diff --git a/block/io.c b/block/io.c
index ec8b317818..2593823f62 100644
--- a/block/io.c
+++ b/block/io.c
@@ -933,8 +933,7 @@ int coroutine_fn bdrv_co_pwrite_sync(BdrvChild *child, int64_t offset,
 {
     int ret;
     IO_CODE();
-
-    assume_graph_lock(); /* FIXME */
+    assert_bdrv_graph_readable();
 
     ret = bdrv_co_pwrite(child, offset, bytes, buf, flags);
     if (ret < 0) {
diff --git a/block/qcow2.h b/block/qcow2.h
index 7487bcfcf9..c59e33c01c 100644
--- a/block/qcow2.h
+++ b/block/qcow2.h
@@ -893,7 +893,7 @@ int qcow2_inc_refcounts_imrt(BlockDriverState *bs, BdrvCheckResult *res,
 int qcow2_change_refcount_order(BlockDriverState *bs, int refcount_order,
                                 BlockDriverAmendStatusCB *status_cb,
                                 void *cb_opaque, Error **errp);
-int coroutine_fn qcow2_shrink_reftable(BlockDriverState *bs);
+int coroutine_fn GRAPH_RDLOCK qcow2_shrink_reftable(BlockDriverState *bs);
 int64_t qcow2_get_last_cluster(BlockDriverState *bs, int64_t size);
 int coroutine_fn qcow2_detect_metadata_preallocation(BlockDriverState *bs);
 
diff --git a/include/block/block-io.h b/include/block/block-io.h
index ec26f07d60..bbe8a5659a 100644
--- a/include/block/block-io.h
+++ b/include/block/block-io.h
@@ -60,9 +60,10 @@ int co_wrapper_mixed_bdrv_rdlock
 bdrv_pwrite_sync(BdrvChild *child, int64_t offset, int64_t bytes,
                  const void *buf, BdrvRequestFlags flags);
 
-int coroutine_fn bdrv_co_pwrite_sync(BdrvChild *child, int64_t offset,
-                                     int64_t bytes, const void *buf,
-                                     BdrvRequestFlags flags);
+int coroutine_fn GRAPH_RDLOCK
+bdrv_co_pwrite_sync(BdrvChild *child, int64_t offset, int64_t bytes,
+                    const void *buf, BdrvRequestFlags flags);
+
 /*
  * Efficiently zero a region of the disk image.  Note that this is a regular
  * I/O request like read or write and should have a reasonable size.  This