ext4: address scalability issue by removing extent cache statistics

Andi Kleen and Tim Chen have reported that under certain circumstances
the extent cache statistics are causing scalability problems due to
cache line bounces.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Cc: stable@vger.kernel.org

fs/ext4/extents.c

@@ -2066,10 +2066,6 @@ static int ext4_ext_check_cache(struct inode *inode, ext4_lblk_t block,
 		ret = 1;
 	}
 errout:
-	if (!ret)
-		sbi->extent_cache_misses++;
-	else
-		sbi->extent_cache_hits++;
 	trace_ext4_ext_in_cache(inode, block, ret);
 	spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
 	return ret;