Re: [PATCH v4 0/5] Fix easy bits of the negative dentry problem

[Miklos Szeredi]

On Wed, 21 Oct 2026 at 02:01, NeilBrown <neilb@xxxxxxxxxxx> wrote:
>
> On Tue, 20 Oct 2026, Ian Kent wrote:

> > The source of my concern was originally the traversal of the entire
> > list of child directory dentries in the notification code to set a
> > flag that depended on a parent dentry setting.
>
> And why this is a problem?

It's a latency issue  at umount and when the dentry list does need
shrinking.  Keeping perfectly useless dentries around does have a cost
in that respect.

> I think I can fix that, but I would like a report of "task X takes 5
> seconds which is a problem because ...."

I think we had that discussion at LSF, and as far as I remember it is
not theoretical, but I don't know where to dig that info out.

Maybe someone on the Cc list (Amir, Christian, Jan) can remember?

Thanks,
Miklos