nfsd: don't destroy global nfs4_file table in per-net shutdown

The nfs4_file table is global, so shutting it down when a containerized
nfsd is shut down is wrong and can lead to double-frees. Tear down the
nfs4_file_rhltable in nfs4_state_shutdown instead of
nfs4_state_shutdown_net.

Fixes: d47b295e ("NFSD: Use rhashtable for managing nfs4_file objects")
Link: https://bugzilla.redhat.com/show_bug.cgi?id=2169017Reported-by: JianHong Yin <jiyin@redhat.com>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

fs/nfsd/nfs4state.c

@@ -8182,7 +8182,6 @@ nfs4_state_shutdown_net(struct net *net)
 
 	nfsd4_client_tracking_exit(net);
 	nfs4_state_destroy_net(net);
-	rhltable_destroy(&nfs4_file_rhltable);
 #ifdef CONFIG_NFSD_V4_2_INTER_SSC
 	nfsd4_ssc_shutdown_umount(nn);
 #endif
@@ -8192,6 +8191,7 @@ void
 nfs4_state_shutdown(void)
 {
 	nfsd4_destroy_callback_queue();
+	rhltable_destroy(&nfs4_file_rhltable);
 }
 
 static void