[PATCHv3 04/10] linux/kernel: introduce lower_48_bits macro

[Keith Busch <kbusch@kernel.org>]

Recent data integrity field enhancements allow 48-bit reference tags.
Introduce a helper macro since this will be a repeated operation.

Suggested-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Keith Busch <kbusch@kernel.org>
---
 include/linux/kernel.h | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/include/linux/kernel.h b/include/linux/kernel.h
index 33f47a996513..c1fa9fc2b5cd 100644
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h
@@ -63,6 +63,12 @@
 }					\
 )
 
+/**
+ * lower_48_bits - return bits 0-47 of a number
+ * @n: the number we're accessing
+ */
+#define lower_48_bits(n) ((u64)((n) & 0xffffffffffffull))
+
 /**
  * upper_32_bits - return bits 32-63 of a number
  * @n: the number we're accessing
-- 
2.25.4