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[209.132.180.67]) by mx.google.com with ESMTP id p1si275647plk.260.2019.02.21.19.27.47; Thu, 21 Feb 2019 19:28:02 -0800 (PST) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726647AbfBVD1V (ORCPT + 99 others); Thu, 21 Feb 2019 22:27:21 -0500 Received: from szxga07-in.huawei.com ([45.249.212.35]:40840 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726213AbfBVD1V (ORCPT ); Thu, 21 Feb 2019 22:27:21 -0500 Received: from DGGEMS411-HUB.china.huawei.com (unknown [172.30.72.59]) by Forcepoint Email with ESMTP id E81A61C945A12FC41B04; Fri, 22 Feb 2019 11:27:17 +0800 (CST) Received: from [127.0.0.1] (10.134.22.195) by DGGEMS411-HUB.china.huawei.com (10.3.19.211) with Microsoft SMTP Server id 14.3.408.0; Fri, 22 Feb 2019 11:27:08 +0800 Subject: Re: [f2fs-dev] [PATCH] f2fs: don't clear CP_QUOTA_NEED_FSCK_FLAG To: Jaegeuk Kim CC: , 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> <20190222024058.GA6093@jaegeuk-macbookpro.roam.corp.google.com> From: Chao Yu Message-ID: <0e00fefb-d0af-6143-afcd-6d8c8fa34743@huawei.com> Date: Fri, 22 Feb 2019 11:27:08 +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: <20190222024058.GA6093@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 2019/2/22 10:40, Jaegeuk Kim wrote: > 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()? Not sure in coverage of spin_lock, system can guarantee codes being executed orderly. > >>> >>>> 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. Agreed, do you mind adding one line comment there to notice that? Thanks, > >> >> 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 >>> >>> . >>> > > . >