Re: [PATCH v9 13/15] xfs: add xfs_compute_atomic_write_unit_max()

Darrick J. Wong
2025-05-01T16:23:09Z

On Thu, May 01, 2025 at 06:00:12AM +0100, John Garry wrote:
> On 01/05/2025 05:30, Darrick J. Wong wrote:
> > On Wed, Apr 30, 2025 at 08:52:00AM +0100, John Garry wrote:
> > > On 25/04/2025 17:45, John Garry wrote:
> > > > +static inline xfs_extlen_t xfs_calc_perag_awu_max(struct xfs_mount *mp)
> > > > +{
> > > > + if (mp->m_ddev_targp->bt_bdev_awu_min > 0)
> > > > + return max_pow_of_two_factor(mp->m_sb.sb_agblocks);
> > > > + return mp->m_ag_max_usable;
> > > I think that this should be rounddown_pow_of_two(mp->m_ag_max_usable)
> > >
> > > ditto for rt
> > >
> > > I will fix (unless disagree).
> > I don't think this needs fixing. If there's no hardware support on the
> > device, then we can do any size of atomic write that we want.
>
> Check man pages for statx:
>
> stx_atomic_write_unit_min
> stx_atomic_write_unit_max
> ... These values are each guaranteed to be
> a power-of-2.
>
> Same is enforced for size for RWF_ATOMIC.

Ok then.

--D