From 5f3777945d22248d805fb7c134e206c2d943b77b Mon Sep 17 00:00:00 2001
From: Paolo Bonzini <pbonzini@redhat.com>
Date: Thu, 12 Apr 2012 14:01:01 +0200
Subject: block: push bdrv_change_backing_file error checking up from drivers

This check applies to all drivers, but QED lacks it.

Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 block.c | 5 +++++
 1 file changed, 5 insertions(+)

(limited to 'block.c')

diff --git a/block.c b/block.c
index a307fe1..068e41d 100644
--- a/block.c
+++ b/block.c
@@ -1460,6 +1460,11 @@ int bdrv_change_backing_file(BlockDriverState *bs,
 {
     BlockDriver *drv = bs->drv;
 
+    /* Backing file format doesn't make sense without a backing file */
+    if (backing_fmt && !backing_file) {
+        return -EINVAL;
+    }
+
     if (drv->bdrv_change_backing_file != NULL) {
         return drv->bdrv_change_backing_file(bs, backing_file, backing_fmt);
     } else {
-- 
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