mm/net: Rename and move page fragment handling from net/ to mm/

This change moves the __alloc_page_frag functionality out of the networking
stack and into the page allocation portion of mm.  The idea it so help make
this maintainable by placing it with other page allocation functions.

Since we are moving it from skbuff.c to page_alloc.c I have also renamed
the basic defines and structure from netdev_alloc_cache to page_frag_cache
to reflect that this is now part of a different kernel subsystem.

I have also added a simple __free_page_frag function which can handle
freeing the frags based on the skb->head pointer.  The model for this is
based off of __free_pages since we don't actually need to deal with all of
the cases that put_page handles.  I incorporated the virt_to_head_page call
and compound_order into the function as it actually allows for a signficant
size reduction by reducing code duplication.

Signed-off-by: Alexander Duyck <alexander.h.duyck@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 5 insertions, 0 deletions

diff --git a/include/linux/gfp.h b/include/linux/gfp.h
index 97a9373e61e8..70a7fee1efb3 100644
--- a/include/linux/gfp.h
+++ b/include/linux/gfp.h
@@ -366,6 +366,11 @@ extern void free_pages(unsigned long addr, unsigned int order);
 extern void free_hot_cold_page(struct page *page, bool cold);
 extern void free_hot_cold_page_list(struct list_head *list, bool cold);
 
+struct page_frag_cache;
+extern void *__alloc_page_frag(struct page_frag_cache *nc,
+			       unsigned int fragsz, gfp_t gfp_mask);
+extern void __free_page_frag(void *addr);
+
 extern void __free_kmem_pages(struct page *page, unsigned int order);
 extern void free_kmem_pages(unsigned long addr, unsigned int order);