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/interval_tree_generic.h>
  12
  13 static inline unsigned long vma_start_pgoff(struct vm_area_struct *v)
  14 {
  15         return v->vm_pgoff;
  16 }
  17
  18 static inline unsigned long vma_last_pgoff(struct vm_area_struct *v)
  19 {
  20         return v->vm_pgoff + ((v->vm_end - v->vm_start) >> PAGE_SHIFT) - 1;
  21 }
  22
  23 INTERVAL_TREE_DEFINE(struct vm_area_struct, shared.linear.rb,
  24                      unsigned long, shared.linear.rb_subtree_last,
  25                      vma_start_pgoff, vma_last_pgoff,, vma_interval_tree)
  26
  27 /* Insert node immediately after prev in the interval tree */
  28 void vma_interval_tree_insert_after(struct vm_area_struct *node,
  29                                     struct vm_area_struct *prev,
  30                                     struct rb_root *root)
  31 {
  32         struct rb_node **link;
  33         struct vm_area_struct *parent;
  34         unsigned long last = vma_last_pgoff(node);
  35
  36         VM_BUG_ON(vma_start_pgoff(node) != vma_start_pgoff(prev));
  37
  38         if (!prev->shared.linear.rb.rb_right) {
  39                 parent = prev;
  40                 link = &prev->shared.linear.rb.rb_right;
  41         } else {
  42                 parent = rb_entry(prev->shared.linear.rb.rb_right,
  43                                   struct vm_area_struct, shared.linear.rb);
  44                 if (parent->shared.linear.rb_subtree_last < last)
  45                         parent->shared.linear.rb_subtree_last = last;
  46                 while (parent->shared.linear.rb.rb_left) {
  47                         parent = rb_entry(parent->shared.linear.rb.rb_left,
  48                                 struct vm_area_struct, shared.linear.rb);
  49                         if (parent->shared.linear.rb_subtree_last < last)
  50                                 parent->shared.linear.rb_subtree_last = last;
  51                 }
  52                 link = &parent->shared.linear.rb.rb_left;
  53         }
  54
  55         node->shared.linear.rb_subtree_last = last;
  56         rb_link_node(&node->shared.linear.rb, &parent->shared.linear.rb, link);
  57         rb_insert_augmented(&node->shared.linear.rb, root,
  58                             &vma_interval_tree_augment);
  59 }