[PATCH v2 05/10] block: Convert bdrv_query_block_graph_info to coroutine

[Fabiano Rosas]

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 function is a candidate because it calls bdrv_do_query_node_info(),
which in turn calls bdrv_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_getlength(), bdrv_get_allocated_file_size(), bdrv_get_info(),
   bdrv_get_specific_info();

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

Signed-off-by: Fabiano Rosas <farosas@suse.de>
---
 block/qapi.c         | 12 +++++++-----
 include/block/qapi.h |  6 +++++-
 qemu-img.c           |  2 --
 3 files changed, 12 insertions(+), 8 deletions(-)

diff --git a/block/qapi.c b/block/qapi.c
index 1cbb0935ff..a2e71edaff 100644
--- a/block/qapi.c
+++ b/block/qapi.c
@@ -375,7 +375,7 @@ 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
@@ -384,15 +384,17 @@ 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)
 {
     BlockGraphInfo *info;
     BlockChildInfoList **children_list_tail;
     BdrvChild *c;
     ERRP_GUARD();
 
+    assert_bdrv_graph_readable();
+
     info = g_new0(BlockGraphInfo, 1);
     bdrv_do_query_node_info(bs, qapi_BlockGraphInfo_base(info), errp);
     if (*errp) {
@@ -408,7 +410,7 @@ 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;
         }
diff --git a/include/block/qapi.h b/include/block/qapi.h
index 8663971c58..7035bcd1ae 100644
--- a/include/block/qapi.h
+++ b/include/block/qapi.h
@@ -25,6 +25,7 @@
 #ifndef BLOCK_QAPI_H
 #define BLOCK_QAPI_H
 
+#include "block/block-common.h"
 #include "block/graph-lock.h"
 #include "block/snapshot.h"
 #include "qapi/qapi-types-block-core.h"
@@ -41,7 +42,10 @@ void bdrv_query_image_info(BlockDriverState *bs,
                            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);
 
diff --git a/qemu-img.c b/qemu-img.c
index 27f48051b0..8066286f5e 100644
--- a/qemu-img.c
+++ b/qemu-img.c
@@ -2945,9 +2945,7 @@ 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);
-- 
2.35.3