io_uring: improve io_double_lock_ctx fail handling

msg_ring will fail the request if it can't lock rings, instead punt it
to io-wq as was originally intended.

Cc: stable@vger.kernel.org
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/4697f05afcc37df5c8f89e2fe6d9c7c19f0241f9.1670384893.git.asml.silence@gmail.comSigned-off-by: Jens Axboe <axboe@kernel.dk>

io_uring/msg_ring.c

@@ -164,6 +164,8 @@ int io_msg_ring(struct io_kiocb *req, unsigned int issue_flags)
 	}
 
 done:
+	if (ret == -EAGAIN)
+		return -EAGAIN;
 	if (ret < 0)
 		req_set_fail(req);
 	io_req_set_res(req, ret, 0);