On Wed, Apr 23, 2025 at 07:58:50AM -0700, Darrick J. Wong wrote:
> > > +xfs_calc_default_atomic_ioend_reservation(
> > > + struct xfs_mount *mp,
> > > + struct xfs_trans_resv *resp)
> > > +{
> > > + if (xfs_has_reflink(mp))
> > > + resp->tr_atomic_ioend = resp->tr_itruncate;
> > > + else
> > > + memset(&resp->tr_atomic_ioend, 0,
> > > + sizeof(resp->tr_atomic_ioend));
> > > +}
> >
> > What is the point of zeroing out the structure for the non-reflink
> > case? Just as a poision for not using it when not supported as no
> > code should be doing that? Just thinking of this because it is a
> > potentially nasty landmine for the zoned atomic support.
>
> Yes. I thought about adding a really stupid helper:
Why don't we just always set up the xfs_trans_resv structure? We
do that for all kinds of other transactions not supported as well,
don't we?
> static inline bool xfs_has_sw_atomic_write(struct xfs_mount *mp)
> {
> return xfs_has_reflink(mp);
> }
>
> But that seemed too stupid so I left it out. Maybe it wasn't so dumb,
> since that would be where you'd enable ZNS support by changing that to:
>
> return xfs_has_reflink(mp) || xfs_has_zoned(mp);
But that helper might actually be useful in various places, so
independent of the above I'm in favor of it.
