net: Convert skb_frag_t to bio_vec

There are a lot of users of frag->page_offset, so use a union
to avoid converting those users today.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/bvec.h

@@ -18,7 +18,10 @@
 struct bio_vec {
 	struct page	*bv_page;
 	unsigned int	bv_len;
+	union {
+		__u32		page_offset;
 		unsigned int	bv_offset;
+	};
 };
 
 struct bvec_iter {

include/linux/skbuff.h

@@ -14,6 +14,7 @@
 #include <linux/compiler.h>
 #include <linux/time.h>
 #include <linux/bug.h>
+#include <linux/bvec.h>
 #include <linux/cache.h>
 #include <linux/rbtree.h>
 #include <linux/socket.h>
@@ -308,13 +309,7 @@ extern int sysctl_max_skb_frags;
  */
 #define GSO_BY_FRAGS	0xFFFF
 
-typedef struct skb_frag_struct skb_frag_t;
-
-struct skb_frag_struct {
-	struct page *bv_page;
-	unsigned int bv_len;
-	__u32 page_offset;
-};
+typedef struct bio_vec skb_frag_t;
 
 /**
  * skb_frag_size - Returns the size of a skb fragment