[3/3] block: rename IOPRIO_BE_NR

Commit Message

Damien Le Moal Aug. 2, 2021, 9:21 a.m. UTC

The BFQ scheduler and ioprio_check_cap() both assume that the RT
priority class (IOPRIO_CLASS_RT) can have up to 8 different priority
levels. This is controlled using the macro IOPRIO_BE_NR, which is badly
named as the number of levels applies to the RT class too.

Rename IOPRIO_BE_NR to IOPRIO_NR_LEVELS to make things clear.

Signed-off-by: Damien Le Moal <[e-mail]>
---
 block/bfq-iosched.c         | 8 ++++----
 block/bfq-iosched.h         | 4 ++--
 block/bfq-wf2q.c            | 6 +++---
 block/ioprio.c              | 3 +--
 fs/f2fs/sysfs.c             | 2 +-
 include/uapi/linux/ioprio.h | 4 ++--
 6 files changed, 13 insertions(+), 14 deletions(-)

Comments

Bart Van Assche Aug. 2, 2021, 3:56 p.m. UTC | #1

On 8/2/21 2:21 AM, Damien Le Moal wrote:
>   /*
> - * 8 best effort priority levels are supported
> + * The RT an BE priority classes support up to 8 priority levels.
>    */
> -#define IOPRIO_BE_NR	(8)
> +#define IOPRIO_NR_LEVELS	(8)

Is this kind of change acceptable in a UAPI header? Can this change 
break the build of user space applications?

If this change is acceptable, how about the name IOPRIO_NR_BE_LEVELS? 
Additionally, please leave out the parentheses since these are not 
necessary.

Thanks,

Bart.

Damien Le Moal Aug. 2, 2021, 10:50 p.m. UTC | #2

On 2021/08/03 0:56, Bart Van Assche wrote:
> On 8/2/21 2:21 AM, Damien Le Moal wrote:
>>   /*
>> - * 8 best effort priority levels are supported
>> + * The RT an BE priority classes support up to 8 priority levels.
>>    */
>> -#define IOPRIO_BE_NR	(8)
>> +#define IOPRIO_NR_LEVELS	(8)
> 
> Is this kind of change acceptable in a UAPI header? Can this change 
> break the build of user space applications?

These definitions moving to a uapi header is new in 5.15. So they are not
currently in an uapi header. This is our chance to clean things up.

> 
> If this change is acceptable, how about the name IOPRIO_NR_BE_LEVELS? 
> Additionally, please leave out the parentheses since these are not 
> necessary.

As the commit message mentions, the 8 possible priority levels are used for the
RT class too. So it is not just about the BE class. That is why I would prefer
removing "BE" from the macro name. Or, we need 2 macro: IOPRIO_NR_BE_LEVELS and
IOPRIO_NR_RT_LEVELS. But that will only force adding duplicated checks in
functions like ioprio_check_cap().

> 
> Thanks,
> 
> Bart.
>

Patch

diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c
index 1f38d75524ae..d5824cab34d7 100644
--- a/block/bfq-iosched.c
+++ b/block/bfq-iosched.c
@@ -2505,7 +2505,7 @@  void bfq_end_wr_async_queues(struct bfq_data *bfqd,
 	int i, j;
 
 	for (i = 0; i < 2; i++)
-		for (j = 0; j < IOPRIO_BE_NR; j++)
+		for (j = 0; j < IOPRIO_NR_LEVELS; j++)
 			if (bfqg->async_bfqq[i][j])
 				bfq_bfqq_end_wr(bfqg->async_bfqq[i][j]);
 	if (bfqg->async_idle_bfqq)
@@ -5290,10 +5290,10 @@  bfq_set_next_ioprio_data(struct bfq_queue *bfqq, struct bfq_io_cq *bic)
 		break;
 	}
 
-	if (bfqq->new_ioprio >= IOPRIO_BE_NR) {
+	if (bfqq->new_ioprio >= IOPRIO_NR_LEVELS) {
 		pr_crit("bfq_set_next_ioprio_data: new_ioprio %d\n",
 			bfqq->new_ioprio);
-		bfqq->new_ioprio = IOPRIO_BE_NR - 1;
+		bfqq->new_ioprio = IOPRIO_NR_LEVELS - 1;
 	}
 
 	bfqq->entity.new_weight = bfq_ioprio_to_weight(bfqq->new_ioprio);
@@ -6822,7 +6822,7 @@  void bfq_put_async_queues(struct bfq_data *bfqd, struct bfq_group *bfqg)
 	int i, j;
 
 	for (i = 0; i < 2; i++)
-		for (j = 0; j < IOPRIO_BE_NR; j++)
+		for (j = 0; j < IOPRIO_NR_LEVELS; j++)
 			__bfq_put_async_bfqq(bfqd, &bfqg->async_bfqq[i][j]);
 
 	__bfq_put_async_bfqq(bfqd, &bfqg->async_idle_bfqq);
diff --git a/block/bfq-iosched.h b/block/bfq-iosched.h
index 99c2a3cb081e..385e28a843d1 100644
--- a/block/bfq-iosched.h
+++ b/block/bfq-iosched.h
@@ -931,7 +931,7 @@  struct bfq_group {
 
 	void *bfqd;
 
-	struct bfq_queue *async_bfqq[2][IOPRIO_BE_NR];
+	struct bfq_queue *async_bfqq[2][IOPRIO_NR_LEVELS];
 	struct bfq_queue *async_idle_bfqq;
 
 	struct bfq_entity *my_entity;
@@ -948,7 +948,7 @@  struct bfq_group {
 	struct bfq_entity entity;
 	struct bfq_sched_data sched_data;
 
-	struct bfq_queue *async_bfqq[2][IOPRIO_BE_NR];
+	struct bfq_queue *async_bfqq[2][IOPRIO_NR_LEVELS];
 	struct bfq_queue *async_idle_bfqq;
 
 	struct rb_root rq_pos_tree;
diff --git a/block/bfq-wf2q.c b/block/bfq-wf2q.c
index 7a462df71f68..b74cc0da118e 100644
--- a/block/bfq-wf2q.c
+++ b/block/bfq-wf2q.c
@@ -505,7 +505,7 @@  static void bfq_active_insert(struct bfq_service_tree *st,
  */
 unsigned short bfq_ioprio_to_weight(int ioprio)
 {
-	return (IOPRIO_BE_NR - ioprio) * BFQ_WEIGHT_CONVERSION_COEFF;
+	return (IOPRIO_NR_LEVELS - ioprio) * BFQ_WEIGHT_CONVERSION_COEFF;
 }
 
 /**
@@ -514,12 +514,12 @@  unsigned short bfq_ioprio_to_weight(int ioprio)
  *
  * To preserve as much as possible the old only-ioprio user interface,
  * 0 is used as an escape ioprio value for weights (numerically) equal or
- * larger than IOPRIO_BE_NR * BFQ_WEIGHT_CONVERSION_COEFF.
+ * larger than IOPRIO_NR_LEVELS * BFQ_WEIGHT_CONVERSION_COEFF.
  */
 static unsigned short bfq_weight_to_ioprio(int weight)
 {
 	return max_t(int, 0,
-		     IOPRIO_BE_NR * BFQ_WEIGHT_CONVERSION_COEFF - weight);
+		     IOPRIO_NR_LEVELS * BFQ_WEIGHT_CONVERSION_COEFF - weight);
 }
 
 static void bfq_get_entity(struct bfq_entity *entity)
diff --git a/block/ioprio.c b/block/ioprio.c
index bee628f9f1b2..ca6b136c5586 100644
--- a/block/ioprio.c
+++ b/block/ioprio.c
@@ -74,9 +74,8 @@  int ioprio_check_cap(int ioprio)
 			fallthrough;
 			/* rt has prio field too */
 		case IOPRIO_CLASS_BE:
-			if (data >= IOPRIO_BE_NR || data < 0)
+			if (data >= IOPRIO_NR_LEVELS || data < 0)
 				return -EINVAL;
-
 			break;
 		case IOPRIO_CLASS_IDLE:
 			break;
diff --git a/fs/f2fs/sysfs.c b/fs/f2fs/sysfs.c
index 6642246206bd..daad532a4e2b 100644
--- a/fs/f2fs/sysfs.c
+++ b/fs/f2fs/sysfs.c
@@ -378,7 +378,7 @@  static ssize_t __sbi_store(struct f2fs_attr *a,
 		ret = kstrtol(name, 10, &data);
 		if (ret)
 			return ret;
-		if (data >= IOPRIO_BE_NR || data < 0)
+		if (data >= IOPRIO_NR_LEVELS || data < 0)
 			return -EINVAL;
 
 		cprc->ckpt_thread_ioprio = IOPRIO_PRIO_VALUE(class, data);
diff --git a/include/uapi/linux/ioprio.h b/include/uapi/linux/ioprio.h
index 27dc7fb0ba12..fe47b58c4274 100644
--- a/include/uapi/linux/ioprio.h
+++ b/include/uapi/linux/ioprio.h
@@ -37,9 +37,9 @@  static inline bool ioprio_valid(unsigned short ioprio)
 }
 
 /*
- * 8 best effort priority levels are supported
+ * The RT an BE priority classes support up to 8 priority levels.
  */
-#define IOPRIO_BE_NR	(8)
+#define IOPRIO_NR_LEVELS	(8)
 
 enum {
 	IOPRIO_WHO_PROCESS = 1,