From: Max Reitz <mreitz@redhat.com>

When BDSs are created by qemu itself (e.g. as filters in block jobs),
they may not have a "driver" option in their options QDict.  When
generating a json:{} filename, however, it must always be present.

Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Message-id: 20190201192935.18394-31-mreitz@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
---
 block.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/block.c b/block.c
index 9d9929e1a2..35e78e2172 100644
--- a/block.c
+++ b/block.c
@@ -5618,6 +5618,12 @@ static bool append_strong_runtime_options(QDict *d, BlockDriverState *bs)
         }
     }
 
+    if (!qdict_haskey(d, "driver")) {
+        /* Drivers created with bdrv_new_open_driver() may not have a
+         * @driver option.  Add it here. */
+        qdict_put_str(d, "driver", bs->drv->format_name);
+    }
+
     return found_any;
 }
 
-- 
2.20.1