Re: [PATCH v7 14/19] iomap: Fix iomap_dio_rw return value for user copies

[Christoph Hellwig]

On Fri, Aug 27, 2021 at 06:49:21PM +0200, Andreas Gruenbacher wrote:
> When a user copy fails in one of the helpers of iomap_dio_rw, fail with
> -EFAULT instead of returning 0.  This matches what iomap_dio_bio_actor
> returns when it gets an -EFAULT from bio_iov_iter_get_pages.  With these
> changes, iomap_dio_actor now consistently fails with -EFAULT when a user
> page cannot be faulted in.
> 
> Signed-off-by: Andreas Gruenbacher <agruenba@xxxxxxxxxx>
> ---
>  fs/iomap/direct-io.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/iomap/direct-io.c b/fs/iomap/direct-io.c
> index 9398b8c31323..8054f5d6c273 100644
> --- a/fs/iomap/direct-io.c
> +++ b/fs/iomap/direct-io.c
> @@ -370,7 +370,7 @@ iomap_dio_hole_actor(loff_t length, struct iomap_dio *dio)
>  {
>  	length = iov_iter_zero(length, dio->submit.iter);
>  	dio->size += length;
> -	return length;
> +	return length ? length : -EFAULT;

What's wrong with a good old:

	if (!length)
		return -EFAULT;
	return length?

Besides this nit and the fact that the patch needs a reabse it looks
good to me:

Reviewed-by: Christoph Hellwig <hch@xxxxxx>