xfs: convert directory vector functions to constants

Next step in the vectorisation process is the directory free block
encode/decode operations. There are relatively few of these, though
there are quite a number of calls to them.

Binary sizes:

   text    data     bss     dec     hex filename
 794490   96802    1096  892388   d9de4 fs/xfs/xfs.o.orig
 792986   96802    1096  890884   d9804 fs/xfs/xfs.o.p1
 792350   96802    1096  890248   d9588 fs/xfs/xfs.o.p2
 789293   96802    1096  887191   d8997 fs/xfs/xfs.o.p3
 789005   96802    1096  886903   d8997 fs/xfs/xfs.o.p4
 789061   96802    1096  886959   d88af fs/xfs/xfs.o.p5
 789733   96802    1096  887631   d8b4f fs/xfs/xfs.o.p6
 791421   96802    1096  889319   d91e7 fs/xfs/xfs.o.p7
 791701   96802    1096  889599   d92ff fs/xfs/xfs.o.p8

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Ben Myers <bpm@sgi.com>
Signed-off-by: Ben Myers <bpm@sgi.com>

diff --git a/fs/xfs/xfs_dir2.h b/fs/xfs/xfs_dir2.h
index 6119534..4264cb9 100644
--- a/fs/xfs/xfs_dir2.h
+++ b/fs/xfs/xfs_dir2.h
@@ -92,10 +92,15 @@
 	struct xfs_da_node_entry *
 		(*node_tree_p)(struct xfs_da_intnode *dap);
 
+	int	(*free_hdr_size)(void);
 	void	(*free_hdr_to_disk)(struct xfs_dir2_free *to,
 				    struct xfs_dir3_icfree_hdr *from);
 	void	(*free_hdr_from_disk)(struct xfs_dir3_icfree_hdr *to,
 				      struct xfs_dir2_free *from);
+	int	(*free_max_bests)(struct xfs_mount *mp);
+	__be16 * (*free_bests_p)(struct xfs_dir2_free *free);
+	xfs_dir2_db_t (*db_to_fdb)(struct xfs_mount *mp, xfs_dir2_db_t db);
+	int	(*db_to_fdindex)(struct xfs_mount *mp, xfs_dir2_db_t db);
 };
 
 extern const struct xfs_dir_ops *