[PULL,21/28] block: Mark bdrv_add/del_child() and caller GRAPH_WRLOCK

diff --git a/include/block/block-global-state.h b/include/block/block-global-state.h
index 0f6df8f1a2..f31660c7b1 100644
--- a/include/block/block-global-state.h
+++ b/include/block/block-global-state.h
@@ -276,9 +276,11 @@  int bdrv_try_change_aio_context(BlockDriverState *bs, AioContext *ctx,
 int bdrv_probe_blocksizes(BlockDriverState *bs, BlockSizes *bsz);
 int bdrv_probe_geometry(BlockDriverState *bs, HDGeometry *geo);
 
-void bdrv_add_child(BlockDriverState *parent, BlockDriverState *child,
-                    Error **errp);
-void bdrv_del_child(BlockDriverState *parent, BdrvChild *child, Error **errp);
+void GRAPH_WRLOCK
+bdrv_add_child(BlockDriverState *parent, BlockDriverState *child, Error **errp);
+
+void GRAPH_WRLOCK
+bdrv_del_child(BlockDriverState *parent, BdrvChild *child, Error **errp);
 
 /**
  *
diff --git a/include/block/block_int-common.h b/include/block/block_int-common.h
index 3feb67ec4a..2ca3758cb8 100644
--- a/include/block/block_int-common.h
+++ b/include/block/block_int-common.h
@@ -393,10 +393,11 @@  struct BlockDriver {
      */
     int (*bdrv_probe_geometry)(BlockDriverState *bs, HDGeometry *geo);
 
-    void (*bdrv_add_child)(BlockDriverState *parent, BlockDriverState *child,
-                           Error **errp);
-    void (*bdrv_del_child)(BlockDriverState *parent, BdrvChild *child,
-                           Error **errp);
+    void GRAPH_WRLOCK_PTR (*bdrv_add_child)(
+        BlockDriverState *parent, BlockDriverState *child, Error **errp);
+
+    void GRAPH_WRLOCK_PTR (*bdrv_del_child)(
+        BlockDriverState *parent, BdrvChild *child, Error **errp);
 
     /**
      * Informs the block driver that a permission change is intended. The
diff --git a/block/quorum.c b/block/quorum.c
index 620a50ba2c..05220cab7f 100644
--- a/block/quorum.c
+++ b/block/quorum.c
@@ -1066,8 +1066,8 @@  static void quorum_close(BlockDriverState *bs)
     g_free(s->children);
 }
 
-static void quorum_add_child(BlockDriverState *bs, BlockDriverState *child_bs,
-                             Error **errp)
+static void GRAPH_WRLOCK
+quorum_add_child(BlockDriverState *bs, BlockDriverState *child_bs, Error **errp)
 {
     BDRVQuorumState *s = bs->opaque;
     BdrvChild *child;
@@ -1093,29 +1093,22 @@  static void quorum_add_child(BlockDriverState *bs, BlockDriverState *child_bs,
     }
     s->next_child_index++;
 
-    bdrv_drained_begin(bs);
-
     /* We can safely add the child now */
     bdrv_ref(child_bs);
 
-    bdrv_graph_wrlock(child_bs);
     child = bdrv_attach_child(bs, child_bs, indexstr, &child_of_bds,
                               BDRV_CHILD_DATA, errp);
-    bdrv_graph_wrunlock();
     if (child == NULL) {
         s->next_child_index--;
-        goto out;
+        return;
     }
     s->children = g_renew(BdrvChild *, s->children, s->num_children + 1);
     s->children[s->num_children++] = child;
     quorum_refresh_flags(bs);
-
-out:
-    bdrv_drained_end(bs);
 }
 
-static void quorum_del_child(BlockDriverState *bs, BdrvChild *child,
-                             Error **errp)
+static void GRAPH_WRLOCK
+quorum_del_child(BlockDriverState *bs, BdrvChild *child, Error **errp)
 {
     BDRVQuorumState *s = bs->opaque;
     char indexstr[INDEXSTR_LEN];
@@ -1145,18 +1138,14 @@  static void quorum_del_child(BlockDriverState *bs, BdrvChild *child,
         s->next_child_index--;
     }
 
-    bdrv_drained_begin(bs);
-
     /* We can safely remove this child now */
     memmove(&s->children[i], &s->children[i + 1],
             (s->num_children - i - 1) * sizeof(BdrvChild *));
     s->children = g_renew(BdrvChild *, s->children, --s->num_children);
-    bdrv_graph_wrlock(NULL);
+
     bdrv_unref_child(bs, child);
-    bdrv_graph_wrunlock();
 
     quorum_refresh_flags(bs);
-    bdrv_drained_end(bs);
 }
 
 static void quorum_gather_child_options(BlockDriverState *bs, QDict *target,
diff --git a/blockdev.c b/blockdev.c
index 372eaf198c..325b7a3bef 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -3545,8 +3545,8 @@  out:
     aio_context_release(aio_context);
 }
 
-static BdrvChild *bdrv_find_child(BlockDriverState *parent_bs,
-                                  const char *child_name)
+static BdrvChild * GRAPH_RDLOCK
+bdrv_find_child(BlockDriverState *parent_bs, const char *child_name)
 {
     BdrvChild *child;
 
@@ -3565,9 +3565,11 @@  void qmp_x_blockdev_change(const char *parent, const char *child,
     BlockDriverState *parent_bs, *new_bs = NULL;
     BdrvChild *p_child;
 
+    bdrv_graph_wrlock(NULL);
+
     parent_bs = bdrv_lookup_bs(parent, parent, errp);
     if (!parent_bs) {
-        return;
+        goto out;
     }
 
     if (!child == !node) {
@@ -3576,7 +3578,7 @@  void qmp_x_blockdev_change(const char *parent, const char *child,
         } else {
             error_setg(errp, "Either child or node must be specified");
         }
-        return;
+        goto out;
     }
 
     if (child) {
@@ -3584,7 +3586,7 @@  void qmp_x_blockdev_change(const char *parent, const char *child,
         if (!p_child) {
             error_setg(errp, "Node '%s' does not have child '%s'",
                        parent, child);
-            return;
+            goto out;
         }
         bdrv_del_child(parent_bs, p_child, errp);
     }
@@ -3593,10 +3595,13 @@  void qmp_x_blockdev_change(const char *parent, const char *child,
         new_bs = bdrv_find_node(node);
         if (!new_bs) {
             error_setg(errp, "Node '%s' not found", node);
-            return;
+            goto out;
         }
         bdrv_add_child(parent_bs, new_bs, errp);
     }
+
+out:
+    bdrv_graph_wrunlock();
 }
 
 BlockJobInfoList *qmp_query_block_jobs(Error **errp)