mballoc: don't change cpa if cur_distance is equal to new_distance

In ext4_mb_check_group_pa(), cur_distance is selected to return only when it's smaller than new_distance, this is unreasonable. If cur_distance is equal to new_distance, current code will return new_distance to update cpa from ext4_mb_use_preallocated(), which is unnecessary and a wast of CPU cycles.

This patch makes new_distance to return only when it's smaller then cur_distance, which avoids unnecessary cpa update in ext4_mb_use_preallocated().

---
 fs/ext4/mballoc.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

index 851f49b..5f564d7 100644
@@ -3188,7 +3188,7 @@ ext4_mb_check_group_pa(ext4_fsblk_t goal_block,
 	cur_distance = abs(goal_block - cpa->pa_pstart);
 	new_distance = abs(goal_block - pa->pa_pstart);
 
-	if (cur_distance < new_distance)
+	if (cur_distance <= new_distance)
 		return cpa;
 
 	/* drop the previous reference */

Coly Li