Re: [PATCH 36/43] xfs: disable reflink for zoned file systems

Christoph Hellwig
2024-12-15T06:26:58Z

On Fri, Dec 13, 2024 at 03:12:47PM -0800, Darrick J. Wong wrote:
> On Wed, Dec 11, 2024 at 09:55:01AM +0100, Christoph Hellwig wrote:
> > While the zoned on-disk format supports reflinks, the GC code currently
> > always unshares reflinks when moving blocks to new zones, thus making the
> > feature unusuable. Disable reflinks until the GC code is refcount aware.
>
> This goes back to the question I had in the gc patch -- can we let
> userspace do its own reflink-aware freespace copygc, and only use the
> in-kernel gc if userspace doesn't respond fast enough? I imagine
> someone will want to share used blocks on zoned storage at some point.

I'm pretty sure we could, if we're willing to deal with worse decision
making, worse performance and potential for deadlocks while dealing with
a bigger and more complicated code base. But why?