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Date:   Thu, 9 Sep 2021 12:17:58 +0100
From:   Christoph Hellwig <hch@infradead.org>
To:     Andreas Gruenbacher <agruenba@redhat.com>
Cc:     Linus Torvalds <torvalds@linux-foundation.org>,
        Alexander Viro <viro@zeniv.linux.org.uk>,
        Christoph Hellwig <hch@infradead.org>,
        "Darrick J. Wong" <djwong@kernel.org>, Jan Kara <jack@suse.cz>,
        Matthew Wilcox <willy@infradead.org>, cluster-devel@redhat.com,
        linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
        ocfs2-devel@oss.oracle.com
Subject: Re: [PATCH v7 14/19] iomap: Fix iomap_dio_rw return value for user
 copies
Message-ID: <YTntZj0T3pWhApoe@infradead.org>
References: <20210827164926.1726765-1-agruenba@redhat.com>
 <20210827164926.1726765-15-agruenba@redhat.com>
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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@redhat.com>
> ---
>  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@lst.de>