diff --git a/libxfs/xfs_ag.c b/libxfs/xfs_ag.c
index 926a241..2aa38a6 100644
--- a/libxfs/xfs_ag.c
+++ b/libxfs/xfs_ag.c
@@ -271,6 +271,27 @@
 	return __xfs_agino_range(mp, xfs_ag_block_count(mp, agno), first, last);
 }
 
+/*
+ * Update the perag of the previous tail AG if it has been changed during
+ * recovery (i.e. recovery of a growfs).
+ */
+int
+xfs_update_last_ag_size(
+	struct xfs_mount	*mp,
+	xfs_agnumber_t		prev_agcount)
+{
+	struct xfs_perag	*pag = xfs_perag_grab(mp, prev_agcount - 1);
+
+	if (!pag)
+		return -EFSCORRUPTED;
+	pag->block_count = __xfs_ag_block_count(mp, prev_agcount - 1,
+			mp->m_sb.sb_agcount, mp->m_sb.sb_dblocks);
+	__xfs_agino_range(mp, pag->block_count, &pag->agino_min,
+			&pag->agino_max);
+	xfs_perag_rele(pag);
+	return 0;
+}
+
 int
 xfs_initialize_perag(
 	struct xfs_mount	*mp,
diff --git a/libxfs/xfs_ag.h b/libxfs/xfs_ag.h
index 043b661..4ae1937 100644
--- a/libxfs/xfs_ag.h
+++ b/libxfs/xfs_ag.h
@@ -150,6 +150,7 @@
 void xfs_free_perag_range(struct xfs_mount *mp, xfs_agnumber_t first_agno,
 		xfs_agnumber_t end_agno);
 int xfs_initialize_perag_data(struct xfs_mount *mp, xfs_agnumber_t agno);
+int xfs_update_last_ag_size(struct xfs_mount *mp, xfs_agnumber_t prev_agcount);
 
 /* Passive AG references */
 struct xfs_perag *xfs_perag_get(struct xfs_mount *mp, xfs_agnumber_t agno);