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 5F1EFC433DF for ; Mon, 6 Jul 2020 14:10:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3EE942073E for ; Mon, 6 Jul 2020 14:10:17 +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="Q7louwU7" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729223AbgGFOKN (ORCPT ); Mon, 6 Jul 2020 10:10:13 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52870 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729121AbgGFOKN (ORCPT ); Mon, 6 Jul 2020 10:10:13 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 47BF9C061755; Mon, 6 Jul 2020 07:10:13 -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=jr5pej1wSJwvDermowQo12UoHtgzyC4iW6ylZEO386k=; b=Q7louwU7AJBdH4Ne2fjJUP4uJO Gp34JEslK4c8hczFMpZByibgLIInVpBTt5Ng3f+MnJ5OmanRP6hil92vM8VT1pFNB10CdyGNtfeRy fBSY1nh4ok1c1gq4A2OXkz4CGNte1TCLB+M2G6moP7j12OPiCWwFHYM6ULoYLAH6fnraGwF5WB6bs cClfugBzi22sYLcItDMJ5oG804iPek4AxSRt4ArnyI9oOacegAY99AcWkZ4ZnDi8C+/barbkcPCkE TwsnDkeIRp60jXXom3TfHeNwKAfv81W/nSWwQ6T2Ptyu4VNdjnIcyiSz4scwe4XrmT4sEKbS/aYx/ HHiqqJYg==; Received: from willy by casper.infradead.org with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1jsRoo-0003s1-56; Mon, 06 Jul 2020 14:10:02 +0000 Date: Mon, 6 Jul 2020 15:10:02 +0100 From: Matthew Wilcox To: Jens Axboe Cc: Kanchan Joshi , viro@zeniv.linux.org.uk, bcrl@kvack.org, hch@infradead.org, Damien.LeMoal@wdc.com, asml.silence@gmail.com, linux-fsdevel@vger.kernel.org, mb@lightnvm.io, linux-kernel@vger.kernel.org, linux-aio@kvack.org, io-uring@vger.kernel.org, linux-block@vger.kernel.org, Selvakumar S , Nitesh Shetty , Javier Gonzalez Subject: Re: [PATCH v3 4/4] io_uring: add support for zone-append Message-ID: <20200706141002.GZ25523@casper.infradead.org> References: <1593974870-18919-1-git-send-email-joshi.k@samsung.com> <1593974870-18919-5-git-send-email-joshi.k@samsung.com> <20200705210947.GW25523@casper.infradead.org> <239ee322-9c38-c838-a5b2-216787ad2197@kernel.dk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <239ee322-9c38-c838-a5b2-216787ad2197@kernel.dk> Sender: io-uring-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org On Sun, Jul 05, 2020 at 03:12:50PM -0600, Jens Axboe wrote: > On 7/5/20 3:09 PM, Matthew Wilcox wrote: > > On Sun, Jul 05, 2020 at 03:00:47PM -0600, Jens Axboe wrote: > >> On 7/5/20 12:47 PM, Kanchan Joshi wrote: > >>> From: Selvakumar S > >>> > >>> For zone-append, block-layer will return zone-relative offset via ret2 > >>> of ki_complete interface. Make changes to collect it, and send to > >>> user-space using cqe->flags. > > I'm surprised you aren't more upset by the abuse of cqe->flags for the > > address. > > Yeah, it's not great either, but we have less leeway there in terms of > how much space is available to pass back extra data. > > > What do you think to my idea of interpreting the user_data as being a > > pointer to somewhere to store the address? Obviously other things > > can be stored after the address in the user_data. > > I don't like that at all, as all other commands just pass user_data > through. This means the application would have to treat this very > differently, and potentially not have a way to store any data for > locating the original command on the user side. I think you misunderstood me. You seem to have thought I meant "use the user_data field to return the address" when I actually meant "interpret the user_data field as a pointer to where userspace wants the address stored".