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>

6 files changed, 24 insertions, 30 deletions

diff --git a/block/parallels.c b/block/parallels.c
index 695899fc4b..ceb7a15d62 100644
--- a/block/parallels.c
+++ b/block/parallels.c
@@ -616,7 +616,7 @@ static int coroutine_fn parallels_co_create_opts(const char *filename,
     BlockdevCreateOptions *create_options = NULL;
     Error *local_err = NULL;
     BlockDriverState *bs = NULL;
-    QDict *qdict = NULL;
+    QDict *qdict;
     QObject *qobj;
     Visitor *v;
     int ret;
@@ -654,14 +654,13 @@ static int coroutine_fn parallels_co_create_opts(const char *filename,
     qdict_put_str(qdict, "file", bs->node_name);
 
     qobj = qdict_crumple_for_keyval_qiv(qdict, errp);
-    qobject_unref(qdict);
-    qdict = qobject_to(QDict, qobj);
-    if (qdict == NULL) {
+    if (!qobj) {
         ret = -EINVAL;
         goto done;
     }
 
-    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);
 
diff --git a/block/qcow.c b/block/qcow.c
index 860b058240..2f81f081fd 100644
--- a/block/qcow.c
+++ b/block/qcow.c
@@ -946,7 +946,7 @@ static int coroutine_fn qcow_co_create_opts(const char *filename,
 {
     BlockdevCreateOptions *create_options = NULL;
     BlockDriverState *bs = NULL;
-    QDict *qdict = NULL;
+    QDict *qdict;
     QObject *qobj;
     Visitor *v;
     const char *val;
@@ -998,14 +998,13 @@ static int coroutine_fn qcow_co_create_opts(const char *filename,
     qdict_put_str(qdict, "file", bs->node_name);
 
     qobj = qdict_crumple_for_keyval_qiv(qdict, errp);
-    qobject_unref(qdict);
-    qdict = qobject_to(QDict, qobj);
-    if (qdict == NULL) {
+    if (!qobj) {
         ret = -EINVAL;
         goto fail;
     }
 
-    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);
 
diff --git a/block/qcow2.c b/block/qcow2.c
index 0a27afa2ef..8c338661db 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);
 
diff --git a/block/qed.c b/block/qed.c
index 88fa36d409..fcec760b26 100644
--- a/block/qed.c
+++ b/block/qed.c
@@ -722,7 +722,7 @@ static int coroutine_fn bdrv_qed_co_create_opts(const char *filename,
                                                 Error **errp)
 {
     BlockdevCreateOptions *create_options = NULL;
-    QDict *qdict = NULL;
+    QDict *qdict;
     QObject *qobj;
     Visitor *v;
     BlockDriverState *bs = NULL;
@@ -764,14 +764,13 @@ static int coroutine_fn bdrv_qed_co_create_opts(const char *filename,
     qdict_put_str(qdict, "file", bs->node_name);
 
     qobj = qdict_crumple_for_keyval_qiv(qdict, errp);
-    qobject_unref(qdict);
-    qdict = qobject_to(QDict, qobj);
-    if (qdict == NULL) {
+    if (!qobj) {
         ret = -EINVAL;
         goto fail;
     }
 
-    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);
 
diff --git a/block/vhdx.c b/block/vhdx.c
index 78b29d9fc7..f2aec3d2cd 100644
--- a/block/vhdx.c
+++ b/block/vhdx.c
@@ -1965,7 +1965,7 @@ static int coroutine_fn vhdx_co_create_opts(const char *filename,
                                             Error **errp)
 {
     BlockdevCreateOptions *create_options = NULL;
-    QDict *qdict = NULL;
+    QDict *qdict;
     QObject *qobj;
     Visitor *v;
     BlockDriverState *bs = NULL;
@@ -2006,14 +2006,13 @@ static int coroutine_fn vhdx_co_create_opts(const char *filename,
     qdict_put_str(qdict, "file", bs->node_name);
 
     qobj = qdict_crumple_for_keyval_qiv(qdict, errp);
-    qobject_unref(qdict);
-    qdict = qobject_to(QDict, qobj);
-    if (qdict == NULL) {
+    if (!qobj) {
         ret = -EINVAL;
         goto fail;
     }
 
-    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);
 
diff --git a/block/vpc.c b/block/vpc.c
index 16178e5a90..a9bb04149d 100644
--- a/block/vpc.c
+++ b/block/vpc.c
@@ -1081,7 +1081,7 @@ static int coroutine_fn vpc_co_create_opts(const char *filename,
                                            QemuOpts *opts, Error **errp)
 {
     BlockdevCreateOptions *create_options = NULL;
-    QDict *qdict = NULL;
+    QDict *qdict;
     QObject *qobj;
     Visitor *v;
     BlockDriverState *bs = NULL;
@@ -1120,14 +1120,13 @@ static int coroutine_fn vpc_co_create_opts(const char *filename,
     qdict_put_str(qdict, "file", bs->node_name);
 
     qobj = qdict_crumple_for_keyval_qiv(qdict, errp);
-    qobject_unref(qdict);
-    qdict = qobject_to(QDict, qobj);
-    if (qdict == NULL) {
+    if (!qobj) {
         ret = -EINVAL;
         goto fail;
     }
 
-    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);