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From: Anthony Liguori <aliguori@us.ibm.com>
Date: Wed, 27 Oct 2010 14:44:09 -0500
Message-Id: <1288208649-27542-1-git-send-email-aliguori@us.ibm.com>
Subject: [Qemu-devel] [PATCH] block: fix the use of protocols in backing
	files (v2)
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To: qemu-devel@nongnu.org
Cc: Kevin Wolf <kwolf@redhat.com>, Anthony Liguori <aliguori@us.ibm.com>, Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>, Adam Litke <agl@us.ibm.com>

Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
---
v1 -> v2
 - Fix up CODING_STYLE of modified code

diff --git a/block.c b/block.c
index 1a965b2..029017e 100644
--- a/block.c
+++ b/block.c
@@ -603,10 +603,17 @@ int bdrv_open(BlockDriverState *bs, const char *filename, int flags,
         BlockDriver *back_drv = NULL;
 
         bs->backing_hd = bdrv_new("");
-        path_combine(backing_filename, sizeof(backing_filename),
-                     filename, bs->backing_file);
-        if (bs->backing_format[0] != '\0')
-            back_drv = bdrv_find_format(bs->backing_format);
+        back_drv = bdrv_find_protocol(bs->backing_file);
+        if (!back_drv) {
+            path_combine(backing_filename, sizeof(backing_filename),
+                         filename, bs->backing_file);
+            if (bs->backing_format[0] != '\0') {
+                back_drv = bdrv_find_format(bs->backing_format);
+            }
+        } else {
+            pstrcpy(backing_filename, sizeof(backing_filename),
+                    bs->backing_file);
+        }
 
         /* backing files always opened read-only */
         back_flags =
-- 
1.7.0.4