mean and variance: Promote to lib/math

Small statistics library, for taking in a series of value and computing
mean, weighted mean, standard deviation and weighted deviation.

The main use case is for statistics on latency measurements.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Cc: Daniel Hill <daniel@gluo.nz>
Cc: Darrick J. Wong <djwong@kernel.org>

11 files changed, 28 insertions, 19 deletions

diff --git a/MAINTAINERS b/MAINTAINERS
index 8d1052fa6a69..de635cfd354d 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -13379,6 +13379,15 @@ S:	Maintained
 F:	drivers/net/mdio/mdio-regmap.c
 F:	include/linux/mdio/mdio-regmap.h
 
+MEAN AND VARIANCE LIBRARY
+M:	Daniel B. Hill <daniel@gluo.nz>
+M:	Kent Overstreet <kent.overstreet@linux.dev>
+S:	Maintained
+T:	git https://github.com/YellowOnion/linux/
+F:	include/linux/mean_and_variance.h
+F:	lib/math/mean_and_variance.c
+F:	lib/math/mean_and_variance_test.c
+
 MEASUREMENT COMPUTING CIO-DAC IIO DRIVER
 M:	William Breathitt Gray <william.gray@linaro.org>
 L:	linux-iio@vger.kernel.org
diff --git a/fs/bcachefs/Kconfig b/fs/bcachefs/Kconfig
index 5cdfef3b551a..72d1179262b3 100644
--- a/fs/bcachefs/Kconfig
+++ b/fs/bcachefs/Kconfig
@@ -24,6 +24,7 @@ config BCACHEFS_FS
 	select XXHASH
 	select SRCU
 	select SYMBOLIC_ERRNAME
+	select MEAN_AND_VARIANCE
 	help
 	The bcachefs filesystem - a modern, copy on write filesystem, with
 	support for multiple devices, compression, checksumming, etc.
@@ -86,12 +87,3 @@ config BCACHEFS_SIX_OPTIMISTIC_SPIN
 	Instead of immediately sleeping when attempting to take a six lock that
 	is held by another thread, spin for a short while, as long as the
 	thread owning the lock is running.
-
-config MEAN_AND_VARIANCE_UNIT_TEST
-	tristate "mean_and_variance unit tests" if !KUNIT_ALL_TESTS
-	depends on KUNIT
-	depends on BCACHEFS_FS
-	default KUNIT_ALL_TESTS
-	help
-	  This option enables the kunit tests for mean_and_variance module.
-	  If unsure, say N.
diff --git a/fs/bcachefs/Makefile b/fs/bcachefs/Makefile
index 1a05cecda7cc..b11ba74b8ad4 100644
--- a/fs/bcachefs/Makefile
+++ b/fs/bcachefs/Makefile
@@ -57,7 +57,6 @@ bcachefs-y		:=	\
 	keylist.o		\
 	logged_ops.o		\
 	lru.o			\
-	mean_and_variance.o	\
 	migrate.o		\
 	move.o			\
 	movinggc.o		\
@@ -88,5 +87,3 @@ bcachefs-y		:=	\
 	util.o			\
 	varint.o		\
 	xattr.o
-
-obj-$(CONFIG_MEAN_AND_VARIANCE_UNIT_TEST)   += mean_and_variance_test.o
diff --git a/fs/bcachefs/util.c b/fs/bcachefs/util.c
index 56b815fd9fc6..d7ea95abb9df 100644
--- a/fs/bcachefs/util.c
+++ b/fs/bcachefs/util.c
@@ -22,9 +22,9 @@
 #include <linux/string.h>
 #include <linux/types.h>
 #include <linux/sched/clock.h>
+#include <linux/mean_and_variance.h>
 
 #include "eytzinger.h"
-#include "mean_and_variance.h"
 #include "util.h"
 
 static const char si_units[] = "?kMGTPEZY";
diff --git a/fs/bcachefs/util.h b/fs/bcachefs/util.h
index b414736d59a5..0059481995ef 100644
--- a/fs/bcachefs/util.h
+++ b/fs/bcachefs/util.h
@@ -17,8 +17,7 @@
 #include <linux/slab.h>
 #include <linux/vmalloc.h>
 #include <linux/workqueue.h>
-
-#include "mean_and_variance.h"
+#include <linux/mean_and_variance.h>
 
 #include "darray.h"
 
diff --git a/fs/bcachefs/mean_and_variance.h b/include/linux/mean_and_variance.h
index 64df11ab422b..64df11ab422b 100644
--- a/fs/bcachefs/mean_and_variance.h
+++ b/include/linux/mean_and_variance.h
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 975a07f9f1cc..817ddfe132cd 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -2191,6 +2191,15 @@ config CPUMASK_KUNIT_TEST
 
 	  If unsure, say N.
 
+config MEAN_AND_VARIANCE_UNIT_TEST
+	tristate "mean_and_variance unit tests" if !KUNIT_ALL_TESTS
+	depends on KUNIT
+	select MEAN_AND_VARIANCE
+	default KUNIT_ALL_TESTS
+	help
+	  This option enables the kunit tests for mean_and_variance module.
+	  If unsure, say N.
+
 config TEST_LIST_SORT
 	tristate "Linked list sorting test" if !KUNIT_ALL_TESTS
 	depends on KUNIT
diff --git a/lib/math/Kconfig b/lib/math/Kconfig
index 0634b428d0cb..7530ae9a3584 100644
--- a/lib/math/Kconfig
+++ b/lib/math/Kconfig
@@ -15,3 +15,6 @@ config PRIME_NUMBERS
 
 config RATIONAL
 	tristate
+
+config MEAN_AND_VARIANCE
+	tristate
diff --git a/lib/math/Makefile b/lib/math/Makefile
index 91fcdb0c9efe..8cdfa13a67ce 100644
--- a/lib/math/Makefile
+++ b/lib/math/Makefile
@@ -4,6 +4,8 @@ obj-y += div64.o gcd.o lcm.o int_log.o int_pow.o int_sqrt.o reciprocal_div.o
 obj-$(CONFIG_CORDIC)		+= cordic.o
 obj-$(CONFIG_PRIME_NUMBERS)	+= prime_numbers.o
 obj-$(CONFIG_RATIONAL)		+= rational.o
+obj-$(CONFIG_MEAN_AND_VARIANCE) += mean_and_variance.o
 
 obj-$(CONFIG_TEST_DIV64)	+= test_div64.o
 obj-$(CONFIG_RATIONAL_KUNIT_TEST) += rational-test.o
+obj-$(CONFIG_MEAN_AND_VARIANCE_UNIT_TEST)   += mean_and_variance_test.o
diff --git a/fs/bcachefs/mean_and_variance.c b/lib/math/mean_and_variance.c
index bf0ef668fd38..ba90293204ba 100644
--- a/fs/bcachefs/mean_and_variance.c
+++ b/lib/math/mean_and_variance.c
@@ -40,10 +40,9 @@
 #include <linux/limits.h>
 #include <linux/math.h>
 #include <linux/math64.h>
+#include <linux/mean_and_variance.h>
 #include <linux/module.h>
 
-#include "mean_and_variance.h"
-
 u128_u u128_div(u128_u n, u64 d)
 {
 	u128_u r;
diff --git a/fs/bcachefs/mean_and_variance_test.c b/lib/math/mean_and_variance_test.c
index 019583c3ca0e..f45591a169d8 100644
--- a/fs/bcachefs/mean_and_variance_test.c
+++ b/lib/math/mean_and_variance_test.c
@@ -1,7 +1,6 @@
 // SPDX-License-Identifier: GPL-2.0
 #include <kunit/test.h>
-
-#include "mean_and_variance.h"
+#include <linux/mean_and_variance.h>
 
 #define MAX_SQR (SQRT_U64_MAX*SQRT_U64_MAX)