[PATCH 15/20] balloon: Convert to migrate_folio

[Matthew Wilcox]

On Tue, Jun 07, 2022 at 09:36:21AM +0200, David Hildenbrand wrote:
> On 06.06.22 22:40, Matthew Wilcox (Oracle) wrote:
> >  const struct address_space_operations balloon_aops = {
> > -	.migratepage = balloon_page_migrate,
> > +	.migrate_folio = balloon_migrate_folio,
> >  	.isolate_page = balloon_page_isolate,
> >  	.putback_page = balloon_page_putback,
> >  };
> 
> I assume you're working on conversion of the other callbacks as well,
> because otherwise, this ends up looking a bit inconsistent and confusing :)

My intention was to finish converting aops for the next merge window.

However, it seems to me that we goofed back in 2016 by merging
commit bda807d44454.  isolate_page() and putback_page() should
never have been part of address_space_operations.

I'm about to embark on creating a new migrate_operations struct
for drivers to use that contains only isolate/putback/migrate.
No filesystem uses isolate/putback, so those can just be deleted.
Both migrate_operations & address_space_operations will contain a
migrate callback.