lockd: set svc_serv->sv_maxconn to a more reasonable value (try #3)

The default method for calculating the number of connections allowed
per RPC service arbitrarily limits single-threaded services to 80
connections. This is too low for services like lockd and artificially
limits the number of TCP clients that it can support.

Have lockd set a default sv_maxconn value to 1024 (which is the typical
default value for RLIMIT_NOFILE. Also add a module parameter to allow an
admin to set this to an arbitrary value.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Acked-by: Neil Brown <neilb@suse.de>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>

1 files changed, 8 insertions, 0 deletions

diff --git a/fs/lockd/svc.c b/fs/lockd/svc.c
index 252d80163d02..bc3c3cb62db5 100644
--- a/fs/lockd/svc.c
+++ b/fs/lockd/svc.c
@@ -62,6 +62,9 @@ static unsigned long		nlm_timeout = LOCKD_DFLT_TIMEO;
 static int                      nlm_udpport, nlm_tcpport;
 int                             nsm_use_hostnames = 0;
 
+/* RLIM_NOFILE defaults to 1024. That seems like a reasonable default here. */
+static unsigned int             nlm_max_connections = 1024;
+
 /*
  * Constants needed for the sysctl interface.
  */
@@ -143,6 +146,9 @@ lockd(void *vrqstp)
                 long timeout = MAX_SCHEDULE_TIMEOUT;
                 RPC_IFDEBUG(char buf[RPC_MAX_ADDRBUFLEN]);
 
+                /* update sv_maxconn if it has changed */
+                rqstp->rq_server->sv_maxconn = nlm_max_connections;
+
                 if (signalled()) {
                         flush_signals(current);
                         if (nlmsvc_ops) {
@@ -276,6 +282,7 @@ int lockd_up(void)
         }
 
         svc_sock_update_bufs(serv);
+        serv->sv_maxconn = nlm_max_connections;
 
         nlmsvc_task = kthread_run(lockd, nlmsvc_rqst, serv->sv_name);
         if (IS_ERR(nlmsvc_task)) {
@@ -485,6 +492,7 @@ module_param_call(nlm_udpport, param_set_port, param_get_int,
 module_param_call(nlm_tcpport, param_set_port, param_get_int,
                   &nlm_tcpport, 0644);
 module_param(nsm_use_hostnames, bool, 0644);
+module_param(nlm_max_connections, uint, 0644);
 
 /*
  * Initialising and terminating the module.