Re: [PATCH v1 04/11] mm: migrate: remove migrate_folio_extra()

[Kefeng Wang <wangkefeng.wang@xxxxxxxxxx>]

On 2024/4/16 20:40, Miaohe Lin wrote:
> On 2024/3/21 11:27, Kefeng Wang wrote:
> > The migrate_folio_extra() only called in migrate.c now, convert it
> > a static function and take a new src_private argument which could
> > be shared by migrate_folio() and filemap_migrate_folio() to simplify
> > code a bit.
> >
> > Signed-off-by: Kefeng Wang <wangkefeng.wang@xxxxxxxxxx>
> > ---
> >   include/linux/migrate.h |  2 --
> >   mm/migrate.c            | 33 +++++++++++----------------------
> >   2 files changed, 11 insertions(+), 24 deletions(-)
> >
> > diff --git a/include/linux/migrate.h b/include/linux/migrate.h
> > index 2ce13e8a309b..517f70b70620 100644
> > --- a/include/linux/migrate.h
> > +++ b/include/linux/migrate.h
> > @@ -63,8 +63,6 @@ extern const char *migrate_reason_names[MR_TYPES];
> >   #ifdef CONFIG_MIGRATION
> >   
> >   void putback_movable_pages(struct list_head *l);
> > -int migrate_folio_extra(struct address_space *mapping, struct folio *dst,
> > -		struct folio *src, enum migrate_mode mode, int extra_count);
> >   int migrate_folio(struct address_space *mapping, struct folio *dst,
> >   		struct folio *src, enum migrate_mode mode);
> >   int migrate_pages(struct list_head *l, new_folio_t new, free_folio_t free,
> > diff --git a/mm/migrate.c b/mm/migrate.c
> > index cb4cbaa42a35..c006b0b44013 100644
> > --- a/mm/migrate.c
> > +++ b/mm/migrate.c
> > @@ -658,18 +658,19 @@ EXPORT_SYMBOL(folio_migrate_copy);
> >    *                    Migration functions
> >    ***********************************************************/
> >   
> > -int migrate_folio_extra(struct address_space *mapping, struct folio *dst,
> > -		struct folio *src, enum migrate_mode mode, int extra_count)
> > +static int __migrate_folio(struct address_space *mapping, struct folio *dst,
> > +			   struct folio *src, void *src_private,
> > +			   enum migrate_mode mode)
> >   {
> >   	int rc;
> >   
> > -	BUG_ON(folio_test_writeback(src));	/* Writeback must be complete */
> > -
> > -	rc = folio_migrate_mapping(mapping, dst, src, extra_count);
> > -
> > +	rc = folio_migrate_mapping(mapping, dst, src, 0);
> >   	if (rc != MIGRATEPAGE_SUCCESS)
> >   		return rc;
> >   
> > +	if (src_private)
>
> src_private seems unneeded. It can be replaced with folio_get_private(src)?

__migrate_folio() is used by migrate_folio() and filemap_migrate_folio(),
but migrate_folio() is for LRU folio, when swapcache folio, the
folio->private is handled from folio_migrate_mapping(), we should not
try to call folio_detach_private/folio_attach_private().

> Thanks.
> .