LXR linux/include/linux/ioprio.h

   1/* SPDX-License-Identifier: GPL-2.0 */
   2#ifndef IOPRIO_H
   3#define IOPRIO_H
   4
   5#include <linux/sched.h>
   6#include <linux/sched/rt.h>
   7#include <linux/iocontext.h>
   8
   9/*
  10 * Gives us 8 prio classes with 13-bits of data for each class
  11 */
  12#define IOPRIO_CLASS_SHIFT      (13)
  13#define IOPRIO_PRIO_MASK        ((1UL << IOPRIO_CLASS_SHIFT) - 1)
  14
  15#define IOPRIO_PRIO_CLASS(mask) ((mask) >> IOPRIO_CLASS_SHIFT)
  16#define IOPRIO_PRIO_DATA(mask)  ((mask) & IOPRIO_PRIO_MASK)
  17#define IOPRIO_PRIO_VALUE(class, data)  (((class) << IOPRIO_CLASS_SHIFT) | data)
  18
  19#define ioprio_valid(mask)      (IOPRIO_PRIO_CLASS((mask)) != IOPRIO_CLASS_NONE)
  20
  21/*
  22 * These are the io priority groups as implemented by CFQ. RT is the realtime
  23 * class, it always gets premium service. BE is the best-effort scheduling
  24 * class, the default for any process. IDLE is the idle scheduling class, it
  25 * is only served when no one else is using the disk.
  26 */
  27enum {
  28        IOPRIO_CLASS_NONE,
  29        IOPRIO_CLASS_RT,
  30        IOPRIO_CLASS_BE,
  31        IOPRIO_CLASS_IDLE,
  32};
  33
  34/*
  35 * 8 best effort priority levels are supported
  36 */
  37#define IOPRIO_BE_NR    (8)
  38
  39enum {
  40        IOPRIO_WHO_PROCESS = 1,
  41        IOPRIO_WHO_PGRP,
  42        IOPRIO_WHO_USER,
  43};
  44
  45/*
  46 * Fallback BE priority
  47 */
  48#define IOPRIO_NORM     (4)
  49
  50/*
  51 * if process has set io priority explicitly, use that. if not, convert
  52 * the cpu scheduler nice value to an io priority
  53 */
  54static inline int task_nice_ioprio(struct task_struct *task)
  55{
  56        return (task_nice(task) + 20) / 5;
  57}
  58
  59/*
  60 * This is for the case where the task hasn't asked for a specific IO class.
  61 * Check for idle and rt task process, and return appropriate IO class.
  62 */
  63static inline int task_nice_ioclass(struct task_struct *task)
  64{
  65        if (task->policy == SCHED_IDLE)
  66                return IOPRIO_CLASS_IDLE;
  67        else if (task_is_realtime(task))
  68                return IOPRIO_CLASS_RT;
  69        else
  70                return IOPRIO_CLASS_BE;
  71}
  72
  73/*
  74 * If the calling process has set an I/O priority, use that. Otherwise, return
  75 * the default I/O priority.
  76 */
  77static inline int get_current_ioprio(void)
  78{
  79        struct io_context *ioc = current->io_context;
  80
  81        if (ioc)
  82                return ioc->ioprio;
  83        return IOPRIO_PRIO_VALUE(IOPRIO_CLASS_NONE, 0);
  84}
  85
  86/*
  87 * For inheritance, return the highest of the two given priorities
  88 */
  89extern int ioprio_best(unsigned short aprio, unsigned short bprio);
  90
  91extern int set_task_ioprio(struct task_struct *task, int ioprio);
  92
  93#ifdef CONFIG_BLOCK
  94extern int ioprio_check_cap(int ioprio);
  95#else
  96static inline int ioprio_check_cap(int ioprio)
  97{
  98        return -ENOTBLK;
  99}
 100#endif /* CONFIG_BLOCK */
 101
 102#endif
 103