# Re: \[PATCH 13/19\] vfs: Add a mount-notification facility \[ver \#16\]

- From: David Howells \<dhowells@redhat.com\>
- Date: 2020-02-21 12:24:59 
- List: linux-api
- Page: https://ratatoskr.run/linux-api/2020/02/173524
- Thread: https://ratatoskr.run/linux-api/2020/02/173129/t.md

```text
Jann Horn [ref] wrote:

> > + * Post mount notifications to all watches going rootwards along the tree.
> > + *
> > + * Must be called with the mount_lock held.
> 
> Please put such constraints into lockdep assertions instead of
> comments; that way, violations can actually be detected.

What's the best way to write a lockdep assertion?

	BUG_ON(!lockdep_is_held(lock));

David

```