content-Disposition: inline In-Reply-To: <153367990333.37314.16218849614019392916.stgit-Cxk7aZI4ujnJARH06PadV2t3HXsI98Cx0E9HWUfgJXw@public.gmane.org> 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 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. Honza -- Jan Kara SUSE Labs, CR