[openSUSE] block: Convert qmp_query_named_block_nodes to coroutine (bsc#1211000)

We're converting callers of bdrv_get_allocated_file_size() to run in
coroutines because that function will be made asynchronous when called
(indirectly) from the QMP dispatcher.

This QMP command is a candidate because it indirectly calls
bdrv_get_allocated_file_size() through bdrv_block_device_info() ->
bdrv_query_image_info() -> bdrv_query_image_info().

The previous patches have determined that bdrv_query_image_info() and
bdrv_do_query_node_info() are coroutine-safe so we can just make the
QMP command run in a coroutine.

Signed-off-by: Lin Ma <lma@suse.com>
Signed-off-by: Fabiano Rosas <farosas@suse.de>
References: bsc#1211000
[relax the main loop requirement at bdrv_named_nodes_list]
Signed-off-by: Fabiano Rosas <farosas@suse.de>

block.c

@@ -6344,11 +6344,11 @@ BlockDeviceInfoList *bdrv_named_nodes_list(bool flat,
     BlockDriverState *bs;
 
     GLOBAL_STATE_CODE();
-    GRAPH_RDLOCK_GUARD_MAINLOOP();
+    GRAPH_RDLOCK_GUARD();
 
     list = NULL;
     QTAILQ_FOREACH(bs, &graph_bdrv_states, node_list) {
-        BlockDeviceInfo *info = bdrv_block_device_info(NULL, bs, flat, errp);
+        BlockDeviceInfo *info = bdrv_co_block_device_info(NULL, bs, flat, errp);
         if (!info) {
             qapi_free_BlockDeviceInfoList(list);
             return NULL;

blockdev.c

@@ -2871,9 +2871,9 @@ void qmp_drive_backup(DriveBackup *backup, Error **errp)
     blockdev_do_action(&action, errp);
 }
 
-BlockDeviceInfoList *qmp_query_named_block_nodes(bool has_flat,
-                                                 bool flat,
-                                                 Error **errp)
+BlockDeviceInfoList *coroutine_fn qmp_query_named_block_nodes(bool has_flat,
+                                                              bool flat,
+                                                              Error **errp)
 {
     bool return_flat = has_flat && flat;
 

qapi/block-core.json

@@ -1985,7 +1985,8 @@
 { 'command': 'query-named-block-nodes',
   'returns': [ 'BlockDeviceInfo' ],
   'data': { '*flat': 'bool' },
-  'allow-preconfig': true }
+  'allow-preconfig': true,
+  'coroutine': true}
 
 ##
 # @XDbgBlockGraphNodeType: