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Date: Fri, 5 Oct 2007 00:41:49 +0100
From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Jan Engelhardt <jengelh@computergmbh.de>, linux-kernel@vger.kernel.org,
       dada1@cosmosbay.com, linux-fsdevel@vger.kernel.org
Subject: Re: [patch 1/2] getattr - fill the size of pipes
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> Cute feature, but it is (I assume) a Linux-specific extension and is
> something which we'll need to maintain for ever and it invites

Actually it used to work on the old old Linux pipe code.

> unportability to older Linuxes and other OSes and it introduces some risk
> of breakage of existing applications.  And it slows down fstat on a pipe.

Most Sys5 based boxes happen to put the right value there but not
everyone and its not guaranteed in the slightest
> 
> Given that the info can already be obtained via ioctl(FIONREAD) anyway, I
> don't think that (gain > pain)?

Nor me - any application trying to reduce the syscall count would just do
a very large read and get the data and size in one go.