1 files changed, 69 insertions, 1 deletions

diff --git a/tests/unit/test-bdrv-graph-mod.c b/tests/unit/test-bdrv-graph-mod.c
index c4f7d16039..80a9a20066 100644
--- a/tests/unit/test-bdrv-graph-mod.c
+++ b/tests/unit/test-bdrv-graph-mod.c
@@ -1,7 +1,7 @@
 /*
  * Block node graph modifications tests
  *
- * Copyright (c) 2019 Virtuozzo International GmbH. All rights reserved.
+ * Copyright (c) 2019-2021 Virtuozzo International GmbH. All rights reserved.
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -44,6 +44,21 @@ static BlockDriver bdrv_no_perm = {
     .bdrv_child_perm = no_perm_default_perms,
 };
 
+static void exclusive_write_perms(BlockDriverState *bs, BdrvChild *c,
+                                  BdrvChildRole role,
+                                  BlockReopenQueue *reopen_queue,
+                                  uint64_t perm, uint64_t shared,
+                                  uint64_t *nperm, uint64_t *nshared)
+{
+    *nperm = BLK_PERM_WRITE;
+    *nshared = BLK_PERM_ALL & ~BLK_PERM_WRITE;
+}
+
+static BlockDriver bdrv_exclusive_writer = {
+    .format_name = "exclusive-writer",
+    .bdrv_child_perm = exclusive_write_perms,
+};
+
 static BlockDriverState *no_perm_node(const char *name)
 {
     return bdrv_new_open_driver(&bdrv_no_perm, name, BDRV_O_RDWR, &error_abort);
@@ -55,6 +70,12 @@ static BlockDriverState *pass_through_node(const char *name)
                                 BDRV_O_RDWR, &error_abort);
 }
 
+static BlockDriverState *exclusive_writer_node(const char *name)
+{
+    return bdrv_new_open_driver(&bdrv_exclusive_writer, name,
+                                BDRV_O_RDWR, &error_abort);
+}
+
 /*
  * test_update_perm_tree
  *
@@ -185,8 +206,50 @@ static void test_should_update_child(void)
     blk_unref(root);
 }
 
+/*
+ * test_parallel_exclusive_write
+ *
+ * Check that when we replace node, old permissions of the node being removed
+ * doesn't break the replacement.
+ */
+static void test_parallel_exclusive_write(void)
+{
+    BlockDriverState *top = exclusive_writer_node("top");
+    BlockDriverState *base = no_perm_node("base");
+    BlockDriverState *fl1 = pass_through_node("fl1");
+    BlockDriverState *fl2 = pass_through_node("fl2");
+
+    /*
+     * bdrv_attach_child() eats child bs reference, so we need two @base
+     * references for two filters:
+     */
+    bdrv_ref(base);
+
+    bdrv_attach_child(top, fl1, "backing", &child_of_bds, BDRV_CHILD_DATA,
+                      &error_abort);
+    bdrv_attach_child(fl1, base, "backing", &child_of_bds, BDRV_CHILD_FILTERED,
+                      &error_abort);
+    bdrv_attach_child(fl2, base, "backing", &child_of_bds, BDRV_CHILD_FILTERED,
+                      &error_abort);
+
+    bdrv_replace_node(fl1, fl2, &error_abort);
+
+    bdrv_unref(fl2);
+    bdrv_unref(top);
+}
+
 int main(int argc, char *argv[])
 {
+    int i;
+    bool debug = false;
+
+    for (i = 1; i < argc; i++) {
+        if (!strcmp(argv[i], "-d")) {
+            debug = true;
+            break;
+        }
+    }
+
     bdrv_init();
     qemu_init_main_loop(&error_abort);
 
@@ -196,5 +259,10 @@ int main(int argc, char *argv[])
     g_test_add_func("/bdrv-graph-mod/should-update-child",
                     test_should_update_child);
 
+    if (debug) {
+        g_test_add_func("/bdrv-graph-mod/parallel-exclusive-write",
+                        test_parallel_exclusive_write);
+    }
+
     return g_test_run();
 }