From 1ac35f061af011442eeb731632f6daae991ecf7c Mon Sep 17 00:00:00 2001
From: "Darrick J. Wong" <darrick.wong@oracle.com>
Date: Wed, 26 Aug 2020 10:54:27 -0700
Subject: [PATCH] xfs: use the finobt block counts to speed up mount times
Git-commit: 1ac35f061af011442eeb731632f6daae991ecf7c
Patch-mainline: v5.10-rc1
References: bsc#1203387

Now that we have reliable finobt block counts, use them to speed up the
per-AG block reservation calculations at mount time.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Acked-by: Anthony Iliopoulos <ailiop@suse.com>

---
 fs/xfs/libxfs/xfs_ialloc_btree.c | 28 +++++++++++++++++++++++++++-
 1 file changed, 27 insertions(+), 1 deletion(-)

diff --git a/fs/xfs/libxfs/xfs_ialloc_btree.c b/fs/xfs/libxfs/xfs_ialloc_btree.c
index 84d5376e0a0f..f8e57ae2ba83 100644
--- a/fs/xfs/libxfs/xfs_ialloc_btree.c
+++ b/fs/xfs/libxfs/xfs_ialloc_btree.c
@@ -582,6 +582,28 @@ xfs_inobt_count_blocks(
 	return error;
 }
 
+/* Read finobt block count from AGI header. */
+static int
+xfs_finobt_read_blocks(
+	struct xfs_mount	*mp,
+	struct xfs_trans	*tp,
+	xfs_agnumber_t		agno,
+	xfs_extlen_t		*tree_blocks)
+{
+	struct xfs_buf		*agbp;
+	struct xfs_agi		*agi;
+	int			error;
+
+	error = xfs_ialloc_read_agi(mp, tp, agno, &agbp);
+	if (error)
+		return error;
+
+	agi = agbp->b_addr;
+	*tree_blocks = be32_to_cpu(agi->agi_fblocks);
+	xfs_trans_brelse(tp, agbp);
+	return 0;
+}
+
 /*
  * Figure out how many blocks to reserve and how many are used by this btree.
  */
@@ -598,7 +620,11 @@ xfs_finobt_calc_reserves(
 	if (!xfs_sb_version_hasfinobt(&mp->m_sb))
 		return 0;
 
-	error = xfs_inobt_count_blocks(mp, agno, XFS_BTNUM_FINO, &tree_len);
+	if (xfs_sb_version_hasinobtcounts(&mp->m_sb))
+		error = xfs_finobt_read_blocks(mp, NULL, agno, &tree_len);
+	else
+		error = xfs_inobt_count_blocks(mp, agno, XFS_BTNUM_FINO,
+				&tree_len);
 	if (error)
 		return error;
 
-- 
2.35.3