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=-2.2 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 B65F3C2D0CE for ; Wed, 22 Jan 2020 01:56:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8B1F92253D for ; Wed, 22 Jan 2020 01:56:03 +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="xg6QbYvQ" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728901AbgAVB4C (ORCPT ); Tue, 21 Jan 2020 20:56:02 -0500 Received: from mail-pj1-f67.google.com ([209.85.216.67]:40828 "EHLO mail-pj1-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726584AbgAVB4C (ORCPT ); Tue, 21 Jan 2020 20:56:02 -0500 Received: by mail-pj1-f67.google.com with SMTP id bg7so2574215pjb.5 for ; Tue, 21 Jan 2020 17:56:02 -0800 (PST) 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=ughD8EkfzZ2MT9taNPpfqufT1vIfrbzj2d5lhoDdcCs=; b=xg6QbYvQI8Lcp3eyVvMHPQjo5nOSDbFcfnYJPf7c4tc4M68KNnggamZ05z0iPvQ6Tz oZRfs8nHGynhSz/3eOxGfNmxZM1kwjPwZwvQV2BGqUP3i/OZo/PI2BQHgL+MMAalMie6 LjiGfByiRHSh1xSWJ8xeXBZTYdXmFzIPpSFaFRnEHrbpE52buXvhuTzBMFxHfcmem7Cz n8GPqQGJ4O0dZ/1r7DALHyfTy+h/WEa1BsmK3bmIXkdE9kzNXBVnsy+eeEhjeh0PoAuh g8gm++dFXs9PEqIsVEDP+LLsRPzklv/oDqNoLtix0WwNnlEp+ulMD8/33Mib1fc/qlJ/ NMzQ== 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=ughD8EkfzZ2MT9taNPpfqufT1vIfrbzj2d5lhoDdcCs=; b=WIVEir8ha/DNWzuTnd3bgrHruy8elBfJwHAjg/z+GKjg/ucEQKVahZQKWaGbJuC8p3 JaOZ29nbzFWzEjqIj9fTDOg04JS4qE8gxogqncwi7xec5aiE437W7U96FIRDQI4HJCj9 g/9YXiNpd+Hc0vwubc3W1d4weld4KmbCM0cp1GYGg/ocpkekSNfksSG5+caHdINmDUHM Bt/biP48j6F2fzXheRiuvv3wJJfNnVfdSkaMghfJ4l7TZnuAIoCenNHenTAsUrzCapdL YkU/kzTsnoq3FCpcw8iI3GbiYrNJkaZa2J12PGQStJ8HQ00pUZjqAaSgidAl9C5yqBnb jTfg== X-Gm-Message-State: APjAAAUy4CIVglAzW8IHdT0K1rIflbH8LGopDzKf6hUno/DyYI2nCV34 Hmj/0D6rCwDCY8Td7QqXZi4pBQ== X-Google-Smtp-Source: APXvYqwa8UKyJwV77XoBvUAWxuZJ8PJJ53EHBLJTOfOLb2DJYwRJN7ZRS5CUg7lkEkhIx6E7ZnhWHg== X-Received: by 2002:a17:902:9f98:: with SMTP id g24mr8564576plq.325.1579658161685; Tue, 21 Jan 2020 17:56:01 -0800 (PST) Received: from [192.168.1.188] ([66.219.217.145]) by smtp.gmail.com with ESMTPSA id 3sm678609pjg.27.2020.01.21.17.56.00 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 21 Jan 2020 17:56:01 -0800 (PST) Subject: Re: [POC RFC 0/3] splice(2) support for io_uring To: Pavel Begunkov , io-uring@vger.kernel.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org Cc: Alexander Viro References: From: Jens Axboe Message-ID: <63119dd6-7668-a7bc-ea24-1db4909762bb@kernel.dk> Date: Tue, 21 Jan 2020 18:55:59 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.4.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 1/21/20 5:05 PM, Pavel Begunkov wrote: > It works well for basic cases, but there is still work to be done. E.g. > it misses @hash_reg_file checks for the second (output) file. Anyway, > there are some questions I want to discuss: > > - why sqe->len is __u32? Splice uses size_t, and I think it's better > to have something wider (e.g. u64) for fututre use. That's the story > behind added sqe->splice_len. IO operations in Linux generally are INT_MAX, so the u32 is plenty big. That's why I chose it. For this specifically, if you look at splice: if (unlikely(len > MAX_RW_COUNT)) len = MAX_RW_COUNT; so anything larger is truncated anyway. > - it requires 2 fds, and it's painful. Currently file managing is done > by common path (e.g. io_req_set_file(), __io_req_aux_free()). I'm > thinking to make each opcode function handle file grabbing/putting > themself with some helpers, as it's done in the patch for splice's > out-file. > 1. Opcode handler knows, whether it have/needs a file, and thus > doesn't need extra checks done in common path. > 2. It will be more consistent with splice. > Objections? Ideas? Sounds reasonable to me, but always easier to judge in patch form :-) > - do we need offset pointers with fallback to file->f_pos? Or is it > enough to have offset value. Jens, I remember you added the first > option somewhere, could you tell the reasoning? I recently added support for -1/cur position, which splice also uses. So you should be fine with that. -- Jens Axboe