xen/ioemu-bdrv-open-CACHE_WB.patch

Index: xen-4.0.1-testing/tools/ioemu-qemu-xen/hw/xen_blktap.c
===================================================================
--- xen-4.0.1-testing.orig/tools/ioemu-qemu-xen/hw/xen_blktap.c
+++ xen-4.0.1-testing/tools/ioemu-qemu-xen/hw/xen_blktap.c
@@ -257,8 +257,11 @@ static int open_disk(struct td_state *s,
 	drv = blktap_drivers[i].drv;
 	DPRINTF("%s driver specified\n", drv ? drv->format_name : "No");
 
-	/* Open the image */
-	if (bdrv_open2(bs, path, flags, drv) != 0) {
+	/* Open the image
+         * Use BDRV_O_CACHE_WB for write-through caching,
+         * no flags for write-back caching
+         */
+	if (bdrv_open2(bs, path, flags|BDRV_O_CACHE_WB, drv) != 0) {
 		fprintf(stderr, "Could not open image file %s\n", path);
 		return -ENOMEM;
 	}