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Subject: Re: [RFC] atomic create+open
From: Trond Myklebust <trond.myklebust@fys.uio.no>
To: Miklos Szeredi <miklos@szeredi.hu>
Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org
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Date: Fri, 07 Oct 2005 11:13:55 -0400
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fr den 07.10.2005 Klokka 15:59 (+0200) skreiv Miklos Szeredi:

> You can replace the inode in ->create_open() if you want to.

Thinking a bit more clearly after a cup of coffee. This statement isn't
even true.

Your pseudo-code offers no guarantees that you are the sole user of the
dentry once you get to create_open().

> Or let the VFS redo the lookup (as if d_revalidate() returned 0).

Which may return yet another result for the dentry and another race.
There is no guarantee that you will ever make progress if someone is
doing something like.

while true
do
  echo "1" > foo
  echo "2" > foo
done

on the server.

Cheers,
  Trond