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 hlist_node       cache_list;
  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 was
  52                                         * sent, else this is when update was
  53                                         * received, though it is alway set to
  54                                         * be *after* ->flush_time.
  55                                         */
  56        struct kref     ref;
  57        unsigned long   flags;
  58};
  59#define CACHE_VALID     0       /* Entry contains valid data */
  60#define CACHE_NEGATIVE  1       /* Negative entry - there is no match for the key */
  61#define CACHE_PENDING   2       /* An upcall has been sent but no reply received yet*/
  62#define CACHE_CLEANED   3       /* Entry has been cleaned from cache */
  63
  64#define CACHE_NEW_EXPIRY 120    /* keep new things pending confirmation for 120 seconds */
  65
  66struct cache_detail_procfs {
  67        struct proc_dir_entry   *proc_ent;
  68        struct proc_dir_entry   *flush_ent, *channel_ent, *content_ent;
  69};
  70
  71struct cache_detail_pipefs {
  72        struct dentry *dir;
  73};
  74
  75struct cache_detail {
  76        struct module *         owner;
  77        int                     hash_size;
  78        struct hlist_head *     hash_table;
  79        rwlock_t                hash_lock;
  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
 109                                                         * last_refresh at or earlier
 110                                                         * than this.  last_refresh
 111                                                         * is never set at or earlier
 112                                                         * than this.
 113                                                         */
 114        struct list_head        others;
 115        time_t                  nextcheck;
 116        int                     entries;
 117
 118        /* fields for communication over channel */
 119        struct list_head        queue;
 120
 121        atomic_t                readers;                /* how many time is /chennel open */
 122        time_t                  last_close;             /* if no readers, when did last close */
 123        time_t                  last_warn;              /* when we last warned about no readers */
 124
 125        union {
 126                struct cache_detail_procfs procfs;
 127                struct cache_detail_pipefs pipefs;
 128        } u;
 129        struct net              *net;
 130};
 131
 132
 133/* this must be embedded in any request structure that
 134 * identifies an object that will want a callback on
 135 * a cache fill
 136 */
 137struct cache_req {
 138        struct cache_deferred_req *(*defer)(struct cache_req *req);
 139        int thread_wait;  /* How long (jiffies) we can block the
 140                           * current thread to wait for updates.
 141                           */
 142};
 143/* this must be embedded in a deferred_request that is being
 144 * delayed awaiting cache-fill
 145 */
 146struct cache_deferred_req {
 147        struct hlist_node       hash;   /* on hash chain */
 148        struct list_head        recent; /* on fifo */
 149        struct cache_head       *item;  /* cache item we wait on */
 150        void                    *owner; /* we might need to discard all defered requests
 151                                         * owned by someone */
 152        void                    (*revisit)(struct cache_deferred_req *req,
 153                                           int too_many);
 154};
 155
 156/*
 157 * timestamps kept in the cache are expressed in seconds
 158 * since boot.  This is the best for measuring differences in
 159 * real time.
 160 */
 161static inline time_t seconds_since_boot(void)
 162{
 163        struct timespec boot;
 164        getboottime(&boot);
 165        return get_seconds() - boot.tv_sec;
 166}
 167
 168static inline time_t convert_to_wallclock(time_t sinceboot)
 169{
 170        struct timespec boot;
 171        getboottime(&boot);
 172        return boot.tv_sec + sinceboot;
 173}
 174
 175extern const struct file_operations cache_file_operations_pipefs;
 176extern const struct file_operations content_file_operations_pipefs;
 177extern const struct file_operations cache_flush_operations_pipefs;
 178
 179extern struct cache_head *
 180sunrpc_cache_lookup(struct cache_detail *detail,
 181                    struct cache_head *key, int hash);
 182extern struct cache_head *
 183sunrpc_cache_update(struct cache_detail *detail,
 184                    struct cache_head *new, struct cache_head *old, int hash);
 185
 186extern int
 187sunrpc_cache_pipe_upcall(struct cache_detail *detail, struct cache_head *h);
 188
 189
 190extern void cache_clean_deferred(void *owner);
 191
 192static inline struct cache_head  *cache_get(struct cache_head *h)
 193{
 194        kref_get(&h->ref);
 195        return h;
 196}
 197
 198
 199static inline void cache_put(struct cache_head *h, struct cache_detail *cd)
 200{
 201        if (atomic_read(&h->ref.refcount) <= 2 &&
 202            h->expiry_time < cd->nextcheck)
 203                cd->nextcheck = h->expiry_time;
 204        kref_put(&h->ref, cd->cache_put);
 205}
 206
 207static inline int cache_is_expired(struct cache_detail *detail, struct cache_head *h)
 208{
 209        return  (h->expiry_time < seconds_since_boot()) ||
 210                (detail->flush_time >= h->last_refresh);
 211}
 212
 213extern int cache_check(struct cache_detail *detail,
 214                       struct cache_head *h, struct cache_req *rqstp);
 215extern void cache_flush(void);
 216extern void cache_purge(struct cache_detail *detail);
 217#define NEVER (0x7FFFFFFF)
 218extern void __init cache_initialize(void);
 219extern int cache_register_net(struct cache_detail *cd, struct net *net);
 220extern void cache_unregister_net(struct cache_detail *cd, struct net *net);
 221
 222extern struct cache_detail *cache_create_net(struct cache_detail *tmpl, struct net *net);
 223extern void cache_destroy_net(struct cache_detail *cd, struct net *net);
 224
 225extern void sunrpc_init_cache_detail(struct cache_detail *cd);
 226extern void sunrpc_destroy_cache_detail(struct cache_detail *cd);
 227extern int sunrpc_cache_register_pipefs(struct dentry *parent, const char *,
 228                                        umode_t, struct cache_detail *);
 229extern void sunrpc_cache_unregister_pipefs(struct cache_detail *);
 230
 231/* Must store cache_detail in seq_file->private if using next three functions */
 232extern void *cache_seq_start(struct seq_file *file, loff_t *pos);
 233extern void *cache_seq_next(struct seq_file *file, void *p, loff_t *pos);
 234extern void cache_seq_stop(struct seq_file *file, void *p);
 235
 236extern void qword_add(char **bpp, int *lp, char *str);
 237extern void qword_addhex(char **bpp, int *lp, char *buf, int blen);
 238extern int qword_get(char **bpp, char *dest, int bufsize);
 239
 240static inline int get_int(char **bpp, int *anint)
 241{
 242        char buf[50];
 243        char *ep;
 244        int rv;
 245        int len = qword_get(bpp, buf, sizeof(buf));
 246
 247        if (len < 0)
 248                return -EINVAL;
 249        if (len == 0)
 250                return -ENOENT;
 251
 252        rv = simple_strtol(buf, &ep, 0);
 253        if (*ep)
 254                return -EINVAL;
 255
 256        *anint = rv;
 257        return 0;
 258}
 259
 260static inline int get_uint(char **bpp, unsigned int *anint)
 261{
 262        char buf[50];
 263        int len = qword_get(bpp, buf, sizeof(buf));
 264
 265        if (len < 0)
 266                return -EINVAL;
 267        if (len == 0)
 268                return -ENOENT;
 269
 270        if (kstrtouint(buf, 0, anint))
 271                return -EINVAL;
 272
 273        return 0;
 274}
 275
 276static inline int get_time(char **bpp, time_t *time)
 277{
 278        char buf[50];
 279        long long ll;
 280        int len = qword_get(bpp, buf, sizeof(buf));
 281
 282        if (len < 0)
 283                return -EINVAL;
 284        if (len == 0)
 285                return -ENOENT;
 286
 287        if (kstrtoll(buf, 0, &ll))
 288                return -EINVAL;
 289
 290        *time = (time_t)ll;
 291        return 0;
 292}
 293
 294static inline time_t get_expiry(char **bpp)
 295{
 296        time_t rv;
 297        struct timespec boot;
 298
 299        if (get_time(bpp, &rv))
 300                return 0;
 301        if (rv < 0)
 302                return 0;
 303        getboottime(&boot);
 304        return rv - boot.tv_sec;
 305}
 306
 307#endif /*  _LINUX_SUNRPC_CACHE_H_ */
 308