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 8717df3d1798f53b044704abe4e7649f8f9f5e79..534630da0d8896a0dead17fbe8452942519007a7 100644 (file)
--- a/libxfs/xfs_rtrmap_btree.c
+++ b/libxfs/xfs_rtrmap_btree.c
@@ -543,3 +543,42 @@ 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_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 6ce76b828de0f363cff8f1adb75816783c42c56b..8887b53aa9247e9f15b9a830c4eae9fcd2197815 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);
 #define xfs_rtrmapbt_create_path(mp, rgno) \
        xfs_rtinode_create_path((mp), (rgno), "rmap")
 
+xfs_filblks_t xfs_rtrmapbt_calc_reserves(struct xfs_mount *mp);
+
 #endif /* __XFS_RTRMAP_BTREE_H__ */