[patch 17/38] ext4: Replace get_cycles() usage with ktime_get()

get_cycles() is not guaranteed to be functional on all systems/platforms
and the values returned are unitless and not easy to map to something
useful.

Use ktime_get() instead, which provides nanosecond timestamps and is
functional everywhere.

This is part of a larger effort to limit get_cycles() usage to low level
architecture code.

Signed-off-by: Thomas Gleixner <[email protected]>
Cc: "Theodore Ts'o" <[email protected]>
Cc: [email protected]
---
 fs/ext4/mballoc.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -1289,7 +1289,7 @@ void ext4_mb_generate_buddy(struct super
 	ext4_grpblk_t len;
 	unsigned free = 0;
 	unsigned fragments = 0;
-	unsigned long long period = get_cycles();
+	ktime_t period = ktime_get();
 
 	/* initialize buddy from bitmap which is aggregation
 	 * of on-disk bitmap and preallocations */
@@ -1328,7 +1328,7 @@ void ext4_mb_generate_buddy(struct super
 
 	clear_bit(EXT4_GROUP_INFO_NEED_INIT_BIT, &(grp->bb_state));
 
-	period = get_cycles() - period;
+	period = ktime_get() - period;
 	atomic_inc(&sbi->s_mb_buddies_generated);
 	atomic64_add(period, &sbi->s_mb_generation_time);
 }