From cce0741ed9ab3e72381c8c1db34c1bc6232a8ce5 Mon Sep 17 00:00:00 2001
From: "Darrick J. Wong" <djwong@kernel.org>
Date: Sat, 10 Aug 2024 21:41:15 +0200
Subject: [PATCH] xfs: add metadata reservations for realtime rmap btrees

Source kernel commit: 96e6d68712d5d66f3980fc5e6f889c4428bf8c38

Reserve some free blocks so that we will always have enough free blocks
in the data volume to handle expansion of the realtime rmap btree.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 libxfs/xfs_metafile.c     |  6 +++++-
 libxfs/xfs_rtrmap_btree.c | 39 +++++++++++++++++++++++++++++++++++++++
 libxfs/xfs_rtrmap_btree.h |  2 ++
 3 files changed, 46 insertions(+), 1 deletion(-)

diff --git a/libxfs/xfs_metafile.c b/libxfs/xfs_metafile.c
index 5c70e1cf2..fd537db32 100644
--- a/libxfs/xfs_metafile.c
+++ b/libxfs/xfs_metafile.c
@@ -203,7 +203,11 @@ void
 xfs_metafile_resv_free(
 	struct xfs_inode	*ip)
 {
-	if (!ip)
+	/*
+	 * We can end up here for the rt bitmap/summary inodes that don't have
+	 * reservations.  Just exist early in that case.
+	 */
+	if (!ip || !ip->i_delayed_blks)
 		return;
 
 	ASSERT(xfs_is_metadir_inode(ip));
diff --git a/libxfs/xfs_rtrmap_btree.c b/libxfs/xfs_rtrmap_btree.c
index e421635af..d3f7760ea 100644
--- a/libxfs/xfs_rtrmap_btree.c
+++ b/libxfs/xfs_rtrmap_btree.c
@@ -544,3 +544,42 @@ xfs_rtrmapbt_compute_maxlevels(
 	/* Add one level to handle the inode root level. */
 	mp->m_rtrmap_maxlevels = min(d_maxlevels, r_maxlevels) + 1;
 }
+
+/* Calculate the rtrmap btree size for some records. */
+static unsigned long long
+xfs_rtrmapbt_calc_size(
+	struct xfs_mount	*mp,
+	unsigned long long	len)
+{
+	return xfs_btree_calc_size(mp->m_rtrmap_mnr, len);
+}
+
+/*
+ * Calculate the maximum rmap btree size.
+ */
+static unsigned long long
+xfs_rtrmapbt_max_size(
+	struct xfs_mount	*mp,
+	xfs_rtblock_t		rtblocks)
+{
+	/* Bail out if we're uninitialized, which can happen in mkfs. */
+	if (mp->m_rtrmap_mxr[0] == 0)
+		return 0;
+
+	return xfs_rtrmapbt_calc_size(mp, rtblocks);
+}
+
+/*
+ * Figure out how many blocks to reserve and how many are used by this btree.
+ */
+xfs_filblks_t
+xfs_rtrmapbt_calc_reserves(
+	struct xfs_mount	*mp)
+{
+	if (!xfs_has_rtrmapbt(mp))
+		return 0;
+
+	/* 1/64th (~1.5%) of the space, and enough for 1 record per block. */
+	return max_t(xfs_filblks_t, mp->m_rgblocks >> 6,
+			xfs_rtrmapbt_max_size(mp, mp->m_rgblocks));
+}
diff --git a/libxfs/xfs_rtrmap_btree.h b/libxfs/xfs_rtrmap_btree.h
index 0f7326797..bb0ebc07f 100644
--- a/libxfs/xfs_rtrmap_btree.h
+++ b/libxfs/xfs_rtrmap_btree.h
@@ -80,4 +80,6 @@ unsigned int xfs_rtrmapbt_maxlevels_ondisk(void);
 int __init xfs_rtrmapbt_init_cur_cache(void);
 void xfs_rtrmapbt_destroy_cur_cache(void);
 
+xfs_filblks_t xfs_rtrmapbt_calc_reserves(struct xfs_mount *mp);
+
 #endif	/* __XFS_RTRMAP_BTREE_H__ */
-- 
2.50.1