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smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=SNhMFzvI; 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="SNhMFzvI" Received: by smtp.kernel.org (Postfix) with ESMTPSA id BC95FC4CED3; Wed, 6 Nov 2024 07:40:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1730878855; bh=8wA53S4ezlIPTVZA/MykpScLT344CmnrMjVY2QQPs+k=; h=Date:Cc:Subject:To:References:From:In-Reply-To:From; b=SNhMFzvIsfvyyCKV08GxdIG6SyWcfw5/kaol0V28q0uGXbbN+A2kZm6iXXBIznX5+ Ztx4UjQNf6yKeewYOdi77XHO1W+FvqX22YeH2blsW1uTnoiNhqrktAvb/pA1d4B4my yfVKhu6rQjoWx7G8FpT1Yi8ZjmpRDoAcPM5bMMXC7tM0cet4dx+xU19BDKTJGW1YiQ FHqISBwzS67zch7DQiNtExR8bJALHdAdwifxRcVk2s8fq1XlbaGf0aCgOx5coHiU37 JoX+MefZ6hRjlv+euOcGJ7XfLQ1LJWwfpIKUCzvWOZPfw7KgmMHFRcOnfMqwnXXbzd RVKKr/aIPNbOg== Message-ID: <0a8f96da-302d-4d6c-9ab6-0b66a05cbcfd@kernel.org> Date: Wed, 6 Nov 2024 15:40:50 +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 , Zhiguo Niu , jaegeuk@kernel.org, linux-f2fs-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org, ke.wang@unisoc.com, Hao_hao.Wang@unisoc.com Subject: Re: [PATCH V2] f2fs: fix to adjust appropriate length for fiemap To: Zhiguo Niu References: <1730685372-2995-1-git-send-email-zhiguo.niu@unisoc.com> <22873055-370b-4240-83ff-96bcfa91413a@kernel.org> <9199e9fc-7b5b-4069-b79b-65ba5ae1b0f6@kernel.org> Content-Language: en-US From: Chao Yu In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 2024/11/6 14:08, Zhiguo Niu wrote: > Chao Yu 于2024年11月6日周三 10:40写道： >> >> On 2024/11/6 10:26, Zhiguo Niu wrote: >>> Chao Yu 于2024年11月6日周三 10:16写道： >>>> >>>> On 2024/11/5 19:02, Zhiguo Niu wrote: >>>>> Chao Yu 于2024年11月5日周二 18:39写道： >>>>>> >>>>>> On 2024/11/5 15:28, Zhiguo Niu wrote: >>>>>>> Chao Yu 于2024年11月5日周二 15:04写道： >>>>>>>> >>>>>>>> On 2024/11/4 9:56, Zhiguo Niu wrote: >>>>>>>>> If user give a file size as "length" parameter for fiemap >>>>>>>>> operations, but if this size is non-block size aligned, >>>>>>>>> it will show 2 segments fiemap results even this whole file >>>>>>>>> is contiguous on disk, such as the following results: >>>>>>>>> >>>>>>>>> ./f2fs_io fiemap 0 19034 ylog/analyzer.py >>>>>>>>> Fiemap: offset = 0 len = 19034 >>>>>>>>> logical addr. physical addr. length flags >>>>>>>>> 0 0000000000000000 0000000020baa000 0000000000004000 00001000 >>>>>>>>> 1 0000000000004000 0000000020bae000 0000000000001000 00001001 >>>>>>>>> >>>>>>>>> after this patch: >>>>>>>>> ./f2fs_io fiemap 0 19034 ylog/analyzer.py >>>>>>>>> Fiemap: offset = 0 len = 19034 >>>>>>>>> logical addr. physical addr. length flags >>>>>>>>> 0 0000000000000000 00000000315f3000 0000000000005000 00001001 >>>>>>>>> >>>>>>>>> Signed-off-by: Zhiguo Niu >>>>>>>>> --- >>>>>>>>> V2: correct commit msg according to Chao's questions >>>>>>>>> f2fs_io has been modified for testing, the length for fiemap is >>>>>>>>> real file size, not block number >>>>>>>>> --- >>>>>>>>> fs/f2fs/data.c | 4 ++-- >>>>>>>>> 1 file changed, 2 insertions(+), 2 deletions(-) >>>>>>>>> >>>>>>>>> diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c >>>>>>>>> index 306b86b0..9fc229d 100644 >>>>>>>>> --- a/fs/f2fs/data.c >>>>>>>>> +++ b/fs/f2fs/data.c >>>>>>>>> @@ -1966,8 +1966,8 @@ int f2fs_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo, >>>>>>>>> goto out; >>>>>>>>> } >>>>>>>>> >>>>>>>>> - if (bytes_to_blks(inode, len) == 0) >>>>>>>>> - len = blks_to_bytes(inode, 1); >>>>>>>>> + if (len & (blks_to_bytes(inode, 1) - 1)) >>>>>>>>> + len = round_up(len, blks_to_bytes(inode, 1)); >>>>>>>> >>>>>>>> How do you think of getting rid of above alignment for len? >>>>>>>> >>>>>>>>> >>>>>>>>> start_blk = bytes_to_blks(inode, start); >>>>>>>>> last_blk = bytes_to_blks(inode, start + len - 1); >>>>>>>> >>>>>>>> And round up end position w/: >>>>>>>> >>>>>>>> last_blk = bytes_to_blks(inode, round_up(start + len - 1, F2FS_BLKSIZE)); >>>>>>> Hi Chao, >>>>>>> I think this will change the current code logic >>>>>>> ------------- >>>>>>> if (start_blk > last_blk) >>>>>>> goto out; >>>>>>> ------------- >>>>>>> for example, a file with size 19006, but the length from the user is 16384. >>>>>>> before this modification, last_blk = bytes_to_blks(inode, start + >>>>>>> len - 1) = (inode, 16383) = 3 >>>>>>> after the first f2fs_map_blocks(). start_blk change to be 4, >>>>>>> after the second f2fs_map_blocks(), fiemap_fill_nex_exten will be >>>>>>> called to fill user parameter and then >>>>>>> will goto out because start_blk > last_blk, then fiemap flow finishes. >>>>>>> but after this modification, last_blk will be 4 >>>>>>> will do f2fs_map_blocks() until reach the max_file_blocks(inode) >>>>>> >>>>>> Yes, you're right, however, w/ this patch, it may change last_blk, e.g. >>>>>> >>>>>> xfs_io file -c "fiemap -v 0 19006" vs xfs_io file -c "fiemap -v 2 19006" >>>>>> start_blk and last_blk will be: 0, 4 and 0, 5. >>>>> Hi Chao, >>>>> yes, but w/o this patch , the original code still has the same situation?? >>>>> for example >>>>> xfs_io file -c "fiemap -v 0 16384" vs xfs_io file -c "fiemap -v 2 16384" >>>>> start_blk and last_blk will be: 0, 3 and 0, 4. >>>> >>>> For the case "fiemap -v 2 19006", offset is 2, and length is 19006, so last_offset >>>> is 19008, and last_blk should be 4 rather than 5, right? >>> hi Chao, >>> it is right w/o my patch. >>>> >>>> And for you case, it calculates last_blk correctly. >>> So you suggest that "Should we round_up len after start_blk & last_blk >>> calculation?" >> >> Zhiguo, >> >> Yes, I think alignment of len should not affect calculation of last_blk. >> >> I mean this, >> >> --- >> fs/f2fs/data.c | 6 +++--- >> include/linux/f2fs_fs.h | 3 ++- >> 2 files changed, 5 insertions(+), 4 deletions(-) >> >> diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c >> index 7d1bb9518a40..cbbb956f420d 100644 >> --- a/fs/f2fs/data.c >> +++ b/fs/f2fs/data.c >> @@ -1967,12 +1967,12 @@ int f2fs_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo, >> goto out; >> } >> >> - if (bytes_to_blks(inode, len) == 0) >> - len = blks_to_bytes(inode, 1); >> - >> start_blk = bytes_to_blks(inode, start); >> last_blk = bytes_to_blks(inode, start + len - 1); >> >> + if (len & F2FS_BLKSIZE_MASK) >> + len = round_up(len, F2FS_BLKSIZE); >> + > Hi Chao, > this verion verify pass with my test case. > > but there is still another issue in orginal code: > ylog/analyzer.py size = 19034 > if I input the following cmd(start/length are both real size, not block number) > /f2fs_io fiemap 2 16384 ylog/analyzer.py > and the results shows: > Fiemap: offset = 2 len = 16384 > logical addr. physical addr. length flags > 0 0000000000000000 0000000e2ebca000 0000000000004000 00001000 > 1 0000000000004000 0000000e2ebce000 0000000000001000 00001001 > so start_blk/last_blk should be calculate it in the following way? IIUC, the root cause is f2fs_map_blocks() will truncate size of returned extent to F2FS_BYTES_TO_BLK(len), so whenever parameter @len doesn't cover last extent, it triggers this bug. next: memset(&map, 0, sizeof(map)); map.m_lblk = start_blk; map.m_len = F2FS_BYTES_TO_BLK(len); --- limit max size of extent it founds map.m_next_pgofs = &next_pgofs; map.m_seg_type = NO_CHECK_TYPE; ... ret = f2fs_map_blocks(inode, &map, F2FS_GET_BLOCK_FIEMAP); xfs_io file -c "fiemap -v 2 16384" file: EXT: FILE-OFFSET BLOCK-RANGE TOTAL FLAGS 0: [0..31]: 139272..139303 32 0x1000 1: [32..39]: 139304..139311 8 0x1001 xfs_io file -c "fiemap -v 0 16384" file: EXT: FILE-OFFSET BLOCK-RANGE TOTAL FLAGS 0: [0..31]: 139272..139303 32 0x1000 xfs_io file -c "fiemap -v 0 16385" file: EXT: FILE-OFFSET BLOCK-RANGE TOTAL FLAGS 0: [0..39]: 139272..139311 40 0x1001 Thoughts? Thanks, > before: > start_blk = bytes_to_blks(inode, start); > last_blk = bytes_to_blks(inode, start + len - 1); > after: > > start_blk = bytes_to_blks(inode, start); > last_blk = start_blk + bytes_to_blks(inode, len - 1); > thanks! >> next: >> memset(&map, 0, sizeof(map)); >> map.m_lblk = start_blk; >> diff --git a/include/linux/f2fs_fs.h b/include/linux/f2fs_fs.h >> index b0b821edfd97..954e8e8344b7 100644 >> --- a/include/linux/f2fs_fs.h >> +++ b/include/linux/f2fs_fs.h >> @@ -24,10 +24,11 @@ >> #define NEW_ADDR ((block_t)-1) /* used as block_t addresses */ >> #define COMPRESS_ADDR ((block_t)-2) /* used as compressed data flag */ >> >> +#define F2FS_BLKSIZE_MASK (F2FS_BLKSIZE - 1) >> #define F2FS_BYTES_TO_BLK(bytes) ((bytes) >> F2FS_BLKSIZE_BITS) >> #define F2FS_BLK_TO_BYTES(blk) ((blk) << F2FS_BLKSIZE_BITS) >> #define F2FS_BLK_END_BYTES(blk) (F2FS_BLK_TO_BYTES(blk + 1) - 1) >> -#define F2FS_BLK_ALIGN(x) (F2FS_BYTES_TO_BLK((x) + F2FS_BLKSIZE - 1)) >> +#define F2FS_BLK_ALIGN(x) (F2FS_BYTES_TO_BLK((x) + F2FS_BLKSIZE - 1)) >> >> /* 0, 1(node nid), 2(meta nid) are reserved node id */ >> #define F2FS_RESERVED_NODE_NUM 3 >> -- >> 2.40.1 >> >> >> >>> Thanks >>>> >>>> Thanks, >>>> >>>>> but overall last_blk will change loop counts but has not affect on the results. >>>>>> >>>>>> Should we round_up len after start_blk & last_blk calculation? >>>>> I thinks it is ok ,but just a little bit redundant with the following >>>>> handling about len. >>>>> >>>>> if (bytes_to_blks(inode, len) == 0) >>>>> len = blks_to_bytes(inode, 1); >>>>> >>>>> Based on the above situation, >>>>> do you have any other good suggestions? ^^ >>>>> thanks! >>>>> >>>>>> >>>>>> Thanks, >>>>>> >>>>>>> thanks！ >>>>>>>> >>>>>>>> Thanks, >>>>>>>> >>>>>> >>>> >>