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Date: Tue, 20 Jun 2006 09:23:51 -0600
From: "Brian F. G. Bidulock" <bidulock@openss7.org>
To: Theodore Tso <tytso@mit.edu>, Jan Engelhardt <jengelh@linux01.gwdg.de>,
       linux-kernel@vger.kernel.org
Subject: Re: [RFC] [PATCH 2/8] inode-diet: Move i_pipe into a union
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Theodore,

On Mon, 19 Jun 2006, Theodore Tso wrote:
> 
> As was mentioned in earlier comment, this will be problematic for the
> out-of-tree System V Streams code, which hijacks i_pipe as another
> place to store 4 bytes of random data needed for the Streams code (I
> believe they needed a pointer to the stream head -- the v_str pointer
> in a legacy Unix system's inode).  But, that is an out-of-tree kernel
> module, and it's a clear abuse of the i_pipe element in any case.

It's used for implementing STREAMS-based FIFOs.  Which is a proper use
of i_pipe (which is for FIFOs).  Pipes (both mainline and STREAMS-based
pipes) can use i_private instead of i_pipe.

For the same reason why i_pipe cannot be combined with i_private.