ext4: fix abs() usage in ext4_mb_check_group_pa

The ext4_fsblk_t type is a long long, which should not be used
with abs(), as is done in ext4_mb_check_group_pa().

This patch modifies ext4_mb_check_group_pa() to use abs64()
instead.
Signed-off-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

fs/ext4/mballoc.c

@@ -3333,8 +3333,8 @@ ext4_mb_check_group_pa(ext4_fsblk_t goal_block,
 		atomic_inc(&pa->pa_count);
 		return pa;
 	}
-	cur_distance = abs(goal_block - cpa->pa_pstart);
-	new_distance = abs(goal_block - pa->pa_pstart);
+	cur_distance = abs64(goal_block - cpa->pa_pstart);
+	new_distance = abs64(goal_block - pa->pa_pstart);
 
 	if (cur_distance <= new_distance)
 		return cpa;