Re: [PATCH 1/2] iomap: remove the length variable in iomap_seek_data

["Darrick J. Wong" <djwong@kernel.org>]

On Tue, Jul 06, 2021 at 07:05:40AM +0200, Christoph Hellwig wrote:
> The length variable is rather pointless given that it can be trivially
> deduced from offset and size.  Also the initial calculation can lead
> to KASAN warnings.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> Reported-by: Leizhen (ThunderTown) <thunder.leizhen@huawei.com>

Looks good!
Reviewed-by: Darrick J. Wong <djwong@kernel.org>

--D

> ---
>  fs/iomap/seek.c | 16 ++++++----------
>  1 file changed, 6 insertions(+), 10 deletions(-)
> 
> diff --git a/fs/iomap/seek.c b/fs/iomap/seek.c
> index dab1b02eba5b7f..50b8f1418f2668 100644
> --- a/fs/iomap/seek.c
> +++ b/fs/iomap/seek.c
> @@ -83,27 +83,23 @@ loff_t
>  iomap_seek_data(struct inode *inode, loff_t offset, const struct iomap_ops *ops)
>  {
>  	loff_t size = i_size_read(inode);
> -	loff_t length = size - offset;
>  	loff_t ret;
>  
>  	/* Nothing to be found before or beyond the end of the file. */
>  	if (offset < 0 || offset >= size)
>  		return -ENXIO;
>  
> -	while (length > 0) {
> -		ret = iomap_apply(inode, offset, length, IOMAP_REPORT, ops,
 -				  &offset, iomap_seek_data_actor);
> +	while (offset < size) {
> +		ret = iomap_apply(inode, offset, size - offset, IOMAP_REPORT,
> +				  ops, &offset, iomap_seek_data_actor);
>  		if (ret < 0)
>  			return ret;
>  		if (ret == 0)
> -			break;
> -
> +			return offset;
>  		offset += ret;
> -		length -= ret;
>  	}
>  
> -	if (length <= 0)
> -		return -ENXIO;
> -	return offset;
> +	/* We've reached the end of the file without finding data */
> +	return -ENXIO;
>  }
>  EXPORT_SYMBOL_GPL(iomap_seek_data);
> -- 
> 2.30.2
>