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