>From 86bf3c9eb5ce43280224f9271a4ad016b0dd3fb1 Mon Sep 17 00:00:00 2001
From: Anthony Liguori <address@hidden>
Date: Fri, 29 Oct 2010 09:36:53 -0500
Subject: [PATCH 1/2] block: make bdrv_flush() fall back to bdrv_aio_flush

Signed-off-by: Anthony Liguori <address@hidden>

diff --git a/block.c b/block.c
index 985d0b7..fc8defd 100644
--- a/block.c
+++ b/block.c
@@ -1453,14 +1453,51 @@ const char *bdrv_get_device_name(BlockDriverState *bs)
     return bs->device_name;
 }
 
+static void bdrv_flush_em_cb(void *opaque, int ret)
+{
+    int *pcomplete = opaque;
+    *pcomplete = 1;
+}
+
+static void bdrv_flush_em(BlockDriverState *bs)
+{
+    int complete = 0;
+    BlockDriverAIOCB *acb;
+
+    if (!bs->drv->bdrv_aio_flush) {
+        return;
+    }
+
+    async_context_push();
+
+    acb = bs->drv->bdrv_aio_flush(bs, bdrv_flush_em_cb, &complete);
+    if (!acb) {
+        goto out;
+    }
+
+    while (!complete) {
+        qemu_aio_wait();
+    }
+
+out:
+    async_context_pop();
+}
+
 void bdrv_flush(BlockDriverState *bs)
 {
     if (bs->open_flags & BDRV_O_NO_FLUSH) {
         return;
     }
 
-    if (bs->drv && bs->drv->bdrv_flush)
+    if (!bs->drv) {
+        return;
+    }
+
+    if (bs->drv->bdrv_flush) {
         bs->drv->bdrv_flush(bs);
+    } else {
+        bdrv_flush_em(bs);
+    }
 }
 
 void bdrv_flush_all(void)
-- 
1.7.0.4