NFSD: Zero counters when the filecache is re-initialized

If nfsd_file_cache_init() is called after a shutdown, be sure the
stat counters are reset.

Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

fs/nfsd/filecache.c

@@ -824,6 +824,8 @@ nfsd_file_cache_shutdown_net(struct net *net)
 void
 nfsd_file_cache_shutdown(void)
 {
+	int i;
+
 	set_bit(NFSD_FILE_SHUTDOWN, &nfsd_file_lru_flags);
 
 	lease_unregister_notifier(&nfsd_file_lease_notifier);
@@ -847,6 +849,15 @@ nfsd_file_cache_shutdown(void)
 	nfsd_file_hashtbl = NULL;
 	destroy_workqueue(nfsd_filecache_wq);
 	nfsd_filecache_wq = NULL;
+
+	for_each_possible_cpu(i) {
+		per_cpu(nfsd_file_cache_hits, i) = 0;
+		per_cpu(nfsd_file_acquisitions, i) = 0;
+		per_cpu(nfsd_file_releases, i) = 0;
+		per_cpu(nfsd_file_total_age, i) = 0;
+		per_cpu(nfsd_file_pages_flushed, i) = 0;
+		per_cpu(nfsd_file_evictions, i) = 0;
+	}
 }
 
 static bool