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=-11.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 1FE7AC5517A for ; Thu, 12 Nov 2020 06:57:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C630B208FE for ; Thu, 12 Nov 2020 06:57:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726827AbgKLG5f (ORCPT ); Thu, 12 Nov 2020 01:57:35 -0500 Received: from szxga05-in.huawei.com ([45.249.212.191]:8067 "EHLO szxga05-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725898AbgKLG53 (ORCPT ); Thu, 12 Nov 2020 01:57:29 -0500 Received: from DGGEMS401-HUB.china.huawei.com (unknown [172.30.72.60]) by szxga05-in.huawei.com (SkyGuard) with ESMTP id 4CWspy39nHzLxcb; Thu, 12 Nov 2020 14:57:14 +0800 (CST) Received: from [10.136.114.67] (10.136.114.67) by smtp.huawei.com (10.3.19.201) with Microsoft SMTP Server (TLS) id 14.3.487.0; Thu, 12 Nov 2020 14:57:22 +0800 Subject: Re: [f2fs-dev] [PATCH v3] f2fs: avoid race condition for shinker count To: Jaegeuk Kim , , , CC: Light Hsieh References: <20201109170012.2129411-1-jaegeuk@kernel.org> <20201112053414.GB3826485@google.com> <20201112054051.GA4092972@google.com> From: Chao Yu Message-ID: <4aae85c2-1829-06c0-8fd1-4148100dc0b9@huawei.com> Date: Thu, 12 Nov 2020 14:57:22 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <20201112054051.GA4092972@google.com> Content-Type: text/plain; charset="windows-1252"; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.136.114.67] X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2020/11/12 13:40, Jaegeuk Kim wrote: > Light reported sometimes shinker gets nat_cnt < dirty_nat_cnt resulting in > wrong do_shinker work. Let's avoid to get stale data by using nat_tree_lock. > > Reported-by: Light Hsieh > Signed-off-by: Jaegeuk Kim > --- > v3: > - fix to use NM_I(sbi) > > fs/f2fs/shrinker.c | 6 +++++- > 1 file changed, 5 insertions(+), 1 deletion(-) > > diff --git a/fs/f2fs/shrinker.c b/fs/f2fs/shrinker.c > index d66de5999a26..555712ba06d8 100644 > --- a/fs/f2fs/shrinker.c > +++ b/fs/f2fs/shrinker.c > @@ -18,7 +18,11 @@ static unsigned int shrinker_run_no; > > static unsigned long __count_nat_entries(struct f2fs_sb_info *sbi) > { > - long count = NM_I(sbi)->nat_cnt - NM_I(sbi)->dirty_nat_cnt; > + long count; > + > + down_read(&NM_I(sbi)->nat_tree_lock); > + count = NM_I(sbi)->nat_cnt - NM_I(sbi)->dirty_nat_cnt; > + up_read(&NM_I(sbi)->nat_tree_lock); > > return count > 0 ? count : 0; Minor thing, Just return count is enough? since count should never be smaller than 0. Anyway, Reviewed-by: Chao Yu Thanks, Thanks, > } >