+ /*
+ * 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;
+