Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751795AbdIKMIF (ORCPT ); Mon, 11 Sep 2017 08:08:05 -0400 Received: from bombadil.infradead.org ([65.50.211.133]:58179 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750965AbdIKMID (ORCPT ); Mon, 11 Sep 2017 08:08:03 -0400 Date: Mon, 11 Sep 2017 05:07:57 -0700 From: Christoph Hellwig To: Al Viro Cc: Dave Chinner , Dave Jones , "Darrick J. Wong" , Linux Kernel , linux-xfs@vger.kernel.org Subject: Re: iov_iter_pipe warning. Message-ID: <20170911120757.GA29476@infradead.org> References: <20170829042542.GO4757@magnolia> <20170906200337.b5wj3gpfebliindw@codemonkey.org.uk> <20170906234617.GW17782@dastard> <20170908010441.GZ5426@ZenIV.linux.org.uk> <20170910010756.hnmb233ch7pmnrlx@codemonkey.org.uk> <20170910025712.GC5426@ZenIV.linux.org.uk> <20170910211110.GM17782@dastard> <20170910211907.GF5426@ZenIV.linux.org.uk> <20170910220814.GN17782@dastard> <20170910230723.GG5426@ZenIV.linux.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170910230723.GG5426@ZenIV.linux.org.uk> User-Agent: Mutt/1.8.3 (2017-05-23) X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 589 Lines: 11 On Mon, Sep 11, 2017 at 12:07:23AM +0100, Al Viro wrote: > BTW, another problem I see there is that iomap_dio_actor() should *NOT* > assume that do-while loop in there will always manage to shove 'length' > bytes out in case of success. That is simply not true for pipe-backed > destination. And I'm not sure if outright failures halfway through > are handled correctly. What does it need a copy of dio->submit.iter for, > anyway? Why not work with dio->submit.iter directly? > -- So that we only walk the pagetables and pin down the pages that we can actually use in this iteration.