NFS: Start PF_INET6 callback 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 NFSv4 callback 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 the NFS
client can try to start a PF_INET6 listener, but it isn't required
to be available.

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

1 files changed, 12 insertions, 0 deletions

diff --git a/fs/nfs/callback.c b/fs/nfs/callback.c
index 0ef47dff89be..a886e692ddd0 100644
--- a/fs/nfs/callback.c
+++ b/fs/nfs/callback.c
@@ -38,6 +38,7 @@ static struct svc_program nfs4_callback_program;
 
 unsigned int nfs_callback_set_tcpport;
 unsigned short nfs_callback_tcpport;
+unsigned short nfs_callback_tcpport6;
 static const int nfs_set_port_min = 0;
 static const int nfs_set_port_max = 65535;
 
@@ -119,6 +120,17 @@ int nfs_callback_up(void)
         dprintk("NFS: Callback listener port = %u (af %u)\n",
                         nfs_callback_tcpport, PF_INET);
 
+#if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
+        ret = svc_create_xprt(serv, "tcp", PF_INET6,
+                                nfs_callback_set_tcpport, SVC_SOCK_ANONYMOUS);
+        if (ret > 0) {
+                nfs_callback_tcpport6 = ret;
+                dprintk("NFS: Callback listener port = %u (af %u)\n",
+                                nfs_callback_tcpport6, PF_INET6);
+        } else if (ret != -EAFNOSUPPORT)
+                goto out_err;
+#endif  /* defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE) */
+
         nfs_callback_info.rqst = svc_prepare_thread(serv, &serv->sv_pools[0]);
         if (IS_ERR(nfs_callback_info.rqst)) {
                 ret = PTR_ERR(nfs_callback_info.rqst);