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#ifndef IOPRIO_H

#define IOPRIO_H

#include <linux/sched.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 task_struct *task)

{

        if (ioprio_valid(task->ioprio))

                return IOPRIO_PRIO_DATA(task->ioprio);

        return IOPRIO_NORM;

}

static inline int task_ioprio_class(struct task_struct *task)

{

        if (ioprio_valid(task->ioprio))

                return IOPRIO_PRIO_CLASS(task->ioprio);

        return IOPRIO_CLASS_BE;

}

static inline int task_nice_ioprio(struct task_struct *task)

{

        return (task_nice(task) + 20) / 5;

}

/*

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

 */

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

#endif