--- zzzz-none-000/linux-3.10.107/drivers/xen/biomerge.c	2017-06-27 09:49:32.000000000 +0000
+++ scorpion-7490-727/linux-3.10.107/drivers/xen/biomerge.c	2021-02-04 17:41:59.000000000 +0000
@@ -6,10 +6,18 @@
 bool xen_biovec_phys_mergeable(const struct bio_vec *vec1,
 			       const struct bio_vec *vec2)
 {
-	unsigned long mfn1 = pfn_to_mfn(page_to_pfn(vec1->bv_page));
-	unsigned long mfn2 = pfn_to_mfn(page_to_pfn(vec2->bv_page));
+#if XEN_PAGE_SIZE == PAGE_SIZE
+	unsigned long bfn1 = pfn_to_bfn(page_to_pfn(vec1->bv_page));
+	unsigned long bfn2 = pfn_to_bfn(page_to_pfn(vec2->bv_page));
 
 	return __BIOVEC_PHYS_MERGEABLE(vec1, vec2) &&
-		((mfn1 == mfn2) || ((mfn1+1) == mfn2));
+		((bfn1 == bfn2) || ((bfn1+1) == bfn2));
+#else
+	/*
+	 * XXX: Add support for merging bio_vec when using different page
+	 * size in Xen and Linux.
+	 */
+	return 0;
+#endif
 }
 EXPORT_SYMBOL(xen_biovec_phys_mergeable);