mm: replace vma prio_tree 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
12 #define ITSTRUCT   struct vm_area_struct
13 #define ITRB       shared.linear.rb
14 #define ITTYPE     unsigned long
15 #define ITSUBTREE  shared.linear.rb_subtree_last
16 #define ITSTART(n) ((n)->vm_pgoff)
17 #define ITLAST(n)  ((n)->vm_pgoff + \
18                     (((n)->vm_end - (n)->vm_start) >> PAGE_SHIFT) - 1)
19 #define ITSTATIC
20 #define ITPREFIX   vma_interval_tree
21
22 #include <linux/interval_tree_tmpl.h>
23
24 /* Insert old immediately after vma in the interval tree */
25 void vma_interval_tree_add(struct vm_area_struct *vma,
26                            struct vm_area_struct *old,
27                            struct address_space *mapping)
28 {
29         struct rb_node **link;
30         struct vm_area_struct *parent;
31         unsigned long last;
32
33         if (unlikely(vma->vm_flags & VM_NONLINEAR)) {
34                 list_add(&vma->shared.nonlinear, &old->shared.nonlinear);
35                 return;
36         }
37
38         last = ITLAST(vma);
39
40         if (!old->shared.linear.rb.rb_right) {
41                 parent = old;
42                 link = &old->shared.linear.rb.rb_right;
43         } else {
44                 parent = rb_entry(old->shared.linear.rb.rb_right,
45                                   struct vm_area_struct, shared.linear.rb);
46                 if (parent->shared.linear.rb_subtree_last < last)
47                         parent->shared.linear.rb_subtree_last = last;
48                 while (parent->shared.linear.rb.rb_left) {
49                         parent = rb_entry(parent->shared.linear.rb.rb_left,
50                                 struct vm_area_struct, shared.linear.rb);
51                         if (parent->shared.linear.rb_subtree_last < last)
52                                 parent->shared.linear.rb_subtree_last = last;
53                 }
54                 link = &parent->shared.linear.rb.rb_left;
55         }
56
57         vma->shared.linear.rb_subtree_last = last;
58         rb_link_node(&vma->shared.linear.rb, &parent->shared.linear.rb, link);
59         rb_insert_augmented(&vma->shared.linear.rb, &mapping->i_mmap,
60                             &vma_interval_tree_augment_callbacks);
61 }