Re: [PATCH 41/43] xfs: support write life time based data placement

Christoph Hellwig
2024-12-18T07:10:52Z

On Tue, Dec 17, 2024 at 09:14:47AM -0800, Darrick J. Wong wrote:
> > We've been thinking about that a lot. Right now we don't have an
> > immediate use case for it, but it sure would be nice to have it without
> > needing another incompat bit. But then we'd need to find some space
> > (3 bits to be exact) in the on-disk inode for it that doesn't make
> > otherwise useful space unavaіlable for more widely useful things.
> > If you have a good idea I'll look into implementing it.
>
> How about reusing the dmapi fields in xfs_dinode, seeing as we forced
> them to zero in the base metadir series? Or do you have another use in
> mind for those 6 bytes?

I've always seen those a general space reserve for things that could
be useful for all inodes as they are fairly large and contiguous. For
these three bits I'd rather still them where it doesn't hurt too much.
But maybe I'm overthinking it.