[PATCH] disk stats accounting fix

We should only account file system requests, ones originating from
__make_request(). Otherwise it skews the counters and they go negative
really fast.

drivers/block/ll_rw_blk.c

@@ -2354,7 +2354,7 @@ void end_that_request_last(struct request *req)
 	struct gendisk *disk = req->rq_disk;
 	struct completion *waiting = req->waiting;
 
-	if (disk) {
+	if (disk && blk_fs_request(req)) {
 		unsigned long duration = jiffies - req->start_time;
 		switch (rq_data_dir(req)) {
 		    case WRITE: