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Date: Mon, 20 Jun 2016 06:35:30 +0100
From: Al Viro <viro@ZenIV.linux.org.uk>
To: "J. R. Okajima" <hooanon05g@gmail.com>
Cc: linux-fsdevel@vger.kernel.org
Subject: Re: Q. hlist_bl_add_head_rcu() in d_alloc_parallel()
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On Mon, Jun 20, 2016 at 01:34:14PM +0900, J. R. Okajima wrote:
> 
> Al Viro:
> > How would processB get past d_wait_lookup()?  It would have to have
> 
> By the first d_unhashed() test in the loop, processB doesn't reach
> d_wait_lookup().

Huh?  What first d_unhashed()...  <stares>

That check is definitely bogus and I'm completely at loss as to WTF is it
doing there.  Thanks for catching that; this kind of idiotic braino can
escape notice when rereading the code again and again, unfortunately ;-/

Fixed, will push to Linus tonight or tomorrow.