Re: what is our answer to ZFS?

From: Jan Harkes
Date: Tue Nov 22 2005 - 10:27:52 EST

On Tue, Nov 22, 2005 at 09:50:47AM -0500, Theodore Ts'o wrote:
> I will note though that there are people who are asking for 64-bit
> inode numbers on 32-bit platforms, since 2**32 inodes are not enough
> for certain distributed/clustered filesystems. And this is something
> we don't yet support today, and probably will need to think about much
> sooner than 128-bit filesystems....

As far as the kernel is concerned this hasn't been a problem in a while
(2.4.early). The iget4 operation that was introduced by reiserfs (now
iget5) pretty much makes it possible for a filesystem to use anything to
identify it's inodes. The 32-bit inode numbers are simply used as a hash

The only thing that tends to break are userspace archiving tools like
tar, which assume that 2 objects with the same 32-bit st_ino value are
identical. I think that by now several actually double check that the
inode linkcount is larger than 1.

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