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Date: Mon, 7 Oct 2013 20:03:57 +0100
From: Al Viro <viro@ZenIV.linux.org.uk>
To: Andre Richter <andre.o.richter@gmail.com>
Cc: linux-kernel@vger.kernel.org
Subject: Re: file_inode() vs f_mapping->host
Message-ID: <20131007190357.GA13318@ZenIV.linux.org.uk>
References: <CAKqeN29hu55Q0qXioaZKAppK-aA68rCaDUFg2z2AvUSEnnyMDA@mail.gmail.com>
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On Mon, Oct 07, 2013 at 01:08:09PM +0200, Andre Richter wrote:
> Hi all,
> 
> in this thread ( https://lkml.org/lkml/2013/3/17/128 ), Al Viro argues
> that file_inode() is not equal to f_mapping->host in certain cases.
> 
> I'm asking, because in arch/x86/kernel/msr.c, msr_seek() retrieves the
> inode via f_mapping while one function later, msr_read() uses
> file_inode().
> Is this on purpose?

Both of those should use file_inode(), but in that case both expressions
yield the same value.  And no, it's not on purpose in case of msr.c -
just a historical accident.