Re: [PATCH v10 28/33] mm/filemap: Add folio_wait_bit

[Vlastimil Babka]

On 5/11/21 11:47 PM, Matthew Wilcox (Oracle) wrote:
> Rename wait_on_page_bit() to folio_wait_bit().  We must always wait on
> the folio, otherwise we won't be woken up due to the tail page hashing
> to a different bucket from the head page.
> 
> This commit shrinks the kernel by 691 bytes, mostly due to moving
> the page waitqueue lookup into folio_wait_bit_common().
> 
> Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
> Reviewed-by: Christoph Hellwig <hch@xxxxxx>
> Acked-by: Jeff Layton <jlayton@xxxxxxxxxx>


Acked-by: Vlastimil Babka <vbabka@xxxxxxx>


Nit below.

> ---
>  include/linux/pagemap.h | 10 +++---
>  mm/filemap.c            | 77 +++++++++++++++++++----------------------
>  mm/page-writeback.c     |  4 +--
>  3 files changed, 43 insertions(+), 48 deletions(-)
> 
> diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
> index 06b69cd03da3..e524e1b7190a 100644
> --- a/include/linux/pagemap.h
> +++ b/include/linux/pagemap.h
> @@ -714,11 +714,11 @@ static inline int lock_page_or_retry(struct page *page, struct mm_struct *mm,
>  }
>  
>  /*
> - * This is exported only for wait_on_page_locked/wait_on_page_writeback, etc.,
> + * This is exported only for folio_wait_locked/folio_wait_writeback, etc.,
>   * and should not be used directly.
>   */
> -extern void wait_on_page_bit(struct page *page, int bit_nr);
> -extern int wait_on_page_bit_killable(struct page *page, int bit_nr);
> +extern void folio_wait_bit(struct folio *folio, int bit_nr);
> +extern int folio_wait_bit_killable(struct folio *folio, int bit_nr);

Nit: you remove these 'externs' in other patches, not here?