Re: [PATCH v8 12/15] filemap: Remove checks in mapping_set_folio_order_range()

[jane.chu@oracle.com]

On 7/31/2026 1:07 PM, Matthew Wilcox (Oracle) wrote:
> These checks make it impossible to use mapping_set_folio_order_range() 
> in hugetlb. They add very little value and can simply be removed. 
> Signed-off-by: Matthew Wilcox (Oracle) <willy@ infradead. org> --- 
> include/linux/pagemap. h | 34 ++++++++++++++--------------------
> 
> 
> These checks make it impossible to use mapping_set_folio_order_range()
> in hugetlb.  They add very little value and can simply be removed.
> 
> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
> ---
>   include/linux/pagemap.h | 34 ++++++++++++++--------------------
>   1 file changed, 14 insertions(+), 20 deletions(-)
> 
> diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
> index 2c3718d592d6..968b791cfd14 100644
> --- a/include/linux/pagemap.h
> +++ b/include/linux/pagemap.h
> @@ -373,7 +373,7 @@ static inline void mapping_set_gfp_mask(struct address_space *m, gfp_t mask)
>    * assumptions about maximum order if THP are disabled, but 8 seems like
>    * a good order (that's 1MB if you're using 4kB pages)
>    */
> -#ifdef CONFIG_TRANSPARENT_HUGEPAGE
> +#ifdef CONFIG_LARGE_FOLIO
>   #define PREFERRED_MAX_PAGECACHE_ORDER	HPAGE_PMD_ORDER
>   #else
>   #define PREFERRED_MAX_PAGECACHE_ORDER	8
> @@ -394,7 +394,7 @@ static inline void mapping_set_gfp_mask(struct address_space *m, gfp_t mask)
>    */
>   static inline size_t mapping_max_folio_size_supported(void)
>   {
> -	if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE))
> +	if (IS_ENABLED(CONFIG_LARGE_FOLIO))
>   		return 1U << (PAGE_SHIFT + MAX_PAGECACHE_ORDER);
>   	return PAGE_SIZE;
>   }
> @@ -405,29 +405,23 @@ static inline size_t mapping_max_folio_size_supported(void)
>    * @min: Minimum folio order (between 0-MAX_PAGECACHE_ORDER inclusive).
>    * @max: Maximum folio order (between @min-MAX_PAGECACHE_ORDER inclusive).
>    *
> - * The filesystem should call this function in its inode constructor to
> - * indicate which base size (min) and maximum size (max) of folio the VFS
> - * can use to cache the contents of the file.  This should only be used
> - * if the filesystem needs special handling of folio sizes (ie there is
> - * something the core cannot know).
> + * The filesystem should call this function in its inode constructor
> + * to indicate which size folios can be used to cache the contents of
> + * the inode.  This should only be used if the filesystem needs special
> + * handling of folio sizes (ie there is something the core cannot know).
>    * Do not tune it based on, eg, i_size.
>    *
> + * hugetlb calls this with orders larger than MAX_PAGECACHE_ORDER.
> + * Normal filesystems should not do this.
> + *
>    * Context: This should not be called while the inode is active as it
>    * is non-atomic.
>    */
>   static inline void mapping_set_folio_order_range(struct address_space *mapping,
> -						 unsigned int min,
> -						 unsigned int max)
> +		unsigned int min, unsigned int max)
>   {
> -	if (!IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE))
> +	if (!IS_ENABLED(CONFIG_LARGE_FOLIO))
>   		return;
> -
> -	if (min > MAX_PAGECACHE_ORDER)
> -		min = MAX_PAGECACHE_ORDER;
> -
> -	if (max > MAX_PAGECACHE_ORDER)
> -		max = MAX_PAGECACHE_ORDER;
> -
>   	if (max < min)
>   		max = min;
>   
> @@ -460,7 +454,7 @@ static inline void mapping_set_large_folios(struct address_space *mapping)
>   static inline unsigned int
>   mapping_max_folio_order(const struct address_space *mapping)
>   {
> -	if (!IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE))
> +	if (!IS_ENABLED(CONFIG_LARGE_FOLIO))
>   		return 0;
>   	return (mapping->flags & AS_FOLIO_ORDER_MAX_MASK) >> AS_FOLIO_ORDER_MAX;
>   }
> @@ -468,7 +462,7 @@ mapping_max_folio_order(const struct address_space *mapping)
>   static inline unsigned int
>   mapping_min_folio_order(const struct address_space *mapping)
>   {
> -	if (!IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE))
> +	if (!IS_ENABLED(CONFIG_LARGE_FOLIO))
>   		return 0;
>   	return (mapping->flags & AS_FOLIO_ORDER_MIN_MASK) >> AS_FOLIO_ORDER_MIN;
>   }
> @@ -524,7 +518,7 @@ static inline bool mapping_large_folio_support(const struct address_space *mappi
>    *
>    * Return: True if PMD-sized folios are supported, otherwise false.
>    */
> -#ifdef CONFIG_TRANSPARENT_HUGEPAGE
> +#ifdef CONFIG_LARGE_FOLIO
>   static inline bool mapping_pmd_folio_support(const struct address_space *mapping)
>   {
>   	/* AS_FOLIO_ORDER is only reasonable for pagecache folios */
> -- 
> 2.47.3
> 

Nice.
Reviewed-by: Jane Chu <jane.chu@oracle.com>

thanks,
-jane