text: #ifndef __DRBD_INTERVAL_H
  #define __DRBD_INTERVAL_H
  
  #include <linux/types.h>
  #include <linux/rbtree.h>
  
  struct drbd_interval {
  	struct rb_node rb;
  	sector_t sector;	/* start sector of the interval */
  	unsigned int size;	/* size in bytes */
  	sector_t end;		/* highest interval end in subtree */
  	int local:1		/* local or remote request? */;
  	int waiting:1;
  };
  
  static inline void drbd_clear_interval(struct drbd_interval *i)
  {
  	RB_CLEAR_NODE(&i->rb);
  }
  
  static inline bool drbd_interval_empty(struct drbd_interval *i)
  {
  	return RB_EMPTY_NODE(&i->rb);
  }
  
  extern bool drbd_insert_interval(struct rb_root *, struct drbd_interval *);
  extern bool drbd_contains_interval(struct rb_root *, sector_t,
  				   struct drbd_interval *);
  extern void drbd_remove_interval(struct rb_root *, struct drbd_interval *);
  extern struct drbd_interval *drbd_find_overlap(struct rb_root *, sector_t,
  					unsigned int);
  extern struct drbd_interval *drbd_next_overlap(struct drbd_interval *, sector_t,
  					unsigned int);
  
  #define drbd_for_each_overlap(i, root, sector, size)		\
  	for (i = drbd_find_overlap(root, sector, size);		\
  	     i;							\
  	     i = drbd_next_overlap(i, sector, size))
  
  #endif  /* __DRBD_INTERVAL_H */
  