Re: [PATCH 21/26] xfs: make the RT allocator rtgroup aware

Christoph Hellwig
2024-08-27T05:00:55Z

On Mon, Aug 26, 2024 at 07:16:09PM -0700, Darrick J. Wong wrote:
> > Hmmm. Could we initialise it in memory only for !rtg filesystems,
> > and make sure we never write it back via a check in the
> > xfs_sb_to_disk() formatter function?
>
> Only if the incore sb_rgextents becomes u64, which will then cause the
> incore and ondisk superblock structures not to match anymore. There's
> probably not much reason to keep them the same anymore. That said, up
> until recently the metadir patchset actually broke the two apart, but
> then hch and I put things back to reduce our own confusion.

Note that the incore sb really isn't much of a thing. It's a random
structure that only exists embedded into the XFS mount. The only
reason we keep adding fields to it is because some of the conversion
functions from/to disk are a mess. The RT growfs cleanups earlier
in this patchbomb actually take care of a large part of that, so
we should be able to retire it in the not too distant future.