[PATCH v2 03/15] block: Support data lifetime in the I/O priority bitfield

[Bart Van Assche <bvanassche@acm.org>]

The NVMe and SCSI standards define 64 different data lifetimes. Support
storing this information in the I/O priority bitfield.

The current allocation of the 16 bits in the I/O priority bitfield is as
follows:
* 15..13: I/O priority class
* 12..6: unused
* 5..3: I/O hint (CDL)
* 2..0: I/O priority level

This patch changes this into the following:
* 15..13: I/O priority class
* 12: unused
* 11..6: data lifetime
* 5..3: I/O hint (CDL)
* 2..0: I/O priority level

Cc: Damien Le Moal <dlemoal@kernel.org>
Cc: Niklas Cassel <niklas.cassel@wdc.com>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
---
 include/uapi/linux/ioprio.h | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/include/uapi/linux/ioprio.h b/include/uapi/linux/ioprio.h
index bee2bdb0eedb..efe9bc450872 100644
--- a/include/uapi/linux/ioprio.h
+++ b/include/uapi/linux/ioprio.h
@@ -71,7 +71,7 @@ enum {
  * class and level.
  */
 #define IOPRIO_HINT_SHIFT		IOPRIO_LEVEL_NR_BITS
-#define IOPRIO_HINT_NR_BITS		10
+#define IOPRIO_HINT_NR_BITS		3
 #define IOPRIO_NR_HINTS			(1 << IOPRIO_HINT_NR_BITS)
 #define IOPRIO_HINT_MASK		(IOPRIO_NR_HINTS - 1)
 #define IOPRIO_PRIO_HINT(ioprio)	\
@@ -102,6 +102,12 @@ enum {
 	IOPRIO_HINT_DEV_DURATION_LIMIT_7 = 7,
 };
 
+#define IOPRIO_LIFETIME_SHIFT		(IOPRIO_HINT_SHIFT + IOPRIO_HINT_NR_BITS)
+#define IOPRIO_LIFETIME_NR_BITS		6
+#define IOPRIO_LIFETIME_MASK		((1u << IOPRIO_LIFETIME_NR_BITS) - 1)
+#define IOPRIO_PRIO_LIFETIME(ioprio)					\
+	((ioprio >> IOPRIO_LIFETIME_SHIFT) & IOPRIO_LIFETIME_MASK)
+
 #define IOPRIO_BAD_VALUE(val, max) ((val) < 0 || (val) >= (max))
 
 /*