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block: fix default IO priority handling 

The default IO priority is the best effort (BE) class with the
normal priority level IOPRIO_NORM (4). However, get_task_ioprio()
returns IOPRIO_CLASS_NONE/IOPRIO_NORM as the default priority and
get_current_ioprio() returns IOPRIO_CLASS_NONE/0. Let's be consistent
with the defined default and have both of these functions return the
default priority IOPRIO_PRIO_VALUE(IOPRIO_CLASS_BE, IOPRIO_NORM) when
the user did not define another default IO priority for the task.

In include/uapi/linux/ioprio.h, introduce the IOPRIO_BE_NORM macro as
an alias to IOPRIO_NORM to clarify that this default level applies to
the BE priotity class. In include/linux/ioprio.h, define the macro
IOPRIO_DEFAULT as IOPRIO_PRIO_VALUE(IOPRIO_CLASS_BE, IOPRIO_BE_NORM)
and use this new macro when setting a priority to the default.

Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
Link: https://lore.kernel.org/r/20210811033702.368488-7-damien.lemoal@wdc.com
[axboe: drop unnecessary lightnvm change]
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Damien Le Moal 2021-08-11 12:37:02 +09:00 committed by Jens Axboe
parent 202bc942c5
commit e70344c059
4 changed files with 13 additions and 7 deletions
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2
block/bfq-iosched.c
View File

@ -5411,7 +5411,7 @@ static struct bfq_queue **bfq_async_queue_prio(struct bfq_data *bfqd,
case IOPRIO_CLASS_RT:
return &bfqg->async_bfqq[0][ioprio];
case IOPRIO_CLASS_NONE:
ioprio = IOPRIO_NORM;
ioprio = IOPRIO_BE_NORM;
fallthrough;
case IOPRIO_CLASS_BE:
return &bfqg->async_bfqq[1][ioprio];

6
block/ioprio.c
View File

@ -170,7 +170,7 @@ static int get_task_ioprio(struct task_struct *p)
ret = security_task_getioprio(p);
if (ret)
goto out;
ret = IOPRIO_PRIO_VALUE(IOPRIO_CLASS_NONE, IOPRIO_NORM);
ret = IOPRIO_DEFAULT;
task_lock(p);
if (p->io_context)
ret = p->io_context->ioprio;
@ -182,9 +182,9 @@ static int get_task_ioprio(struct task_struct *p)
int ioprio_best(unsigned short aprio, unsigned short bprio)
{
if (!ioprio_valid(aprio))
aprio = IOPRIO_PRIO_VALUE(IOPRIO_CLASS_BE, IOPRIO_NORM);
aprio = IOPRIO_DEFAULT;
if (!ioprio_valid(bprio))
bprio = IOPRIO_PRIO_VALUE(IOPRIO_CLASS_BE, IOPRIO_NORM);
bprio = IOPRIO_DEFAULT;
return min(aprio, bprio);
}

7
include/linux/ioprio.h
View File

@ -8,6 +8,11 @@
#include <uapi/linux/ioprio.h>
/*
* Default IO priority.
*/
#define IOPRIO_DEFAULT IOPRIO_PRIO_VALUE(IOPRIO_CLASS_BE, IOPRIO_BE_NORM)
/*
* Check that a priority value has a valid class.
*/
@ -51,7 +56,7 @@ static inline int get_current_ioprio(void)
if (ioc)
return ioc->ioprio;
return IOPRIO_PRIO_VALUE(IOPRIO_CLASS_NONE, 0);
return IOPRIO_DEFAULT;
}
/*

5
include/uapi/linux/ioprio.h
View File

@ -44,8 +44,9 @@ enum {
};
/*
* Fallback BE priority
* Fallback BE priority level.
*/
#define IOPRIO_NORM (4)
#define IOPRIO_NORM 4
#define IOPRIO_BE_NORM IOPRIO_NORM
#endif /* _UAPI_LINUX_IOPRIO_H */