Good point we need something probably a lock to prevent proc_mnt from
going away here. We might do a little better if we were starting with
a specific dentry, those at least have some rcu properties but that isn't
a big help.
Hmm. Perhaps there is a way to completely restructure this flushing
of dentries. It is just an optimization after all so we don't get too many
stale dentries building up.
It might just be worth it simply kill proc_flush_mnt altogether. I know
it is measurable when we don't do the flushing but perhaps there can
be a work struct that periodically wakes up and smacks stale proc dentries.
Right now I really don't think proc_flush_task is worth the hassle it
Grumble, Grumble more thinking to do.