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Date: Tue, 14 Dec 2010 13:12:04 -0800
From: Andrew Morton <akpm@linux-foundation.org>
To: Stefani Seibold <stefani@seibold.net>
Cc: linux-kernel@vger.kernel.org, Al Viro <viro@zeniv.linux.org.uk>,
        Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: [PATCH] cramfs: generate unique inode number for better inode
 cache usage
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On Tue, 14 Dec 2010 22:02:30 +0100
Stefani Seibold <stefani@seibold.net> wrote:

> Am Dienstag, den 14.12.2010, 12:51 -0800 schrieb Andrew Morton:
> > On Sun, 12 Dec 2010 11:48:42 +0100
> > stefani@seibold.net wrote:
> > 
> > > This patch generates a unique inode numbers for any entries in the cram file
> > > system. For files which did not contain data's (device nodes, fifos and
> > > sockets) the offset of the directory entry inside + 1 will be used as the
> > > inode number.
> > > 
> > > The + 1 for the inode will it make possible to distinguish between
> > > a file which contains no data and files which has data, the later one has
> > > a inode value where the lower two bits are always 0.
> > > 
> > > It also reimplement the behavoir to set the size and the number of block
> > > to 0 for special file, which is the right value for devices, fifos and
> > > sockets.
> > > 
> > > As a little benefit it will be also more compatible which older
> > > mkcramfs, because it will never use the cramfs_inode->offset for
> > > creating a inode number for special files.
> > 
> > Did you look at using iunique() to generate cramfs inode numbers?
> 
> iunique() will create random inode numbers, depending on the order of
> the accessed files.

It generates non-unique inode numbers and uses Weird Nonstandard
Private Stuff in a place where we could use standard kernel facilities.