block/rnbd: Use blk_opf_t where appropriate

Improve static type checking by using the new blk_opf_t type to represent
the combination of a request and request flags.

Acked-by: Jack Wang <[e-mail]>
Cc: Md. Haris Iqbal <[e-mail]>
Signed-off-by: Bart Van Assche <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Jens Axboe <[e-mail]>

drivers/block/rnbd/rnbd-proto.h

···
 	return true;
 }
 
-static inline u32 rnbd_to_bio_flags(u32 rnbd_opf)
+static inline blk_opf_t rnbd_to_bio_flags(u32 rnbd_opf)
 {
-	u32 bio_opf;
+	blk_opf_t bio_opf;
 
 	switch (rnbd_op(rnbd_opf)) {
 	case RNBD_OP_READ:
···
 		break;
 	default:
 		WARN(1, "Unknown request type %d (flags %llu)\n",
-		     req_op(rq), (unsigned long long)rq->cmd_flags);
+		     (__force u32)req_op(rq),
+		     (__force unsigned long long)rq->cmd_flags);
 		rnbd_opf = 0;
 	}