Re: [PATCH v3 23/28] xfs: don't allow to enable DAX on fs-verity sealsed inode

["Darrick J. Wong" <djwong@kernel.org>]

On Fri, Oct 06, 2023 at 08:49:17PM +0200, Andrey Albershteyn wrote:
> fs-verity doesn't support DAX. Forbid filesystem to enable DAX on
> inodes which already have fs-verity enabled. The opposite is checked
> when fs-verity is enabled, it won't be enabled if DAX is.

Why can't we allow S_DAX and S_VERITY at the same time?  Is there a
design problem that prohibits checking the verity data when we go to
copy the pmem to userspace or take a read fault, or is S_DAX support
simply not implemented?

--D

> 
> Signed-off-by: Andrey Albershteyn <aalbersh@redhat.com>
> ---
>  fs/xfs/xfs_iops.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/fs/xfs/xfs_iops.c b/fs/xfs/xfs_iops.c
> index 9f2d5c2505ae..3153767f0d6f 100644
> --- a/fs/xfs/xfs_iops.c
> +++ b/fs/xfs/xfs_iops.c
> @@ -1209,6 +1209,8 @@ xfs_inode_should_enable_dax(
>  		return false;
>  	if (!xfs_inode_supports_dax(ip))
>  		return false;
> +	if (ip->i_diflags2 & XFS_DIFLAG2_VERITY)
> +		return false;
>  	if (xfs_has_dax_always(ip->i_mount))
>  		return true;
>  	if (ip->i_diflags2 & XFS_DIFLAG2_DAX)
> -- 
> 2.40.1
>