LXR linux/include/linux/sunrpc/cache.h

   1/*
   2 * include/linux/sunrpc/cache.h
   3 *
   4 * Generic code for various authentication-related caches
   5 * used by sunrpc clients and servers.
   6 *
   7 * Copyright (C) 2002 Neil Brown <neilb@cse.unsw.edu.au>
   8 *
   9 * Released under terms in GPL version 2.  See COPYING.
  10 *
  11 */
  12
  13#ifndef _LINUX_SUNRPC_CACHE_H_
  14#define _LINUX_SUNRPC_CACHE_H_
  15
  16#include <linux/kref.h>
  17#include <linux/slab.h>
  18#include <linux/atomic.h>
  19#include <linux/proc_fs.h>
  20
  21/*
  22 * Each cache requires:
  23 *  - A 'struct cache_detail' which contains information specific to the cache
  24 *    for common code to use.
  25 *  - An item structure that must contain a "struct cache_head"
  26 *  - A lookup function defined using DefineCacheLookup
  27 *  - A 'put' function that can release a cache item. It will only
  28 *    be called after cache_put has succeed, so there are guarantee
  29 *    to be no references.
  30 *  - A function to calculate a hash of an item's key.
  31 *
  32 * as well as assorted code fragments (e.g. compare keys) and numbers
  33 * (e.g. hash size, goal_age, etc).
  34 *
  35 * Each cache must be registered so that it can be cleaned regularly.
  36 * When the cache is unregistered, it is flushed completely.
  37 *
  38 * Entries have a ref count and a 'hashed' flag which counts the existence
  39 * in the hash table.
  40 * We only expire entries when refcount is zero.
  41 * Existence in the cache is counted  the refcount.
  42 */
  43
  44/* Every cache item has a common header that is used
  45 * for expiring and refreshing entries.
  46 * 
  47 */
  48struct cache_head {
  49        struct cache_head * next;
  50        time_t          expiry_time;    /* After time time, don't use the data */
  51        time_t          last_refresh;   /* If CACHE_PENDING, this is when upcall 
  52                                         * was sent, else this is when update was received
  53                                         */
  54        struct kref     ref;
  55        unsigned long   flags;
  56};
  57#define CACHE_VALID     0       /* Entry contains valid data */
  58#define CACHE_NEGATIVE  1       /* Negative entry - there is no match for the key */
  59#define CACHE_PENDING   2       /* An upcall has been sent but no reply received yet*/
  60#define CACHE_CLEANED   3       /* Entry has been cleaned from cache */
  61
  62#define CACHE_NEW_EXPIRY 120    /* keep new things pending confirmation for 120 seconds */
  63
  64struct cache_detail_procfs {
  65        struct proc_dir_entry   *proc_ent;
  66        struct proc_dir_entry   *flush_ent, *channel_ent, *content_ent;
  67};
  68
  69struct cache_detail_pipefs {
  70        struct dentry *dir;
  71};
  72
  73struct cache_detail {
  74        struct module *         owner;
  75        int                     hash_size;
  76        struct cache_head **    hash_table;
  77        rwlock_t                hash_lock;
  78
  79        atomic_t                inuse; /* active user-space update or lookup */
  80
  81        char                    *name;
  82        void                    (*cache_put)(struct kref *);
  83
  84        int                     (*cache_upcall)(struct cache_detail *,
  85                                                struct cache_head *);
  86
  87        void                    (*cache_request)(struct cache_detail *cd,
  88                                                 struct cache_head *ch,
  89                                                 char **bpp, int *blen);
  90
  91        int                     (*cache_parse)(struct cache_detail *,
  92                                               char *buf, int len);
  93
  94        int                     (*cache_show)(struct seq_file *m,
  95                                              struct cache_detail *cd,
  96                                              struct cache_head *h);
  97        void                    (*warn_no_listener)(struct cache_detail *cd,
  98                                              int has_died);
  99
 100        struct cache_head *     (*alloc)(void);
 101        int                     (*match)(struct cache_head *orig, struct cache_head *new);
 102        void                    (*init)(struct cache_head *orig, struct cache_head *new);
 103        void                    (*update)(struct cache_head *orig, struct cache_head *new);
 104
 105        /* fields below this comment are for internal use
 106         * and should not be touched by cache owners
 107         */
 108        time_t                  flush_time;             /* flush all cache items with last_refresh
 109                                                         * earlier than this */
 110        struct list_head        others;
 111        time_t                  nextcheck;
 112        int                     entries;
 113
 114        /* fields for communication over channel */
 115        struct list_head        queue;
 116
 117        atomic_t                readers;                /* how many time is /chennel open */
 118        time_t                  last_close;             /* if no readers, when did last close */
 119        time_t                  last_warn;              /* when we last warned about no readers */
 120
 121        union {
 122                struct cache_detail_procfs procfs;
 123                struct cache_detail_pipefs pipefs;
 124        } u;
 125        struct net              *net;
 126};
 127
 128
 129/* this must be embedded in any request structure that
 130 * identifies an object that will want a callback on
 131 * a cache fill
 132 */
 133struct cache_req {
 134        struct cache_deferred_req *(*defer)(struct cache_req *req);
 135        int thread_wait;  /* How long (jiffies) we can block the
 136                           * current thread to wait for updates.
 137                           */
 138};
 139/* this must be embedded in a deferred_request that is being
 140 * delayed awaiting cache-fill
 141 */
 142struct cache_deferred_req {
 143        struct hlist_node       hash;   /* on hash chain */
 144        struct list_head        recent; /* on fifo */
 145        struct cache_head       *item;  /* cache item we wait on */
 146        void                    *owner; /* we might need to discard all defered requests
 147                                         * owned by someone */
 148        void                    (*revisit)(struct cache_deferred_req *req,
 149                                           int too_many);
 150};
 151
 152/*
 153 * timestamps kept in the cache are expressed in seconds
 154 * since boot.  This is the best for measuring differences in
 155 * real time.
 156 */
 157static inline time_t seconds_since_boot(void)
 158{
 159        struct timespec boot;
 160        getboottime(&boot);
 161        return get_seconds() - boot.tv_sec;
 162}
 163
 164static inline time_t convert_to_wallclock(time_t sinceboot)
 165{
 166        struct timespec boot;
 167        getboottime(&boot);
 168        return boot.tv_sec + sinceboot;
 169}
 170
 171extern const struct file_operations cache_file_operations_pipefs;
 172extern const struct file_operations content_file_operations_pipefs;
 173extern const struct file_operations cache_flush_operations_pipefs;
 174
 175extern struct cache_head *
 176sunrpc_cache_lookup(struct cache_detail *detail,
 177                    struct cache_head *key, int hash);
 178extern struct cache_head *
 179sunrpc_cache_update(struct cache_detail *detail,
 180                    struct cache_head *new, struct cache_head *old, int hash);
 181
 182extern int
 183sunrpc_cache_pipe_upcall(struct cache_detail *detail, struct cache_head *h);
 184
 185
 186extern void cache_clean_deferred(void *owner);
 187
 188static inline struct cache_head  *cache_get(struct cache_head *h)
 189{
 190        kref_get(&h->ref);
 191        return h;
 192}
 193
 194
 195static inline void cache_put(struct cache_head *h, struct cache_detail *cd)
 196{
 197        if (atomic_read(&h->ref.refcount) <= 2 &&
 198            h->expiry_time < cd->nextcheck)
 199                cd->nextcheck = h->expiry_time;
 200        kref_put(&h->ref, cd->cache_put);
 201}
 202
 203static inline int cache_is_expired(struct cache_detail *detail, struct cache_head *h)
 204{
 205        return  (h->expiry_time < seconds_since_boot()) ||
 206                (detail->flush_time > h->last_refresh);
 207}
 208
 209extern int cache_check(struct cache_detail *detail,
 210                       struct cache_head *h, struct cache_req *rqstp);
 211extern void cache_flush(void);
 212extern void cache_purge(struct cache_detail *detail);
 213#define NEVER (0x7FFFFFFF)
 214extern void __init cache_initialize(void);
 215extern int cache_register_net(struct cache_detail *cd, struct net *net);
 216extern void cache_unregister_net(struct cache_detail *cd, struct net *net);
 217
 218extern struct cache_detail *cache_create_net(struct cache_detail *tmpl, struct net *net);
 219extern void cache_destroy_net(struct cache_detail *cd, struct net *net);
 220
 221extern void sunrpc_init_cache_detail(struct cache_detail *cd);
 222extern void sunrpc_destroy_cache_detail(struct cache_detail *cd);
 223extern int sunrpc_cache_register_pipefs(struct dentry *parent, const char *,
 224                                        umode_t, struct cache_detail *);
 225extern void sunrpc_cache_unregister_pipefs(struct cache_detail *);
 226
 227extern void qword_add(char **bpp, int *lp, char *str);
 228extern void qword_addhex(char **bpp, int *lp, char *buf, int blen);
 229extern int qword_get(char **bpp, char *dest, int bufsize);
 230
 231static inline int get_int(char **bpp, int *anint)
 232{
 233        char buf[50];
 234        char *ep;
 235        int rv;
 236        int len = qword_get(bpp, buf, sizeof(buf));
 237
 238        if (len < 0)
 239                return -EINVAL;
 240        if (len == 0)
 241                return -ENOENT;
 242
 243        rv = simple_strtol(buf, &ep, 0);
 244        if (*ep)
 245                return -EINVAL;
 246
 247        *anint = rv;
 248        return 0;
 249}
 250
 251static inline int get_uint(char **bpp, unsigned int *anint)
 252{
 253        char buf[50];
 254        int len = qword_get(bpp, buf, sizeof(buf));
 255
 256        if (len < 0)
 257                return -EINVAL;
 258        if (len == 0)
 259                return -ENOENT;
 260
 261        if (kstrtouint(buf, 0, anint))
 262                return -EINVAL;
 263
 264        return 0;
 265}
 266
 267static inline int get_time(char **bpp, time_t *time)
 268{
 269        char buf[50];
 270        long long ll;
 271        int len = qword_get(bpp, buf, sizeof(buf));
 272
 273        if (len < 0)
 274                return -EINVAL;
 275        if (len == 0)
 276                return -ENOENT;
 277
 278        if (kstrtoll(buf, 0, &ll))
 279                return -EINVAL;
 280
 281        *time = (time_t)ll;
 282        return 0;
 283}
 284
 285static inline time_t get_expiry(char **bpp)
 286{
 287        time_t rv;
 288        struct timespec boot;
 289
 290        if (get_time(bpp, &rv))
 291                return 0;
 292        if (rv < 0)
 293                return 0;
 294        getboottime(&boot);
 295        return rv - boot.tv_sec;
 296}
 297
 298#endif /*  _LINUX_SUNRPC_CACHE_H_ */
 299