linux-kernel - Re: [PATCH v5 11/12] mm: drop page_index and simplify folio

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Date: Sat, 11 May 2024 13:39:50 +0800
From: "Huang, Ying" <ying.huang@...el.com>
To: Kairui Song <ryncsn@...il.com>
Cc: linux-mm@...ck.org,  Kairui Song <kasong@...cent.com>,  Andrew Morton
 <akpm@...ux-foundation.org>,  Matthew Wilcox <willy@...radead.org>,  Chris
 Li <chrisl@...nel.org>,  Barry Song <v-songbaohua@...o.com>,  Ryan Roberts
 <ryan.roberts@....com>,  Neil Brown <neilb@...e.de>,  Minchan Kim
 <minchan@...nel.org>,  David Hildenbrand <david@...hat.com>,  Hugh Dickins
 <hughd@...gle.com>,  Yosry Ahmed <yosryahmed@...gle.com>,
  linux-fsdevel@...r.kernel.org,  linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 11/12] mm: drop page_index and simplify folio_index

Kairui Song <ryncsn@...il.com> writes:

> From: Kairui Song <kasong@...cent.com>
>
> There are two helpers for retrieving the index within address space
> for mixed usage of swap cache and page cache:
>
> - page_index
> - folio_index
>
> This commit drops page_index, as we have eliminated all users, and
> converts folio_index's helper __page_file_index to use folio to avoid
> the page convertion.
>
> Signed-off-by: Kairui Song <kasong@...cent.com>

LGTM, Thanks!

Reviewed-by: "Huang, Ying" <ying.huang@...el.com>

> ---
>  include/linux/mm.h      | 13 -------------
>  include/linux/pagemap.h |  8 ++++----
>  mm/swapfile.c           |  7 +++----
>  3 files changed, 7 insertions(+), 21 deletions(-)
>
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index 9849dfda44d4..e2718cac0fda 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -2290,19 +2290,6 @@ static inline void *folio_address(const struct folio *folio)
>  	return page_address(&folio->page);
>  }
>  
> -extern pgoff_t __page_file_index(struct page *page);
> -
> -/*
> - * Return the pagecache index of the passed page.  Regular pagecache pages
> - * use ->index whereas swapcache pages use swp_offset(->private)
> - */
> -static inline pgoff_t page_index(struct page *page)
> -{
> -	if (unlikely(PageSwapCache(page)))
> -		return __page_file_index(page);
> -	return page->index;
> -}
> -
>  /*
>   * Return true only if the page has been allocated with
>   * ALLOC_NO_WATERMARKS and the low watermark was not
> diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
> index a324582ea702..0cfa5810cde3 100644
> --- a/include/linux/pagemap.h
> +++ b/include/linux/pagemap.h
> @@ -778,7 +778,7 @@ static inline struct page *grab_cache_page_nowait(struct address_space *mapping,
>  			mapping_gfp_mask(mapping));
>  }
>  
> -#define swapcache_index(folio)	__page_file_index(&(folio)->page)
> +extern pgoff_t __folio_swap_cache_index(struct folio *folio);
>  
>  /**
>   * folio_index - File index of a folio.
> @@ -793,9 +793,9 @@ static inline struct page *grab_cache_page_nowait(struct address_space *mapping,
>   */
>  static inline pgoff_t folio_index(struct folio *folio)
>  {
> -        if (unlikely(folio_test_swapcache(folio)))
> -                return swapcache_index(folio);
> -        return folio->index;
> +	if (unlikely(folio_test_swapcache(folio)))
> +		return __folio_swap_cache_index(folio);
> +	return folio->index;
>  }
>  
>  /**
> diff --git a/mm/swapfile.c b/mm/swapfile.c
> index f6ca215fb92f..0b0ae6e8c764 100644
> --- a/mm/swapfile.c
> +++ b/mm/swapfile.c
> @@ -3474,12 +3474,11 @@ struct address_space *swapcache_mapping(struct folio *folio)
>  }
>  EXPORT_SYMBOL_GPL(swapcache_mapping);
>  
> -pgoff_t __page_file_index(struct page *page)
> +pgoff_t __folio_swap_cache_index(struct folio *folio)
>  {
> -	swp_entry_t swap = page_swap_entry(page);
> -	return swp_offset(swap);
> +	return swp_offset(folio->swap);
>  }
> -EXPORT_SYMBOL_GPL(__page_file_index);
> +EXPORT_SYMBOL_GPL(__folio_swap_cache_index);
>  
>  /*
>   * add_swap_count_continuation - called when a swap count is duplicated