[PATCH v2 3/3] nfsd: add new reply_cache_stats file in nfsdfs

[Jeff Layton <jlayton@redhat.com>]

For presenting statistics relating to duplicate reply cache.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
---
 fs/nfsd/cache.h    |  1 +
 fs/nfsd/nfscache.c | 37 +++++++++++++++++++++++++++++++++----
 fs/nfsd/nfsctl.c   |  9 +++++++++
 3 files changed, 43 insertions(+), 4 deletions(-)

diff --git a/fs/nfsd/cache.h b/fs/nfsd/cache.h
index 87fd141..d5c5b3e 100644
--- a/fs/nfsd/cache.h
+++ b/fs/nfsd/cache.h
@@ -82,6 +82,7 @@ int	nfsd_reply_cache_init(void);
 void	nfsd_reply_cache_shutdown(void);
 int	nfsd_cache_lookup(struct svc_rqst *);
 void	nfsd_cache_update(struct svc_rqst *, int, __be32 *);
+int	nfsd_reply_cache_stats_open(struct inode *, struct file *);
 
 #ifdef CONFIG_NFSD_V4
 void	nfsd4_set_statp(struct svc_rqst *rqstp, __be32 *statp);
diff --git a/fs/nfsd/nfscache.c b/fs/nfsd/nfscache.c
index ad1d069..b155afa 100644
--- a/fs/nfsd/nfscache.c
+++ b/fs/nfsd/nfscache.c
@@ -23,12 +23,17 @@
 static struct hlist_head *	cache_hash;
 static struct list_head 	lru_head;
 static struct kmem_cache	*drc_slab;
-static unsigned int		num_drc_entries;
-static unsigned int		max_drc_entries;
-static unsigned int		drc_mem_usage;
-static unsigned int		csum_misses;
 
 /*
+ * Stats on the duplicate reply cache code. All of these and the "rc" fields
+ * in nfsdstats are protected by the cache_lock
+ */
+static unsigned int		num_drc_entries; /* number of entries */
+static unsigned int		max_drc_entries; /* max number of entries */
+static unsigned int		drc_mem_usage;   /* memory used by cache */
+static unsigned int		csum_misses;     /* cache misses due only to
+						    csum comparison failures */
+/*
  * Calculate the hash index from an XID.
  */
 static inline u32 request_hash(u32 xid)
@@ -545,3 +550,27 @@ nfsd_cache_append(struct svc_rqst *rqstp, struct kvec *data)
 	vec->iov_len += data->iov_len;
 	return 1;
 }
+
+/*
+ * Note that fields may be added, removed or reordered in the future. Programs
+ * scraping this file for info should test the labels to ensure they're
+ * getting the correct field.
+ */
+static int nfsd_reply_cache_stats_show(struct seq_file *m, void *v)
+{
+	spin_lock(&cache_lock);
+	seq_printf(m, "max entries:     %u\n", max_drc_entries);
+	seq_printf(m, "num entries:     %u\n", num_drc_entries);
+	seq_printf(m, "mem usage:       %u\n", drc_mem_usage);
+	seq_printf(m, "cache hits:      %u\n", nfsdstats.rchits);
+	seq_printf(m, "cache misses:    %u\n", nfsdstats.rcmisses);
+	seq_printf(m, "not cached:      %u\n", nfsdstats.rcnocache);
+	seq_printf(m, "checksum misses: %u\n", csum_misses);
+	spin_unlock(&cache_lock);
+	return 0;
+}
+
+int nfsd_reply_cache_stats_open(struct inode *inode, struct file *file)
+{
+	return single_open(file, nfsd_reply_cache_stats_show, NULL);
+}
diff --git a/fs/nfsd/nfsctl.c b/fs/nfsd/nfsctl.c
index 29c3f0d..5dea5af 100644
--- a/fs/nfsd/nfsctl.c
+++ b/fs/nfsd/nfsctl.c
@@ -35,6 +35,7 @@ enum {
 	NFSD_Threads,
 	NFSD_Pool_Threads,
 	NFSD_Pool_Stats,
+	NFSD_Reply_Cache_Stats,
 	NFSD_Versions,
 	NFSD_Ports,
 	NFSD_MaxBlkSize,
@@ -194,6 +195,13 @@ static const struct file_operations pool_stats_operations = {
 	.owner		= THIS_MODULE,
 };
 
+static struct file_operations reply_cache_stats_operations = {
+	.open		= nfsd_reply_cache_stats_open,
+	.read		= seq_read,
+	.llseek		= seq_lseek,
+	.release	= single_release,
+};
+
 /*----------------------------------------------------------------------------*/
 /*
  * payload - write methods
@@ -1024,6 +1032,7 @@ static int nfsd_fill_super(struct super_block * sb, void * data, int silent)
 		[NFSD_Threads] = {"threads", &transaction_ops, S_IWUSR|S_IRUSR},
 		[NFSD_Pool_Threads] = {"pool_threads", &transaction_ops, S_IWUSR|S_IRUSR},
 		[NFSD_Pool_Stats] = {"pool_stats", &pool_stats_operations, S_IRUGO},
+		[NFSD_Reply_Cache_Stats] = {"reply_cache_stats", &reply_cache_stats_operations, S_IRUGO},
 		[NFSD_Versions] = {"versions", &transaction_ops, S_IWUSR|S_IRUSR},
 		[NFSD_Ports] = {"portlist", &transaction_ops, S_IWUSR|S_IRUGO},
 		[NFSD_MaxBlkSize] = {"max_block_size", &transaction_ops, S_IWUSR|S_IRUGO},
-- 
1.7.11.7