xfs: add metadata reservations for realtime rmap btrees

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>

diff --git a/libxfs/xfs_rtrmap_btree.c b/libxfs/xfs_rtrmap_btree.c
index d90b5d7d91fc3fe5a764e6cb0fa2b20cb9322398..9cda53bbd514cb6feee50da828963f404299d424 100644 (file)
--- a/libxfs/xfs_rtrmap_btree.c
+++ b/libxfs/xfs_rtrmap_btree.c
@@ -607,3 +607,42 @@ xfs_rtrmapbt_create_path(
        *pathp = path;
        return 0;
 }
+
+/* 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_sb.sb_rgblocks >> 6,
+                       xfs_rtrmapbt_max_size(mp, mp->m_sb.sb_rgblocks));
+}

diff --git a/libxfs/xfs_rtrmap_btree.h b/libxfs/xfs_rtrmap_btree.h
index 0396ba7c4176e4b5bf4c092b3fabdecc8d3780e8..1d51fe05ad7a17b548485d71924111ceeff4eeec 100644 (file)
--- a/libxfs/xfs_rtrmap_btree.h
+++ b/libxfs/xfs_rtrmap_btree.h
@@ -84,4 +84,6 @@ void xfs_rtrmapbt_destroy_cur_cache(void);
 int xfs_rtrmapbt_create_path(struct xfs_mount *mp, xfs_rgnumber_t rgno,
                struct xfs_imeta_path **pathp);
 
+xfs_filblks_t xfs_rtrmapbt_calc_reserves(struct xfs_mount *mp);
+
 #endif /* __XFS_RTRMAP_BTREE_H__ */