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=-8.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=unavailable 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 42BDAC3F2CD for ; Tue, 3 Mar 2020 12:07:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2163D20857 for ; Tue, 3 Mar 2020 12:07:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729108AbgCCMG2 (ORCPT ); Tue, 3 Mar 2020 07:06:28 -0500 Received: from szxga07-in.huawei.com ([45.249.212.35]:44020 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1729061AbgCCMG1 (ORCPT ); Tue, 3 Mar 2020 07:06:27 -0500 Received: from DGGEMS403-HUB.china.huawei.com (unknown [172.30.72.59]) by Forcepoint Email with ESMTP id F0E6F5C8ACCE3BF70899; Tue, 3 Mar 2020 20:06:23 +0800 (CST) Received: from [10.134.22.195] (10.134.22.195) by smtp.huawei.com (10.3.19.203) with Microsoft SMTP Server (TLS) id 14.3.439.0; Tue, 3 Mar 2020 20:06:22 +0800 Subject: Re: [PATCH 1/2] f2fs: Fix mount failure due to SPO after a successful online resize FS To: Sahitya Tummala CC: Jaegeuk Kim , , References: <1582799978-22277-1-git-send-email-stummala@codeaurora.org> <20200302043948.GE20234@codeaurora.org> From: Chao Yu Message-ID: <4d228adb-7038-1c03-e877-93221b920104@huawei.com> Date: Tue, 3 Mar 2020 20:06:21 +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: <20200302043948.GE20234@codeaurora.org> 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 Hi Sahitya, On 2020/3/2 12:39, Sahitya Tummala wrote: > Hi Chao, > > On Fri, Feb 28, 2020 at 04:35:37PM +0800, Chao Yu wrote: >> Hi Sahitya, >> >> Good catch. >> >> On 2020/2/27 18:39, Sahitya Tummala wrote: >>> Even though online resize is successfully done, a SPO immediately >>> after resize, still causes below error in the next mount. >>> >>> [ 11.294650] F2FS-fs (sda8): Wrong user_block_count: 2233856 >>> [ 11.300272] F2FS-fs (sda8): Failed to get valid F2FS checkpoint >>> >>> This is because after FS metadata is updated in update_fs_metadata() >>> if the SBI_IS_DIRTY is not dirty, then CP will not be done to reflect >>> the new user_block_count. >>> >>> Signed-off-by: Sahitya Tummala >>> --- >>> fs/f2fs/gc.c | 1 + >>> 1 file changed, 1 insertion(+) >>> >>> diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c >>> index a92fa49..a14a75f 100644 >>> --- a/fs/f2fs/gc.c >>> +++ b/fs/f2fs/gc.c >>> @@ -1577,6 +1577,7 @@ int f2fs_resize_fs(struct f2fs_sb_info *sbi, __u64 block_count) >>> >>> update_fs_metadata(sbi, -secs); >>> clear_sbi_flag(sbi, SBI_IS_RESIZEFS); >> >> Need a barrier here to keep order in between above code and set_sbi_flag(DIRTY)? > > I don't think a barrier will help here. Let us say there is a another context > doing CP already, then it races with update_fs_metadata(), so it may or may not > see the resize updates and it will also clear the SBI_IS_DIRTY flag set by resize > (even with a barrier). I agreed, actually, we didn't consider race condition in between CP and update_fs_metadata(), it should be fixed. > > I think we need to synchronize this with CP context, so that these resize changes > will be reflected properly. Please see the new diff below and help with the review. > > diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c > index a14a75f..5554af8 100644 > --- a/fs/f2fs/gc.c > +++ b/fs/f2fs/gc.c > @@ -1467,6 +1467,7 @@ static void update_fs_metadata(struct f2fs_sb_info *sbi, int secs) > long long user_block_count = > le64_to_cpu(F2FS_CKPT(sbi)->user_block_count); > > + clear_sbi_flag(sbi, SBI_IS_DIRTY); Why clear dirty flag here? And why not use cp_mutex to protect update_fs_metadata() in error path of f2fs_sync_fs() below? > SM_I(sbi)->segment_count = (int)SM_I(sbi)->segment_count + segs; > MAIN_SEGS(sbi) = (int)MAIN_SEGS(sbi) + segs; > FREE_I(sbi)->free_sections = (int)FREE_I(sbi)->free_sections + secs; > @@ -1575,9 +1576,12 @@ int f2fs_resize_fs(struct f2fs_sb_info *sbi, __u64 block_count) > goto out; > } > > + mutex_lock(&sbi->cp_mutex); > update_fs_metadata(sbi, -secs); > clear_sbi_flag(sbi, SBI_IS_RESIZEFS); > set_sbi_flag(sbi, SBI_IS_DIRTY); > + mutex_unlock(&sbi->cp_mutex); > + > err = f2fs_sync_fs(sbi->sb, 1); > if (err) { > update_fs_metadata(sbi, secs); ^^^^^^^^^^^^^^ In addition, I found that we missed to use sb_lock to protect f2fs_super_block fields update, will submit a patch for that. Thanks, > > thanks, > >> >>> + set_sbi_flag(sbi, SBI_IS_DIRTY); >>> err = f2fs_sync_fs(sbi->sb, 1); >>> if (err) { >>> update_fs_metadata(sbi, secs); >> >> Do we need to add clear_sbi_flag(, SBI_IS_DIRTY) into update_fs_metadata(), so above >> path can be covered as well? >> >> Thanks, >> >>> >