[PATCH v2 18/20] block: Mark bdrv_query_block_graph_info() and callers GRAPH_RDLOCK

[Kevin Wolf <kwolf@redhat.com>]

This adds GRAPH_RDLOCK annotations to declare that callers of
bdrv_query_block_graph_info() need to hold a reader lock for the graph
because it accesses the children list of a node.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
---
 include/block/qapi.h | 7 ++++---
 qemu-img.c           | 2 ++
 2 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/include/block/qapi.h b/include/block/qapi.h
index 8773b9b191..18d48ddb70 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/graph-lock.h"
 #include "block/snapshot.h"
 #include "qapi/qapi-types-block-core.h"
 
@@ -43,9 +44,9 @@ void bdrv_query_image_info(BlockDriverState *bs,
                            bool flat,
                            bool skip_implicit_filters,
                            Error **errp);
-void bdrv_query_block_graph_info(BlockDriverState *bs,
-                                 BlockGraphInfo **p_info,
-                                 Error **errp);
+void GRAPH_RDLOCK
+bdrv_query_block_graph_info(BlockDriverState *bs, BlockGraphInfo **p_info,
+                            Error **errp);
 
 void bdrv_snapshot_dump(QEMUSnapshotInfo *sn);
 void bdrv_image_info_specific_dump(ImageInfoSpecific *info_spec,
diff --git a/qemu-img.c b/qemu-img.c
index 9aeac69fa6..9f9f0a7629 100644
--- a/qemu-img.c
+++ b/qemu-img.c
@@ -2938,6 +2938,8 @@ static BlockGraphInfoList *collect_image_info_list(bool image_opts,
         }
         bs = blk_bs(blk);
 
+        GRAPH_RDLOCK_GUARD_MAINLOOP();
+
         /*
          * Note that the returned BlockGraphInfo object will not have
          * information about this image's backing node, because we have opened
-- 
2.40.1