[PATCH 21/56] xfs: add metadata reservations for realtime rmap btrees

Darrick J. Wong
2025-02-06T22:40:35Z

Source kernel commit: 8491a55cfc73ff5c2c637a70ade51d4d08abb90a

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>
Reviewed-by: Christoph Hellwig <hch@lst.de>
---
libxfs/xfs_rtrmap_btree.c | 41 +++++++++++++++++++++++++++++++++++++++++
libxfs/xfs_rtrmap_btree.h | 2 ++
2 files changed, 43 insertions(+)

diff --git a/libxfs/xfs_rtrmap_btree.c b/libxfs/xfs_rtrmap_btree.c
index 4c3b4a302bd778..08d1e75f190854 100644
--- a/libxfs/xfs_rtrmap_btree.c
+++ b/libxfs/xfs_rtrmap_btree.c
@@ -538,3 +538,44 @@ 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)
+{
+ uint32_t blocks = mp->m_groups[XG_TYPE_RTG].blocks;
+
+ if (!xfs_has_rtrmapbt(mp))
+ return 0;
+
+ /* Reserve 1% of the rtgroup or enough for 1 block per record. */
+ return max_t(xfs_filblks_t, blocks / 100,
+ xfs_rtrmapbt_max_size(mp, blocks));
+}
diff --git a/libxfs/xfs_rtrmap_btree.h b/libxfs/xfs_rtrmap_btree.h
index 7d1a3a49a2d69b..eaa2942297e20c 100644
--- a/libxfs/xfs_rtrmap_btree.h
+++ b/libxfs/xfs_rtrmap_btree.h
@@ -79,4 +79,6 @@ 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__ */