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 }