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

- From: David Howells \<dhowells@redhat.com\>
- Date: 2020-08-03 12:32:04 
- List: linux-api
- Page: https://ratatoskr.run/linux-api/2020/08/185821
- Thread: https://ratatoskr.run/keyrings/2020/03/175521/t.md

```text
Ian Kent [ref] wrote:

> > I'm changing it so that the fields are 64-bit, but initialised with the
> > existing mount ID in the notifications set.  The fsinfo set changes that
> > to a unique ID.  I'm tempted to make the unique IDs start at UINT_MAX+1 to
> > disambiguate them.
> 
> Mmm ... so what would I use as a mount id that's not used, like NULL
> for strings?

Zero is skipped, so you could use that.

> I'm using -1 now but changing this will mean I need something
> different.

It's 64-bits, so you're not likely to see it reach -1, even if it does start
at UINT_MAX+1.

David

```