block: Clean up a misuse of qobject_to() in .bdrv_co_create_opts()

The following pattern occurs in the .bdrv_co_create_opts() methods of
parallels, qcow, qcow2, qed, vhdx and vpc:

    qobj = qdict_crumple_for_keyval_qiv(qdict, errp);
    qobject_unref(qdict);
    qdict = qobject_to(QDict, qobj);
    if (qdict == NULL) {
         ret = -EINVAL;
         goto done;
    }

    v = qobject_input_visitor_new_keyval(QOBJECT(qdict));
    [...]
    ret = 0;
done:
    qobject_unref(qdict);
    [...]
    return ret;

If qobject_to() fails, we return failure without setting errp.  That's
wrong.  As far as I can tell, it cannot fail here.  Clean it up
anyway, by removing the useless conversion.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

1 files changed, 4 insertions, 5 deletions

diff --git a/block/qcow2.c b/block/qcow2.c
index 0a27afa..8c33866 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -3080,7 +3080,7 @@ static int coroutine_fn qcow2_co_create_opts(const char *filename, QemuOpts *opt
                                              Error **errp)
 {
     BlockdevCreateOptions *create_options = NULL;
-    QDict *qdict = NULL;
+    QDict *qdict;
     QObject *qobj;
     Visitor *v;
     BlockDriverState *bs = NULL;
@@ -3153,14 +3153,13 @@ static int coroutine_fn qcow2_co_create_opts(const char *filename, QemuOpts *opt
 
     /* Now get the QAPI type BlockdevCreateOptions */
     qobj = qdict_crumple_for_keyval_qiv(qdict, errp);
-    qobject_unref(qdict);
-    qdict = qobject_to(QDict, qobj);
-    if (qdict == NULL) {
+    if (!qobj) {
         ret = -EINVAL;
         goto finish;
     }
 
-    v = qobject_input_visitor_new_keyval(QOBJECT(qdict));
+    v = qobject_input_visitor_new_keyval(qobj);
+    qobject_unref(qobj);
     visit_type_BlockdevCreateOptions(v, NULL, &create_options, &local_err);
     visit_free(v);