commit 1cb6f506444ddf00bb163e5ffa28ab1051b65642
author Kevin Wolf <kwolf@redhat.com> Fri Apr 12 20:27:07 2013 +0200
committer Kevin Wolf <kwolf@redhat.com> Mon Apr 22 11:37:12 2013 +0200
tree 9b7339e0c47e76046ce1da446060b7feea489e85
parent 56d1b4d21d444619302d3f1291a133b1c2b9b072

block: Allow overriding backing.file.filename

If a filename is passed in the driver-specific options from the command
line, the backing file path from the image is ignored now.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>

block.c

diff --git a/block.c b/block.c
index 6e07f45..819eb4e 100644
--- a/block.c
+++ b/block.c
@@ -889,7 +889,9 @@
     }
 
     bs->open_flags &= ~BDRV_O_NO_BACKING;
-    if (bs->backing_file[0] == '\0' && qdict_size(options) == 0) {
+    if (qdict_haskey(options, "file.filename")) {
+        backing_filename[0] = '\0';
+    } else if (bs->backing_file[0] == '\0' && qdict_size(options) == 0) {
         QDECREF(options);
         return 0;
     }