block: convert to bio_first_bvec_all & bio_first_page_all

This patch converts to bio_first_bvec_all() & bio_first_page_all() for
retrieving the 1st bvec/page, and prepares for supporting multipage bvec.

Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

kernel/power/swap.c

@@ -240,7 +240,7 @@ static void hib_init_batch(struct hib_bio_batch *hb)
 static void hib_end_io(struct bio *bio)
 {
 	struct hib_bio_batch *hb = bio->bi_private;
-	struct page *page = bio->bi_io_vec[0].bv_page;
+	struct page *page = bio_first_page_all(bio);
 
 	if (bio->bi_status) {
 		pr_alert("Read-error on swap-device (%u:%u:%Lu)\n",