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 C0E3EC32771 for ; Sun, 19 Jan 2020 01:57:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 91A1B24697 for ; Sun, 19 Jan 2020 01:57:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727106AbgASB5N (ORCPT ); Sat, 18 Jan 2020 20:57:13 -0500 Received: from szxga04-in.huawei.com ([45.249.212.190]:9658 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1727083AbgASB5N (ORCPT ); Sat, 18 Jan 2020 20:57:13 -0500 Received: from DGGEMS411-HUB.china.huawei.com (unknown [172.30.72.60]) by Forcepoint Email with ESMTP id 40710B6CE2308EE686D5; Sun, 19 Jan 2020 09:57:11 +0800 (CST) Received: from [127.0.0.1] (10.173.220.96) by DGGEMS411-HUB.china.huawei.com (10.3.19.211) with Microsoft SMTP Server id 14.3.439.0; Sun, 19 Jan 2020 09:57:05 +0800 Subject: Re: [RFC] iomap: fix race between readahead and direct write To: Matthew Wilcox CC: , , , , , , , References: <20200116063601.39201-1-yukuai3@huawei.com> <20200118230826.GA5583@bombadil.infradead.org> <20200119014213.GA16943@bombadil.infradead.org> From: "yukuai (C)" Message-ID: <857fa4e7-c529-40cf-9916-151d91e815c4@huawei.com> Date: Sun, 19 Jan 2020 09:57:03 +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: <20200119014213.GA16943@bombadil.infradead.org> Content-Type: text/plain; charset="gbk"; format=flowed Content-Transfer-Encoding: 8bit X-Originating-IP: [10.173.220.96] X-CFilter-Loop: Reflected Sender: linux-xfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-xfs@vger.kernel.org On 2020/1/19 9:42, Matthew Wilcox wrote: > Did you read my patch series? The current code allocates pages, > but does not put them in the page cache until after iomap is called. > My patch series changes that to put the pages in the page cache as soon > as they're allocated, and before iomap is called. The current code to determin if page need to be allocated: page = xa_load(&mapping->i_pages, page_offset); if (page && !xa_is_value(page)) { /* ©®* Page already present? Kick off the current batch of ©®* contiguous pages before continuing with the next ©®* batch. ©®*/ if (nr_pages) read_pages(mapping, filp, &page_pool, nr_pages, gfp_mask); nr_pages = 0; continue; } page = __page_cache_alloc(gfp_mask); if (!page) break; Page will be allocated if the page do not exist in page cache. And I don't see your patch series change that. Or am I missing something? ThanksŁˇ Yu Kuai