[Cluster-devel] DLM: Do not count redundant connection attempts against retries

[David Teigland <teigland@redhat.com>]

On Thu, Apr 20, 2017 at 04:02:20PM -0400, Bob Peterson wrote:
> Hi,
> 
> Before this patch, multiple GFS2 mounts would result in multiple
> connection attempts. They were all ignored, and rightly so, but
> they were being counted against the connection attempt retries.
> This patch moves the retry check later those redundant attempts
> are simply ignored, as they should be.

Each mount/dlm_new_lockspace() calls dlm_lowcomm_connect_node() to
establish connections to other nodes in the lockspace.  If a connection to
a node already exists, nothing is needed, but it seems strange this isn't
checked earlier, e.g. in dlm_lowcomms_connect_node() or
lowcomms_connect_sock().  Maybe concurrent closes or connects require
checking things in tcp_connect_to_sock()?

Dave

> 
> Signed-off-by: Bob Peterson <rpeterso@redhat.com>
> ---
> diff --git a/fs/dlm/lowcomms.c b/fs/dlm/lowcomms.c
> index 7d398d3..42c8457 100644
> --- a/fs/dlm/lowcomms.c
> +++ b/fs/dlm/lowcomms.c
> @@ -1123,13 +1123,13 @@ static void tcp_connect_to_sock(struct connection *con)
>  	}
>  
>  	mutex_lock(&con->sock_mutex);
> -	if (con->retries++ > MAX_CONNECT_RETRIES)
> -		goto out;
> -
>  	/* Some odd races can cause double-connects, ignore them */
>  	if (con->sock)
>  		goto out;
>  
> +	if (con->retries++ > MAX_CONNECT_RETRIES)
> +		goto out;
> +
>  	/* Create a socket to communicate with */
>  	result = sock_create_kern(&init_net, dlm_local_addr[0]->ss_family,
>  				  SOCK_STREAM, IPPROTO_TCP, &sock);