diff mbox series

[2/2] dax: Use folios more widely within DAX

Message ID 20241216155408.8102-2-willy@infradead.org
State New
Headers show
Series [1/2] dax: Remove access to page->index | expand

Commit Message

Matthew Wilcox (Oracle) Dec. 16, 2024, 3:53 p.m. UTC 
Convert from pfn to folio instead of page and use those folios
throughout to avoid accesses to page->index and page->mapping.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
 fs/dax.c | 53 +++++++++++++++++++++++++++--------------------------
 1 file changed, 27 insertions(+), 26 deletions(-)

Comments

Jane Chu Dec. 16, 2024, 5:49 p.m. UTC | #1 
On 12/16/2024 7:53 AM, Matthew Wilcox (Oracle) wrote:

> Convert from pfn to folio instead of page and use those folios
> throughout to avoid accesses to page->index and page->mapping.
>
> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
> ---
>   fs/dax.c | 53 +++++++++++++++++++++++++++--------------------------
>   1 file changed, 27 insertions(+), 26 deletions(-)
>
> diff --git a/fs/dax.c b/fs/dax.c
> index 21b47402b3dc..972febc6fb9d 100644
> --- a/fs/dax.c
> +++ b/fs/dax.c
> @@ -320,38 +320,39 @@ static unsigned long dax_end_pfn(void *entry)
>   	for (pfn = dax_to_pfn(entry); \
>   			pfn < dax_end_pfn(entry); pfn++)
>   
> -static inline bool dax_page_is_shared(struct page *page)
> +static inline bool dax_folio_is_shared(struct folio *folio)
>   {
> -	return page->mapping == PAGE_MAPPING_DAX_SHARED;
> +	return folio->mapping == PAGE_MAPPING_DAX_SHARED;
>   }
>   
>   /*
> - * Set the page->mapping with PAGE_MAPPING_DAX_SHARED flag, increase the
> + * Set the folio->mapping with PAGE_MAPPING_DAX_SHARED flag, increase the
>    * refcount.
>    */
> -static inline void dax_page_share_get(struct page *page)
> +static inline void dax_folio_share_get(struct folio *folio)
>   {
> -	if (page->mapping != PAGE_MAPPING_DAX_SHARED) {
> +	if (folio->mapping != PAGE_MAPPING_DAX_SHARED) {
>   		/*
>   		 * Reset the index if the page was already mapped
>   		 * regularly before.
>   		 */
> -		if (page->mapping)
> -			page->share = 1;
> -		page->mapping = PAGE_MAPPING_DAX_SHARED;
> +		if (folio->mapping)
> +			folio->page.share = 1;
> +		folio->mapping = PAGE_MAPPING_DAX_SHARED;
>   	}
> -	page->share++;
> +	folio->page.share++;
>   }
>   
> -static inline unsigned long dax_page_share_put(struct page *page)
> +static inline unsigned long dax_folio_share_put(struct folio *folio)
>   {
> -	return --page->share;
> +	return --folio->page.share;
>   }
>   
>   /*
> - * When it is called in dax_insert_entry(), the shared flag will indicate that
> - * whether this entry is shared by multiple files.  If so, set the page->mapping
> - * PAGE_MAPPING_DAX_SHARED, and use page->share as refcount.
> + * When it is called in dax_insert_entry(), the shared flag will indicate
> + * that whether this entry is shared by multiple files.  If so, set
> + * the folio->mapping PAGE_MAPPING_DAX_SHARED, and use page->share
> + * as refcount.
>    */
>   static void dax_associate_entry(void *entry, struct address_space *mapping,
>   		struct vm_area_struct *vma, unsigned long address, bool shared)
> @@ -364,14 +365,14 @@ static void dax_associate_entry(void *entry, struct address_space *mapping,
>   
>   	index = linear_page_index(vma, address & ~(size - 1));
>   	for_each_mapped_pfn(entry, pfn) {
> -		struct page *page = pfn_to_page(pfn);
> +		struct folio *folio = pfn_folio(pfn);
>   
>   		if (shared) {
> -			dax_page_share_get(page);
> +			dax_folio_share_get(folio);
>   		} else {
> -			WARN_ON_ONCE(page->mapping);
> -			page->mapping = mapping;
> -			page->index = index + i++;
> +			WARN_ON_ONCE(folio->mapping);
> +			folio->mapping = mapping;
> +			folio->index = index + i++;
>   		}
>   	}
>   }
> @@ -385,17 +386,17 @@ static void dax_disassociate_entry(void *entry, struct address_space *mapping,
>   		return;
>   
>   	for_each_mapped_pfn(entry, pfn) {
> -		struct page *page = pfn_to_page(pfn);
> +		struct folio *folio = pfn_folio(pfn);
>   
> -		WARN_ON_ONCE(trunc && page_ref_count(page) > 1);
> -		if (dax_page_is_shared(page)) {
> +		WARN_ON_ONCE(trunc && folio_ref_count(folio) > 1);
> +		if (dax_folio_is_shared(folio)) {
>   			/* keep the shared flag if this page is still shared */
> -			if (dax_page_share_put(page) > 0)
> +			if (dax_folio_share_put(folio) > 0)
>   				continue;
>   		} else
> -			WARN_ON_ONCE(page->mapping && page->mapping != mapping);
> -		page->mapping = NULL;
> -		page->index = 0;
> +			WARN_ON_ONCE(folio->mapping && folio->mapping != mapping);
> +		folio->mapping = NULL;
> +		folio->index = 0;
>   	}
>   }
>   

Looks good.

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

-jane
Alistair Popple Dec. 16, 2024, 10:25 p.m. UTC | #2 
On Mon, Dec 16, 2024 at 03:53:56PM +0000, Matthew Wilcox (Oracle) wrote:
> Convert from pfn to folio instead of page and use those folios
> throughout to avoid accesses to page->index and page->mapping.
> 
> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
> ---
>  fs/dax.c | 53 +++++++++++++++++++++++++++--------------------------
>  1 file changed, 27 insertions(+), 26 deletions(-)
> 
> diff --git a/fs/dax.c b/fs/dax.c
> index 21b47402b3dc..972febc6fb9d 100644
> --- a/fs/dax.c
> +++ b/fs/dax.c
> @@ -320,38 +320,39 @@ static unsigned long dax_end_pfn(void *entry)
>  	for (pfn = dax_to_pfn(entry); \
>  			pfn < dax_end_pfn(entry); pfn++)
>  
> -static inline bool dax_page_is_shared(struct page *page)
> +static inline bool dax_folio_is_shared(struct folio *folio)
>  {
> -	return page->mapping == PAGE_MAPPING_DAX_SHARED;
> +	return folio->mapping == PAGE_MAPPING_DAX_SHARED;

This will conflict with my series which introduces compound ZONE_DEVICE
pages to free up a PTE bit and allow FS DAX pages to be refcounted
normally. The main change is here -
https://lore.kernel.org/ linux-mm/39a896451e59b735f205e34da5510ead5e4cd47d.1732239628.git-series.apopple@nvidia.com/

I'm hoping we can get that in linux-next "soon".

>  }
>  
>  /*
> - * Set the page->mapping with PAGE_MAPPING_DAX_SHARED flag, increase the
> + * Set the folio->mapping with PAGE_MAPPING_DAX_SHARED flag, increase the
>   * refcount.
>   */
> -static inline void dax_page_share_get(struct page *page)
> +static inline void dax_folio_share_get(struct folio *folio)
>  {
> -	if (page->mapping != PAGE_MAPPING_DAX_SHARED) {
> +	if (folio->mapping != PAGE_MAPPING_DAX_SHARED) {
>  		/*
>  		 * Reset the index if the page was already mapped
>  		 * regularly before.
>  		 */
> -		if (page->mapping)
> -			page->share = 1;
> -		page->mapping = PAGE_MAPPING_DAX_SHARED;
> +		if (folio->mapping)
> +			folio->page.share = 1;

It also moves the share accounting to the folio as well so we could remove the
whole page->index/share union once that's merged.

> +		folio->mapping = PAGE_MAPPING_DAX_SHARED;
>  	}
> -	page->share++;
> +	folio->page.share++;
>  }
>  
> -static inline unsigned long dax_page_share_put(struct page *page)
> +static inline unsigned long dax_folio_share_put(struct folio *folio)
>  {
> -	return --page->share;
> +	return --folio->page.share;
>  }
>  
>  /*
> - * When it is called in dax_insert_entry(), the shared flag will indicate that
> - * whether this entry is shared by multiple files.  If so, set the page->mapping
> - * PAGE_MAPPING_DAX_SHARED, and use page->share as refcount.
> + * When it is called in dax_insert_entry(), the shared flag will indicate
> + * that whether this entry is shared by multiple files.  If so, set
> + * the folio->mapping PAGE_MAPPING_DAX_SHARED, and use page->share
> + * as refcount.
>   */
>  static void dax_associate_entry(void *entry, struct address_space *mapping,
>  		struct vm_area_struct *vma, unsigned long address, bool shared)
> @@ -364,14 +365,14 @@ static void dax_associate_entry(void *entry, struct address_space *mapping,
>  
>  	index = linear_page_index(vma, address & ~(size - 1));
>  	for_each_mapped_pfn(entry, pfn) {
> -		struct page *page = pfn_to_page(pfn);
> +		struct folio *folio = pfn_folio(pfn);
>  
>  		if (shared) {
> -			dax_page_share_get(page);
> +			dax_folio_share_get(folio);
>  		} else {
> -			WARN_ON_ONCE(page->mapping);
> -			page->mapping = mapping;
> -			page->index = index + i++;
> +			WARN_ON_ONCE(folio->mapping);
> +			folio->mapping = mapping;
> +			folio->index = index + i++;
>  		}
>  	}
>  }
> @@ -385,17 +386,17 @@ static void dax_disassociate_entry(void *entry, struct address_space *mapping,
>  		return;
>  
>  	for_each_mapped_pfn(entry, pfn) {
> -		struct page *page = pfn_to_page(pfn);
> +		struct folio *folio = pfn_folio(pfn);
>  
> -		WARN_ON_ONCE(trunc && page_ref_count(page) > 1);
> -		if (dax_page_is_shared(page)) {
> +		WARN_ON_ONCE(trunc && folio_ref_count(folio) > 1);
> +		if (dax_folio_is_shared(folio)) {
>  			/* keep the shared flag if this page is still shared */
> -			if (dax_page_share_put(page) > 0)
> +			if (dax_folio_share_put(folio) > 0)
>  				continue;
>  		} else
> -			WARN_ON_ONCE(page->mapping && page->mapping != mapping);
> -		page->mapping = NULL;
> -		page->index = 0;
> +			WARN_ON_ONCE(folio->mapping && folio->mapping != mapping);
> +		folio->mapping = NULL;
> +		folio->index = 0;
>  	}
>  }
>  
> -- 
> 2.45.2
> 
>
diff mbox series

Patch

diff --git a/fs/dax.c b/fs/dax.c
index 21b47402b3dc..972febc6fb9d 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -320,38 +320,39 @@  static unsigned long dax_end_pfn(void *entry)
 	for (pfn = dax_to_pfn(entry); \
 			pfn < dax_end_pfn(entry); pfn++)
 
-static inline bool dax_page_is_shared(struct page *page)
+static inline bool dax_folio_is_shared(struct folio *folio)
 {
-	return page->mapping == PAGE_MAPPING_DAX_SHARED;
+	return folio->mapping == PAGE_MAPPING_DAX_SHARED;
 }
 
 /*
- * Set the page->mapping with PAGE_MAPPING_DAX_SHARED flag, increase the
+ * Set the folio->mapping with PAGE_MAPPING_DAX_SHARED flag, increase the
  * refcount.
  */
-static inline void dax_page_share_get(struct page *page)
+static inline void dax_folio_share_get(struct folio *folio)
 {
-	if (page->mapping != PAGE_MAPPING_DAX_SHARED) {
+	if (folio->mapping != PAGE_MAPPING_DAX_SHARED) {
 		/*
 		 * Reset the index if the page was already mapped
 		 * regularly before.
 		 */
-		if (page->mapping)
-			page->share = 1;
-		page->mapping = PAGE_MAPPING_DAX_SHARED;
+		if (folio->mapping)
+			folio->page.share = 1;
+		folio->mapping = PAGE_MAPPING_DAX_SHARED;
 	}
-	page->share++;
+	folio->page.share++;
 }
 
-static inline unsigned long dax_page_share_put(struct page *page)
+static inline unsigned long dax_folio_share_put(struct folio *folio)
 {
-	return --page->share;
+	return --folio->page.share;
 }
 
 /*
- * When it is called in dax_insert_entry(), the shared flag will indicate that
- * whether this entry is shared by multiple files.  If so, set the page->mapping
- * PAGE_MAPPING_DAX_SHARED, and use page->share as refcount.
+ * When it is called in dax_insert_entry(), the shared flag will indicate
+ * that whether this entry is shared by multiple files.  If so, set
+ * the folio->mapping PAGE_MAPPING_DAX_SHARED, and use page->share
+ * as refcount.
  */
 static void dax_associate_entry(void *entry, struct address_space *mapping,
 		struct vm_area_struct *vma, unsigned long address, bool shared)
@@ -364,14 +365,14 @@  static void dax_associate_entry(void *entry, struct address_space *mapping,
 
 	index = linear_page_index(vma, address & ~(size - 1));
 	for_each_mapped_pfn(entry, pfn) {
-		struct page *page = pfn_to_page(pfn);
+		struct folio *folio = pfn_folio(pfn);
 
 		if (shared) {
-			dax_page_share_get(page);
+			dax_folio_share_get(folio);
 		} else {
-			WARN_ON_ONCE(page->mapping);
-			page->mapping = mapping;
-			page->index = index + i++;
+			WARN_ON_ONCE(folio->mapping);
+			folio->mapping = mapping;
+			folio->index = index + i++;
 		}
 	}
 }
@@ -385,17 +386,17 @@  static void dax_disassociate_entry(void *entry, struct address_space *mapping,
 		return;
 
 	for_each_mapped_pfn(entry, pfn) {
-		struct page *page = pfn_to_page(pfn);
+		struct folio *folio = pfn_folio(pfn);
 
-		WARN_ON_ONCE(trunc && page_ref_count(page) > 1);
-		if (dax_page_is_shared(page)) {
+		WARN_ON_ONCE(trunc && folio_ref_count(folio) > 1);
+		if (dax_folio_is_shared(folio)) {
 			/* keep the shared flag if this page is still shared */
-			if (dax_page_share_put(page) > 0)
+			if (dax_folio_share_put(folio) > 0)
 				continue;
 		} else
-			WARN_ON_ONCE(page->mapping && page->mapping != mapping);
-		page->mapping = NULL;
-		page->index = 0;
+			WARN_ON_ONCE(folio->mapping && folio->mapping != mapping);
+		folio->mapping = NULL;
+		folio->index = 0;
 	}
 }