block: add cmd_flags to print_req_error

I ran into a bug where after hibernation due to incompatible
backends, the block driver returned BLK_STS_NOTSUPP, with the
current message it's hard to find out what the command flags
were. Adding req->cmd_flags help make the problem easier to
diagnose.
Reviewed-by: Eduardo Valentin <eduval@amazon.com>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Balbir Singh <sblbir@amzn.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block/blk-core.c

@@ -173,10 +173,11 @@ static void print_req_error(struct request *req, blk_status_t status)
 	if (WARN_ON_ONCE(idx >= ARRAY_SIZE(blk_errors)))
 		return;
 
-	printk_ratelimited(KERN_ERR "%s: %s error, dev %s, sector %llu\n",
-			   __func__, blk_errors[idx].name, req->rq_disk ?
-			   req->rq_disk->disk_name : "?",
-			   (unsigned long long)blk_rq_pos(req));
+	printk_ratelimited(KERN_ERR "%s: %s error, dev %s, sector %llu flags %x\n",
+				__func__, blk_errors[idx].name,
+				req->rq_disk ?  req->rq_disk->disk_name : "?",
+				(unsigned long long)blk_rq_pos(req),
+				req->cmd_flags);
 }
 
 static void req_bio_endio(struct request *rq, struct bio *bio,