# Re: \[PATCH 13/17\] watch\_queue: Implement mount topology and attribute change notifications \[ver \#5\]

- From: Miklos Szeredi \<miklos@szeredi.hu\>
- Date: 2020-08-05 07:43:55 
- List: linux-api
- Page: https://ratatoskr.run/linux-api/2020/08/185992
- Thread: https://ratatoskr.run/keyrings/2020/03/175521/t.md

```text
On Wed, Aug 5, 2020 at 3:54 AM Ian Kent [ref] wrote:
>

> > > It's way more useful to have these in the notification than
> > > obtainable
> > > via fsinfo() IMHO.
> >
> > What is it useful for?
>
> Only to verify that you have seen all the notifications.
>
> If you have to grab that info with a separate call then the count
> isn't necessarily consistent because other notifications can occur
> while you grab it.

No, no no.   The watch queue will signal an overflow, without any
additional overhead for the normal case.  If you think of this as a
protocol stack, then the overflow detection happens on the transport
layer, instead of the application layer.  The application layer is
responsible for restoring state in case of a transport layer error,
but detection of that error is not the responsibility of the
application layer.


Thanks,
Miklos
```