Ocfs2 devel - Jun 2022 - [PATCH 15/20] balloon: Convert to migrate_folio

On 06.06.22 22:40, Matthew Wilcox (Oracle) wrote:
> This is little more than changing the types over; there's no real work
> being done in this function.
> 
> Signed-off-by: Matthew Wilcox (Oracle) <willy at infradead.org>
> ---
>  mm/balloon_compaction.c | 15 +++++++--------
>  1 file changed, 7 insertions(+), 8 deletions(-)
> 
> diff --git a/mm/balloon_compaction.c b/mm/balloon_compaction.c
> index 4b8eab4b3f45..3f75b876ad76 100644
> --- a/mm/balloon_compaction.c
> +++ b/mm/balloon_compaction.c
> @@ -230,11 +230,10 @@ static void balloon_page_putback(struct page *page)
>  
>  
>  /* move_to_new_page() counterpart for a ballooned page */
> -static int balloon_page_migrate(struct address_space *mapping,
> -		struct page *newpage, struct page *page,
> -		enum migrate_mode mode)
> +static int balloon_migrate_folio(struct address_space *mapping,
> +		struct folio *dst, struct folio *src, enum migrate_mode mode)
>  {
> -	struct balloon_dev_info *balloon = balloon_page_device(page);
> +	struct balloon_dev_info *balloon =
balloon_page_device(&src->page);
>  
>  	/*
>  	 * We can not easily support the no copy case here so ignore it as it
> @@ -244,14 +243,14 @@ static int balloon_page_migrate(struct address_space
*mapping,
>  	if (mode == MIGRATE_SYNC_NO_COPY)
>  		return -EINVAL;
>  
> -	VM_BUG_ON_PAGE(!PageLocked(page), page);
> -	VM_BUG_ON_PAGE(!PageLocked(newpage), newpage);
> +	VM_BUG_ON_FOLIO(!folio_test_locked(src), src);
> +	VM_BUG_ON_FOLIO(!folio_test_locked(dst), dst);
>  
> -	return balloon->migratepage(balloon, newpage, page, mode);
> +	return balloon->migratepage(balloon, &dst->page,
&src->page, mode);
>  }
>  
>  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 :)

Change LGTM.

-- 
Thanks,

David / dhildenb

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.