btrfs: move math functions to misc.h

Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/misc.h

@@ -5,6 +5,7 @@
 
 #include <linux/sched.h>
 #include <linux/wait.h>
+#include <asm/div64.h>
 
 #define in_range(b, first, len) ((b) >= (first) && (b) < (first) + (len))
 
@@ -30,4 +31,20 @@ static inline void cond_wake_up_nomb(struct wait_queue_head *wq)
 		wake_up(wq);
 }
 
+static inline u64 div_factor(u64 num, int factor)
+{
+	if (factor == 10)
+		return num;
+	num *= factor;
+	return div_u64(num, 10);
+}
+
+static inline u64 div_factor_fine(u64 num, int factor)
+{
+	if (factor == 100)
+		return num;
+	num *= factor;
+	return div_u64(num, 100);
+}
+
 #endif