xfs: add function pointers for get/update keys to the btree

Add some function pointers to bc_ops to get the btree keys for
leaf and node blocks, and to update parent keys of a block.
Convert the _btree_updkey calls to use our new pointer, and
modify the tree shape changing code to call the appropriate
get_*_keys pointer instead of _btree_copy_keys because the
overlapping btree has to calculate high key values.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

fs/xfs/libxfs/xfs_alloc_btree.c

@@ -403,6 +403,10 @@ static const struct xfs_btree_ops xfs_allocbt_ops = {
 	.keys_inorder		= xfs_allocbt_keys_inorder,
 	.recs_inorder		= xfs_allocbt_recs_inorder,
 #endif
+
+	.get_leaf_keys		= xfs_btree_get_leaf_keys,
+	.get_node_keys		= xfs_btree_get_node_keys,
+	.update_keys		= xfs_btree_update_keys,
 };
 
 /*