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 DBFA0C433DF for ; Fri, 19 Jun 2020 16:16:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B4DB121707 for ; Fri, 19 Jun 2020 16:16:38 +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="ofA1AzoF" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2390563AbgFSQQh (ORCPT ); Fri, 19 Jun 2020 12:16:37 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56032 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388905AbgFSPDD (ORCPT ); Fri, 19 Jun 2020 11:03:03 -0400 Received: from mail-pl1-x642.google.com (mail-pl1-x642.google.com [IPv6:2607:f8b0:4864:20::642]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BB7CCC0613EE for ; Fri, 19 Jun 2020 08:03:03 -0700 (PDT) Received: by mail-pl1-x642.google.com with SMTP id j4so4032824plk.3 for ; Fri, 19 Jun 2020 08:03:03 -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=+LnqhKjbJEUfkGCu1m/2g+LppzzVyXYZg47hg3uhOd0=; b=ofA1AzoFRZ4MiXl9EfIriR7S7EEDw0MZ3OcZfvwiug8/LxQyXqMBhQNc2t5MB4T+MP 1cBRaqv+Adlb0QGtdhesz8tTqpZT/UwhaqJF283gfDbIcx+/t4EHoPX+zzrLRht1fkO7 /eKNTyjuZrSpP6Fa3jjLRB/oeFGV5+We667m5i+qOfK6jAKzhPFN4LZ7Aea1U3BBlq5y r3hyxLdpzzZk0u/q8g8dw5E33HSygPnaxl4wZAuLkwk+LRt7Wwyb1K0YLAGrwQ694bzP HPTAc7nLX+UjyYmLYhVbNDjEQQ2xyaNr+kVwkozO+qmrizxiTxaohrM6KVBv8BSzuh7G rPbw== 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=+LnqhKjbJEUfkGCu1m/2g+LppzzVyXYZg47hg3uhOd0=; b=SWNGhGiw4Zbe3dQ6Re9wHq24AXbnikJ/S5/zUst4+0oGp7dloZUpN2iDunfjkOZlxR ifb0r5xoHya0gUMtvqNW8qdVdggwgfAttGPl3lUK3d+Xgxu944AhQHsg/ffhP8qwNJcE XnoCYBA/4XPMNacBdyws9WdDQy+Yt0r/bbbk0Ot801acf+CwUXoH+eHTno8raQiVlO/Y MdqcAAzGIR8NUWDdjozuRGCSMvRyeKMQLuuKE5XTglsq2AIf3ubPFHRAKyJk3AcRVD+V 9MrndhlhmsC/CUWPl2WpGcwr0/kakJMFhRhISe14WKcjXYotOQClrBae/pfon08X6m3F K5Tg== X-Gm-Message-State: AOAM5314+Ym7UPz99OVOAuen1phovuvIjjqcNETHIXxtCx/TdxWeMC3K KUmgxjlC/A40cXAraxEG6yq9Og== X-Google-Smtp-Source: ABdhPJzxl6m4GmVs1yhzQxBYGEsuQSldHuD3SkC6vlqhKC8YiMob8skih3KD4PgAX5KiZe8FPTwA+g== X-Received: by 2002:a17:902:d392:: with SMTP id e18mr8544615pld.295.1592578983045; Fri, 19 Jun 2020 08:03:03 -0700 (PDT) Received: from [192.168.1.188] ([66.219.217.173]) by smtp.gmail.com with ESMTPSA id q65sm6281283pfc.155.2020.06.19.08.02.59 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 19 Jun 2020 08:03:01 -0700 (PDT) Subject: Re: [PATCH 3/3] io_uring: add support for zone-append To: Pavel Begunkov , "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> <31f1c27e-4a3d-a411-3d3b-f88a2d92ce7b@kernel.dk> <24297973-82ad-a629-e5f5-38a5b12db83a@gmail.com> From: Jens Axboe Message-ID: Date: Fri, 19 Jun 2020 09:02:58 -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: <24297973-82ad-a629-e5f5-38a5b12db83a@gmail.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: io-uring-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org On 6/19/20 8:59 AM, Pavel Begunkov wrote: > On 19/06/2020 17:15, Jens Axboe wrote: >> On 6/19/20 3:41 AM, 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. >> >> If you need 64-bit of return value, then it's not going to work. Even >> with the existing patches, reusing cqe->flags isn't going to fly, as >> it would conflict with eg doing zone append writes with automatic >> buffer selection. > > Buffer selection is for reads/recv kind of requests, but appends > are writes. In theory they can co-exist using cqe->flags. Yeah good point, since it's just writes, doesn't matter. But the other point still stands, it could potentially conflict with other flags, but I guess only to the extent where both flags would need extra storage in ->flags. So not a huge concern imho. -- Jens Axboe