lockd: Start PF_INET6 listener only if IPv6 support is available

Apparently a lot of people need to disable IPv6 completely on their
distributor-built systems, which have CONFIG_IPV6_MODULE enabled at
build time.

They do this by blacklisting the ipv6.ko module.  This causes the
creation of the lockd service listener to fail if CONFIG_IPV6_MODULE
is set, but the module cannot be loaded.

Now that the kernel's PF_INET6 RPC listeners are completely separate
from PF_INET listeners, we can always start PF_INET.  Then lockd can
try to start PF_INET6, but it isn't required to be available.

Note this has the added benefit that NLM callbacks from AF_INET6
servers will never come from AF_INET remotes.  We no longer have to
worry about matching mapped IPv4 addresses to AF_INET when comparing
addresses.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

1 files changed, 21 insertions, 9 deletions

diff --git a/fs/lockd/svc.c b/fs/lockd/svc.c
index 566932b98fd3..abf83881f68a 100644
--- a/fs/lockd/svc.c
+++ b/fs/lockd/svc.c
@@ -193,20 +193,30 @@ lockd(void *vrqstp)
         return 0;
 }
 
-static int create_lockd_listener(struct svc_serv *serv, char *name,
-                                 unsigned short port)
+static int create_lockd_listener(struct svc_serv *serv, const char *name,
+                                 const int family, const unsigned short port)
 {
         struct svc_xprt *xprt;
 
-        xprt = svc_find_xprt(serv, name, 0, 0);
+        xprt = svc_find_xprt(serv, name, family, 0);
         if (xprt == NULL)
-                return svc_create_xprt(serv, name, PF_INET,
-                                        port, SVC_SOCK_DEFAULTS);
-
+                return svc_create_xprt(serv, name, family, port,
+                                                SVC_SOCK_DEFAULTS);
         svc_xprt_put(xprt);
         return 0;
 }
 
+static int create_lockd_family(struct svc_serv *serv, const int family)
+{
+        int err;
+
+        err = create_lockd_listener(serv, "udp", family, nlm_udpport);
+        if (err < 0)
+                return err;
+
+        return create_lockd_listener(serv, "tcp", family, nlm_tcpport);
+}
+
 /*
  * Ensure there are active UDP and TCP listeners for lockd.
  *
@@ -222,13 +232,15 @@ static int make_socks(struct svc_serv *serv)
         static int warned;
         int err;
 
-        err = create_lockd_listener(serv, "udp", nlm_udpport);
+        err = create_lockd_family(serv, PF_INET);
         if (err < 0)
                 goto out_err;
 
-        err = create_lockd_listener(serv, "tcp", nlm_tcpport);
-        if (err < 0)
+#if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
+        err = create_lockd_family(serv, PF_INET6);
+        if (err < 0 && err != -EAFNOSUPPORT)
                 goto out_err;
+#endif  /* CONFIG_IPV6 || CONFIG_IPV6_MODULE */
 
         warned = 0;
         return 0;