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=-8.2 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable 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 B4A52C433E1 for ; Fri, 19 Jun 2020 14:18:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9513021556 for ; Fri, 19 Jun 2020 14:18:29 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=kernel-dk.20150623.gappssmtp.com header.i=@kernel-dk.20150623.gappssmtp.com header.b="hidq+qn7" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732901AbgFSOS3 (ORCPT ); Fri, 19 Jun 2020 10:18:29 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49174 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732461AbgFSOS2 (ORCPT ); Fri, 19 Jun 2020 10:18:28 -0400 Received: from mail-pf1-x442.google.com (mail-pf1-x442.google.com [IPv6:2607:f8b0:4864:20::442]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7A74AC06174E for ; Fri, 19 Jun 2020 07:18:27 -0700 (PDT) Received: by mail-pf1-x442.google.com with SMTP id s23so4483579pfh.7 for ; Fri, 19 Jun 2020 07:18:27 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel-dk.20150623.gappssmtp.com; s=20150623; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=9or/nd2d0kK7Srn2OMQLnMS4JaBmTgv5NtC1m4CDz3Y=; b=hidq+qn73oekrZJeQMWvr4WMZb+WfQeaHhkjy+TnzASODcN9o/1ZBvqpqAtEUZxR4U gyg+xm4oXC2LDoBZRsJE1HxWJCN+07pFM5nlU5K9jY+UEq8tHgEE61Zk6Mk89kK8lwAb sDrZdLakvgdwHEsFJaLYxjIadPi+VCV+rIlEENKVvRrAsADkM4n5F8WsRnCWZAGIM73i 9Ql+al+T/hFRQDcZyKztART3ffyxrCy96sT83D94Dk453GQx24udsnLi0orp5BJlodSx sYOUQVm6qBpfacFyXlsS5apBeHo30Y6P3118Od1ODxlyhY26fwlpwHgJN8oC1w5T9JFL f+CQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=9or/nd2d0kK7Srn2OMQLnMS4JaBmTgv5NtC1m4CDz3Y=; b=aXTG9mTxCHUZPCKAOoa+Z2yHdB0whBHnIW7Vlm1I5pBAAlvpKg05G7TNZa5HwzGwvD h9r7ZVfqYB36oaaKPJg9QNYUQRYdQvd27Lo3nXgaoj13IuRC8G2nkhW49mMFHgmxOtrW w9S1zEK4MIAmamLkHgDlsU7zhH/bMkiRjt7hgxQ8m52n686sKrZhHAgRAiaTkUFBeq5j zzzkiGAxzS+1thbcWP2WhJJuMJbX+kw14lZVe6r7wAf3BF1YgSMdTl2qcpRaobl02bRR fARzJnsL/X2vzc5pZO9StnRbiAr3MELaFYYYs6jpXrpBzxXIRl+GWg9rsseuF8wCLi4M 5Tjw== X-Gm-Message-State: AOAM533Fh0l2xc6vW5KPA188Yt1NYEkHupk37u6RgXqfMtqbtimHORQy JyWoFJDeMgs13K2lrGIhxL2pWQ== X-Google-Smtp-Source: ABdhPJyq/7BnpxKFYtTRDKR2zWyWUKbYgkCdtzqo4m2gOrQzccrbLP76ZiUIJDnBffhkSs+UaKQkyg== X-Received: by 2002:a63:d958:: with SMTP id e24mr3366189pgj.348.1592576306944; Fri, 19 Jun 2020 07:18:26 -0700 (PDT) Received: from [192.168.1.188] ([66.219.217.173]) by smtp.gmail.com with ESMTPSA id m15sm5347046pgv.45.2020.06.19.07.18.24 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 19 Jun 2020 07:18:25 -0700 (PDT) Subject: Re: [PATCH 3/3] io_uring: add support for zone-append To: =?UTF-8?Q?Matias_Bj=c3=b8rling?= , "javier.gonz@samsung.com" , Damien Le Moal Cc: Kanchan Joshi , "viro@zeniv.linux.org.uk" , "bcrl@kvack.org" , "linux-fsdevel@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "linux-aio@kvack.org" , "io-uring@vger.kernel.org" , "linux-block@vger.kernel.org" , "selvakuma.s1@samsung.com" , "nj.shetty@samsung.com" References: <1592414619-5646-1-git-send-email-joshi.k@samsung.com> <1592414619-5646-4-git-send-email-joshi.k@samsung.com> <20200618083529.ciifu4chr4vrv2j5@mpHalley.local> <20200618091113.eu2xdp6zmdooy5d2@mpHalley.local> <20200619094149.uaorbger326s6yzz@mpHalley.local> <2ba2079c-9a5d-698a-a8f0-cbd6fdb9a9f0@lightnvm.io> From: Jens Axboe Message-ID: Date: Fri, 19 Jun 2020 08:18:24 -0600 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.8.0 MIME-Version: 1.0 In-Reply-To: <2ba2079c-9a5d-698a-a8f0-cbd6fdb9a9f0@lightnvm.io> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: io-uring-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org On 6/19/20 5:15 AM, Matias Bjørling wrote: > On 19/06/2020 11.41, javier.gonz@samsung.com wrote: >> Jens, >> >> Would you have time to answer a question below in this thread? >> >> On 18.06.2020 11:11, javier.gonz@samsung.com wrote: >>> On 18.06.2020 08:47, Damien Le Moal wrote: >>>> On 2020/06/18 17:35, javier.gonz@samsung.com wrote: >>>>> On 18.06.2020 07:39, Damien Le Moal wrote: >>>>>> On 2020/06/18 2:27, Kanchan Joshi wrote: >>>>>>> From: Selvakumar S >>>>>>> >>>>>>> Introduce three new opcodes for zone-append - >>>>>>> >>>>>>>   IORING_OP_ZONE_APPEND     : non-vectord, similiar to >>>>>>> IORING_OP_WRITE >>>>>>>   IORING_OP_ZONE_APPENDV    : vectored, similar to IORING_OP_WRITEV >>>>>>>   IORING_OP_ZONE_APPEND_FIXED : append using fixed-buffers >>>>>>> >>>>>>> Repurpose cqe->flags to return zone-relative offset. >>>>>>> >>>>>>> Signed-off-by: SelvaKumar S >>>>>>> Signed-off-by: Kanchan Joshi >>>>>>> Signed-off-by: Nitesh Shetty >>>>>>> Signed-off-by: Javier Gonzalez >>>>>>> --- >>>>>>> fs/io_uring.c                 | 72 >>>>>>> +++++++++++++++++++++++++++++++++++++++++-- >>>>>>> include/uapi/linux/io_uring.h |  8 ++++- >>>>>>> 2 files changed, 77 insertions(+), 3 deletions(-) >>>>>>> >>>>>>> diff --git a/fs/io_uring.c b/fs/io_uring.c >>>>>>> index 155f3d8..c14c873 100644 >>>>>>> --- a/fs/io_uring.c >>>>>>> +++ b/fs/io_uring.c >>>>>>> @@ -649,6 +649,10 @@ struct io_kiocb { >>>>>>>     unsigned long        fsize; >>>>>>>     u64            user_data; >>>>>>>     u32            result; >>>>>>> +#ifdef CONFIG_BLK_DEV_ZONED >>>>>>> +    /* zone-relative offset for append, in bytes */ >>>>>>> +    u32            append_offset; >>>>>> >>>>>> this can overflow. u64 is needed. >>>>> >>>>> We chose to do it this way to start with because struct io_uring_cqe >>>>> only has space for u32 when we reuse the flags. >>>>> >>>>> We can of course create a new cqe structure, but that will come with >>>>> larger changes to io_uring for supporting append. >>>>> >>>>> Do you believe this is a better approach? >>>> >>>> The problem is that zone size are 32 bits in the kernel, as a number >>>> of sectors. >>>> So any device that has a zone size smaller or equal to 2^31 512B >>>> sectors can be >>>> accepted. Using a zone relative offset in bytes for returning zone >>>> append result >>>> is OK-ish, but to match the kernel supported range of possible zone >>>> size, you >>>> need 31+9 bits... 32 does not cut it. >>> >>> Agree. Our initial assumption was that u32 would cover current zone size >>> requirements, but if this is a no-go, we will take the longer path. >> >> Converting to u64 will require a new version of io_uring_cqe, where we >> extend at least 32 bits. I believe this will need a whole new allocation >> and probably ioctl(). >> >> Is this an acceptable change for you? We will of course add support for >> liburing when we agree on the right way to do this. > > I took a quick look at the code. No expert, but why not use the existing > userdata variable? use the lowest bits (40 bits) for the Zone Starting > LBA, and use the highest (24 bits) as index into the completion data > structure? > > If you want to pass the memory address (same as what fio does) for the > data structure used for completion, one may also play some tricks by > using a relative memory address to the data structure. For example, the > x86_64 architecture uses 48 address bits for its memory addresses. With > 24 bit, one can allocate the completion entries in a 32MB memory range, > and then use base_address + index to get back to the completion data > structure specified in the sqe. For any current request, sqe->user_data is just provided back as cqe->user_data. This would make these requests behave differently from everything else in that sense, which seems very confusing to me if I was an application writer. But generally I do agree with you, there are lots of ways to make < 64-bit work as a tag without losing anything or having to jump through hoops to do so. The lack of consistency introduced by having zone append work differently is ugly, though. -- Jens Axboe