fail_make_request: cleanup should_fail_request

This changes should_fail_request() to more usable wrapper function of
should_fail(). It can avoid putting #ifdef CONFIG_FAIL_MAKE_REQUEST in
the middle of a function.

Signed-off-by: Akinobu Mita <[e-mail]>
Cc: Jens Axboe <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

block/blk-core.c

···
 }
 __setup("fail_make_request=", setup_fail_make_request);
 
-static int should_fail_request(struct bio *bio)
+static bool should_fail_request(struct hd_struct *part, unsigned int bytes)
 {
-	struct hd_struct *part = bio->bi_bdev->bd_part;
-
-	if (part_to_disk(part)->part0.make_it_fail || part->make_it_fail)
-		return should_fail(&fail_make_request, bio->bi_size);
-
-	return 0;
+	return part->make_it_fail && should_fail(&fail_make_request, bytes);
 }
 
 static int __init fail_make_request_debugfs(void)
···
 
 #else /* CONFIG_FAIL_MAKE_REQUEST */
 
-static inline int should_fail_request(struct bio *bio)
+static inline bool should_fail_request(struct hd_struct *part,
+					unsigned int bytes)
 {
-	return 0;
+	return false;
 }
 
 #endif /* CONFIG_FAIL_MAKE_REQUEST */
···
 	old_dev = 0;
 	do {
 		char b[BDEVNAME_SIZE];
+		struct hd_struct *part;
 
 		q = bdev_get_queue(bio->bi_bdev);
 		if (unlikely(!q)) {
···
 		if (unlikely(test_bit(QUEUE_FLAG_DEAD, &q->queue_flags)))
 			goto end_io;
 
-		if (should_fail_request(bio))
+		part = bio->bi_bdev->bd_part;
+		if (should_fail_request(part, bio->bi_size) ||
+		    should_fail_request(&part_to_disk(part)->part0,
+					bio->bi_size))
 			goto end_io;
 
 		/*
···
 	if (blk_rq_check_limits(q, rq))
 		return -EIO;
 
-#ifdef CONFIG_FAIL_MAKE_REQUEST
-	if (rq->rq_disk && rq->rq_disk->part0.make_it_fail &&
-	    should_fail(&fail_make_request, blk_rq_bytes(rq)))
+	if (rq->rq_disk &&
+	    should_fail_request(&rq->rq_disk->part0, blk_rq_bytes(rq)))
 		return -EIO;
-#endif
 
 	spin_lock_irqsave(q->queue_lock, flags);