nvme/tcp: handle tls partially sent records in write_space()

With TLS enabled, records that are encrypted and appended to TLS TX
list can fail to see a retry if the underlying TCP socket is busy, for
example, hitting an EAGAIN from tcp_sendmsg_locked(). This is not known
to the NVMe TCP driver, as the TLS layer successfully generated a record.

Typically, the TLS write_space() callback would ensure such records are
retried, but in the NVMe TCP Host driver, write_space() invokes
nvme_tcp_write_space(). This causes a partially sent record in the TLS TX
list to timeout after not being retried.

This patch fixes the above by calling queue->write_space(), which calls
into the TLS layer to retry any pending records.

Fixes: be8e82c ("nvme-tcp: enable TLS handshake upcall")
Signed-off-by: Wilfred Mallawa <wilfred.mallawa@wdc.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Keith Busch <kbusch@kernel.org>

Author: twilfredo

drivers/nvme/host/tcp.c

@@ -1081,6 +1081,9 @@ static void nvme_tcp_write_space(struct sock *sk)
 	queue = sk->sk_user_data;
 	if (likely(queue && sk_stream_is_writeable(sk))) {
 		clear_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
+		/* Ensure pending TLS partial records are retried */
+		if (nvme_tcp_queue_tls(queue))
+			queue->write_space(sk);
 		queue_work_on(queue->io_cpu, nvme_tcp_wq, &queue->io_work);
 	}
 	read_unlock_bh(&sk->sk_callback_lock);