dm bufio: clean up rbtree block ordering

dm-bufio uses unnatural ordering in the rb-tree - blocks with smaller
numbers were put to the right node and blocks with bigger numbers were
put to the left node.

Reverse that logic so that it's natural.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

drivers/md/dm-bufio.c

@@ -256,7 +256,7 @@ static struct dm_buffer *__find(struct dm_bufio_client *c, sector_t block)
 		if (b->block == block)
 			return b;
 
-		n = (b->block < block) ? n->rb_left : n->rb_right;
+		n = block < b->block ? n->rb_left : n->rb_right;
 	}
 
 	return NULL;
@@ -276,8 +276,8 @@ static void __insert(struct dm_bufio_client *c, struct dm_buffer *b)
 		}
 
 		parent = *new;
-		new = (found->block < b->block) ?
-			&((*new)->rb_left) : &((*new)->rb_right);
+		new = b->block < found->block ?
+			&found->node.rb_left : &found->node.rb_right;
 	}
 
 	rb_link_node(&b->node, parent, new);