mm anon rmap: replace same_anon_vma linked list with an interval tree.
[linux-3.10.git] / mm / interval_tree.c
1 /*
2  * mm/interval_tree.c - interval tree for mapping->i_mmap
3  *
4  * Copyright (C) 2012, Michel Lespinasse <walken@google.com>
5  *
6  * This file is released under the GPL v2.
7  */
8
9 #include <linux/mm.h>
10 #include <linux/fs.h>
11 #include <linux/rmap.h>
12 #include <linux/interval_tree_generic.h>
13
14 static inline unsigned long vma_start_pgoff(struct vm_area_struct *v)
15 {
16         return v->vm_pgoff;
17 }
18
19 static inline unsigned long vma_last_pgoff(struct vm_area_struct *v)
20 {
21         return v->vm_pgoff + ((v->vm_end - v->vm_start) >> PAGE_SHIFT) - 1;
22 }
23
24 INTERVAL_TREE_DEFINE(struct vm_area_struct, shared.linear.rb,
25                      unsigned long, shared.linear.rb_subtree_last,
26                      vma_start_pgoff, vma_last_pgoff,, vma_interval_tree)
27
28 /* Insert node immediately after prev in the interval tree */
29 void vma_interval_tree_insert_after(struct vm_area_struct *node,
30                                     struct vm_area_struct *prev,
31                                     struct rb_root *root)
32 {
33         struct rb_node **link;
34         struct vm_area_struct *parent;
35         unsigned long last = vma_last_pgoff(node);
36
37         VM_BUG_ON(vma_start_pgoff(node) != vma_start_pgoff(prev));
38
39         if (!prev->shared.linear.rb.rb_right) {
40                 parent = prev;
41                 link = &prev->shared.linear.rb.rb_right;
42         } else {
43                 parent = rb_entry(prev->shared.linear.rb.rb_right,
44                                   struct vm_area_struct, shared.linear.rb);
45                 if (parent->shared.linear.rb_subtree_last < last)
46                         parent->shared.linear.rb_subtree_last = last;
47                 while (parent->shared.linear.rb.rb_left) {
48                         parent = rb_entry(parent->shared.linear.rb.rb_left,
49                                 struct vm_area_struct, shared.linear.rb);
50                         if (parent->shared.linear.rb_subtree_last < last)
51                                 parent->shared.linear.rb_subtree_last = last;
52                 }
53                 link = &parent->shared.linear.rb.rb_left;
54         }
55
56         node->shared.linear.rb_subtree_last = last;
57         rb_link_node(&node->shared.linear.rb, &parent->shared.linear.rb, link);
58         rb_insert_augmented(&node->shared.linear.rb, root,
59                             &vma_interval_tree_augment);
60 }
61
62 static inline unsigned long avc_start_pgoff(struct anon_vma_chain *avc)
63 {
64         return vma_start_pgoff(avc->vma);
65 }
66
67 static inline unsigned long avc_last_pgoff(struct anon_vma_chain *avc)
68 {
69         return vma_last_pgoff(avc->vma);
70 }
71
72 INTERVAL_TREE_DEFINE(struct anon_vma_chain, rb, unsigned long, rb_subtree_last,
73                      avc_start_pgoff, avc_last_pgoff,, anon_vma_interval_tree)