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=-8.7 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,USER_AGENT_MUTT 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 E1E40C43381 for ; Fri, 22 Feb 2019 02:41:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A2C4120836 for ; Fri, 22 Feb 2019 02:41:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1550803262; bh=zgZODAaN3JFe/+ySn9/5dnZavkUPHoDISxeUU0mz/Vs=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=JKkPdiOUtjw/qWY9ssgeleiFc7XatO/Ki6NmhsnDerSd+FhNuc+uy56R828f7QG3n sMcITMsm2Gqac5NuRurJdlvl3QyeHO305Dw1MJhuuzM5duoeJZ/lxjvdVaHYndd4p5 oBWqjRQg0U7OrWTGmyOt/c+h62Cx6C1fXQruofl8= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726773AbfBVClB (ORCPT ); Thu, 21 Feb 2019 21:41:01 -0500 Received: from mail.kernel.org ([198.145.29.99]:58716 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726247AbfBVClA (ORCPT ); Thu, 21 Feb 2019 21:41:00 -0500 Received: from localhost (unknown [104.132.1.80]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 555CA207E0; Fri, 22 Feb 2019 02:40:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1550803259; bh=zgZODAaN3JFe/+ySn9/5dnZavkUPHoDISxeUU0mz/Vs=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=LTItYop3fBCrD+rGkddHl2Esidl1U5F0vvGK319u7Ypk43fpUet41JX+OX4Jn3HGv vH61XT7eHmp7TS0E10HCoc1MFzqMWEUdkLsu/T9vR09gjVtfLXrI3wiZT1jei2CYPK 6qUEK5RBIEqopBCmu7wyIT4MXPaG1CFgO8fcQwTE= Date: Thu, 21 Feb 2019 18:40:58 -0800 From: Jaegeuk Kim To: Chao Yu Cc: linux-kernel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net Subject: Re: [f2fs-dev] [PATCH] f2fs: don't clear CP_QUOTA_NEED_FSCK_FLAG Message-ID: <20190222024058.GA6093@jaegeuk-macbookpro.roam.corp.google.com> References: <20190212023343.52215-1-jaegeuk@kernel.org> <20190216045530.GA57019@jaegeuk-macbookpro.roam.corp.google.com> <29a4fd24-6340-41df-7199-6e89b70c6341@huawei.com> <20190220070855.GA91331@jaegeuk-macbookpro.roam.corp.google.com> <7580aa2e-b2eb-a686-a19d-4e82a713944a@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <7580aa2e-b2eb-a686-a19d-4e82a713944a@huawei.com> User-Agent: Mutt/1.8.2 (2017-04-18) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 02/20, Chao Yu wrote: > On 2019/2/20 15:25, Chao Yu wrote: > > On 2019/2/20 15:08, Jaegeuk Kim wrote: > >> On 02/18, Chao Yu wrote: > >>> On 2019/2/16 12:55, Jaegeuk Kim wrote: > >>>> On 02/13, Chao Yu wrote: > >>>>> On 2019/2/12 10:33, Jaegeuk Kim wrote: > >>>>>> If we met this once, let fsck.f2fs clear this only. > >>>>>> Note that, this addresses all the subtle fault injection test. > >>>>>> > >>>>>> Signed-off-by: Jaegeuk Kim > >>>>>> --- > >>>>>> fs/f2fs/checkpoint.c | 2 -- > >>>>>> 1 file changed, 2 deletions(-) > >>>>>> > >>>>>> diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c > >>>>>> index 03fea4efd64b..10a3ada28715 100644 > >>>>>> --- a/fs/f2fs/checkpoint.c > >>>>>> +++ b/fs/f2fs/checkpoint.c > >>>>>> @@ -1267,8 +1267,6 @@ static void update_ckpt_flags(struct f2fs_sb_info *sbi, struct cp_control *cpc) > >>>>>> > >>>>>> if (is_sbi_flag_set(sbi, SBI_QUOTA_SKIP_FLUSH)) > >>>>>> __set_ckpt_flags(ckpt, CP_QUOTA_NEED_FSCK_FLAG); > >>>>>> - else > >>>>>> - __clear_ckpt_flags(ckpt, CP_QUOTA_NEED_FSCK_FLAG); > >>>>> > >>>>> I didn't get it, previously, if we didn't persist all quota file's data in > >>>>> checkpoint, then we will tag CP_QUOTA_NEED_FSCK_FLAG in CP area, but in current > >>>>> checkpoint, we have persisted all quota file's data, quota files are consistent > >>>>> with all other files in filesystem, why we can't remove this NEED_FSCK flag..? > >>>> > >>>> I said it's subtle. So, I guessed 1) set CP_QUOTA_NEED_FSCK_FLAG, 2) clear > >>> > >>> I know it's subtle... and I agreed we can fix it like this in upstream > >>> first, but in our product, it's not rare that we hit the > >>> QUOTA_SKIP_FLUSH(its value is 4) case, later we may encounter long latency > >>> caused by quota repairing of fsck. > >>> > >>>> SBI_QUOTA_SKIP_FLUSH by checkpoint, 3) clear CP_QUOTA_NEED_FSCK_FLAG by another > >>>> checkpoint? > >>> > >>> But later if QUOTA_NEED_REPAIR is set, we will set QUOTA_NEED_FSCK_FLAG > >>> again, right? > >>> > >>> if (is_sbi_flag_set(sbi, SBI_QUOTA_NEED_REPAIR)) > >>> __set_ckpt_flags(ckpt, CP_QUOTA_NEED_FSCK_FLAG); > >>> > >>> > >>> So in order to figure out whether this is caused by out-of-order execution > >>> of below assignments: > >>> > >>> if (is_sbi_flag_set(sbi, SBI_QUOTA_SKIP_FLUSH)) > >>> __set_ckpt_flags(ckpt, CP_QUOTA_NEED_FSCK_FLAG); > >>> else > >>> __clear_ckpt_flags(ckpt, CP_QUOTA_NEED_FSCK_FLAG); --- clear flag later > >>> > >>> if (is_sbi_flag_set(sbi, SBI_QUOTA_NEED_REPAIR)) > >>> __set_ckpt_flags(ckpt, CP_QUOTA_NEED_FSCK_FLAG); --- set flag first > >>> > >>> > >>> Could you have a try: > >>> > >>> if (is_sbi_flag_set(sbi, SBI_QUOTA_NEED_REPAIR) || > >>> is_sbi_flag_set(sbi, SBI_QUOTA_SKIP_FLUSH)) > >>> __set_ckpt_flags(ckpt, CP_QUOTA_NEED_FSCK_FLAG); > >>> else > >>> __clear_ckpt_flags(ckpt, CP_QUOTA_NEED_FSCK_FLAG); > >> > >> What does this mean? I'm in doubt we have a missing case where we clear this > > > > Cpu pipeline / compiler can make code out-of-order execution, which means: > > > > a = 1; > > b = 2; > > > > may actually be executed as the order of: > > > > b = 2; > > a = 1; > > > > So I doubt that below two line codes can be executed out-of-order: > > > > else > > __clear_ckpt_flags(ckpt, CP_QUOTA_NEED_FSCK_FLAG); --- clear flag later > > > > if () > > __set_ckpt_flags(ckpt, CP_QUOTA_NEED_FSCK_FLAG); --- set flag first In spin_lock_irqsave()? > > > >> flag, CP_QUOTA_NEED_FSCK_FLAG. > > > > Agreed, I've checked each operation in f2fs_quota_operations yesterday, and > > didn't find any missing places yet... > > Oh, I mean the place where set SBI_QUOTA_NEED_REPAIR, I also doubt we > missed to set the flag. So, I may need to keep this patch untill we find the missing case. I'll keep an eye on this. > > Thanks, > > > > > Thanks, > > > >> > >>> > >>> Thanks, > >>> > >>>> > >>>>> > >>>>> Thanks, > >>>>> > >>>>>> > >>>>>> if (is_sbi_flag_set(sbi, SBI_QUOTA_NEED_REPAIR)) > >>>>>> __set_ckpt_flags(ckpt, CP_QUOTA_NEED_FSCK_FLAG); > >>>>>> > >>>> > >>>> . > >>>> > >> > >> . > >> > > > > > > > > _______________________________________________ > > Linux-f2fs-devel mailing list > > Linux-f2fs-devel@lists.sourceforge.net > > https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel > > > > . > >