Commit e70344c0 authored by Damien Le Moal's avatar Damien Le Moal Committed by Jens Axboe
Browse files

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: default avatarDamien 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: default avatarJens Axboe <axboe@kernel.dk>
parent 202bc942

block/bfq-iosched.c

+1 −1
Original line number Diff line number Diff line
@@ -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];

block/ioprio.c

+3 −3
Original line number Diff line number Diff line
@@ -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);

}

include/linux/ioprio.h

+6 −1
Original line number Diff line number Diff line
@@ -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;

}



/*

include/uapi/linux/ioprio.h

+3 −2
Original line number Diff line number Diff line
@@ -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 */