xfs: don't reserve per-AG space for an internal log

[linux.git] / fs / xfs / libxfs / xfs_rmap_btree.c

diff --git a/fs/xfs/libxfs/xfs_rmap_btree.c b/fs/xfs/libxfs/xfs_rmap_btree.c
index 5738e11055e6bbeaf9602b353555450b24908600..5d1f8884c8886eedc81bb54acd90c8445ad62826 100644 (file)
--- a/fs/xfs/libxfs/xfs_rmap_btree.c
+++ b/fs/xfs/libxfs/xfs_rmap_btree.c
@@ -578,6 +578,15 @@ xfs_rmapbt_calc_reserves(
        tree_len = be32_to_cpu(agf->agf_rmap_blocks);
        xfs_trans_brelse(tp, agbp);
 
+       /*
+        * The log is permanently allocated, so the space it occupies will
+        * never be available for the kinds of things that would require btree
+        * expansion.  We therefore can pretend the space isn't there.
+        */
+       if (mp->m_sb.sb_logstart &&
+           XFS_FSB_TO_AGNO(mp, mp->m_sb.sb_logstart) == agno)
+               agblocks -= mp->m_sb.sb_logblocks;
+
        /* Reserve 1% of the AG or enough for 1 block per record. */
        *ask += max(agblocks / 100, xfs_rmapbt_max_size(mp, agblocks));
        *used += tree_len;