Re: [PATCH] mm: simplify swapdev_block

["Rafael J. Wysocki" <rjw@rjwysocki.net>]

On Tuesday, February 9, 2021 6:14:19 PM CET Christoph Hellwig wrote:
> Open code the parts of map_swap_entry that was actually used by
> swapdev_block, and remove the now unused map_swap_entry function.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>

Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

> ---
>  mm/swapfile.c | 30 +++---------------------------
>  1 file changed, 3 insertions(+), 27 deletions(-)
> 
> diff --git a/mm/swapfile.c b/mm/swapfile.c
> index 351999a84e6e4e..21a98cb8d646e3 100644
> --- a/mm/swapfile.c
> +++ b/mm/swapfile.c
> @@ -1790,9 +1790,6 @@ int free_swap_and_cache(swp_entry_t entry)
>  }
>  
>  #ifdef CONFIG_HIBERNATION
> -
> -static sector_t map_swap_entry(swp_entry_t, struct block_device**);
> -
>  /*
>   * Find the swap type that corresponds to given device (if any).
>   *
> @@ -1852,12 +1849,13 @@ int find_first_swap(dev_t *device)
>   */
>  sector_t swapdev_block(int type, pgoff_t offset)
>  {
> -	struct block_device *bdev;
>  	struct swap_info_struct *si = swap_type_to_swap_info(type);
> +	struct swap_extent *se;
>  
>  	if (!si || !(si->flags & SWP_WRITEOK))
>  		return 0;
> -	return map_swap_entry(swp_entry(type, offset), &bdev);
> +	se = offset_to_swap_extent(si, offset);
> +	return se->start_block + (offset - se->start_page);
>  }
>  
>  /*
> @@ -2283,28 +2281,6 @@ static void drain_mmlist(void)
>  	spin_unlock(&mmlist_lock);
>  }
>  
> -#ifdef CONFIG_HIBERNATION
> -/*
> - * Use this swapdev's extent info to locate the (PAGE_SIZE) block which
> - * corresponds to page offset for the specified swap entry.
> - * Note that the type of this function is sector_t, but it returns page offset
> - * into the bdev, not sector offset.
> - */
> -static sector_t map_swap_entry(swp_entry_t entry, struct block_device **bdev)
> -{
> -	struct swap_info_struct *sis;
> -	struct swap_extent *se;
> -	pgoff_t offset;
> -
> -	sis = swp_swap_info(entry);
> -	*bdev = sis->bdev;
> -
> -	offset = swp_offset(entry);
> -	se = offset_to_swap_extent(sis, offset);
> -	return se->start_block + (offset - se->start_page);
> -}
> -#endif
> -
>  /*
>   * Free all of a swapdev's extent information
>   */
>