Re: [PATCH] xfs: dax: facilitate EXPERIMENTAL warning for dax=inode case

[Eric Sandeen <sandeen@xxxxxxxxxxx>]

On 8/26/21 1:09 PM, Darrick J. Wong wrote:
> On Thu, Aug 26, 2021 at 12:30:12PM -0500, Bill O'Donnell wrote:

> > @@ -1584,7 +1586,7 @@ xfs_fs_fill_super(
> >   	if (xfs_has_crc(mp))
> >   		sb->s_flags |= SB_I_VERSION;
> >   
> > -	if (xfs_has_dax_always(mp)) {
> > +	if (xfs_has_dax_always(mp) || xfs_has_dax_inode(mp)) {
>
> Er... can't this be done without burning another feature bit by:
>
> 	if (xfs_has_dax_always(mp) || (!xfs_has_dax_always(mp) &&
> 				       !xfs_has_dax_never(mp))) {
> 		...
> 		xfs_warn(mp, "DAX IS EXPERIMENTAL");
> 	}

changing this conditional in this way will also fail dax=inode mounts on
reflink-capable (i.e. default) filesystems, no?

-	if (xfs_has_dax_always(mp)) {
+	if (xfs_has_dax_always(mp) || $NEW_DAX_INODE_TEST) {

...
                if (xfs_has_reflink(mp)) {
                        xfs_alert(mp,
                "DAX and reflink cannot be used together!");
                        error = -EINVAL;
                        goto out_filestream_unmount;
                }
        }

-Eric