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 hlist_node       c_hash;
  23         struct list_head        c_lru;
  24
  25         unsigned char           c_state,        /* unused, inprog, done */
  26                                 c_type,         /* status, buffer */
  27                                 c_secure : 1;   /* req came from port < 1024 */
  28         struct sockaddr_in      c_addr;
  29         __be32                  c_xid;
  30         u32                     c_prot;
  31         u32                     c_proc;
  32         u32                     c_vers;
  33         unsigned long           c_timestamp;
  34         union {
  35                 struct kvec     u_vec;
  36                 __be32          u_status;
  37         }                       c_u;
  38 };
  39
  40 #define c_replvec               c_u.u_vec
  41 #define c_replstat              c_u.u_status
  42
  43 /* cache entry states */
  44 enum {
  45         RC_UNUSED,
  46         RC_INPROG,
  47         RC_DONE
  48 };
  49
  50 /* return values */
  51 enum {
  52         RC_DROPIT,
  53         RC_REPLY,
  54         RC_DOIT,
  55         RC_INTR
  56 };
  57
  58 /*
  59  * Cache types.
  60  * We may want to add more types one day, e.g. for diropres and
  61  * attrstat replies. Using cache entries with fixed length instead
  62  * of buffer pointers may be more efficient.
  63  */
  64 enum {
  65         RC_NOCACHE,
  66         RC_REPLSTAT,
  67         RC_REPLBUFF,
  68 };
  69
  70 /*
  71  * If requests are retransmitted within this interval, they're dropped.
  72  */
  73 #define RC_DELAY                (HZ/5)
  74
  75 void    nfsd_cache_init(void);
  76 void    nfsd_cache_shutdown(void);
  77 int     nfsd_cache_lookup(struct svc_rqst *, int);
  78 void    nfsd_cache_update(struct svc_rqst *, int, __be32 *);
  79
  80 #endif /* __KERNEL__ */
  81 #endif /* NFSCACHE_H */