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  */
  21 struct 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 */
  49 enum {
  50         RC_UNUSED,
  51         RC_INPROG,
  52         RC_DONE
  53 };
  54
  55 /* return values */
  56 enum {
  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  */
  68 enum {
  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
  80 int     nfsd_reply_cache_init(void);
  81 void    nfsd_reply_cache_shutdown(void);
  82 int     nfsd_cache_lookup(struct svc_rqst *);
  83 void    nfsd_cache_update(struct svc_rqst *, int, __be32 *);
  84 int     nfsd_reply_cache_stats_open(struct inode *, struct file *);
  85
  86 #endif /* NFSCACHE_H */