diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h
index ab87108..426c43d 100644
--- a/include/linux/dma-mapping.h
+++ b/include/linux/dma-mapping.h
@@ -128,6 +128,7 @@
 };
 
 extern const struct dma_map_ops dma_noop_ops;
+extern const struct dma_map_ops dma_virt_ops;
 
 #define DMA_BIT_MASK(n)	(((n) == 64) ? ~0ULL : ((1ULL<<(n))-1))