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, 1 insertions, 0 deletions

diff --git a/fs/nfs/callback.h b/fs/nfs/callback.h
index bb25d2135ff1..e110e286a262 100644
--- a/fs/nfs/callback.h
+++ b/fs/nfs/callback.h
@@ -72,5 +72,6 @@ extern void nfs_callback_down(void);
 
 extern unsigned int nfs_callback_set_tcpport;
 extern unsigned short nfs_callback_tcpport;
+extern unsigned short nfs_callback_tcpport6;
 
 #endif /* __LINUX_FS_NFS_CALLBACK_H */