[PATCH 38/56] xfs: add metadata reservations for realtime refcount btree

Darrick J. Wong
2025-02-06T22:45:03Z

Source kernel commit: bf0b99411335db18a9ed4fcef278ce9e313f6076

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

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
---
libxfs/xfs_rtrefcount_btree.c | 38 ++++++++++++++++++++++++++++++++++++++
libxfs/xfs_rtrefcount_btree.h | 4 ++++
2 files changed, 42 insertions(+)

diff --git a/libxfs/xfs_rtrefcount_btree.c b/libxfs/xfs_rtrefcount_btree.c
index 46c62bd63458f4..9fa8f1d6eb6749 100644
--- a/libxfs/xfs_rtrefcount_btree.c
+++ b/libxfs/xfs_rtrefcount_btree.c
@@ -417,3 +417,41 @@ xfs_rtrefcountbt_compute_maxlevels(
/* Add one level to handle the inode root level. */
mp->m_rtrefc_maxlevels = min(d_maxlevels, r_maxlevels) + 1;
}
+
+/* Calculate the rtrefcount btree size for some records. */
+unsigned long long
+xfs_rtrefcountbt_calc_size(
+ struct xfs_mount *mp,
+ unsigned long long len)
+{
+ return xfs_btree_calc_size(mp->m_rtrefc_mnr, len);
+}
+
+/*
+ * Calculate the maximum refcount btree size.
+ */
+static unsigned long long
+xfs_rtrefcountbt_max_size(
+ struct xfs_mount *mp,
+ xfs_rtblock_t rtblocks)
+{
+ /* Bail out if we're uninitialized, which can happen in mkfs. */
+ if (mp->m_rtrefc_mxr[0] == 0)
+ return 0;
+
+ return xfs_rtrefcountbt_calc_size(mp, rtblocks);
+}
+
+/*
+ * Figure out how many blocks to reserve and how many are used by this btree.
+ * We need enough space to hold one record for every rt extent in the rtgroup.
+ */
+xfs_filblks_t
+xfs_rtrefcountbt_calc_reserves(
+ struct xfs_mount *mp)
+{
+ if (!xfs_has_rtreflink(mp))
+ return 0;
+
+ return xfs_rtrefcountbt_max_size(mp, mp->m_sb.sb_rgextents);
+}
diff --git a/libxfs/xfs_rtrefcount_btree.h b/libxfs/xfs_rtrefcount_btree.h
index b713b33818800c..3cd44590c9304c 100644
--- a/libxfs/xfs_rtrefcount_btree.h
+++ b/libxfs/xfs_rtrefcount_btree.h
@@ -67,4 +67,8 @@ unsigned int xfs_rtrefcountbt_maxlevels_ondisk(void);
int __init xfs_rtrefcountbt_init_cur_cache(void);
void xfs_rtrefcountbt_destroy_cur_cache(void);

+xfs_filblks_t xfs_rtrefcountbt_calc_reserves(struct xfs_mount *mp);
+unsigned long long xfs_rtrefcountbt_calc_size(struct xfs_mount *mp,
+ unsigned long long len);
+
#endif /* __XFS_RTREFCOUNT_BTREE_H__ */