#ifndef IOPRIO_H
  #define IOPRIO_H
  
  #include <linux/sched.h>

  #include <linux/iocontext.h>

  
  /*
   * Gives us 8 prio classes with 13-bits of data for each class
   */
  #define IOPRIO_BITS		(16)
  #define IOPRIO_CLASS_SHIFT	(13)
  #define IOPRIO_PRIO_MASK	((1UL << IOPRIO_CLASS_SHIFT) - 1)
  
  #define IOPRIO_PRIO_CLASS(mask)	((mask) >> IOPRIO_CLASS_SHIFT)
  #define IOPRIO_PRIO_DATA(mask)	((mask) & IOPRIO_PRIO_MASK)

  #define IOPRIO_PRIO_VALUE(class, data)	(((class) << IOPRIO_CLASS_SHIFT) | data)

  
  #define ioprio_valid(mask)	(IOPRIO_PRIO_CLASS((mask)) != IOPRIO_CLASS_NONE)
  
  /*
   * These are the io priority groups as implemented by CFQ. RT is the realtime
   * class, it always gets premium service. BE is the best-effort scheduling
   * class, the default for any process. IDLE is the idle scheduling class, it
   * is only served when no one else is using the disk.
   */
  enum {
  	IOPRIO_CLASS_NONE,
  	IOPRIO_CLASS_RT,
  	IOPRIO_CLASS_BE,
  	IOPRIO_CLASS_IDLE,
  };
  
  /*
   * 8 best effort priority levels are supported
   */
  #define IOPRIO_BE_NR	(8)

  enum {
  	IOPRIO_WHO_PROCESS = 1,
  	IOPRIO_WHO_PGRP,
  	IOPRIO_WHO_USER,
  };
  
  /*
   * if process has set io priority explicitly, use that. if not, convert
   * the cpu scheduler nice value to an io priority
   */
  #define IOPRIO_NORM	(4)

  static inline int task_ioprio(struct io_context *ioc)

  {

  	if (ioprio_valid(ioc->ioprio))
  		return IOPRIO_PRIO_DATA(ioc->ioprio);

  
  	return IOPRIO_NORM;

  }

  static inline int task_ioprio_class(struct io_context *ioc)

  {

  	if (ioprio_valid(ioc->ioprio))
  		return IOPRIO_PRIO_CLASS(ioc->ioprio);

  
  	return IOPRIO_CLASS_BE;
  }

  static inline int task_nice_ioprio(struct task_struct *task)
  {
  	return (task_nice(task) + 20) / 5;
  }
  
  /*

   * This is for the case where the task hasn't asked for a specific IO class.
   * Check for idle and rt task process, and return appropriate IO class.
   */
  static inline int task_nice_ioclass(struct task_struct *task)
  {
  	if (task->policy == SCHED_IDLE)
  		return IOPRIO_CLASS_IDLE;
  	else if (task->policy == SCHED_FIFO || task->policy == SCHED_RR)
  		return IOPRIO_CLASS_RT;
  	else
  		return IOPRIO_CLASS_BE;
  }
  
  /*

   * For inheritance, return the highest of the two given priorities
   */

  extern int ioprio_best(unsigned short aprio, unsigned short bprio);

  extern int set_task_ioprio(struct task_struct *task, int ioprio);

  #endif