From 90dde9a13c0020ce140bc8d27c1f4c48a070cc97 Mon Sep 17 00:00:00 2001 From: "Roger L. Beckermeyer III" Date: Wed, 18 Dec 2024 08:28:50 +1030 Subject: [PATCH] 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: Josef Bacik Signed-off-by: Roger L. Beckermeyer III Acked-by: Peter Zijlstra (Intel) Reviewed-by: Qu Wenruo Signed-off-by: Qu Wenruo Reviewed-by: David Sterba Signed-off-by: David Sterba --- include/linux/rbtree.h | 37 +++++++++++++++++++++++++++++++++++++ 1 file changed, 37 insertions(+) diff --git a/include/linux/rbtree.h b/include/linux/rbtree.h index 7c173aa64e1e..8d2ba3749866 100644 --- a/include/linux/rbtree.h +++ b/include/linux/rbtree.h @@ -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 -- 2.50.1