Re: [PATCH 02/11] vfs: More precise tests in d_invalidate

From: Linus Torvalds
Date: Sat Feb 15 2014 - 19:04:02 EST


On Sat, Feb 15, 2014 at 3:23 PM, Eric W. Biederman
<ebiederm@xxxxxxxxxxxx> wrote:
>
> Except that today d_invalidate drops the dcache lock and
> calls shrink_dcache_parent. Which gets you into exactly the same
> complex "walk parents and check all siblings" code.

Hmm. It only does that for directories that have sub-entries, though.

I think you may care just about directories (because that's what your
series is about), but d_invalidate() is used for other cases too,
notably d_revalidate() (ie things like stale NFS lookups of normal
files).

That said, I'll have to think about this more. If d_subdir is empty, I
guess d_walk() will be fairly cheap. It's very different, but maybe
not as disastrous as I thought.

Linus
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