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

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

This function is a candidate because it calls bdrv_do_query_node_info(),
which in turn calls bdrv_co_get_allocated_file_size().

All the functions called from bdrv_do_query_node_info() onwards are
coroutine-safe, either have a coroutine version themselves[1] or are
mostly simple code/string manipulation[2].

1) bdrv_co_getlength(), bdrv_co_get_allocated_file_size(),
   bdrv_co_get_info();

2) bdrv_refresh_filename(), bdrv_get_format_name(),
   bdrv_get_full_backing_filename(), bdrv_query_snapshot_info_list(),
   bdrv_get_specific_info();

Link: https://lore.kernel.org/r/20240409145917.6780-1-farosas@suse.de
Reviewed-by: Hanna Czenczek <hreitz@redhat.com>
References: bsc#1211000
Signed-off-by: Fabiano Rosas <farosas@suse.de>
Signed-off-by: Dario Faggioli <dfaggioli@suse.com>

block/qapi.c

@@ -370,7 +370,7 @@ fail:
 }
 
 /**
- * bdrv_query_block_graph_info:
+ * bdrv_co_query_block_graph_info:
  * @bs: root node to start from
  * @p_info: location to store image information
  * @errp: location to store error information
@@ -379,17 +379,19 @@ fail:
  *
  * @p_info will be set only on success. On error, store error in @errp.
  */
-void bdrv_query_block_graph_info(BlockDriverState *bs,
-                                 BlockGraphInfo **p_info,
-                                 Error **errp)
+void coroutine_fn
+bdrv_co_query_block_graph_info(BlockDriverState *bs, BlockGraphInfo **p_info,
+                               Error **errp)
 {
     ERRP_GUARD();
     BlockGraphInfo *info;
     BlockChildInfoList **children_list_tail;
     BdrvChild *c;
 
+    assert_bdrv_graph_readable();
+
     info = g_new0(BlockGraphInfo, 1);
-    bdrv_do_query_node_info(bs, qapi_BlockGraphInfo_base(info), errp);
+    bdrv_co_do_query_node_info(bs, qapi_BlockGraphInfo_base(info), errp);
     if (*errp) {
         goto fail;
     }
@@ -403,7 +405,7 @@ void bdrv_query_block_graph_info(BlockDriverState *bs,
         QAPI_LIST_APPEND(children_list_tail, c_info);
 
         c_info->name = g_strdup(c->name);
-        bdrv_query_block_graph_info(c->bs, &c_info->info, errp);
+        bdrv_co_query_block_graph_info(c->bs, &c_info->info, errp);
         if (*errp) {
             goto fail;
         }

include/block/qapi.h

@@ -41,7 +41,11 @@ bdrv_query_snapshot_info_list(BlockDriverState *bs,
 void GRAPH_RDLOCK
 bdrv_query_image_info(BlockDriverState *bs, ImageInfo **p_info, bool flat,
                       bool skip_implicit_filters, Error **errp);
-void GRAPH_RDLOCK
+
+void coroutine_fn GRAPH_RDLOCK
+bdrv_co_query_block_graph_info(BlockDriverState *bs, BlockGraphInfo **p_info,
+                               Error **errp);
+void co_wrapper_bdrv_rdlock
 bdrv_query_block_graph_info(BlockDriverState *bs, BlockGraphInfo **p_info,
                             Error **errp);
 

qemu-img.c

@@ -2958,10 +2958,7 @@ static BlockGraphInfoList *collect_image_info_list(bool image_opts,
          * duplicate the backing chain information that we obtain by walking
          * the chain manually here.
          */
-        bdrv_graph_rdlock_main_loop();
         bdrv_query_block_graph_info(bs, &info, &err);
-        bdrv_graph_rdunlock_main_loop();
-
         if (err) {
             error_report_err(err);
             blk_unref(blk);