Keeping the existing API is transitional; we do not want to refactor all
the current drivers using the page pool at once.

The netmem abstraction is currently a no-op. The page_pool uses
page_to_netmem() to convert allocated pages to netmem, and uses
netmem_to_page() to convert the netmem back to pages to pass to mm APIs,

Follow up patches to this series add non-paged netmem support to the
page_pool. This change is factored out on its own to limit the code
churn to this 1 patch, for ease of code review.

Signed-off-by: Mina Almasry <redacted>
  #endif /* _NET_NETMEM_H */

diff --git a/include/net/page_pool/helpers.h b/include/net/page_pool/helpers.h
index 873631c79ab16..5e129d5304f53 100644
--- a/include/net/page_pool/helpers.h
+++ b/include/net/page_pool/helpers.h

@@ -55,6 +55,8 @@
  #include <linux/dma-mapping.h>
  
  #include <net/page_pool/types.h>
+#include <net/net_debug.h>
+#include <net/netmem.h>
  
  #ifdef CONFIG_PAGE_POOL_STATS
  /* Deprecated driver-facing API, use netlink instead */

@@ -103,7 +105,7 @@ static inline struct page *page_pool_dev_alloc_pages(struct page_pool *pool)
   * Get a page fragment from the page allocator or page_pool caches.
   *
   * Return:
- * Return allocated page fragment, otherwise return NULL.
+ * Return allocated page fragment, otherwise return 0.

  static inline void *page_pool_alloc_va(struct page_pool *pool,

@@ -172,7 +174,8 @@ static inline void *page_pool_alloc_va(struct page_pool *pool,
  	struct page *page;
  
  	/* Mask off __GFP_HIGHMEM to ensure we can use page_address() */
-	page = page_pool_alloc(pool, &offset, size, gfp & ~__GFP_HIGHMEM);
+	page = netmem_to_page(
+		page_pool_alloc(pool, &offset, size, gfp & ~__GFP_HIGHMEM));
  	if (unlikely(!page))
  		return NULL;
  

@@ -189,7 +192,7 @@ static inline void *page_pool_alloc_va(struct page_pool *pool,
   * it returns va of the allocated page or page fragment.
   *
   * Return:
- * Return the va for the allocated page or page fragment, otherwise return NULL.
+ * Return the va for the allocated page or page fragment, otherwise return 0.

   */
  static inline void *page_pool_dev_alloc_va(struct page_pool *pool,
  					   unsigned int *size)

@@ -212,6 +215,11 @@ page_pool_get_dma_dir(const struct page_pool *pool)
  	return pool->p.dma_dir;
  }
  
+static inline void page_pool_fragment_netmem(netmem_ref netmem, long nr)
+{
+	atomic_long_set(&netmem_to_page(netmem)->pp_ref_count, nr);
+}