Re: [PATCH v3 1/4] iomap: reset per-iter state on non-error iter advances

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

On Fri, Nov 08, 2024 at 07:42:43AM -0500, Brian Foster wrote:
> iomap_iter_advance() zeroes the processed and mapping fields on
> every non-error iteration except for the last expected iteration
> (i.e. return 0 expected to terminate the iteration loop). This
> appears to be circumstantial as nothing currently relies on these
> fields after the final iteration.
> 
> Therefore to better faciliate iomap_iter reuse in subsequent
> patches, update iomap_iter_advance() to always reset per-iteration
> state on successful completion.
> 
> Signed-off-by: Brian Foster <bfoster@redhat.com>

Seems pretty straightforward to me,
Reviewed-by: Darrick J. Wong <djwong@kernel.org>

--D

> ---
>  fs/iomap/iter.c | 11 +++++------
>  1 file changed, 5 insertions(+), 6 deletions(-)
> 
> diff --git a/fs/iomap/iter.c b/fs/iomap/iter.c
> index 79a0614eaab7..3790918646af 100644
> --- a/fs/iomap/iter.c
> +++ b/fs/iomap/iter.c
> @@ -22,26 +22,25 @@
>  static inline int iomap_iter_advance(struct iomap_iter *iter)
>  {
>  	bool stale = iter->iomap.flags & IOMAP_F_STALE;
> +	int ret = 1;
>  
>  	/* handle the previous iteration (if any) */
>  	if (iter->iomap.length) {
>  		if (iter->processed < 0)
>  			return iter->processed;
> -		if (!iter->processed && !stale)
> -			return 0;
>  		if (WARN_ON_ONCE(iter->processed > iomap_length(iter)))
>  			return -EIO;
>  		iter->pos += iter->processed;
>  		iter->len -= iter->processed;
> -		if (!iter->len)
> -			return 0;
> +		if (!iter->len || (!iter->processed && !stale))
> +			ret = 0;
>  	}
>  
> -	/* clear the state for the next iteration */
> +	/* clear the per iteration state */
>  	iter->processed = 0;
>  	memset(&iter->iomap, 0, sizeof(iter->iomap));
>  	memset(&iter->srcmap, 0, sizeof(iter->srcmap));
> -	return 1;
> +	return ret;
>  }
>  
>  static inline void iomap_iter_done(struct iomap_iter *iter)
> -- 
> 2.47.0
> 
>