If CONFIG_LOCKDEP is disabled, then there would be a warning like this:
  CC [M]  fs/nfsd/nfs4state.o
fs/nfsd/nfs4state.c: In function ‘free_client’:
fs/nfsd/nfs4state.c:1051:19: warning: unused variable ‘nn’ [-Wunused-variable]
So, let's add "maybe_unused" tag to this variable.
Reported-by: Toralf Förster <toralf.foerster@gmx.de>
Signed-off-by: Stanislav Kinsbursky <skinsbursky@parallels.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
 static inline void
 free_client(struct nfs4_client *clp)
 {
-       struct nfsd_net *nn = net_generic(clp->net, nfsd_net_id);
+       struct nfsd_net __maybe_unused *nn = net_generic(clp->net, nfsd_net_id);
 
        lockdep_assert_held(&nn->client_lock);
        while (!list_empty(&clp->cl_sessions)) {