dma-contiguous: page-align the size in dma_free_contiguous()

According to the original dma_direct_alloc_pages() code:
{
	unsigned int count = PAGE_ALIGN(size) >> PAGE_SHIFT;

	if (!dma_release_from_contiguous(dev, page, count))
		__free_pages(page, get_order(size));
}

The count parameter for dma_release_from_contiguous() was page
aligned before the right-shifting operation, while the new API
dma_free_contiguous() forgets to have PAGE_ALIGN() at the size.

So this patch simply adds it to prevent any corner case.

Fixes: fdaeec198ada ("dma-contiguous: add dma_{alloc,free}_contiguous() helpers")
Signed-off-by: Nicolin Chen <nicoleotsuka@gmail.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christoph Hellwig <hch@lst.de>

kernel/dma/contiguous.c

@@ -267,7 +267,8 @@ struct page *dma_alloc_contiguous(struct device *dev, size_t size, gfp_t gfp)
  */
 void dma_free_contiguous(struct device *dev, struct page *page, size_t size)
 {
-	if (!cma_release(dev_get_cma_area(dev), page, size >> PAGE_SHIFT))
+	if (!cma_release(dev_get_cma_area(dev), page,
+			 PAGE_ALIGN(size) >> PAGE_SHIFT))
 		__free_pages(page, get_order(size));
 }