bio: use memset() in bio_init()

Use memset() to clear the bio, instead of doing each field manually.
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

fs/bio.c

@@ -127,21 +127,9 @@ static void bio_fs_destructor(struct bio *bio)
 
 void bio_init(struct bio *bio)
 {
-	bio->bi_next = NULL;
-	bio->bi_bdev = NULL;
+	memset(bio, 0, sizeof(*bio));
 	bio->bi_flags = 1 << BIO_UPTODATE;
-	bio->bi_rw = 0;
-	bio->bi_vcnt = 0;
-	bio->bi_idx = 0;
-	bio->bi_phys_segments = 0;
-	bio->bi_hw_segments = 0;
-	bio->bi_hw_front_size = 0;
-	bio->bi_hw_back_size = 0;
-	bio->bi_size = 0;
-	bio->bi_max_vecs = 0;
-	bio->bi_end_io = NULL;
 	atomic_set(&bio->bi_cnt, 1);
-	bio->bi_private = NULL;
 }
 
 /**