/*
   * mm/interval_tree.c - interval tree for mapping->i_mmap
   *
   * Copyright (C) 2012, Michel Lespinasse <walken@google.com>
   *
   * This file is released under the GPL v2.
   */
  
  #include <linux/mm.h>
  #include <linux/fs.h>

  #include <linux/rmap.h>

  #include <linux/interval_tree_generic.h>

  static inline unsigned long vma_start_pgoff(struct vm_area_struct *v)
  {
  	return v->vm_pgoff;
  }
  
  static inline unsigned long vma_last_pgoff(struct vm_area_struct *v)
  {
  	return v->vm_pgoff + ((v->vm_end - v->vm_start) >> PAGE_SHIFT) - 1;
  }

  INTERVAL_TREE_DEFINE(struct vm_area_struct, shared.rb,
  		     unsigned long, shared.rb_subtree_last,

  		     vma_start_pgoff, vma_last_pgoff,, vma_interval_tree)
  
  /* Insert node immediately after prev in the interval tree */
  void vma_interval_tree_insert_after(struct vm_area_struct *node,
  				    struct vm_area_struct *prev,
  				    struct rb_root *root)

  {
  	struct rb_node **link;
  	struct vm_area_struct *parent;

  	unsigned long last = vma_last_pgoff(node);

  	VM_BUG_ON_VMA(vma_start_pgoff(node) != vma_start_pgoff(prev), node);

  	if (!prev->shared.rb.rb_right) {

  		parent = prev;

  		link = &prev->shared.rb.rb_right;

  	} else {

  		parent = rb_entry(prev->shared.rb.rb_right,
  				  struct vm_area_struct, shared.rb);
  		if (parent->shared.rb_subtree_last < last)
  			parent->shared.rb_subtree_last = last;
  		while (parent->shared.rb.rb_left) {
  			parent = rb_entry(parent->shared.rb.rb_left,
  				struct vm_area_struct, shared.rb);
  			if (parent->shared.rb_subtree_last < last)
  				parent->shared.rb_subtree_last = last;

  		}

  		link = &parent->shared.rb.rb_left;

  	}

  	node->shared.rb_subtree_last = last;
  	rb_link_node(&node->shared.rb, &parent->shared.rb, link);
  	rb_insert_augmented(&node->shared.rb, root,

  			    &vma_interval_tree_augment);

  }

  
  static inline unsigned long avc_start_pgoff(struct anon_vma_chain *avc)
  {
  	return vma_start_pgoff(avc->vma);
  }
  
  static inline unsigned long avc_last_pgoff(struct anon_vma_chain *avc)
  {
  	return vma_last_pgoff(avc->vma);
  }
  
  INTERVAL_TREE_DEFINE(struct anon_vma_chain, rb, unsigned long, rb_subtree_last,

  		     avc_start_pgoff, avc_last_pgoff,
  		     static inline, __anon_vma_interval_tree)
  
  void anon_vma_interval_tree_insert(struct anon_vma_chain *node,
  				   struct rb_root *root)
  {
  #ifdef CONFIG_DEBUG_VM_RB
  	node->cached_vma_start = avc_start_pgoff(node);
  	node->cached_vma_last = avc_last_pgoff(node);
  #endif
  	__anon_vma_interval_tree_insert(node, root);
  }
  
  void anon_vma_interval_tree_remove(struct anon_vma_chain *node,
  				   struct rb_root *root)
  {
  	__anon_vma_interval_tree_remove(node, root);
  }
  
  struct anon_vma_chain *
  anon_vma_interval_tree_iter_first(struct rb_root *root,
  				  unsigned long first, unsigned long last)
  {
  	return __anon_vma_interval_tree_iter_first(root, first, last);
  }
  
  struct anon_vma_chain *
  anon_vma_interval_tree_iter_next(struct anon_vma_chain *node,
  				 unsigned long first, unsigned long last)
  {
  	return __anon_vma_interval_tree_iter_next(node, first, last);
  }
  
  #ifdef CONFIG_DEBUG_VM_RB
  void anon_vma_interval_tree_verify(struct anon_vma_chain *node)
  {
  	WARN_ON_ONCE(node->cached_vma_start != avc_start_pgoff(node));
  	WARN_ON_ONCE(node->cached_vma_last != avc_last_pgoff(node));
  }
  #endif