Re: [RFC PATCH 08/10] fsverity: Add call back to verify file holes

[Eric Biggers <ebiggers@kernel.org>]

On Mon, Feb 18, 2019 at 03:34:31PM +0530, Chandan Rajendra wrote:
> readpage() implmentations zero out part of the page-cache page mapping a
> file hole. This commit adds a call back to "struct fsverity_operations"
> which readpage() can invoke to verify the file hole.

I don't see why this is needed.  Since now CONFIG_FS_VERITY will be a bool,
can't you just call fsverity_verify_hole() directly?

> 
> Signed-off-by: Chandan Rajendra <chandan@linux.ibm.com>
> ---
>  fs/ext4/super.c          | 1 +
>  include/linux/fsverity.h | 1 +
>  2 files changed, 2 insertions(+)
> 
> diff --git a/fs/ext4/super.c b/fs/ext4/super.c
> index 4493ddc357c6..94e0d4b56653 100644
> --- a/fs/ext4/super.c
> +++ b/fs/ext4/super.c
> @@ -1459,6 +1459,7 @@ static const struct fsverity_operations ext4_verityops = {
>  	.read_metadata_page	= ext4_read_verity_metadata_page,
>  	.verity_required	= ext4_verity_required,
>  	.readpage_limit		= ext4_readpage_limit,
> +	.check_hole		= fsverity_check_hole,
>  };
>  #endif /* CONFIG_FS_VERITY */
>  
> diff --git a/include/linux/fsverity.h b/include/linux/fsverity.h
> index fc8113acbbfe..8bc28b07d550 100644
> --- a/include/linux/fsverity.h
> +++ b/include/linux/fsverity.h
> @@ -20,6 +20,7 @@ struct fsverity_operations {
>  	struct page *(*read_metadata_page)(struct inode *inode, pgoff_t index);
>  	bool (*verity_required)(struct inode *inode, pgoff_t index);
>  	loff_t (*readpage_limit)(struct inode *inode);
> +	bool (*check_hole)(struct inode *inode, struct page *page);
>  };
>  
>  #ifdef CONFIG_FS_VERITY
> -- 
> 2.19.1
>