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

[Bob Peterson <rpeterso@redhat.com>]

----- Original Message -----
| 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);
| 

Hi,

Perhaps we should ask Chrissie, since afaik, she authored lowcomms.c,
and patch 391fbdc5d5 in particular, which added function dlm_lowcomms_connect_node().
She might have more insight than me, having known the original intent of the code.
Adding her to the cc.

Regards,

Bob Peterson
Red Hat File Systems