Line data    Source code

       1             : /* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
       2             : #ifndef _UAPI_LINUX_IOPRIO_H
       3             : #define _UAPI_LINUX_IOPRIO_H
       4             : 
       5             : #include <linux/stddef.h>
       6             : #include <linux/types.h>
       7             : 
       8             : /*
       9             :  * Gives us 8 prio classes with 13-bits of data for each class
      10             :  */
      11             : #define IOPRIO_CLASS_SHIFT      13
      12             : #define IOPRIO_NR_CLASSES       8
      13             : #define IOPRIO_CLASS_MASK       (IOPRIO_NR_CLASSES - 1)
      14             : #define IOPRIO_PRIO_MASK        ((1UL << IOPRIO_CLASS_SHIFT) - 1)
      15             : 
      16             : #define IOPRIO_PRIO_CLASS(ioprio)       \
      17             :         (((ioprio) >> IOPRIO_CLASS_SHIFT) & IOPRIO_CLASS_MASK)
      18             : #define IOPRIO_PRIO_DATA(ioprio)        ((ioprio) & IOPRIO_PRIO_MASK)
      19             : 
      20             : /*
      21             :  * These are the io priority classes as implemented by the BFQ and mq-deadline
      22             :  * schedulers. RT is the realtime class, it always gets premium service. For
      23             :  * ATA disks supporting NCQ IO priority, RT class IOs will be processed using
      24             :  * high priority NCQ commands. BE is the best-effort scheduling class, the
      25             :  * default for any process. IDLE is the idle scheduling class, it is only
      26             :  * served when no one else is using the disk.
      27             :  */
      28             : enum {
      29             :         IOPRIO_CLASS_NONE       = 0,
      30             :         IOPRIO_CLASS_RT         = 1,
      31             :         IOPRIO_CLASS_BE         = 2,
      32             :         IOPRIO_CLASS_IDLE       = 3,
      33             : 
      34             :         /* Special class to indicate an invalid ioprio value */
      35             :         IOPRIO_CLASS_INVALID    = 7,
      36             : };
      37             : 
      38             : /*
      39             :  * The RT and BE priority classes both support up to 8 priority levels that
      40             :  * can be specified using the lower 3-bits of the priority data.
      41             :  */
      42             : #define IOPRIO_LEVEL_NR_BITS            3
      43             : #define IOPRIO_NR_LEVELS                (1 << IOPRIO_LEVEL_NR_BITS)
      44             : #define IOPRIO_LEVEL_MASK               (IOPRIO_NR_LEVELS - 1)
      45             : #define IOPRIO_PRIO_LEVEL(ioprio)       ((ioprio) & IOPRIO_LEVEL_MASK)
      46             : 
      47             : #define IOPRIO_BE_NR                    IOPRIO_NR_LEVELS
      48             : 
      49             : /*
      50             :  * Possible values for the "which" argument of the ioprio_get() and
      51             :  * ioprio_set() system calls (see "man ioprio_set").
      52             :  */
      53             : enum {
      54             :         IOPRIO_WHO_PROCESS = 1,
      55             :         IOPRIO_WHO_PGRP,
      56             :         IOPRIO_WHO_USER,
      57             : };
      58             : 
      59             : /*
      60             :  * Fallback BE class priority level.
      61             :  */
      62             : #define IOPRIO_NORM     4
      63             : #define IOPRIO_BE_NORM  IOPRIO_NORM
      64             : 
      65             : /*
      66             :  * The 10 bits between the priority class and the priority level are used to
      67             :  * optionally define I/O hints for any combination of I/O priority class and
      68             :  * level. Depending on the kernel configuration, I/O scheduler being used and
      69             :  * the target I/O device being used, hints can influence how I/Os are processed
      70             :  * without affecting the I/O scheduling ordering defined by the I/O priority
      71             :  * class and level.
      72             :  */
      73             : #define IOPRIO_HINT_SHIFT               IOPRIO_LEVEL_NR_BITS
      74             : #define IOPRIO_HINT_NR_BITS             10
      75             : #define IOPRIO_NR_HINTS                 (1 << IOPRIO_HINT_NR_BITS)
      76             : #define IOPRIO_HINT_MASK                (IOPRIO_NR_HINTS - 1)
      77             : #define IOPRIO_PRIO_HINT(ioprio)        \
      78             :         (((ioprio) >> IOPRIO_HINT_SHIFT) & IOPRIO_HINT_MASK)
      79             : 
      80             : /*
      81             :  * I/O hints.
      82             :  */
      83             : enum {
      84             :         /* No hint */
      85             :         IOPRIO_HINT_NONE = 0,
      86             : 
      87             :         /*
      88             :          * Device command duration limits: indicate to the device a desired
      89             :          * duration limit for the commands that will be used to process an I/O.
      90             :          * These will currently only be effective for SCSI and ATA devices that
      91             :          * support the command duration limits feature. If this feature is
      92             :          * enabled, then the commands issued to the device to process an I/O with
      93             :          * one of these hints set will have the duration limit index (dld field)
      94             :          * set to the value of the hint.
      95             :          */
      96             :         IOPRIO_HINT_DEV_DURATION_LIMIT_1 = 1,
      97             :         IOPRIO_HINT_DEV_DURATION_LIMIT_2 = 2,
      98             :         IOPRIO_HINT_DEV_DURATION_LIMIT_3 = 3,
      99             :         IOPRIO_HINT_DEV_DURATION_LIMIT_4 = 4,
     100             :         IOPRIO_HINT_DEV_DURATION_LIMIT_5 = 5,
     101             :         IOPRIO_HINT_DEV_DURATION_LIMIT_6 = 6,
     102             :         IOPRIO_HINT_DEV_DURATION_LIMIT_7 = 7,
     103             : };
     104             : 
     105             : #define IOPRIO_BAD_VALUE(val, max) ((val) < 0 || (val) >= (max))
     106             : 
     107             : /*
     108             :  * Return an I/O priority value based on a class, a level and a hint.
     109             :  */
     110             : static __always_inline __u16 ioprio_value(int class, int level, int hint)
     111             : {
     112           4 :         if (IOPRIO_BAD_VALUE(class, IOPRIO_NR_CLASSES) ||
     113             :             IOPRIO_BAD_VALUE(level, IOPRIO_NR_LEVELS) ||
     114             :             IOPRIO_BAD_VALUE(hint, IOPRIO_NR_HINTS))
     115             :                 return IOPRIO_CLASS_INVALID << IOPRIO_CLASS_SHIFT;
     116             : 
     117           4 :         return (class << IOPRIO_CLASS_SHIFT) |
     118           4 :                 (hint << IOPRIO_HINT_SHIFT) | level;
     119             : }
     120             : 
     121             : #define IOPRIO_PRIO_VALUE(class, level)                 \
     122             :         ioprio_value(class, level, IOPRIO_HINT_NONE)
     123             : #define IOPRIO_PRIO_VALUE_HINT(class, level, hint)      \
     124             :         ioprio_value(class, level, hint)
     125             : 
     126             : #endif /* _UAPI_LINUX_IOPRIO_H */