[PATCH 13/18] nvmet-tcp: allocate socket file

[Sagi Grimberg]

On 3/21/23 14:43, Hannes Reinecke wrote:
> When using the TLS upcall we need to allocate a socket file such
> that the userspace daemon is able to use the socket.
> 
> Signed-off-by: Hannes Reinecke <hare at suse.de>
> ---
>   drivers/nvme/target/tcp.c | 49 ++++++++++++++++++++++++++++-----------
>   1 file changed, 36 insertions(+), 13 deletions(-)
> 
> diff --git a/drivers/nvme/target/tcp.c b/drivers/nvme/target/tcp.c
> index 66e8f9fd0ca7..5c43767c5ecd 100644
> --- a/drivers/nvme/target/tcp.c
> +++ b/drivers/nvme/target/tcp.c
> @@ -96,12 +96,14 @@ struct nvmet_tcp_cmd {
>   
>   enum nvmet_tcp_queue_state {
>   	NVMET_TCP_Q_CONNECTING,
> +	NVMET_TCP_Q_TLS_HANDSHAKE,
>   	NVMET_TCP_Q_LIVE,
>   	NVMET_TCP_Q_DISCONNECTING,
>   };
>   
>   struct nvmet_tcp_queue {
>   	struct socket		*sock;
> +	struct file		*sock_file;
>   	struct nvmet_tcp_port	*port;
>   	struct work_struct	io_work;
>   	struct nvmet_cq		nvme_cq;
> @@ -1455,12 +1457,19 @@ static void nvmet_tcp_release_queue_work(struct work_struct *w)
>   	nvmet_sq_destroy(&queue->nvme_sq);
>   	cancel_work_sync(&queue->io_work);
>   	nvmet_tcp_free_cmd_data_in_buffers(queue);
> -	sock_release(queue->sock);
> +	if (queue->sock_file) {
> +		fput(queue->sock_file);

I don't remember, but does the fput call sock_release
on the final put? I'd move this into a helper nvmet_tcp_close_sock()
or something.

> +		queue->sock_file = NULL;
> +		queue->sock = NULL;

I always get a bit weary when I see that deallocations are setting
pointers to NULL.

> +	} else {
> +		WARN_ON(!queue->sock->ops);
> +		sock_release(queue->sock);
> +		queue->sock = NULL;
> +	}
>   	nvmet_tcp_free_cmds(queue);
>   	if (queue->hdr_digest || queue->data_digest)
>   		nvmet_tcp_free_crypto(queue);
>   	ida_free(&nvmet_tcp_queue_ida, queue->idx);
> -
>   	page = virt_to_head_page(queue->pf_cache.va);
>   	__page_frag_cache_drain(page, queue->pf_cache.pagecnt_bias);
>   	kfree(queue);
> @@ -1583,7 +1592,7 @@ static int nvmet_tcp_set_queue_sock(struct nvmet_tcp_queue *queue)
>   	return ret;
>   }
>   
> -static int nvmet_tcp_alloc_queue(struct nvmet_tcp_port *port,
> +static void nvmet_tcp_alloc_queue(struct nvmet_tcp_port *port,
>   		struct socket *newsock)

Why is this becoming a void function? This absolutely can fail.

>   {
>   	struct nvmet_tcp_queue *queue;
> @@ -1591,7 +1600,7 @@ static int nvmet_tcp_alloc_queue(struct nvmet_tcp_port *port,
>   
>   	queue = kzalloc(sizeof(*queue), GFP_KERNEL);
>   	if (!queue)
> -		return -ENOMEM;
> +		return;
>   
>   	INIT_WORK(&queue->release_work, nvmet_tcp_release_queue_work);
>   	INIT_WORK(&queue->io_work, nvmet_tcp_io_work);
> @@ -1599,15 +1608,28 @@ static int nvmet_tcp_alloc_queue(struct nvmet_tcp_port *port,
>   	queue->port = port;
>   	queue->nr_cmds = 0;
>   	spin_lock_init(&queue->state_lock);
> -	queue->state = NVMET_TCP_Q_CONNECTING;
> +	if (queue->port->nport->disc_addr.tsas.tcp.sectype ==
> +	    NVMF_TCP_SECTYPE_TLS13)
> +		queue->state = NVMET_TCP_Q_TLS_HANDSHAKE;
> +	else
> +		queue->state = NVMET_TCP_Q_CONNECTING;
>   	INIT_LIST_HEAD(&queue->free_list);
>   	init_llist_head(&queue->resp_list);
>   	INIT_LIST_HEAD(&queue->resp_send_list);
>   
> +	if (queue->state == NVMET_TCP_Q_TLS_HANDSHAKE) {
> +		queue->sock_file = sock_alloc_file(queue->sock, O_CLOEXEC, NULL);
> +		if (IS_ERR(queue->sock_file)) {
> +			ret = PTR_ERR(queue->sock_file);
> +			queue->sock_file = NULL;
> +			goto out_free_queue;
> +		}
> +	}
> +
>   	queue->idx = ida_alloc(&nvmet_tcp_queue_ida, GFP_KERNEL);
>   	if (queue->idx < 0) {
>   		ret = queue->idx;
> -		goto out_free_queue;
> +		goto out_sock;
>   	}
>   
>   	ret = nvmet_tcp_alloc_cmd(queue, &queue->connect);
> @@ -1628,7 +1650,7 @@ static int nvmet_tcp_alloc_queue(struct nvmet_tcp_port *port,
>   	if (ret)
>   		goto out_destroy_sq;
>   
> -	return 0;
> +	return;
>   out_destroy_sq:
>   	mutex_lock(&nvmet_tcp_queue_mutex);
>   	list_del_init(&queue->queue_list);
> @@ -1638,9 +1660,14 @@ static int nvmet_tcp_alloc_queue(struct nvmet_tcp_port *port,
>   	nvmet_tcp_free_cmd(&queue->connect);
>   out_ida_remove:
>   	ida_free(&nvmet_tcp_queue_ida, queue->idx);
> +out_sock:
> +	if (queue->sock_file)
> +		fput(queue->sock_file);
> +	else
> +		sock_release(queue->sock);
>   out_free_queue:
>   	kfree(queue);
> -	return ret;
> +	pr_err("failed to allocate queue");

Can we design this better?
It looks backwards that this routine deallocates an argument
coming from the call-site.

I know that this is similar to what happens with kernel_accept
to some extent. But would prefer to avoid this pattern if possible.

>   }
>   
>   static void nvmet_tcp_accept_work(struct work_struct *w)
> @@ -1657,11 +1684,7 @@ static void nvmet_tcp_accept_work(struct work_struct *w)
>   				pr_warn("failed to accept err=%d\n", ret);
>   			return;
>   		}
> -		ret = nvmet_tcp_alloc_queue(port, newsock);
> -		if (ret) {
> -			pr_err("failed to allocate queue\n");
> -			sock_release(newsock);
> -		}
> +		nvmet_tcp_alloc_queue(port, newsock);
>   	}
>   }
>