Re: [PATCH 1/2] xfs_repair: adjust btree bulkloading slack computations to match online repair

Bill O'Donnell
2024-03-13T17:48:09Z

On Tue, Mar 12, 2024 at 07:10:45PM -0700, Darrick J. Wong wrote:
> From: Darrick J. Wong <djwong@kernel.org>
>
> Adjust the lowspace threshold in the new btree block slack computation
> code to match online repair, which uses a straight 10% instead of magic
> shifting to approximate that without division. Repairs aren't that
> frequent in the kernel; and userspace can always do u64 division.
>
> Signed-off-by: Darrick J. Wong <djwong@kernel.org>

Reviewed-by: Bill O'Donnell <bodonnel@redhat.com>

> ---
> repair/bulkload.c | 9 +++++----
> 1 file changed, 5 insertions(+), 4 deletions(-)
>
>
> diff --git a/repair/bulkload.c b/repair/bulkload.c
> index 8dd0a0c3908b..0117f69416cf 100644
> --- a/repair/bulkload.c
> +++ b/repair/bulkload.c
> @@ -106,9 +106,10 @@ bulkload_claim_block(
> * exceptions to this rule:
> *
> * (1) If someone turned one of the debug knobs.
> - * (2) The AG has less than ~9% space free.
> + * (2) The AG has less than ~10% space free.
> *
> - * Note that we actually use 3/32 for the comparison to avoid division.
> + * In the latter case, format the new btree blocks almost completely full to
> + * minimize space usage.
> */
> void
> bulkload_estimate_ag_slack(
> @@ -124,8 +125,8 @@ bulkload_estimate_ag_slack(
> bload->leaf_slack = bload_leaf_slack;
> bload->node_slack = bload_node_slack;
>
> - /* No further changes if there's more than 3/32ths space left. */
> - if (free >= ((sc->mp->m_sb.sb_agblocks * 3) >> 5))
> + /* No further changes if there's more than 10% space left. */
> + if (free >= sc->mp->m_sb.sb_agblocks / 10)
> return;
>
> /*
>
>