[NET] back: Remove unused rx_mmap area. Copying happens inside Xen, so

there is no need for a mapping area inside the driver for copying
receive path.
Signed-off-by: Keir Fraser <keir@xensource.com>

linux-2.6-xen-sparse/drivers/xen/netback/netback.c

@@ -73,8 +73,6 @@ static struct sk_buff_head rx_queue;
 static unsigned long mmap_vstart;
 #define MMAP_VADDR(_req) (mmap_vstart + ((_req) * PAGE_SIZE))
 
-static void *rx_mmap_area;
-
 #define PKT_PROT_LEN 64
 
 static struct {
@@ -1323,12 +1321,6 @@ static void netif_page_release(struct page *page)
 	netif_idx_release(pending_idx);
 }
 
-static void netif_rx_page_release(struct page *page)
-{
-	/* Ready for next use. */
-	set_page_count(page, 1);
-}
-
 irqreturn_t netif_be_int(int irq, void *dev_id, struct pt_regs *regs)
 {
 	netif_t *netif = dev_id;
@@ -1459,16 +1451,6 @@ static int __init netback_init(void)
 		SetPageForeign(page, netif_page_release);
 	}
 
-	page = balloon_alloc_empty_page_range(NET_RX_RING_SIZE);
-	BUG_ON(page == NULL);
-	rx_mmap_area = pfn_to_kaddr(page_to_pfn(page));
-
-	for (i = 0; i < NET_RX_RING_SIZE; i++) {
-		page = virt_to_page(rx_mmap_area + (i * PAGE_SIZE));
-		set_page_count(page, 1);
-		SetPageForeign(page, netif_rx_page_release);
-	}
-
 	pending_cons = 0;
 	pending_prod = MAX_PENDING_REQS;
 	for (i = 0; i < MAX_PENDING_REQS; i++)