linux-kernel - Re: linux-next: manual merge of the akpm tree with Linus' tree

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Message-ID: <CA+55aFyaRsk-KkjppTnqDxy8+y5z9Yvi3TpMZwgGJ7ad7kwM4g@mail.gmail.com>
Date:	Fri, 13 Sep 2013 12:12:20 -0700
From:	Linus Torvalds <torvalds@...ux-foundation.org>
To:	Al Viro <viro@...iv.linux.org.uk>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Stephen Rothwell <sfr@...b.auug.org.au>,
	linux-next <linux-next@...r.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Dave Chinner <dchinner@...hat.com>,
	Glauber Costa <glommer@...nvz.org>
Subject: Re: linux-next: manual merge of the akpm tree with Linus' tree

On Thu, Sep 12, 2013 at 6:12 PM, Linus Torvalds
<torvalds@...ux-foundation.org> wrote:
>
> Damn, the code is too confused. I have to go to a highschool parent
> back-to-school meeting, so I won't get to this until maybe on a plane
> tomorrow. Al, can you please give this a look?

I'm on a plane. I have gogo. Here's my current TOTALLY UNTESTED patch.

It tries to consolidate the dentry LRU stuff into a few helper
functions that right now have anal checking of the flags. Maybe I
overdid it, but the code was really confusing, and I think we got the
free dentry counts wrong, and the bits wrong too, so I tried to be
extra careful.

There are several cases:
 - d_lru_add/del: fairly obvious
 - d_lru_isolate: this is when the LRU callbacks ask us to remove the
entry from the list. This is different from d_lru_del() only in that
it uses the raw list removal, not the lru list helper function. I'm
not sure that's right, but that's what the code used to do.
 - d_lru_shrink_move: move from the "global" lru list to a private shrinker list
 - d_shrink_add/del: fairly obvious.

And then "denty_lru_add/del" that actually take the current state into
account and do the right thing. Those we had before, I'm just
explaining the difference from the low-level operations that have
fixed "from this state to that" semantics

Hmm?

Does it work? Who knows.. But *if* it works, I think it has a higher
chance of getting all the rules for bits and free object counting
right.

Somebody not in a plane please double-check my low-oxygen-pressure thinking..

                  Linus

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