LXR linux/fs/nfsd/cache.h

   1/* SPDX-License-Identifier: GPL-2.0 */
   2/*
   3 * Request reply cache. This was heavily inspired by the
   4 * implementation in 4.3BSD/4.4BSD.
   5 *
   6 * Copyright (C) 1995, 1996 Olaf Kirch <okir@monad.swb.de>
   7 */
   8
   9#ifndef NFSCACHE_H
  10#define NFSCACHE_H
  11
  12#include <linux/sunrpc/svc.h>
  13
  14/*
  15 * Representation of a reply cache entry.
  16 *
  17 * Note that we use a sockaddr_in6 to hold the address instead of the more
  18 * typical sockaddr_storage. This is for space reasons, since sockaddr_storage
  19 * is much larger than a sockaddr_in6.
  20 */
  21struct svc_cacherep {
  22        struct {
  23                /* Keep often-read xid, csum in the same cache line: */
  24                __be32                  k_xid;
  25                __wsum                  k_csum;
  26                u32                     k_proc;
  27                u32                     k_prot;
  28                u32                     k_vers;
  29                unsigned int            k_len;
  30                struct sockaddr_in6     k_addr;
  31        } c_key;
  32
  33        struct rb_node          c_node;
  34        struct list_head        c_lru;
  35        unsigned char           c_state,        /* unused, inprog, done */
  36                                c_type,         /* status, buffer */
  37                                c_secure : 1;   /* req came from port < 1024 */
  38        unsigned long           c_timestamp;
  39        union {
  40                struct kvec     u_vec;
  41                __be32          u_status;
  42        }                       c_u;
  43};
  44
  45#define c_replvec               c_u.u_vec
  46#define c_replstat              c_u.u_status
  47
  48/* cache entry states */
  49enum {
  50        RC_UNUSED,
  51        RC_INPROG,
  52        RC_DONE
  53};
  54
  55/* return values */
  56enum {
  57        RC_DROPIT,
  58        RC_REPLY,
  59        RC_DOIT
  60};
  61
  62/*
  63 * Cache types.
  64 * We may want to add more types one day, e.g. for diropres and
  65 * attrstat replies. Using cache entries with fixed length instead
  66 * of buffer pointers may be more efficient.
  67 */
  68enum {
  69        RC_NOCACHE,
  70        RC_REPLSTAT,
  71        RC_REPLBUFF,
  72};
  73
  74/* Cache entries expire after this time period */
  75#define RC_EXPIRE               (120 * HZ)
  76
  77/* Checksum this amount of the request */
  78#define RC_CSUMLEN              (256U)
  79
  80int     nfsd_reply_cache_init(void);
  81void    nfsd_reply_cache_shutdown(void);
  82int     nfsd_cache_lookup(struct svc_rqst *);
  83void    nfsd_cache_update(struct svc_rqst *, int, __be32 *);
  84int     nfsd_reply_cache_stats_open(struct inode *, struct file *);
  85
  86#endif /* NFSCACHE_H */
  87