swiotlb: map_page fix for highmem systems

The current code calls virt_to_phys() on address that might
be in highmem, which is bad.  This wasn't needed, anyway, because
we already have the physical address we need.

Get rid of the now-unused virtual address as well.
Signed-off-by: Becky Bruce <beckyb@kernel.crashing.org>
Acked-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
Cc: jeremy@goop.org
Cc: ian.campbell@citrix.com
LKML-Reference: <1239199761-22886-4-git-send-email-galak@kernel.crashing.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

lib/swiotlb.c

@@ -640,7 +640,6 @@ dma_addr_t swiotlb_map_page(struct device *dev, struct page *page,
 			    struct dma_attrs *attrs)
 {
 	phys_addr_t phys = page_to_phys(page) + offset;
-	void *ptr = page_address(page) + offset;
 	dma_addr_t dev_addr = swiotlb_phys_to_bus(dev, phys);
 	void *map;
 
@@ -651,7 +650,7 @@ dma_addr_t swiotlb_map_page(struct device *dev, struct page *page,
 	 * buffering it.
 	 */
 	if (!address_needs_mapping(dev, dev_addr, size) &&
-	    !range_needs_mapping(virt_to_phys(ptr), size))
+	    !range_needs_mapping(phys, size))
 		return dev_addr;
 
 	/*