Re: [RFC 0/3] Convert XFS inode hashes to radix trees

[David Chinner <dgc@sgi.com>]

On Wed, Oct 04, 2006 at 08:22:56AM +1000, David Chinner wrote:
> On Tue, Oct 03, 2006 at 02:23:35PM -0700, Chris Wedgwood wrote:
> > On Tue, Oct 03, 2006 at 04:06:10PM +1000, David Chinner wrote:
> > > Overall, the patchset removes more than 200 lines of code from the
> > > xfs inode caching and lookup code and provides more consistent
> > > scalability for large numbers of cached inodes. The only down side
> > > is that it limits us to 32 bit inode numbers of 32 bit platforms due
> > > to the way the radix tree uses unsigned longs for it's indexes
> > 
> >     commit afefdbb28a0a2af689926c30b94a14aea6036719
> >     tree 6ee500575cac928cd90045bcf5b691cf2b8daa09
> >     parent 1d32849b14bc8792e6f35ab27dd990d74b16126c
> >     author David Howells <dhowells@redhat.com> 1159863226 -0700
> >     committer Linus Torvalds <torvalds@g5.osdl.org> 1159887820 -0700
> > 
> >     [PATCH] VFS: Make filldir_t and struct kstat deal in 64-bit inode numbers
> > 
> >     These patches make the kernel pass 64-bit inode numbers internally when
> >     communicating to userspace, even on a 32-bit system.  They are required
> >     because some filesystems have intrinsic 64-bit inode numbers: NFS3+ and XFS
> >     for example.  The 64-bit inode numbers are then propagated to userspace
> >     automatically where the arch supports it.
> >     [...]
> > 
> > Doing this will mean XFS won't be able to support 32-bit inodes on
> > 32-bit platforms the above (merged) patch --- though given that cheap
> > 64-bit systems are now abundant does anyone really care?
> 
> That's a good question. In a recent thread on linux-fsdevel about
> these patches Christoph Hellwig pointed out that 32bit user space is
> not ready for 64 bit inodes, so it's probably going to be a while
> before the second half of this mod is ready (which exports 64 bit
> inodes ito userspace on 32bit platforms).

Ahhh.... I think I misread what Chris wrote here - _32_ bit inodes on
32 bit platforms not working? I can't see how this would be the
case with the mods I posted given that they are entirely internal to
XFS and don't change any external inode number interfaces. And the
above commit shouldn't break XFS either.

Cheers,

Dave.
-- 
Dave Chinner
Principal Engineer
SGI Australian Software Group