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

[Kefeng Wang <wangkefeng.wang@huawei.com>]

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@huawei.com>
>> ---
>>   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.
> .