Date: Fri, 13 Jun 2003 01:23:02 +0530
From: Dipankar Sarma <dipankar@in.ibm.com>
To: Trond Myklebust <trond.myklebust@fys.uio.no>
Cc: John M Flinchbaugh <glynis@butterfly.hjsoft.com>,
       linux-kernel@vger.kernel.org, Linus Torvalds <torvalds@transmeta.com>,
       Maneesh Soni <maneesh@in.ibm.com>
Subject: Re: 2.5.70-bk16: nfs crash
Message-ID: <20030612195302.GH1438@in.ibm.com>
Reply-To: dipankar@in.ibm.com
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On Thu, Jun 12, 2003 at 09:26:29AM -0700, Trond Myklebust wrote:
> I still need a real fix for d_move(). In addition, I'm getting worried

Linus' fix allowing unhashed src dentries seems ok, if that is what
you are looking for.


> about the changes in functionality that you've introduced here. It
> seems to me that your lockless scheme opens for a *lot* of races:
> 
> Look at all those functions that take dcache_lock, and then test
> dentry->d_count. Unless I'm missing something here, your d_lookup()
> clearly has them all screwed, no?

Not necessarily. One example is the fact that d_lookup() can
only increase d_count. Besides, dput() decrements d_count
without dcache_lock, so I am not sure holding dcache_lock during
d_count test buys you much.

We will do some audit tomorrow and see if there are issues here.

Thanks
Dipankar
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