Re: [PATCH V2] f2fs: fix to adjust appropriate length for fiemap

[Chao Yu <chao@kernel.org>]

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

Hi Zhiguo,

Any testcase to reproduce this bug? w/o this patch, it looks output
from fiemap looks fine?

f2fs_io fiemap 0 19034 file
Fiemap: offset = 0 len = 19034
	logical addr.    physical addr.   length           flags
0	0000000000000000 0000000004401000 0000000000005000 00001001

Thanks,

> 
> Signed-off-by: Zhiguo Niu <zhiguo.niu@unisoc.com>
> ---
> 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));
>   
>   	start_blk = bytes_to_blks(inode, start);
>   	last_blk = bytes_to_blks(inode, start + len - 1);