[dm-devel] [PATCH 2/5] s390, dax: Add dax zero_page_range operation to dcssblk driver

[Christoph Hellwig]

> diff --git a/drivers/s390/block/dcssblk.c b/drivers/s390/block/dcssblk.c
> index 63502ca537eb..f6709200bcd0 100644
> --- a/drivers/s390/block/dcssblk.c
> +++ b/drivers/s390/block/dcssblk.c
> @@ -62,6 +62,7 @@ static const struct dax_operations dcssblk_dax_ops = {
>  	.dax_supported = generic_fsdax_supported,
>  	.copy_from_iter = dcssblk_dax_copy_from_iter,
>  	.copy_to_iter = dcssblk_dax_copy_to_iter,
> +	.zero_page_range = dcssblk_dax_zero_page_range,
>  };
>  
>  struct dcssblk_dev_info {
> @@ -941,6 +942,12 @@ dcssblk_dax_direct_access(struct dax_device *dax_dev, pgoff_t pgoff,
>  	return __dcssblk_direct_access(dev_info, pgoff, nr_pages, kaddr, pfn);
>  }
>  
> +static int dcssblk_dax_zero_page_range(struct dax_device *dax_dev,pgoff_t pgoff,
> +				       unsigned offset, size_t len)
> +{
> +	return generic_dax_zero_page_range(dax_dev, pgoff, offset, len);
> +}

Wouldn't this need a forward declaration?  Then again given that dcssblk
is the only caller of generic_dax_zero_page_range we might as well merge
the two.  If you want to keep the generic one it could be wired up to
dcssblk_dax_ops directly, though.