v4.19.13 snapshot.
diff --git a/fs/xfs/libxfs/xfs_ag.h b/fs/xfs/libxfs/xfs_ag.h
new file mode 100644
index 0000000..412702e
--- /dev/null
+++ b/fs/xfs/libxfs/xfs_ag.h
@@ -0,0 +1,30 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (c) 2018 Red Hat, Inc.
+ * All rights reserved.
+ */
+
+#ifndef __LIBXFS_AG_H
+#define __LIBXFS_AG_H 1
+
+struct xfs_mount;
+struct xfs_trans;
+
+struct aghdr_init_data {
+	/* per ag data */
+	xfs_agblock_t		agno;		/* ag to init */
+	xfs_extlen_t		agsize;		/* new AG size */
+	struct list_head	buffer_list;	/* buffer writeback list */
+	xfs_rfsblock_t		nfree;		/* cumulative new free space */
+
+	/* per header data */
+	xfs_daddr_t		daddr;		/* header location */
+	size_t			numblks;	/* size of header */
+	xfs_btnum_t		type;		/* type of btree root block */
+};
+
+int xfs_ag_init_headers(struct xfs_mount *mp, struct aghdr_init_data *id);
+int xfs_ag_extend_space(struct xfs_mount *mp, struct xfs_trans *tp,
+			struct aghdr_init_data *id, xfs_extlen_t len);
+
+#endif /* __LIBXFS_AG_H */