1 files changed, 87 insertions, 13 deletions

diff --git a/include/uapi/linux/ioprio.h b/include/uapi/linux/ioprio.h
index f70f2596a6bf..99440b2e8c35 100644
--- a/include/uapi/linux/ioprio.h
+++ b/include/uapi/linux/ioprio.h
@@ -2,22 +2,23 @@
 #ifndef _UAPI_LINUX_IOPRIO_H
 #define _UAPI_LINUX_IOPRIO_H
 
+#include <linux/stddef.h>
+#include <linux/types.h>
+
 /*
  * Gives us 8 prio classes with 13-bits of data for each class
  */
 #define IOPRIO_CLASS_SHIFT	13
-#define IOPRIO_CLASS_MASK	0x07
+#define IOPRIO_NR_CLASSES	8
+#define IOPRIO_CLASS_MASK	(IOPRIO_NR_CLASSES - 1)
 #define IOPRIO_PRIO_MASK	((1UL << IOPRIO_CLASS_SHIFT) - 1)
 
 #define IOPRIO_PRIO_CLASS(ioprio)	\
 	(((ioprio) >> IOPRIO_CLASS_SHIFT) & IOPRIO_CLASS_MASK)
 #define IOPRIO_PRIO_DATA(ioprio)	((ioprio) & IOPRIO_PRIO_MASK)
-#define IOPRIO_PRIO_VALUE(class, data)	\
-	((((class) & IOPRIO_CLASS_MASK) << IOPRIO_CLASS_SHIFT) | \
-	 ((data) & IOPRIO_PRIO_MASK))
 
 /*
- * These are the io priority groups as implemented by the BFQ and mq-deadline
+ * These are the io priority classes as implemented by the BFQ and mq-deadline
  * schedulers. RT is the realtime class, it always gets premium service. For
  * ATA disks supporting NCQ IO priority, RT class IOs will be processed using
  * high priority NCQ commands. BE is the best-effort scheduling class, the
@@ -25,18 +26,30 @@
  * served when no one else is using the disk.
  */
 enum {
-	IOPRIO_CLASS_NONE,
-	IOPRIO_CLASS_RT,
-	IOPRIO_CLASS_BE,
-	IOPRIO_CLASS_IDLE,
+	IOPRIO_CLASS_NONE	= 0,
+	IOPRIO_CLASS_RT		= 1,
+	IOPRIO_CLASS_BE		= 2,
+	IOPRIO_CLASS_IDLE	= 3,
+
+	/* Special class to indicate an invalid ioprio value */
+	IOPRIO_CLASS_INVALID	= 7,
 };
 
 /*
- * The RT and BE priority classes both support up to 8 priority levels.
+ * The RT and BE priority classes both support up to 8 priority levels that
+ * can be specified using the lower 3-bits of the priority data.
  */
-#define IOPRIO_NR_LEVELS	8
-#define IOPRIO_BE_NR		IOPRIO_NR_LEVELS
+#define IOPRIO_LEVEL_NR_BITS		3
+#define IOPRIO_NR_LEVELS		(1 << IOPRIO_LEVEL_NR_BITS)
+#define IOPRIO_LEVEL_MASK		(IOPRIO_NR_LEVELS - 1)
+#define IOPRIO_PRIO_LEVEL(ioprio)	((ioprio) & IOPRIO_LEVEL_MASK)
+
+#define IOPRIO_BE_NR			IOPRIO_NR_LEVELS
 
+/*
+ * Possible values for the "which" argument of the ioprio_get() and
+ * ioprio_set() system calls (see "man ioprio_set").
+ */
 enum {
 	IOPRIO_WHO_PROCESS = 1,
 	IOPRIO_WHO_PGRP,
@@ -44,9 +57,70 @@ enum {
 };
 
 /*
- * Fallback BE priority level.
+ * Fallback BE class priority level.
  */
 #define IOPRIO_NORM	4
 #define IOPRIO_BE_NORM	IOPRIO_NORM
 
+/*
+ * The 10 bits between the priority class and the priority level are used to
+ * optionally define I/O hints for any combination of I/O priority class and
+ * level. Depending on the kernel configuration, I/O scheduler being used and
+ * the target I/O device being used, hints can influence how I/Os are processed
+ * without affecting the I/O scheduling ordering defined by the I/O priority
+ * class and level.
+ */
+#define IOPRIO_HINT_SHIFT		IOPRIO_LEVEL_NR_BITS
+#define IOPRIO_HINT_NR_BITS		10
+#define IOPRIO_NR_HINTS			(1 << IOPRIO_HINT_NR_BITS)
+#define IOPRIO_HINT_MASK		(IOPRIO_NR_HINTS - 1)
+#define IOPRIO_PRIO_HINT(ioprio)	\
+	(((ioprio) >> IOPRIO_HINT_SHIFT) & IOPRIO_HINT_MASK)
+
+/*
+ * I/O hints.
+ */
+enum {
+	/* No hint */
+	IOPRIO_HINT_NONE = 0,
+
+	/*
+	 * Device command duration limits: indicate to the device a desired
+	 * duration limit for the commands that will be used to process an I/O.
+	 * These will currently only be effective for SCSI and ATA devices that
+	 * support the command duration limits feature. If this feature is
+	 * enabled, then the commands issued to the device to process an I/O with
+	 * one of these hints set will have the duration limit index (dld field)
+	 * set to the value of the hint.
+	 */
+	IOPRIO_HINT_DEV_DURATION_LIMIT_1 = 1,
+	IOPRIO_HINT_DEV_DURATION_LIMIT_2 = 2,
+	IOPRIO_HINT_DEV_DURATION_LIMIT_3 = 3,
+	IOPRIO_HINT_DEV_DURATION_LIMIT_4 = 4,
+	IOPRIO_HINT_DEV_DURATION_LIMIT_5 = 5,
+	IOPRIO_HINT_DEV_DURATION_LIMIT_6 = 6,
+	IOPRIO_HINT_DEV_DURATION_LIMIT_7 = 7,
+};
+
+#define IOPRIO_BAD_VALUE(val, max) ((val) < 0 || (val) >= (max))
+
+/*
+ * Return an I/O priority value based on a class, a level and a hint.
+ */
+static __always_inline __u16 ioprio_value(int class, int level, int hint)
+{
+	if (IOPRIO_BAD_VALUE(class, IOPRIO_NR_CLASSES) ||
+	    IOPRIO_BAD_VALUE(level, IOPRIO_NR_LEVELS) ||
+	    IOPRIO_BAD_VALUE(hint, IOPRIO_NR_HINTS))
+		return IOPRIO_CLASS_INVALID << IOPRIO_CLASS_SHIFT;
+
+	return (class << IOPRIO_CLASS_SHIFT) |
+		(hint << IOPRIO_HINT_SHIFT) | level;
+}
+
+#define IOPRIO_PRIO_VALUE(class, level)			\
+	ioprio_value(class, level, IOPRIO_HINT_NONE)
+#define IOPRIO_PRIO_VALUE_HINT(class, level, hint)	\
+	ioprio_value(class, level, hint)
+
 #endif /* _UAPI_LINUX_IOPRIO_H */