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

Darrick J. Wong
2024-12-18T18:19:11Z

On Wed, Dec 18, 2024 at 08:10:48AM +0100, Christoph Hellwig wrote:
> 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.

Is anyone planning to add persistent write hints to xfs files?

--D