/*
 * 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

#ifdef __KERNEL__
#include <linux/sched.h>

/*
 * Representation of a reply cache entry. The first two members *must*
 * be hash_next and hash_prev.
 */
struct svc_cacherep {
	struct svc_cacherep *	c_hash_next;
	struct svc_cacherep *	c_hash_prev;
	struct svc_cacherep *	c_lru_next;
	struct svc_cacherep *	c_lru_prev;
	unsigned char		c_state,	/* unused, inprog, done */
				c_type,		/* status, buffer */
				c_secure : 1;	/* req came from port < 1024 */
	struct in_addr		c_client;
	u32			c_xid;
	u32			c_proc;
	unsigned long		c_timestamp;
	union {
		struct svc_buf	u_buffer;
		u32		u_status;
	}			c_u;
};

#define c_replbuf		c_u.u_buffer
#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)

void	nfsd_cache_init(void);
void	nfsd_cache_shutdown(void);
int	nfsd_cache_lookup(struct svc_rqst *, int);
void	nfsd_cache_update(struct svc_rqst *, int, u32 *);

#endif /* __KERNEL__ */
#endif /* NFSCACHE_H */
