Commit 90dde9a1 authored by Roger L. Beckermeyer III's avatar Roger L. Beckermeyer III Committed by David Sterba
Browse files

rbtree: add rb_find_add_cached() to rbtree.h 



Adds rb_find_add_cached() as a helper function for use with red-black
trees. Used in btrfs to reduce boilerplate code.

And since it's a new helper, the cmp() function will require both
parameter to be const rb_node pointers.

Suggested-by: default avatarJosef Bacik <josef@toxicpanda.com>
Signed-off-by: default avatarRoger L. Beckermeyer III <beckerlee3@gmail.com>
Acked-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: default avatarQu Wenruo <wqu@suse.com>
Signed-off-by: default avatarQu Wenruo <wqu@suse.com>
Reviewed-by: default avatarDavid Sterba <dsterba@suse.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent 57e42186

include/linux/rbtree.h

+37 −0
Original line number Diff line number Diff line
@@ -210,6 +210,43 @@ rb_add(struct rb_node *node, struct rb_root *tree, 
	rb_insert_color(node, tree);

}



/**

 * rb_find_add_cached() - find equivalent @node in @tree, or add @node

 * @node: node to look-for / insert

 * @tree: tree to search / modify

 * @cmp: operator defining the node order

 *

 * Returns the rb_node matching @node, or NULL when no match is found and @node

 * is inserted.

 */

static __always_inline struct rb_node *

rb_find_add_cached(struct rb_node *node, struct rb_root_cached *tree,

	    int (*cmp)(const struct rb_node *new, const struct rb_node *exist))

{

	bool leftmost = true;

	struct rb_node **link = &tree->rb_root.rb_node;

	struct rb_node *parent = NULL;

	int c;



	while (*link) {

		parent = *link;

		c = cmp(node, parent);



		if (c < 0) {

			link = &parent->rb_left;

		} else if (c > 0) {

			link = &parent->rb_right;

			leftmost = false;

		} else {

			return parent;

		}

	}



	rb_link_node(node, parent, link);

	rb_insert_color_cached(node, tree, leftmost);

	return NULL;

}



/**

 * rb_find_add() - find equivalent @node in @tree, or add @node

 * @node: node to look-for / insert