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smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=fTer/HKO; 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="fTer/HKO" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E3294C4CED0; Mon, 16 Dec 2024 15:38:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1734363530; bh=PjgTGWa37ZcSr/2jgtcKaCjNlthVOPFoC83gHM/tQRI=; h=Date:Cc:Subject:To:References:From:In-Reply-To:From; b=fTer/HKOcTJYfAqsOMfMTG5P8+w6VIESaiXd7pxu4EJGQj7KkBZgVF3uj7iEUwB8q 1eqJcKe+N3h0IGnwKW1c51Vivj4kPlQCdBFVRN6WDEv4QekBxgnRzt8TsnQMsrMR1C mfrg9EtmoBEEX9heIfUa3E0CERcV/3FDbDJSe6CjCZkdPXqMnV4sWZFOisLr5ceMiv 4/A/5lnEspgPjS1mD7YsRzsVOiplC+ohzY8pln4l5mywKF+FPVK4expNxDjQtE4ACD ID3FCVOwgQt49usW+bBc2aUbO8sH3d9y9JFiLKr34g8rBwJn1H9VOuQFSxBpEfq4f3 02pD2WwmvydfA== Message-ID: <8530b8c3-ba11-42f8-970f-1cd5d729fc0f@kernel.org> Date: Mon, 16 Dec 2024 23:38:48 +0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Cc: Chao Yu , Yeongjin Gil , daehojeong@google.com, linux-f2fs-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org, Sungjong Seo , Sunmin Jeong , Jaewook Kim Subject: Re: [PATCH v2] f2fs: compress: don't redirty sparse cluster during {,de}compress To: Jaegeuk Kim , Dan Carpenter References: <20240819083430.31852-1-youngjin.gil@samsung.com> <644671fc-b35d-4c53-ae25-356963466339@stanley.mountain> Content-Language: en-US From: Chao Yu Autocrypt: addr=chao@kernel.org; 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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 2024/12/13 0:11, Jaegeuk Kim wrote: > On 12/12, Dan Carpenter wrote: >> On Mon, Aug 19, 2024 at 05:34:30PM +0900, Yeongjin Gil wrote: >>> In f2fs_do_write_data_page, when the data block is NULL_ADDR, it skips >>> writepage considering that it has been already truncated. >>> This results in an infinite loop as the PAGECACHE_TAG_TOWRITE tag is not >>> cleared during the writeback process for a compressed file including >>> NULL_ADDR in compress_mode=user. >>> >>> This is the reproduction process: >>> >>> 1. dd if=/dev/zero bs=4096 count=1024 seek=1024 of=testfile >>> 2. f2fs_io compress testfile >>> 3. dd if=/dev/zero bs=4096 count=1 conv=notrunc of=testfile >>> 4. f2fs_io decompress testfile >>> >>> To prevent the problem, let's check whether the cluster is fully >>> allocated before redirty its pages. >>> >> >> We were discussing how to detect these sorts of things in the future. >> Presumably a user found this by chance? Xfstests has two tests which deal >> with compression tests/f2fs/002 and tests/f2fs/007. But it feels like >> xfstests is not really the right place for this sort of thing, it would >> be better as part of some sort of fuzz testing. >> >> What do you think? > > Yeah, agreed that we must have tests to catch this. One way may be creating > some basic disk images having some possible valid layout to see f2fs can > work as intended. I feel we can put it in xfstests as wel? > > Chao, thoughts? Hi Jaegeuk, Dan, I'd like to continue to add regression testcases like f2fs/[003-008] to xfstests, so that, we can make sure last change of f2fs won't cause any regression by checking w/ those testcases. Recently, Sheng Yong has introduced a new tool named inject.f2fs [1], and then, built an auto testsuit in f2fs-tools based on inject.f2fs [2], w/ this testsuit, we can construct image by injecting specified fields, and check the image w/ fsck to see whether result is as expected. IMO, it's fine to add new testcases into testsuit to check whether f2fs' behavior is as expected on constructed image w/ valid data layout. So, regression testcase goes into xfstests, and fuzz/common image testcase goes into testsuit of f2fs-tools? what do you think? [1] "f2fs-tools: introduce inject.f2fs" https://lore.kernel.org/linux-f2fs-devel/20240704025740.527171-1-shengyong@oppo.com/ [2] "f2fs-tools: add testcases" https://lore.kernel.org/linux-f2fs-devel/20241029120956.4186731-1-shengyong@oppo.com/ Thanks, > >> >> regards, >> dan carpenter