include/linux/nfsd/cache.h

   1 /*
   2  * include/linux/nfsd/cache.h
   3  *
   4  * Request reply cache. This was heavily inspired by the
   5  * implementation in 4.3BSD/4.4BSD.
   6  *
   7  * Copyright (C) 1995, 1996 Olaf Kirch <okir@monad.swb.de>
   8  */
   9
  10 #ifndef NFSCACHE_H
  11 #define NFSCACHE_H
  12
  13 #ifdef __KERNEL__
  14 #include <linux/in.h>
  15 #include <linux/uio.h>
  16
  17 /*
  18  * Representation of a reply cache entry. The first two members *must*
  19  * be hash_next and hash_prev.
  20  */
  21 struct svc_cacherep {
  22         struct svc_cacherep *   c_hash_next;
  23         struct svc_cacherep *   c_hash_prev;
  24         struct svc_cacherep *   c_lru_next;
  25         struct svc_cacherep *   c_lru_prev;
  26         unsigned char           c_state,        /* unused, inprog, done */
  27                                 c_type,         /* status, buffer */
  28                                 c_secure : 1;   /* req came from port < 1024 */
  29         struct sockaddr_in      c_addr;
  30         u32                     c_xid;
  31         u32                     c_prot;
  32         u32                     c_proc;
  33         u32                     c_vers;
  34         unsigned long           c_timestamp;
  35         union {
  36                 struct kvec     u_vec;
  37                 u32             u_status;
  38         }                       c_u;
  39 };
  40
  41 #define c_replvec               c_u.u_vec
  42 #define c_replstat              c_u.u_status
  43
  44 /* cache entry states */
  45 enum {
  46         RC_UNUSED,
  47         RC_INPROG,
  48         RC_DONE
  49 };
  50
  51 /* return values */
  52 enum {
  53         RC_DROPIT,
  54         RC_REPLY,
  55         RC_DOIT,
  56         RC_INTR
  57 };
  58
  59 /*
  60  * Cache types.
  61  * We may want to add more types one day, e.g. for diropres and
  62  * attrstat replies. Using cache entries with fixed length instead
  63  * of buffer pointers may be more efficient.
  64  */
  65 enum {
  66         RC_NOCACHE,
  67         RC_REPLSTAT,
  68         RC_REPLBUFF,
  69 };
  70
  71 /*
  72  * If requests are retransmitted within this interval, they're dropped.
  73  */
  74 #define RC_DELAY                (HZ/5)
  75
  76 void    nfsd_cache_init(void);
  77 void    nfsd_cache_shutdown(void);
  78 int     nfsd_cache_lookup(struct svc_rqst *, int);
  79 void    nfsd_cache_update(struct svc_rqst *, int, u32 *);
  80
  81 #endif /* __KERNEL__ */
  82 #endif /* NFSCACHE_H */