block: adapt bdrv_append() for inserting filters

bdrv_append is not very good for inserting filters: it does extra
permission update as part of bdrv_set_backing_hd(). During this update
filter may conflict with other parents of top_bs.

Instead, let's first do all graph modifications and after it update
permissions.

append-greedy-filter test-case in test-bdrv-graph-mod is now works, so
move it out of debug option.

Note: bdrv_append() is still only works for backing-child based
filters. It's something to improve later.

Note2: we use the fact that bdrv_append() is used to append new nodes,
without backing child, so we don't need frozen check and inherits_from
logic from bdrv_set_backing_hd().

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Message-Id: <20210428151804.439460-22-vsementsov@virtuozzo.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

1 files changed, 2 insertions, 15 deletions

diff --git a/tests/unit/test-bdrv-graph-mod.c b/tests/unit/test-bdrv-graph-mod.c
index 7b3c8b437a..88f25c0cdb 100644
--- a/tests/unit/test-bdrv-graph-mod.c
+++ b/tests/unit/test-bdrv-graph-mod.c
@@ -388,16 +388,6 @@ static void test_append_greedy_filter(void)
 
 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);
 
@@ -410,11 +400,8 @@ int main(int argc, char *argv[])
                     test_parallel_perm_update);
     g_test_add_func("/bdrv-graph-mod/parallel-exclusive-write",
                     test_parallel_exclusive_write);
-
-    if (debug) {
-        g_test_add_func("/bdrv-graph-mod/append-greedy-filter",
-                        test_append_greedy_filter);
-    }
+    g_test_add_func("/bdrv-graph-mod/append-greedy-filter",
+                    test_append_greedy_filter);
 
     return g_test_run();
 }