block: Mark bdrv_has_zero_init() and callers GRAPH_RDLOCK

This adds GRAPH_RDLOCK annotations to declare that callers of
bdrv_has_zero_init() need to hold a reader lock for the graph because
it calls bdrv_filter_bs(), which accesses bs->file/backing.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-ID: <20231027155333.420094-3-kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/qemu-img.c b/qemu-img.c
index 369c2e8..c061fd0 100644
--- a/qemu-img.c
+++ b/qemu-img.c
@@ -2099,7 +2099,9 @@ static int convert_do_copy(ImgConvertState *s)
     /* Check whether we have zero initialisation or can get it efficiently */
     if (!s->has_zero_init && s->target_is_new && s->min_sparse &&
         !s->target_has_backing) {
+        bdrv_graph_rdlock_main_loop();
         s->has_zero_init = bdrv_has_zero_init(blk_bs(s->target));
+        bdrv_graph_rdunlock_main_loop();
     }
 
     /* Allocate buffer for copied data. For compressed images, only one cluster