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 #include <linux/in.h>
  14 #include <linux/uio.h>
  15
  16 /*
  17  * Representation of a reply cache entry. The first two members *must*
  18  * be hash_next and hash_prev.
  19  */
  20 struct svc_cacherep {
  21         struct hlist_node       c_hash;
  22         struct list_head        c_lru;
  23
  24         unsigned char           c_state,        /* unused, inprog, done */
  25                                 c_type,         /* status, buffer */
  26                                 c_secure : 1;   /* req came from port < 1024 */
  27         struct sockaddr_in      c_addr;
  28         __be32                  c_xid;
  29         u32                     c_prot;
  30         u32                     c_proc;
  31         u32                     c_vers;
  32         unsigned long           c_timestamp;
  33         union {
  34                 struct kvec     u_vec;
  35                 __be32          u_status;
  36         }                       c_u;
  37 };
  38
  39 #define c_replvec               c_u.u_vec
  40 #define c_replstat              c_u.u_status
  41
  42 /* cache entry states */
  43 enum {
  44         RC_UNUSED,
  45         RC_INPROG,
  46         RC_DONE
  47 };
  48
  49 /* return values */
  50 enum {
  51         RC_DROPIT,
  52         RC_REPLY,
  53         RC_DOIT,
  54         RC_INTR
  55 };
  56
  57 /*
  58  * Cache types.
  59  * We may want to add more types one day, e.g. for diropres and
  60  * attrstat replies. Using cache entries with fixed length instead
  61  * of buffer pointers may be more efficient.
  62  */
  63 enum {
  64         RC_NOCACHE,
  65         RC_REPLSTAT,
  66         RC_REPLBUFF,
  67 };
  68
  69 /*
  70  * If requests are retransmitted within this interval, they're dropped.
  71  */
  72 #define RC_DELAY                (HZ/5)
  73
  74 int     nfsd_reply_cache_init(void);
  75 void    nfsd_reply_cache_shutdown(void);
  76 int     nfsd_cache_lookup(struct svc_rqst *, int);
  77 void    nfsd_cache_update(struct svc_rqst *, int, __be32 *);
  78
  79 #endif /* NFSCACHE_H */