[PATCH 13/17] watch_queue: Implement mount topology and attribute change notifications [ver #5]

[Ian Kent]

On Fri, 2020-07-24 at 11:19 +0100, David Howells wrote:
> David Howells <dhowells at redhat.com> wrote:
> 
> > > What guarantees that mount_id is going to remain a 32bit entity?
> > 
> > You think it likely we'd have >4 billion concurrent mounts on a
> > system?  That
> > would require >1.2TiB of RAM just for the struct mount allocations.
> > 
> > But I can expand it to __u64.
> 
> That said, sys_name_to_handle_at() assumes it's a 32-bit signed
> integer, so
> we're currently limited to ~2 billion concurrent mounts:-/

I was wondering about id re-use.

Assuming that ids that are returned to the idr db are re-used
what would the chance that a recently used id would end up
being used?

Would that chance increase as ids are consumed and freed over
time?

Yeah, it's one of those questions ... ;)

Ian