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/*
 * 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/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 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 sockaddr_in      c_addr;
        u32                     c_xid;
        u32                     c_prot;
        u32                     c_proc;
        u32                     c_vers;
        unsigned long           c_timestamp;
        union {
                struct iovec    u_vec;
                u32             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)

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 */