Re: [PATCH] fs/dcache: dentries should free after files unlinked or directories removed

[Linus Torvalds <torvalds@linux-foundation.org>]

On Mon, Sep 4, 2017 at 5:59 AM, Jan Kara <jack@suse.cz> wrote:
>
> The reason why I'm objecting is that the limit on the number of negative
> dentries is another tuning knob, it is for very specific cases, and most of
> sysadmins will have no clue how to set it properly (even I wouldn't have a
> good idea).

We could make some cut at just doing it without any explicit tuning.

In particular, we could probably have some fairly trivial logic to
count negative dentries vs positive ones, and start pruning negative
dentries if we've crossed some threshold and we have more of them than
of the positive kind. That's a fairly obvious "somebody is doing
something bad" measure which wouldn't need a ton of tuning.

That said, I'm not convinced it's a huge deal and worth it - I'm just
saying that I don't think it's necessarily crazy or something I'd NAK
automatically.

                  Linus