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=-6.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED autolearn=ham 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 F28D5C5ACCC for ; Wed, 17 Oct 2018 01:30:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A3C92214C4 for ; Wed, 17 Oct 2018 01:30:27 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A3C92214C4 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=huawei.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727074AbeJQJXh (ORCPT ); Wed, 17 Oct 2018 05:23:37 -0400 Received: from szxga04-in.huawei.com ([45.249.212.190]:14085 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726936AbeJQJXg (ORCPT ); Wed, 17 Oct 2018 05:23:36 -0400 Received: from DGGEMS404-HUB.china.huawei.com (unknown [172.30.72.60]) by Forcepoint Email with ESMTP id 3CFDB17BB7B88; Wed, 17 Oct 2018 09:30:21 +0800 (CST) Received: from [127.0.0.1] (10.134.22.195) by DGGEMS404-HUB.china.huawei.com (10.3.19.204) with Microsoft SMTP Server id 14.3.399.0; Wed, 17 Oct 2018 09:30:13 +0800 Subject: Re: [f2fs-dev] [PATCH] f2fs: clear cold data flag if IO is not counted To: Jaegeuk Kim CC: , References: <20181010212217.52289-1-jaegeuk@kernel.org> <3f08031e-d195-5bc1-67e1-f3b6eab3506b@huawei.com> <20181015230807.GC1296@jaegeuk-macbookpro.roam.corp.google.com> <405b1521-cbfb-9f09-0d16-ae837b756cbb@huawei.com> <20181016031052.GA19956@jaegeuk-macbookpro.roam.corp.google.com> From: Chao Yu Message-ID: Date: Wed, 17 Oct 2018 09:30:12 +0800 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <20181016031052.GA19956@jaegeuk-macbookpro.roam.corp.google.com> Content-Type: text/plain; charset="windows-1252" Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.134.22.195] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2018/10/16 11:10, Jaegeuk Kim wrote: > On 10/16, Chao Yu wrote: >> On 2018/10/16 7:08, Jaegeuk Kim wrote: >>> On 10/15, Chao Yu wrote: >>>> On 2018/10/11 5:22, Jaegeuk Kim wrote: >>>>> If we clear the cold data flag out of the writeback flow, we can miscount >>>>> -1 by end_io. >>>> >>>> I didn't get it, which count do you mean? >>> >>> It's the number of dirty pages. >>> >>> Balancing F2FS Async: >>> - IO (CP: 1, Data: -1, Flush: ( 0 0 1), Discard: ( 0 129304)) cmd: 0 undiscard: 0 Better to add such info in commit message. :) >>> >> >> So I guess the race should be: >> >> GC thread: IRQ >> - move_data_page() >> - set_page_dirty() >> - clear_cold_data() >> - f2fs_write_end_io() >> - type = WB_DATA_TYPE(page); >> here, we get wrong type >> - dec_page_count(sbi, type); >> - f2fs_wait_on_page_writeback() >> >> How about relocate wait_writeback & set_page_dirty to avoid above race: > > Well, wait_on_stable_page() doesn't guarantee its end_io. So, I'm not sure > this is the only case. Yes, you're right, I missed that case. Can you use git-revert to generate the patch? so we can remain original commit info for better backward tracking. How do you think pick up original patch I submitted: https://lkml.org/lkml/2018/7/27/415 Thanks, > >> >> move_data_page() >> >> retry: >> f2fs_wait_on_page_writeback(page, DATA, true); >> set_page_dirty(page); >> >> Thanks, >> >>>> >>>> Thanks, >>>> >>>>> >>>>> Signed-off-by: Jaegeuk Kim >>>>> --- >>>>> fs/f2fs/data.c | 4 ---- >>>>> 1 file changed, 4 deletions(-) >>>>> >>>>> diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c >>>>> index 29a9d3b8f709..4102799b5558 100644 >>>>> --- a/fs/f2fs/data.c >>>>> +++ b/fs/f2fs/data.c >>>>> @@ -2636,10 +2636,6 @@ static int f2fs_set_data_page_dirty(struct page *page) >>>>> if (!PageUptodate(page)) >>>>> SetPageUptodate(page); >>>>> >>>>> - /* don't remain PG_checked flag which was set during GC */ >>>>> - if (is_cold_data(page)) >>>>> - clear_cold_data(page); >>>>> - >>>>> if (f2fs_is_atomic_file(inode) && !f2fs_is_commit_atomic_write(inode)) { >>>>> if (!IS_ATOMIC_WRITTEN_PAGE(page)) { >>>>> f2fs_register_inmem_page(inode, page); >>>>> >>> >>> . >>> > > . >