block: mark bdrv_reopen_queue() and bdrv_reopen_multiple() as GRAPH_UNLOCKED

The function bdrv_reopen_queue() can call bdrv_drain_all_begin(),
which must be called with the graph unlocked.

The function bdrv_reopen_multiple() calls bdrv_reopen_prepare() which
must be called with the graph unlocked.

To mark bdrv_reopen_queue() as GRAPH_UNLOCKED, it is necessary to make
the locked section in reopen_backing_file() shorter.

Signed-off-by: Fiona Ebner <f.ebner@proxmox.com>
Message-ID: <20250530151125.955508-35-f.ebner@proxmox.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

block/replication.c

@@ -364,14 +364,15 @@ static void reopen_backing_file(BlockDriverState *bs, bool writable,
     BlockReopenQueue *reopen_queue = NULL;
 
     GLOBAL_STATE_CODE();
-    GRAPH_RDLOCK_GUARD_MAINLOOP();
 
+    bdrv_graph_rdlock_main_loop();
     /*
      * s->hidden_disk and s->secondary_disk may not be set yet, as they will
      * only be set after the children are writable.
      */
     hidden_disk = bs->file->bs->backing;
     secondary_disk = hidden_disk->bs->backing;
+    bdrv_graph_rdunlock_main_loop();
 
     if (writable) {
         s->orig_hidden_read_only = bdrv_is_read_only(hidden_disk->bs);

include/block/block-global-state.h

@@ -121,11 +121,12 @@ BlockDriverState *bdrv_new_open_driver_opts(BlockDriver *drv,
                                             Error **errp);
 BlockDriverState *bdrv_new_open_driver(BlockDriver *drv, const char *node_name,
                                        int flags, Error **errp);
-BlockReopenQueue *bdrv_reopen_queue(BlockReopenQueue *bs_queue,
-                                    BlockDriverState *bs, QDict *options,
-                                    bool keep_old_opts);
+BlockReopenQueue * GRAPH_UNLOCKED
+bdrv_reopen_queue(BlockReopenQueue *bs_queue, BlockDriverState *bs,
+                  QDict *options, bool keep_old_opts);
 void bdrv_reopen_queue_free(BlockReopenQueue *bs_queue);
-int bdrv_reopen_multiple(BlockReopenQueue *bs_queue, Error **errp);
+int GRAPH_UNLOCKED
+bdrv_reopen_multiple(BlockReopenQueue *bs_queue, Error **errp);
 int bdrv_reopen(BlockDriverState *bs, QDict *opts, bool keep_old_opts,
                 Error **errp);
 int bdrv_reopen_set_read_only(BlockDriverState *bs, bool read_only,