nfsd: add new reply_cache_stats file in nfsdfs

For presenting statistics relating to duplicate reply cache.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
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 @@
 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);