[PATCH 08/17] ioprio: Add a macro named NICE_TO_IOPRIO.

[Dongsheng Yang]

As the task nice value is in [-20, 19] and the io priority is in [0, 7],
and the convert method from niceval to ioprio is implemented with an
opened code in task_nice_ioprio().

This patch move the implementation to a macro NICE_TO_IOPRIO, making
it more readable and modular.

Signed-off-by: Dongsheng Yang <yangds.fnst@xxxxxxxxxxxxxx>
---
 include/linux/ioprio.h | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/include/linux/ioprio.h b/include/linux/ioprio.h
index beb9ce1..c0faa0b 100644
--- a/include/linux/ioprio.h
+++ b/include/linux/ioprio.h
@@ -18,6 +18,11 @@
 #define ioprio_valid(mask)	(IOPRIO_PRIO_CLASS((mask)) != IOPRIO_CLASS_NONE)
 
 /*
+ * Convert the nice value [19,-20] to io priority value [0,7].
+ */
+#define NICE_TO_IOPRIO(nice)	(nice_to_rlimit(nice) / 5)
+
+/*
  * These are the io priority groups as implemented by CFQ. RT is the realtime
  * class, it always gets premium service. BE is the best-effort scheduling
  * class, the default for any process. IDLE is the idle scheduling class, it
@@ -52,7 +57,7 @@ enum {
  */
 static inline int task_nice_ioprio(struct task_struct *task)
 {
-	return (task_nice(task) + 20) / 5;
+	return NICE_TO_IOPRIO(task_nice(task));
 }
 
 /*
-- 
1.8.2.1

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