Re: [PATCH v7 1/6] mm: split SWP_FILE into SWP_ACTIVATED and SWP_FS

[Omar Sandoval <osandov@osandov.com>]

On Wed, Sep 19, 2018 at 02:02:32PM -0400, Johannes Weiner wrote:
> On Tue, Sep 11, 2018 at 03:34:44PM -0700, Omar Sandoval wrote:
> > @@ -2411,8 +2412,10 @@ static int setup_swap_extents(struct swap_info_struct *sis, sector_t *span)
> >  
> >  	if (mapping->a_ops->swap_activate) {
> >  		ret = mapping->a_ops->swap_activate(sis, swap_file, span);
> > +		if (ret >= 0)
> > +			sis->flags |= SWP_ACTIVATED;
> >  		if (!ret) {
> > -			sis->flags |= SWP_FILE;
> > +			sis->flags |= SWP_FS;
> >  			ret = add_swap_extent(sis, 0, sis->max, 0);
> 
> Won't this single, linear extent be in conflict with the discontiguous
> extents you set up in your swap_activate callback in the last patch?

That's only in the case that ->swap_activate() returned 0, which only
nfs_swap_activate() will do. btrfs_swap_activate() and
iomap_swapfile_activate() both return the number of extents they set up.