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From: Peter Chubb <peter@chubb.wattle.id.au>
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Message-ID: <15902.16227.924630.143293@wombat.chubb.wattle.id.au>
Date: Fri, 10 Jan 2003 14:34:59 +1100
To: Andrew McGregor <andrew@indranet.co.nz>
Cc: Peter Chubb <peter@chubb.wattle.id.au>, eric@andante.org,
       linux-kernel@vger.kernel.org
Subject: Re: ISO-9660 Rock Ridge gives different links different inums
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>>>>> "Andrew" == Andrew McGregor <andrew@indranet.co.nz> writes:

Andrew> --On Friday, January 10, 2003 14:08:59 +1100 Peter Chubb
Andrew> <peter@chubb.wattle.id.au> wrote:

>> In linux 2.5.54, multiple links to the same file on a rock-ridge CD
>> have different inode numbers.  This confuses cpio, tar and cp -ra
>> because the multiple links are each copied separately as a single
>> file.
>> 
>> It'll probably also confuse NFS, but I haven't tried that.

Andrew> Shouldn't do, but it will probably make the buffer cache on
Andrew> the server less effective.

>> Currently the inode number appears to be the offset in bytes from
>> the start of the file system to the iso directory entry.  Files
>> with multiple directory entries (i.e., links) therefore have
>> different inums.
>> 
>> I don't know enough about the ISO9660 standard to be sure what's
>> best to do about this.

Andrew> Change it to be the offset to the data area, which should be
Andrew> the same for all of them?

I thought about that, but I'm unsure if there's any way to get from
that offset to the directory information.  As far as I can tell,
there's no concept of an inode separate from directory entry on iso9660
--- the directory entry/entries all contain all the information that
describes a file.  Which means that the inumber has to point to some
directory node.

Preferably, all the inumbers for the same file would point to the same
directory entry; but I can see no easy way to do that.  Keeping an
in-memory table for files with multiple links might be the best way,
as there aren't that many on a typical filesystem.

--
Dr Peter Chubb				    peterc@gelato.unsw.edu.au
You are lost in a maze of BitKeeper repositories, all almost the same.
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