nbd: error out if socket index doesn't match in nbd_handle_reply()

commit fcf3d633 ("nbd: check sock index in nbd_read_stat()") just
add error message when socket index doesn't match. Since the request
and reply must be transmitted over the same socket, it's ok to error
out in such situation.
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Link: https://lore.kernel.org/r/20211101092538.1155842-1-yukuai3@huawei.comSigned-off-by: Jens Axboe <axboe@kernel.dk>

drivers/block/nbd.c

@@ -762,6 +762,8 @@ static struct nbd_cmd *nbd_handle_reply(struct nbd_device *nbd, int index,
 	if (cmd->index != index) {
 		dev_err(disk_to_dev(nbd->disk), "Unexpected reply %d from different sock %d (expected %d)",
 			tag, index, cmd->index);
+		ret = -ENOENT;
+		goto out;
 	}
 	if (cmd->cmd_cookie != nbd_handle_to_cookie(handle)) {
 		dev_err(disk_to_dev(nbd->disk), "Double reply on req %p, cmd_cookie %u, handle cookie %u\n",