From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 835C834E746 for ; Tue, 21 Apr 2026 09:04:31 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776762271; cv=none; b=loZjGcWDCOBAts605/wXYLrKCKjK+bOqt1XOPqBMAGjPfJ+pw3d68AXhSuQmiEKAZmnzbpz5UQyXwIkhdh9ZuU5pkOEAu1HpdqNuqiPZPgxtDBeL/uh9ixbcyaI84Rt5ValQHG9v9t7rK3zyoUZFT1TIxiUVqTN0P7e29D7BV0w= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776762271; c=relaxed/simple; bh=A/KWQMopmFsUYglVJ2p0D/NDGUpoQO0F3Mg9epddvf0=; h=Message-ID:Date:MIME-Version:Cc:Subject:To:References:From: In-Reply-To:Content-Type; b=HxH+87FuENczocJnb9SxWJHprMHEFoHkpC1VPKvno0dm00UcXqm4N9tkkIWLJlo/S4mvcCSZrrEI6H6CPdSfSiGICCMD6kpI63oQrkWRtsUXOf5vUJCSjahHYt9yviMBPX+3k8XKqmZo0FrIGLviOxT71ePUh7VfR8tAyYslSV0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=DmwCklvL; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="DmwCklvL" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9795AC2BCB0; Tue, 21 Apr 2026 09:04:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1776762271; bh=A/KWQMopmFsUYglVJ2p0D/NDGUpoQO0F3Mg9epddvf0=; h=Date:Cc:Subject:To:References:From:In-Reply-To:From; b=DmwCklvLzUKJH3u3+dzoMYnUG5sBHGSyhQPQf/nRr6aUEYcm2iT8F1g+EMK86wRfi QmWO5pVnQ5aJvD2vAWaCnJlFj+TvAu34UwDK9SvwBbXAT+RF468hH4JY7fcrW9pJZP peEtrrcllyU/wlrpZSox+z43E6aoMaZ0QtZgriixk/J0wU6nTdiOaB+wQ5sOD6m+OI 7ImaoR+a19GcLS7EZIyvZFjVZsMJwnMu0A4iW9aExHSZww52UaroU3Fwf9UoFay/YG kdbzq73rzolHO7s2UPVHC9l3ffF9quSVK/2xif77PTZXkJjX5+KUovIiLxB9IIPfDX /Cfn2Tic+c+pg== Message-ID: <9b518ad1-18ad-4eb4-86d4-3a27e40a7635@kernel.org> Date: Tue, 21 Apr 2026 17:04:25 +0800 Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Cc: chao@kernel.org, Yongpeng Yang , stable@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net Subject: Re: [f2fs-dev] [PATCH] f2fs: fix node_cnt race between extent node destroy and writeback To: Yongpeng Yang , Jaegeuk Kim References: <20260403144015.221811-3-monty_pavel@sina.com> <5c222edf-6888-4007-9240-9e7988b2dc71@sina.com> <252cb446-e313-417b-b780-85dcdcf34a87@sina.com> Content-Language: en-US From: Chao Yu In-Reply-To: <252cb446-e313-417b-b780-85dcdcf34a87@sina.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 4/21/2026 4:44 PM, Yongpeng Yang wrote: > > On 4/20/26 15:28, Chao Yu via Linux-f2fs-devel wrote: >> On 4/19/2026 12:29 AM, Yongpeng Yang wrote: >>> >>> On 4/18/26 8:51 AM, Chao Yu via Linux-f2fs-devel wrote: >>>> On 4/17/26 21:26, Yongpeng Yang wrote: >>>>> >>>>> On 4/17/26 17:00, Chao Yu via Linux-f2fs-devel wrote: >>>>>> On 4/3/26 22:40, Yongpeng Yang wrote: >>>>>>> From: Yongpeng Yang >>>>>>> >>>>>>> f2fs_destroy_extent_node() does not set FI_NO_EXTENT before clearing >>>>>>> extent nodes. When called from f2fs_drop_inode() with I_SYNC set, >>>>>>> concurrent kworker writeback can insert new extent nodes into the >>>>>>> same >>>>>>> extent tree, racing with the destroy and triggering f2fs_bug_on() in >>>>>>> __destroy_extent_node(). The scenario is as follows: >>>>>>> >>>>>>> drop inode                            writeback >>>>>>>     - iput >>>>>>>      - f2fs_drop_inode  // I_SYNC set >>>>>>>       - f2fs_destroy_extent_node >>>>>>>        - __destroy_extent_node >>>>>>>         - while (node_cnt) { >>>>>>>            write_lock(&et->lock) >>>>>>>            __free_extent_tree >>>>>>>            write_unlock(&et->lock) >>>>>>>                                           - __writeback_single_inode >>>>>>>                                            - f2fs_outplace_write_data >>>>>>>                                             - >>>>>>> f2fs_update_read_extent_cache >>>>>>>                                              - >>>>>>> __update_extent_tree_range >>>>>>>                                               // FI_NO_EXTENT not >>>>>>> set, >>>>>>>                                               // insert new extent >>>>>>> node >>>>>>>           } // node_cnt == 0, exit while >>>>>>>         - f2fs_bug_on(node_cnt)  // node_cnt > 0 >>>>>>> >>>>>>> Additionally, __update_extent_tree_range() only checks >>>>>>> FI_NO_EXTENT for >>>>>>> EX_READ type, leaving EX_BLOCK_AGE updates completely unprotected. >>>>>>> >>>>>>> This patch set FI_NO_EXTENT under et->lock in >>>>>>> __destroy_extent_node(), >>>>>>> consistent with other callers (__update_extent_tree_range and >>>>>>> __drop_extent_tree) and check FI_NO_EXTENT for both EX_READ and >>>>>>> EX_BLOCK_AGE tree. >>>>>> >>>>>> I suffered below test failure, then I bisect to this change. >>>>>> >>>>>>       generic/475  84s ... [failed, exit status 1]- output mismatch >>>>>> (see / >>>>>> share/git/fstests/results//generic/475.out.bad) >>>>>>       --- tests/generic/475.out   2025-01-12 21:57:40.279440664 +0800 >>>>>>       +++ /share/git/fstests/results//generic/475.out.bad 2026-04-17 >>>>>> 12:08:28.000000000 +0800 >>>>>>       @@ -1,2 +1,6 @@ >>>>>>        QA output created by 475 >>>>>>        Silence is golden. >>>>>>       +mount: /mnt/scratch_f2fs: mount system call failed: Structure >>>>>> needs >>>>>> cleaning. >>>>>>       +       dmesg(1) may have more information after failed mount >>>>>> system >>>>>> call. >>>>>>       +mount failed >>>>>>       +(see /share/git/fstests/results//generic/475.full for details) >>>>>>       ... >>>>>>       (Run 'diff -u /share/git/fstests/tests/generic/475.out / >>>>>> share/git/ >>>>>> fstests/results//generic/475.out.bad'  to see the entire diff) >>>>>> >>>>>> >>>>>>       generic/388  73s ... [failed, exit status 1]- output mismatch >>>>>> (see / >>>>>> share/git/fstests/results//generic/388.out.bad) >>>>>>       --- tests/generic/388.out   2025-01-12 21:57:40.275440602 +0800 >>>>>>       +++ /share/git/fstests/results//generic/388.out.bad 2026-04-17 >>>>>> 11:58:05.000000000 +0800 >>>>>>       @@ -1,2 +1,6 @@ >>>>>>        QA output created by 388 >>>>>>        Silence is golden. >>>>>>       +mount: /mnt/scratch_f2fs: mount system call failed: Structure >>>>>> needs >>>>>> cleaning. >>>>>>       +       dmesg(1) may have more information after failed mount >>>>>> system >>>>>> call. >>>>>>       +cycle mount failed >>>>>>       +(see /share/git/fstests/results//generic/388.full for details) >>>>>>       ... >>>>>>       (Run 'diff -u /share/git/fstests/tests/generic/388.out / >>>>>> share/git/ >>>>>> fstests/results//generic/388.out.bad'  to see the entire diff) >>>>>> >>>>>> >>>>>>       F2FS-fs (dm-0): sanity_check_extent_cache: inode (ino=1761) >>>>>> extent >>>>>> info [220057, 57, 6] is incorrect, run fsck to fix >>>>>> >>>>>> I suspect we may miss any extent updates after we set FI_NO_EXTENT in >>>>>> __destroy_extent_node(), result in failing in >>>>>> sanity_check_extent_cache(). >>>>>> >>>>>> Can we just relocate f2fs_bug_on(node_cnt) rather than complicated >>>>>> change? >>>>>> Thoughts? >>>>> >>>>> Oh, I overlooked largest extent. How about relocate >>>>> f2fs_bug_on(node_cnt) to __destroy_extent_tree? >>>>> >>>>> static void __destroy_extent_tree(struct inode *inode, enum extent_type >>>>> type) >>>>> >>>>>           /* free all extent info belong to this extent tree */ >>>>>           node_cnt = __destroy_extent_node(inode, type); >>>>> +       f2fs_bug_on(sbi, atomic_read(&et->node_cnt)); >>>> >>>>       /* free all extent info belong to this extent tree */ >>>>       node_cnt = __destroy_extent_node(inode, type); >>>> >>>>       /* delete extent tree entry in radix tree */ >>>>       mutex_lock(&eti->extent_tree_lock); >>>>       f2fs_bug_on(sbi, atomic_read(&et->node_cnt));  <--- >>>> >>>> Oh, it has already checked node_cnt, so, maybe we can just remove the >>>> check in >>>> __destroy_extent_node()? >>> >>> Yes. BTW, is it correct to remove the call to f2fs_destroy_extent_node() >>> in f2fs_drop_inode()? It seems this call is unnecessary, since >>> f2fs_evict_inode() will eventually delete all extent nodes properly. >> >> I think it's fine to keep it according to original intention "destroy >> extent_tree for the truncation case" introduced from 3e72f721390d >> ("f2fs: use extent_cache by default"). It helps the performance w/ >> in batch extent node release. > > Oh, I see. This patch has already been merged into the dev branch. Which > of the following approaches would be more appropriate? > 1. Drop the current patch from the dev branch, then submit a patch to > remove the f2fs_bug_on() in __destroy_extent_node. > 2. Send two patches: the first reverts the change, and the second > removes the f2fs_bug_on() in __destroy_extent_node(). It's near the end of merge window, I think we need to keep dev as it is, and create another patch to revert previous change and drop the f2fs_bug_on() as well, what do you think? To Jaegeuk, thoughts? Thanks, > > Thanks > Yongpeng, > >> >> Thanks, >> >>> >>> Thanks >>> Yongpeng, >>> >>>> >>>> Thanks, >>>> >>>> >>>>> >>>>> Thanks >>>>> Yongpeng, >>>>> >>>>>> >>>>>> Thanks, >>>>>> >>>>>>> >>>>>>> Fixes: 3fc5d5a182f6 ("f2fs: fix to shrink read extent node in >>>>>>> batches") >>>>>>> Cc: stable@vger.kernel.org >>>>>>> Signed-off-by: Yongpeng Yang >>>>>>> --- >>>>>>>     fs/f2fs/extent_cache.c | 17 ++++++++++------- >>>>>>>     1 file changed, 10 insertions(+), 7 deletions(-) >>>>>>> >>>>>>> diff --git a/fs/f2fs/extent_cache.c b/fs/f2fs/extent_cache.c >>>>>>> index 0ed84cc065a7..87169fd29d89 100644 >>>>>>> --- a/fs/f2fs/extent_cache.c >>>>>>> +++ b/fs/f2fs/extent_cache.c >>>>>>> @@ -119,9 +119,10 @@ static bool __may_extent_tree(struct inode >>>>>>> *inode, enum extent_type type) >>>>>>>         if (!__init_may_extent_tree(inode, type)) >>>>>>>             return false; >>>>>>>     +    if (is_inode_flag_set(inode, FI_NO_EXTENT)) >>>>>>> +        return false; >>>>>>> + >>>>>>>         if (type == EX_READ) { >>>>>>> -        if (is_inode_flag_set(inode, FI_NO_EXTENT)) >>>>>>> -            return false; >>>>>>>             if (is_inode_flag_set(inode, FI_COMPRESSED_FILE) && >>>>>>>                      !f2fs_sb_has_readonly(F2FS_I_SB(inode))) >>>>>>>                 return false; >>>>>>> @@ -644,6 +645,8 @@ static unsigned int __destroy_extent_node(struct >>>>>>> inode *inode, >>>>>>>           while (atomic_read(&et->node_cnt)) { >>>>>>>             write_lock(&et->lock); >>>>>>> +        if (!is_inode_flag_set(inode, FI_NO_EXTENT)) >>>>>>> +            set_inode_flag(inode, FI_NO_EXTENT); >>>>>>>             node_cnt += __free_extent_tree(sbi, et, nr_shrink); >>>>>>>             write_unlock(&et->lock); >>>>>>>         } >>>>>>> @@ -688,12 +691,12 @@ static void __update_extent_tree_range(struct >>>>>>> inode *inode, >>>>>>>           write_lock(&et->lock); >>>>>>>     -    if (type == EX_READ) { >>>>>>> -        if (is_inode_flag_set(inode, FI_NO_EXTENT)) { >>>>>>> -            write_unlock(&et->lock); >>>>>>> -            return; >>>>>>> -        } >>>>>>> +    if (is_inode_flag_set(inode, FI_NO_EXTENT)) { >>>>>>> +        write_unlock(&et->lock); >>>>>>> +        return; >>>>>>> +    } >>>>>>>     +    if (type == EX_READ) { >>>>>>>             prev = et->largest; >>>>>>>             dei.len = 0; >>>>>> >>>>>> >>>>>> >