--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/include/linux/nfsd/cache.h	Sun Jan 11 20:20:11 2009 +0100
@@ -0,0 +1,79 @@
+/*
+ * include/linux/nfsd/cache.h
+ *
+ * Request reply cache. This was heavily inspired by the
+ * implementation in 4.3BSD/4.4BSD.
+ *
+ * Copyright (C) 1995, 1996 Olaf Kirch <okir@monad.swb.de>
+ */
+
+#ifndef NFSCACHE_H
+#define NFSCACHE_H
+
+#include <linux/in.h>
+#include <linux/uio.h>
+
+/*
+ * Representation of a reply cache entry. The first two members *must*
+ * be hash_next and hash_prev.
+ */
+struct svc_cacherep {
+	struct hlist_node	c_hash;
+	struct list_head	c_lru;
+
+	unsigned char		c_state,	/* unused, inprog, done */
+				c_type,		/* status, buffer */
+				c_secure : 1;	/* req came from port < 1024 */
+	struct sockaddr_in	c_addr;
+	__be32			c_xid;
+	u32			c_prot;
+	u32			c_proc;
+	u32			c_vers;
+	unsigned long		c_timestamp;
+	union {
+		struct kvec	u_vec;
+		__be32		u_status;
+	}			c_u;
+};
+
+#define c_replvec		c_u.u_vec
+#define c_replstat		c_u.u_status
+
+/* cache entry states */
+enum {
+	RC_UNUSED,
+	RC_INPROG,
+	RC_DONE
+};
+
+/* return values */
+enum {
+	RC_DROPIT,
+	RC_REPLY,
+	RC_DOIT,
+	RC_INTR
+};
+
+/*
+ * Cache types.
+ * We may want to add more types one day, e.g. for diropres and
+ * attrstat replies. Using cache entries with fixed length instead
+ * of buffer pointers may be more efficient.
+ */
+enum {
+	RC_NOCACHE,
+	RC_REPLSTAT,
+	RC_REPLBUFF,
+};
+
+/*
+ * If requests are retransmitted within this interval, they're dropped.
+ */
+#define RC_DELAY		(HZ/5)
+
+int	nfsd_reply_cache_init(void);
+void	nfsd_reply_cache_shutdown(void);
+int	nfsd_cache_lookup(struct svc_rqst *, int);
+void	nfsd_cache_update(struct svc_rqst *, int, __be32 *);
+
+#endif /* NFSCACHE_H */