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 #include <uapi/linux/ioprio.h>
  10
  11 /*
  12  * Default IO priority.
  13  */
  14 #define IOPRIO_DEFAULT  IOPRIO_PRIO_VALUE(IOPRIO_CLASS_NONE, 0)
  15
  16 /*
  17  * Check that a priority value has a valid class.
  18  */
  19 static inline bool ioprio_valid(unsigned short ioprio)
  20 {
  21         unsigned short class = IOPRIO_PRIO_CLASS(ioprio);
  22
  23         return class > IOPRIO_CLASS_NONE && class <= IOPRIO_CLASS_IDLE;
  24 }
  25
  26 /*
  27  * if process has set io priority explicitly, use that. if not, convert
  28  * the cpu scheduler nice value to an io priority
  29  */
  30 static inline int task_nice_ioprio(struct task_struct *task)
  31 {
  32         return (task_nice(task) + 20) / 5;
  33 }
  34
  35 /*
  36  * This is for the case where the task hasn't asked for a specific IO class.
  37  * Check for idle and rt task process, and return appropriate IO class.
  38  */
  39 static inline int task_nice_ioclass(struct task_struct *task)
  40 {
  41         if (task->policy == SCHED_IDLE)
  42                 return IOPRIO_CLASS_IDLE;
  43         else if (rt_or_dl_task_policy(task))
  44                 return IOPRIO_CLASS_RT;
  45         else
  46                 return IOPRIO_CLASS_BE;
  47 }
  48
  49 #ifdef CONFIG_BLOCK
  50 /*
  51  * If the task has set an I/O priority, use that. Otherwise, return
  52  * the default I/O priority.
  53  *
  54  * Expected to be called for current task or with task_lock() held to keep
  55  * io_context stable.
  56  */
  57 static inline int __get_task_ioprio(struct task_struct *p)
  58 {
  59         struct io_context *ioc = p->io_context;
  60         int prio;
  61
  62         if (!ioc)
  63                 return IOPRIO_DEFAULT;
  64
  65         if (p != current)
  66                 lockdep_assert_held(&p->alloc_lock);
  67
  68         prio = ioc->ioprio;
  69         if (IOPRIO_PRIO_CLASS(prio) == IOPRIO_CLASS_NONE)
  70                 prio = IOPRIO_PRIO_VALUE(task_nice_ioclass(p),
  71                                          task_nice_ioprio(p));
  72         return prio;
  73 }
  74 #else
  75 static inline int __get_task_ioprio(struct task_struct *p)
  76 {
  77         return IOPRIO_DEFAULT;
  78 }
  79 #endif /* CONFIG_BLOCK */
  80
  81 static inline int get_current_ioprio(void)
  82 {
  83         return __get_task_ioprio(current);
  84 }
  85
  86 extern int set_task_ioprio(struct task_struct *task, int ioprio);
  87
  88 #ifdef CONFIG_BLOCK
  89 extern int ioprio_check_cap(int ioprio);
  90 #else
  91 static inline int ioprio_check_cap(int ioprio)
  92 {
  93         return -ENOTBLK;
  94 }
  95 #endif /* CONFIG_BLOCK */
  96
  97 #endif