On Wed, Oct 13, 2021 at 04:49:39PM +1100, Dave Chinner wrote:
> On Tue, Oct 12, 2021 at 04:33:28PM -0700, Darrick J. Wong wrote:
> > From: Darrick J. Wong <djwong@xxxxxxxxxx>
> >
> > Compute the actual maximum btree height when deciding if per-AG block
> > reservation is critically low. This only affects the sanity check
> > condition, since we /generally/ will trigger on the 10% threshold.
> > This is a long-winded way of saying that we're removing one more
> > usage of XFS_BTREE_MAXLEVELS.
>
> And replacing it with a branchy dynamic calculation that has a
> static, unchanging result. :(
>
> > Signed-off-by: Darrick J. Wong <djwong@xxxxxxxxxx>
> > ---
> > fs/xfs/libxfs/xfs_ag_resv.c | 18 +++++++++++++++++-
> > 1 file changed, 17 insertions(+), 1 deletion(-)
> >
> >
> > diff --git a/fs/xfs/libxfs/xfs_ag_resv.c b/fs/xfs/libxfs/xfs_ag_resv.c
> > index 2aa2b3484c28..d34d4614f175 100644
> > --- a/fs/xfs/libxfs/xfs_ag_resv.c
> > +++ b/fs/xfs/libxfs/xfs_ag_resv.c
> > @@ -60,6 +60,20 @@
> > * to use the reservation system should update ask/used in xfs_ag_resv_init.
> > */
> >
> > +/* Compute maximum possible height for per-AG btree types for this fs. */
> > +static unsigned int
> > +xfs_ag_btree_maxlevels(
> > + struct xfs_mount *mp)
> > +{
> > + unsigned int ret = mp->m_ag_maxlevels;
> > +
> > + ret = max(ret, mp->m_bm_maxlevels[XFS_DATA_FORK]);
> > + ret = max(ret, mp->m_bm_maxlevels[XFS_ATTR_FORK]);
> > + ret = max(ret, M_IGEO(mp)->inobt_maxlevels);
> > + ret = max(ret, mp->m_rmap_maxlevels);
> > + return max(ret, mp->m_refc_maxlevels);
> > +}
>
> Hmmmm. perhaps mp->m_ag_maxlevels should be renamed to
> mp->m_agbno_maxlevels and we pre-calculate mp->m_ag_maxlevels from
I prefer m_alloc_maxlevels for the first one, since "agbno" means "AG
block number" in my head.
As for the second, how about "m_agbtree_maxlevels" since we already use
'agbtree' to refer to per-AG btrees elsewhere?
Other than the naming, I agree with your suggestion.
--D
> the above function and just use the variable in the
> xfs_ag_resv_critical() check?
>
> Cheers,
>
> Dave.
> --
> Dave Chinner
> david@xxxxxxxxxxxxx
