Re: [PATCH 2/2] f2fs: fix to adjust appropriate length for fiemap

[Chao Yu]

On 2024/10/31 13:59, Zhiguo Niu wrote:
> If user give a file size as "length" parameter for fiemap
> operations, but 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, please
> note that this f2fs_io has been modified for testing.
>
>   ./f2fs_io fiemap 0 19304 ylog/analyzer.py
> Fiemap: offset = 0 len = 19304
>          logical addr.    physical addr.   length           flags
> 0       0000000000000000 0000000020baa000 0000000000004000 00001000
> 1       0000000000004000 0000000020bae000 0000000000001000 00001001
>
> after this patch:
>   ./f2fs_io fiemap 0 19304 ylog/analyzer.py
> Fiemap: offset = 0 len = 19304
> 	logical addr.    physical addr.   length           flags
> 0	0000000000000000 00000000315f3000 0000000000005000 00001000

Why is FIEMAP_EXTENT_LAST missing in #0 extent? As we can see it
in #1 extent before your change.

1       0000000000004000 0000000020bae000 0000000000001000 00001001

Thanks,

> Signed-off-by: Zhiguo Niu <zhiguo.niu@xxxxxxxxxx>
> ---
> 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 90fa8ab..8c9bb42 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);