block/copy-before-write: cbw_init(): use options

One more step closer to .bdrv_open(): use options instead of plain
arguments. Move to bdrv_open_child() calls, native for drive open
handlers.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Hanna Reitz <hreitz@redhat.com>
Message-Id: <20210824083856.17408-19-vsementsov@virtuozzo.com>
Signed-off-by: Hanna Reitz <hreitz@redhat.com>

block/copy-before-write.c

@@ -144,25 +144,20 @@ static void cbw_child_perm(BlockDriverState *bs, BdrvChild *c,
     }
 }
 
-static int cbw_init(BlockDriverState *bs, BlockDriverState *source,
-                    BlockDriverState *target, Error **errp)
+static int cbw_init(BlockDriverState *bs, QDict *options, Error **errp)
 {
     BDRVCopyBeforeWriteState *s = bs->opaque;
 
-    bdrv_ref(target);
-    s->target = bdrv_attach_child(bs, target, "target", &child_of_bds,
-                                  BDRV_CHILD_DATA, errp);
-    if (!s->target) {
-        error_prepend(errp, "Cannot attach target child: ");
+    bs->file = bdrv_open_child(NULL, options, "file", bs, &child_of_bds,
+                               BDRV_CHILD_FILTERED | BDRV_CHILD_PRIMARY,
+                               false, errp);
+    if (!bs->file) {
         return -EINVAL;
     }
 
-    bdrv_ref(source);
-    bs->file = bdrv_attach_child(bs, source, "file", &child_of_bds,
-                                 BDRV_CHILD_FILTERED | BDRV_CHILD_PRIMARY,
-                                 errp);
-    if (!bs->file) {
-        error_prepend(errp, "Cannot attach file child: ");
+    s->target = bdrv_open_child(NULL, options, "target", bs, &child_of_bds,
+                                BDRV_CHILD_DATA, false, errp);
+    if (!s->target) {
         return -EINVAL;
     }
 
@@ -209,6 +204,7 @@ BlockDriverState *bdrv_cbw_append(BlockDriverState *source,
     int ret;
     BDRVCopyBeforeWriteState *state;
     BlockDriverState *top;
+    QDict *opts;
 
     assert(source->total_sectors == target->total_sectors);
 
@@ -220,7 +216,12 @@ BlockDriverState *bdrv_cbw_append(BlockDriverState *source,
     }
     state = top->opaque;
 
-    ret = cbw_init(top, source, target, errp);
+    opts = qdict_new();
+    qdict_put_str(opts, "file", bdrv_get_node_name(source));
+    qdict_put_str(opts, "target", bdrv_get_node_name(target));
+
+    ret = cbw_init(top, opts, errp);
+    qobject_unref(opts);
     if (ret < 0) {
         goto fail;
     }