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Date:   Thu, 15 Oct 2020 10:49:01 +0100
From:   Christoph Hellwig <hch@infradead.org>
To:     Brian Foster <bfoster@redhat.com>
Cc:     linux-fsdevel@vger.kernel.org, linux-xfs@vger.kernel.org
Subject: Re: [PATCH 2/2] iomap: zero cached pages over unwritten extents on
 zero range
Message-ID: <20201015094901.GC21420@infradead.org>
References: <20201012140350.950064-1-bfoster@redhat.com>
 <20201012140350.950064-3-bfoster@redhat.com>
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> +iomap_zero_range_skip_uncached(struct inode *inode, loff_t *pos,
> +		loff_t *count, loff_t *written)
> +{
> +	unsigned dirty_offset, bytes = 0;
> +
> +	dirty_offset = page_cache_seek_hole_data(inode, *pos, *count,
> +				SEEK_DATA);
> +	if (dirty_offset == -ENOENT)
> +		bytes = *count;
> +	else if (dirty_offset > *pos)
> +		bytes = dirty_offset - *pos;
> +
> +	if (bytes) {
> +		*pos += bytes;
> +		*count -= bytes;
> +		*written += bytes;
> +	}

I find the calling conventions weird.  why not return bytes and
keep the increments/decrements of the three variables in the caller?