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Subject: [PATCH v3 02/32] NFSD: Report filecache LRU size
From:   Chuck Lever <chuck.lever@oracle.com>
To:     linux-nfs@vger.kernel.org, netdev@vger.kernel.org
Cc:     david@fromorbit.com, jlayton@redhat.com, tgraf@suug.ch
Date:   Fri, 08 Jul 2022 14:23:52 -0400
Message-ID: <165730463235.28142.14209014620135692603.stgit@klimt.1015granger.net>
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Surface the NFSD filecache's LRU list length to help field
troubleshooters monitor filecache issues.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
---
 fs/nfsd/filecache.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/fs/nfsd/filecache.c b/fs/nfsd/filecache.c
index 9cb2d590c036..a0234d194ec1 100644
--- a/fs/nfsd/filecache.c
+++ b/fs/nfsd/filecache.c
@@ -1068,7 +1068,7 @@ 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 int i, count = 0, longest = 0;
-	unsigned long hits = 0;
+	unsigned long lru = 0, hits = 0;
 
 	/*
 	 * No need for spinlocks here since we're not terribly interested in
@@ -1081,6 +1081,7 @@ static int nfsd_file_cache_stats_show(struct seq_file *m, void *v)
 			count += nfsd_file_hashtbl[i].nfb_count;
 			longest = max(longest, nfsd_file_hashtbl[i].nfb_count);
 		}
+		lru = list_lru_count(&nfsd_file_lru);
 	}
 	mutex_unlock(&nfsd_mutex);
 
@@ -1089,6 +1090,7 @@ static int nfsd_file_cache_stats_show(struct seq_file *m, void *v)
 
 	seq_printf(m, "total entries: %u\n", count);
 	seq_printf(m, "longest chain: %u\n", longest);
+	seq_printf(m, "lru entries:   %lu\n", lru);
 	seq_printf(m, "cache hits:    %lu\n", hits);
 	return 0;
 }