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=-2.3 required=3.0 tests=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 22203C33CB6 for ; Fri, 17 Jan 2020 09:39:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id F331520730 for ; Fri, 17 Jan 2020 09:39:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729157AbgAQJjT (ORCPT ); Fri, 17 Jan 2020 04:39:19 -0500 Received: from szxga06-in.huawei.com ([45.249.212.32]:40380 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726596AbgAQJjQ (ORCPT ); Fri, 17 Jan 2020 04:39:16 -0500 Received: from DGGEMS402-HUB.china.huawei.com (unknown [172.30.72.59]) by Forcepoint Email with ESMTP id DF6A24FE3E33B497B782; Fri, 17 Jan 2020 17:39:13 +0800 (CST) Received: from [127.0.0.1] (10.173.220.96) by DGGEMS402-HUB.china.huawei.com (10.3.19.202) with Microsoft SMTP Server id 14.3.439.0; Fri, 17 Jan 2020 17:39:04 +0800 Subject: Re: [RFC] iomap: fix race between readahead and direct write To: Jan Kara CC: , , , , , , , References: <20200116063601.39201-1-yukuai3@huawei.com> <20200116153206.GF8446@quack2.suse.cz> From: "yukuai (C)" Message-ID: Date: Fri, 17 Jan 2020 17:39:03 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <20200116153206.GF8446@quack2.suse.cz> Content-Type: text/plain; charset="gbk"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [10.173.220.96] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2020/1/16 23:32, Jan Kara wrote: > Thanks for the report and the patch. But the data integrity when mixing > buffered and direct IO like this is best effort only. We definitely do not > want to sacrifice performance of common cases or code complexity to make > cases like this work reliably. In the patch, the only thing that is diffrent is that iomap_begin() will be called for each page. However, it seems the performance in sequential read didn't get worse. Is there a specific case that the performance will get worse? Thanks! Yu Kuai!