math64: New separate div64_u64_rem helper
Commit f792685006274a850e6cc0ea9ade275ccdfc90bc ("math64: New
div64_u64_rem helper") implemented div64_u64 in terms of div64_u64_rem.
But div64_u64_rem was removed because it slowed down div64_u64 (and
there were no other users of div64_u64_rem).
Device Mapper's I/O statistics support has a need for div64_u64_rem;
reintroduce this helper as a separate method that doesn't slow down
div64_u64, especially on 32-bit systems.
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Cc: Stanislaw Gruszka <sgruszka@redhat.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
diff --git a/include/linux/math64.h b/include/linux/math64.h
index 2913b86..69ed5f5 100644
--- a/include/linux/math64.h
+++ b/include/linux/math64.h
@@ -31,6 +31,15 @@
}
/**
+ * div64_u64_rem - unsigned 64bit divide with 64bit divisor and remainder
+ */
+static inline u64 div64_u64_rem(u64 dividend, u64 divisor, u64 *remainder)
+{
+ *remainder = dividend % divisor;
+ return dividend / divisor;
+}
+
+/**
* div64_u64 - unsigned 64bit divide with 64bit divisor
*/
static inline u64 div64_u64(u64 dividend, u64 divisor)
@@ -63,6 +72,10 @@
extern s64 div_s64_rem(s64 dividend, s32 divisor, s32 *remainder);
#endif
+#ifndef div64_u64_rem
+extern u64 div64_u64_rem(u64 dividend, u64 divisor, u64 *remainder);
+#endif
+
#ifndef div64_u64
extern u64 div64_u64(u64 dividend, u64 divisor);
#endif