Re: [PATCH] UBIFS: fill f_fsid

[Christoph Hellwig <hch@infradead.org>]

On Mon, Sep 01, 2008 at 10:43:07AM +0100, David Woodhouse wrote:
> On Sun, 2008-08-31 at 17:52 +0300, Artem Bityutskiy wrote:
> > From: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
> > 
> > UBIFS stores 16-bit UUID in the superblock, and it is a good
> > idea to return part of it in 'f_fsid' filed of kstatfs structure.
> 
> I think you mean a 16-byte UUID, not 16-bit?
> 
> > +	memcpy(&buf->f_fsid, c->uuid, sizeof(__kernel_fsid_t));
> 
> For btrfs I xor the first 64 bits with the second 64 bits, and put
> _that_ into f_fsid. You're just putting the first 64 bits in and
> ignoring the second 64 bits. Neither is really _better_ than the other;
> you just alter the circumstances in which you get collisions. But I
> suppose we might as well be consistent about how we do it?

XFS just puts in the st_dev.  And I can't realy find any useful
defintion of what it's supposed to b anyway..