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Date: Wed, 14 Jan 2004 15:12:26 -0500 (EST)
From: Robert Watson <rwatson@freebsd.org>
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To: Bruce Evans <bde@zeta.org.au>
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cc: Don Lewis <truckman@freebsd.org>
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Subject: Re: simplifying linux_emul_convpath()
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On Thu, 15 Jan 2004, Bruce Evans wrote:

> > That inode numbers are subject to collision is a practical reality with
> > the existence of globally scalable distributed file systems.  Many file
> > formats, APIs, and ABIs assume a 32-bit inode number; however, distributed
> > systems like AFS support hundreds of thousands, if not millions, of
> > concurrent users and computer systems.  Expecting each user/computer to
> 
> It's a practical reality that file systems with inode numbers >= 2^32
> cannot work in FreeBSD now. 

So what ends up happening is what Coda and Arla do: take the 96-bit unique
identifier (viceid or fid), hash it to a somewhat unique value, and stick
the result in the vattr returned by VOP_GETATTR().  And sometimes
applications just get confused. Of course, many of those applications were
quite capable of getting confused before -- unless you hold a file open,
you can't prevent its inode number from being reused if the file is
deleted and a new one created. 

Robert N M Watson             FreeBSD Core Team, TrustedBSD Projects
robert@fledge.watson.org      Senior Research Scientist, McAfee Research