block: add bdrv_attach_child_noperm() transaction action

Split no-perm part of bdrv_attach_child as separate transaction action.
It will be used in later commits.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Message-Id: <20210428151804.439460-20-vsementsov@virtuozzo.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

block.c

@@ -85,6 +85,14 @@ static BlockDriverState *bdrv_open_inherit(const char *filename,
 
 static void bdrv_replace_child_noperm(BdrvChild *child,
                                       BlockDriverState *new_bs);
+static int bdrv_attach_child_noperm(BlockDriverState *parent_bs,
+                                    BlockDriverState *child_bs,
+                                    const char *child_name,
+                                    const BdrvChildClass *child_class,
+                                    BdrvChildRole child_role,
+                                    BdrvChild **child,
+                                    Transaction *tran,
+                                    Error **errp);
 
 static int bdrv_reopen_prepare(BDRVReopenState *reopen_state, BlockReopenQueue
                                *queue, Error **errp);
@@ -3079,6 +3087,40 @@ static int bdrv_attach_child_common(BlockDriverState *child_bs,
     return 0;
 }
 
+static int bdrv_attach_child_noperm(BlockDriverState *parent_bs,
+                                    BlockDriverState *child_bs,
+                                    const char *child_name,
+                                    const BdrvChildClass *child_class,
+                                    BdrvChildRole child_role,
+                                    BdrvChild **child,
+                                    Transaction *tran,
+                                    Error **errp)
+{
+    int ret;
+    uint64_t perm, shared_perm;
+
+    assert(parent_bs->drv);
+
+    bdrv_get_cumulative_perm(parent_bs, &perm, &shared_perm);
+    bdrv_child_perm(parent_bs, child_bs, NULL, child_role, NULL,
+                    perm, shared_perm, &perm, &shared_perm);
+
+    ret = bdrv_attach_child_common(child_bs, child_name, child_class,
+                                   child_role, perm, shared_perm, parent_bs,
+                                   child, tran, errp);
+    if (ret < 0) {
+        return ret;
+    }
+
+    QLIST_INSERT_HEAD(&parent_bs->children, *child, next);
+    /*
+     * child is removed in bdrv_attach_child_common_abort(), so don't care to
+     * abort this change separately.
+     */
+
+    return 0;
+}
+
 static void bdrv_detach_child(BdrvChild *child)
 {
     bdrv_replace_child(child, NULL);
@@ -3139,23 +3181,26 @@ BdrvChild *bdrv_attach_child(BlockDriverState *parent_bs,
                              BdrvChildRole child_role,
                              Error **errp)
 {
-    BdrvChild *child;
-    uint64_t perm, shared_perm;
-
-    bdrv_get_cumulative_perm(parent_bs, &perm, &shared_perm);
+    int ret;
+    BdrvChild *child = NULL;
+    Transaction *tran = tran_new();
 
-    assert(parent_bs->drv);
-    bdrv_child_perm(parent_bs, child_bs, NULL, child_role, NULL,
-                    perm, shared_perm, &perm, &shared_perm);
+    ret = bdrv_attach_child_noperm(parent_bs, child_bs, child_name, child_class,
+                                   child_role, &child, tran, errp);
+    if (ret < 0) {
+        goto out;
+    }
 
-    child = bdrv_root_attach_child(child_bs, child_name, child_class,
-                                   child_role, perm, shared_perm, parent_bs,
-                                   errp);
-    if (child == NULL) {
-        return NULL;
+    ret = bdrv_refresh_perms(parent_bs, errp);
+    if (ret < 0) {
+        goto out;
     }
 
-    QLIST_INSERT_HEAD(&parent_bs->children, child, next);
+out:
+    tran_finalize(tran, ret);
+
+    bdrv_unref(child_bs);
+
     return child;
 }