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Subject: Re: [PATCH] Linux-2.5 fix/improve get_pid()
From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: Jamie Lokier <lk@tantalophile.demon.co.uk>
Cc: Linus Torvalds <torvalds@transmeta.com>,
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On Sun, 2002-08-11 at 20:58, Jamie Lokier wrote:
> Alan Cox wrote:
> > If they hold both handles open and stat them and find the same inode
> > number then yes its a bug. We have lots of room for inode numbers to
> > handle 2^30 processes and allow for 2^30 other files
> 
> So, in general, the way to detect hard links requires both objects to be
> open at the same time?  I was sure it was enough to stat(), and check
> (st1.st_ino == st2.st_ino && st1.st_dev == st2.st_dev).
> 
> Admittedly, one of the object could be renamed or deleted in that time
> so it's not 100% reliable on changing filesystems.

Hence you need both open at the same time. 
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