NFSD: Report count of freed filecache items

Surface the count of freed nfsd_file items.
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

fs/nfsd/filecache.c

@@ -44,6 +44,7 @@ struct nfsd_fcache_bucket {
 
 static DEFINE_PER_CPU(unsigned long, nfsd_file_cache_hits);
 static DEFINE_PER_CPU(unsigned long, nfsd_file_acquisitions);
+static DEFINE_PER_CPU(unsigned long, nfsd_file_releases);
 
 struct nfsd_fcache_disposal {
 	struct work_struct work;
@@ -196,6 +197,8 @@ nfsd_file_free(struct nfsd_file *nf)
 {
 	bool flush = false;
 
+	this_cpu_inc(nfsd_file_releases);
+
 	trace_nfsd_file_put_final(nf);
 	if (nf->nf_mark)
 		nfsd_file_mark_put(nf->nf_mark);
@@ -1050,7 +1053,7 @@ nfsd_file_create(struct svc_rqst *rqstp, struct svc_fh *fhp,
  */
 static int nfsd_file_cache_stats_show(struct seq_file *m, void *v)
 {
-	unsigned long hits = 0, acquisitions = 0;
+	unsigned long hits = 0, acquisitions = 0, releases = 0;
 	unsigned int i, count = 0, longest = 0;
 	unsigned long lru = 0;
 
@@ -1072,6 +1075,7 @@ static int nfsd_file_cache_stats_show(struct seq_file *m, void *v)
 	for_each_possible_cpu(i) {
 		hits += per_cpu(nfsd_file_cache_hits, i);
 		acquisitions += per_cpu(nfsd_file_acquisitions, i);
+		releases += per_cpu(nfsd_file_releases, i);
 	}
 
 	seq_printf(m, "total entries: %u\n", count);
@@ -1079,6 +1083,7 @@ static int nfsd_file_cache_stats_show(struct seq_file *m, void *v)
 	seq_printf(m, "lru entries:   %lu\n", lru);
 	seq_printf(m, "cache hits:    %lu\n", hits);
 	seq_printf(m, "acquisitions:  %lu\n", acquisitions);
+	seq_printf(m, "releases:      %lu\n", releases);
 	return 0;
 }