Re: [PATCH 10/15] xfs: compute actual maximum btree height for critical reservation calculation
From: Dave Chinner <david@fromorbit.com>
Date: 2021-10-13 05:49:43
On Tue, Oct 12, 2021 at 04:33:28PM -0700, Darrick J. Wong wrote:
From: Darrick J. Wong <djwong@kernel.org> 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. :(
quoted hunk ↗ jump to hunk
Signed-off-by: Darrick J. Wong <djwong@kernel.org> --- 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 the above function and just use the variable in the xfs_ag_resv_critical() check? Cheers, Dave. -- Dave Chinner david@fromorbit.com