1 files changed, 141 insertions, 0 deletions

diff --git a/include/linux/rbtree.h b/include/linux/rbtree.h
new file mode 100644
index 000000000000..4b7cc4fe366d
--- /dev/null
+++ b/include/linux/rbtree.h
@@ -0,0 +1,141 @@
+/*
+  Red Black Trees
+  (C) 1999  Andrea Arcangeli <andrea@suse.de>
+  
+  This program is free software; you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation; either version 2 of the License, or
+  (at your option) any later version.
+
+  This program is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program; if not, write to the Free Software
+  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+
+  linux/include/linux/rbtree.h
+
+  To use rbtrees you'll have to implement your own insert and search cores.
+  This will avoid us to use callbacks and to drop drammatically performances.
+  I know it's not the cleaner way,  but in C (not in C++) to get
+  performances and genericity...
+
+  Some example of insert and search follows here. The search is a plain
+  normal search over an ordered tree. The insert instead must be implemented
+  int two steps: as first thing the code must insert the element in
+  order as a red leaf in the tree, then the support library function
+  rb_insert_color() must be called. Such function will do the
+  not trivial work to rebalance the rbtree if necessary.
+
+-----------------------------------------------------------------------
+static inline struct page * rb_search_page_cache(struct inode * inode,
+                                                 unsigned long offset)
+{
+        struct rb_node * n = inode->i_rb_page_cache.rb_node;
+        struct page * page;
+
+        while (n)
+        {
+                page = rb_entry(n, struct page, rb_page_cache);
+
+                if (offset < page->offset)
+                        n = n->rb_left;
+                else if (offset > page->offset)
+                        n = n->rb_right;
+                else
+                        return page;
+        }
+        return NULL;
+}
+
+static inline struct page * __rb_insert_page_cache(struct inode * inode,
+                                                   unsigned long offset,
+                                                   struct rb_node * node)
+{
+        struct rb_node ** p = &inode->i_rb_page_cache.rb_node;
+        struct rb_node * parent = NULL;
+        struct page * page;
+
+        while (*p)
+        {
+                parent = *p;
+                page = rb_entry(parent, struct page, rb_page_cache);
+
+                if (offset < page->offset)
+                        p = &(*p)->rb_left;
+                else if (offset > page->offset)
+                        p = &(*p)->rb_right;
+                else
+                        return page;
+        }
+
+        rb_link_node(node, parent, p);
+
+        return NULL;
+}
+
+static inline struct page * rb_insert_page_cache(struct inode * inode,
+                                                 unsigned long offset,
+                                                 struct rb_node * node)
+{
+        struct page * ret;
+        if ((ret = __rb_insert_page_cache(inode, offset, node)))
+                goto out;
+        rb_insert_color(node, &inode->i_rb_page_cache);
+ out:
+        return ret;
+}
+-----------------------------------------------------------------------
+*/
+
+#ifndef _LINUX_RBTREE_H
+#define _LINUX_RBTREE_H
+
+#include <linux/kernel.h>
+#include <linux/stddef.h>
+
+struct rb_node
+{
+        struct rb_node *rb_parent;
+        int rb_color;
+#define RB_RED          0
+#define RB_BLACK        1
+        struct rb_node *rb_right;
+        struct rb_node *rb_left;
+};
+
+struct rb_root
+{
+        struct rb_node *rb_node;
+};
+
+#define RB_ROOT (struct rb_root) { NULL, }
+#define rb_entry(ptr, type, member) container_of(ptr, type, member)
+
+extern void rb_insert_color(struct rb_node *, struct rb_root *);
+extern void rb_erase(struct rb_node *, struct rb_root *);
+
+/* Find logical next and previous nodes in a tree */
+extern struct rb_node *rb_next(struct rb_node *);
+extern struct rb_node *rb_prev(struct rb_node *);
+extern struct rb_node *rb_first(struct rb_root *);
+extern struct rb_node *rb_last(struct rb_root *);
+
+/* Fast replacement of a single node without remove/rebalance/add/rebalance */
+extern void rb_replace_node(struct rb_node *victim, struct rb_node *new, 
+                            struct rb_root *root);
+
+static inline void rb_link_node(struct rb_node * node, struct rb_node * parent,
+                                struct rb_node ** rb_link)
+{
+        node->rb_parent = parent;
+        node->rb_color = RB_RED;
+        node->rb_left = node->rb_right = NULL;
+
+        *rb_link = node;
+}
+
+#endif  /* _LINUX_RBTREE_H */