Re: [PATCH 1/2] xfs: don't catch dax+reflink inodes as corruption in verifier

["Darrick J. Wong" <darrick.wong@oracle.com>]

On Tue, Dec 01, 2020 at 01:16:09PM -0600, Eric Sandeen wrote:
> We don't yet support dax on reflinked files, but that is in the works.
> 
> Further, having the flag set does not automatically mean that the inode
> is actually "in the CPU direct access state," which depends on several
> other conditions in addition to the flag being set.
> 
> As such, we should not catch this as corruption in the verifier - simply
> not actually enabling S_DAX on reflinked files is enough for now.
> 
> Fixes: 4f435ebe7d04 ("xfs: don't mix reflink and DAX mode for now")
> Signed-off-by: Eric Sandeen <sandeen@redhat.com>
> ---
>  fs/xfs/libxfs/xfs_inode_buf.c | 4 ----
>  1 file changed, 4 deletions(-)
> 
> diff --git a/fs/xfs/libxfs/xfs_inode_buf.c b/fs/xfs/libxfs/xfs_inode_buf.c
> index c667c63f2cb0..4d7410e49db4 100644
> --- a/fs/xfs/libxfs/xfs_inode_buf.c
> +++ b/fs/xfs/libxfs/xfs_inode_buf.c
> @@ -547,10 +547,6 @@ xfs_dinode_verify(
>  	if ((flags2 & XFS_DIFLAG2_REFLINK) && (flags & XFS_DIFLAG_REALTIME))
>  		return __this_address;
>  
> -	/* don't let reflink and dax mix */
> -	if ((flags2 & XFS_DIFLAG2_REFLINK) && (flags2 & XFS_DIFLAG2_DAX))
> -		return __this_address;

If we're going to let in inodes with the DAX and REFLINK iflags set,
doesn't that mean that xfs_inode_should_enable_dax needs to return false
if REFLINK is set?

--D

> -
>  	/* COW extent size hint validation */
>  	fa = xfs_inode_validate_cowextsize(mp, be32_to_cpu(dip->di_cowextsize),
>  			mode, flags, flags2);
> -- 
> 2.17.0
>