From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.6 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6096DC433DF for ; Thu, 9 Jul 2020 13:32:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 36B3820672 for ; Thu, 9 Jul 2020 13:32:52 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="MiBl3pGL" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726497AbgGINcw (ORCPT ); Thu, 9 Jul 2020 09:32:52 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37832 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726410AbgGINcv (ORCPT ); Thu, 9 Jul 2020 09:32:51 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 91ECDC08C5CE; Thu, 9 Jul 2020 06:32:51 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=0gGNHKM2ZqkJaYiaW1AZt7LL2IetnqBy8kFTuQiL4bo=; b=MiBl3pGLBwpSRcWZyz1mS/fd2N kjJ3uFquSnFMed6RZRnkiKVo1YzgxY8yEP3Ixuu4t54iAWc6ELxgTFFvVi/7N9pZDGfuug/ymK9d7 VBIDZw/zLA4PhSCql5x3y4vLCkdDKm9BbjwnPS0oInR7JyKJQTqPgFrEh7j75RH/8+4eFJ3aadMM0 QtrtaXPhgetei4O8IWo877ozl1QPEWR51VkR91KYF03EsIrNyJTPzcy7korpcTmV1gZmmyeab/Vko TYnlSXWMQ6+2R5xsOUGp46HdIyp5bq1229BB0/IXXlS369clZOi+Bbu23PYiIRfnHRU6/mD0QJa2I AM7uvYOw==; Received: from willy by casper.infradead.org with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1jtWfR-0000qC-As; Thu, 09 Jul 2020 13:32:49 +0000 Date: Thu, 9 Jul 2020 14:32:49 +0100 From: Matthew Wilcox To: Christoph Hellwig Cc: Jens Axboe , linux-block@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-aio@kvack.org, io-uring@vger.kernel.org, linux-kernel@vger.kernel.org, Kanchan Joshi , Javier Gonzalez Subject: Re: [PATCH 0/2] Remove kiocb ki_complete Message-ID: <20200709133249.GC12769@casper.infradead.org> References: <20200708222637.23046-1-willy@infradead.org> <20200709101705.GA2095@infradead.org> <20200709111036.GA12769@casper.infradead.org> <20200709132611.GA1382@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200709132611.GA1382@infradead.org> Sender: io-uring-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org On Thu, Jul 09, 2020 at 02:26:11PM +0100, Christoph Hellwig wrote: > On Thu, Jul 09, 2020 at 12:10:36PM +0100, Matthew Wilcox wrote: > > On Thu, Jul 09, 2020 at 11:17:05AM +0100, Christoph Hellwig wrote: > > > I really don't like this series at all. If saves a single pointer > > > but introduces a complicated machinery that just doesn't follow any > > > natural flow. And there doesn't seem to be any good reason for it to > > > start with. > > > > Jens doesn't want the kiocb to grow beyond a single cacheline, and we > > want the ability to set the loff_t in userspace for an appending write, > > so the plan was to replace the ki_complete member in kiocb with an > > loff_t __user *ki_posp. > > > > I don't think it's worth worrying about growing kiocb, personally, > > but this seemed like the easiest way to make room for a new pointer. > > The user offset pointer has absolutely no business in the the kiocb > itself - it is a io_uring concept which needs to go into the io_kiocb, > which has 14 bytes left in the last cache line in my build. It would > fit in very well there right next to the result and user pointer. I agree. Jens doesn't.