linux-kernel - Re: umount -l <path>, getcwd and /proc/<pid>/cwd inconsistent

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Message-Id: <1199696154.3156.74.camel@raven.themaw.net>
Date:	Mon, 07 Jan 2008 17:55:54 +0900
From:	Ian Kent <raven@...maw.net>
To:	bjdouma@...all.nl
Cc:	linux-kernel@...r.kernel.org
Subject: Re: umount -l <path>, getcwd and /proc/<pid>/cwd inconsistent


On Mon, 2008-01-07 at 09:29 +0100, Bauke Jan Douma wrote:
> Ian Kent wrote on 07-01-08 04:17:
> > Hi all,
> > 
> > Could someone please help me understand what's happening with, what
> > looks like inconsistent behavior, between getpwd and procfs readlink.
> > 
> > Basically, from a bash shell, setting working directory to a mounted
> > directory all is fine with "pwd" and "/proc/<pid>/cwd". Following a
> > "umount - l" on the mount "pwd" continues to return the expected string
> > but "/proc/<pid>/cwd" returns an empty string.
> > 
> > What I'm really after is why this happens because sys_getcwd and
> > proc_pid_readlink appear to do essentially the same thing to get the
> > string.
> > 
> [snip]
> 
> What does `/bin/pwd' return, when you do that instead of
> plain `pwd' (after the umount)?

I did check that at one point and it returned the same as pwd.
I'll check again later, but I remember I explicitly checked that along
the way.

Ian


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