**Description**

For a DAG that looks like this:

```
A >> B
```

If A fails, B goes into "upstream_failed" state. If a user then marks A "success", B will remain in "upstream_failed" state. It will not automatically start running. This scenario often happens if the failure of A is dealt with outside of Airflow and the user does not want Airflow to run A again. But he usually expect Airflow to run B after A is marked "success".

**Use case / motivation**

After A is marked "success", its downstream tasks B should be cleared automatically and get ready to be scheduled. To avoid changing this behaviour completely, there can be a toggle button next to "Success" that lets the user decide if he wants Airflow to automatically clear downstream tasks that are in "upstream_failed" state.
airflow/www/views.py
self, dag, start_date, end_date, origin, recursive=False, confirmed=False, only_failed=False
    ):
        if confirmed:
            count = dag.clear(
                start_date=start_date,
                end_date=end_date,
                include_subdags=recursive,
                include_parentdag=recursive,
                only_failed=only_failed,
            )
            flash(f"{count} task instances have been cleared")
            return redirect(origin)
        try:
            tis = dag.clear(