diff --git a/libxfs/xfs_ialloc_btree.c b/libxfs/xfs_ialloc_btree.c
index 558ad0a..8dd3018 100644
--- a/libxfs/xfs_ialloc_btree.c
+++ b/libxfs/xfs_ialloc_btree.c
@@ -563,6 +563,36 @@
 					XFS_INODES_PER_CHUNK);
 }
 
+/* Read AGI and create inobt cursor. */
+int
+xfs_inobt_cur(
+	struct xfs_mount	*mp,
+	struct xfs_trans	*tp,
+	xfs_agnumber_t		agno,
+	xfs_btnum_t		which,
+	struct xfs_btree_cur	**curpp,
+	struct xfs_buf		**agi_bpp)
+{
+	struct xfs_btree_cur	*cur;
+	int			error;
+
+	ASSERT(*agi_bpp == NULL);
+	ASSERT(*curpp == NULL);
+
+	error = xfs_ialloc_read_agi(mp, tp, agno, agi_bpp);
+	if (error)
+		return error;
+
+	cur = xfs_inobt_init_cursor(mp, tp, *agi_bpp, agno, which);
+	if (!cur) {
+		xfs_trans_brelse(tp, *agi_bpp);
+		*agi_bpp = NULL;
+		return -ENOMEM;
+	}
+	*curpp = cur;
+	return 0;
+}
+
 static int
 xfs_inobt_count_blocks(
 	struct xfs_mount	*mp,
@@ -571,15 +601,14 @@
 	xfs_btnum_t		btnum,
 	xfs_extlen_t		*tree_blocks)
 {
-	struct xfs_buf		*agbp;
-	struct xfs_btree_cur	*cur;
+	struct xfs_buf		*agbp = NULL;
+	struct xfs_btree_cur	*cur = NULL;
 	int			error;
 
-	error = xfs_ialloc_read_agi(mp, tp, agno, &agbp);
+	error = xfs_inobt_cur(mp, tp, agno, btnum, &cur, &agbp);
 	if (error)
 		return error;
 
-	cur = xfs_inobt_init_cursor(mp, tp, agbp, agno, btnum);
 	error = xfs_btree_count_blocks(cur, tree_blocks);
 	xfs_btree_del_cursor(cur, error);
 	xfs_trans_brelse(tp, agbp);
diff --git a/libxfs/xfs_ialloc_btree.h b/libxfs/xfs_ialloc_btree.h
index ebdd0c6..951305e 100644
--- a/libxfs/xfs_ialloc_btree.h
+++ b/libxfs/xfs_ialloc_btree.h
@@ -64,5 +64,8 @@
 		xfs_agnumber_t agno, xfs_extlen_t *ask, xfs_extlen_t *used);
 extern xfs_extlen_t xfs_iallocbt_calc_size(struct xfs_mount *mp,
 		unsigned long long len);
+int xfs_inobt_cur(struct xfs_mount *mp, struct xfs_trans *tp,
+		xfs_agnumber_t agno, xfs_btnum_t btnum,
+		struct xfs_btree_cur **curpp, struct xfs_buf **agi_bpp);
 
 #endif	/* __XFS_IALLOC_BTREE_H__ */