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        atomic_t                inuse; /* active user-space update or lookup */
  82
  83        char                    *name;
  84        void                    (*cache_put)(struct kref *);
  85
  86        int                     (*cache_upcall)(struct cache_detail *,
  87                                                struct cache_head *);
  88
  89        void                    (*cache_request)(struct cache_detail *cd,
  90                                                 struct cache_head *ch,
  91                                                 char **bpp, int *blen);
  92
  93        int                     (*cache_parse)(struct cache_detail *,
  94                                               char *buf, int len);
  95
  96        int                     (*cache_show)(struct seq_file *m,
  97                                              struct cache_detail *cd,
  98                                              struct cache_head *h);
  99        void                    (*warn_no_listener)(struct cache_detail *cd,
 100                                              int has_died);
 101
 102        struct cache_head *     (*alloc)(void);
 103        int                     (*match)(struct cache_head *orig, struct cache_head *new);
 104        void                    (*init)(struct cache_head *orig, struct cache_head *new);
 105        void                    (*update)(struct cache_head *orig, struct cache_head *new);
 106
 107        /* fields below this comment are for internal use
 108         * and should not be touched by cache owners
 109         */
 110        time_t                  flush_time;             /* flush all cache items with
 111                                                         * last_refresh at or earlier
 112                                                         * than this.  last_refresh
 113                                                         * is never set at or earlier
 114                                                         * than this.
 115                                                         */
 116        struct list_head        others;
 117        time_t                  nextcheck;
 118        int                     entries;
 119
 120        /* fields for communication over channel */
 121        struct list_head        queue;
 122
 123        atomic_t                readers;                /* how many time is /chennel open */
 124        time_t                  last_close;             /* if no readers, when did last close */
 125        time_t                  last_warn;              /* when we last warned about no readers */
 126
 127        union {
 128                struct cache_detail_procfs procfs;
 129                struct cache_detail_pipefs pipefs;
 130        } u;
 131        struct net              *net;
 132};
 133
 134
 135/* this must be embedded in any request structure that
 136 * identifies an object that will want a callback on
 137 * a cache fill
 138 */
 139struct cache_req {
 140        struct cache_deferred_req *(*defer)(struct cache_req *req);
 141        int thread_wait;  /* How long (jiffies) we can block the
 142                           * current thread to wait for updates.
 143                           */
 144};
 145/* this must be embedded in a deferred_request that is being
 146 * delayed awaiting cache-fill
 147 */
 148struct cache_deferred_req {
 149        struct hlist_node       hash;   /* on hash chain */
 150        struct list_head        recent; /* on fifo */
 151        struct cache_head       *item;  /* cache item we wait on */
 152        void                    *owner; /* we might need to discard all defered requests
 153                                         * owned by someone */
 154        void                    (*revisit)(struct cache_deferred_req *req,
 155                                           int too_many);
 156};
 157
 158/*
 159 * timestamps kept in the cache are expressed in seconds
 160 * since boot.  This is the best for measuring differences in
 161 * real time.
 162 */
 163static inline time_t seconds_since_boot(void)
 164{
 165        struct timespec boot;
 166        getboottime(&boot);
 167        return get_seconds() - boot.tv_sec;
 168}
 169
 170static inline time_t convert_to_wallclock(time_t sinceboot)
 171{
 172        struct timespec boot;
 173        getboottime(&boot);
 174        return boot.tv_sec + sinceboot;
 175}
 176
 177extern const struct file_operations cache_file_operations_pipefs;
 178extern const struct file_operations content_file_operations_pipefs;
 179extern const struct file_operations cache_flush_operations_pipefs;
 180
 181extern struct cache_head *
 182sunrpc_cache_lookup(struct cache_detail *detail,
 183                    struct cache_head *key, int hash);
 184extern struct cache_head *
 185sunrpc_cache_update(struct cache_detail *detail,
 186                    struct cache_head *new, struct cache_head *old, int hash);
 187
 188extern int
 189sunrpc_cache_pipe_upcall(struct cache_detail *detail, struct cache_head *h);
 190
 191
 192extern void cache_clean_deferred(void *owner);
 193
 194static inline struct cache_head  *cache_get(struct cache_head *h)
 195{
 196        kref_get(&h->ref);
 197        return h;
 198}
 199
 200
 201static inline void cache_put(struct cache_head *h, struct cache_detail *cd)
 202{
 203        if (atomic_read(&h->ref.refcount) <= 2 &&
 204            h->expiry_time < cd->nextcheck)
 205                cd->nextcheck = h->expiry_time;
 206        kref_put(&h->ref, cd->cache_put);
 207}
 208
 209static inline int cache_is_expired(struct cache_detail *detail, struct cache_head *h)
 210{
 211        return  (h->expiry_time < seconds_since_boot()) ||
 212                (detail->flush_time >= h->last_refresh);
 213}
 214
 215extern int cache_check(struct cache_detail *detail,
 216                       struct cache_head *h, struct cache_req *rqstp);
 217extern void cache_flush(void);
 218extern void cache_purge(struct cache_detail *detail);
 219#define NEVER (0x7FFFFFFF)
 220extern void __init cache_initialize(void);
 221extern int cache_register_net(struct cache_detail *cd, struct net *net);
 222extern void cache_unregister_net(struct cache_detail *cd, struct net *net);
 223
 224extern struct cache_detail *cache_create_net(struct cache_detail *tmpl, struct net *net);
 225extern void cache_destroy_net(struct cache_detail *cd, struct net *net);
 226
 227extern void sunrpc_init_cache_detail(struct cache_detail *cd);
 228extern void sunrpc_destroy_cache_detail(struct cache_detail *cd);
 229extern int sunrpc_cache_register_pipefs(struct dentry *parent, const char *,
 230                                        umode_t, struct cache_detail *);
 231extern void sunrpc_cache_unregister_pipefs(struct cache_detail *);
 232
 233/* Must store cache_detail in seq_file->private if using next three functions */
 234extern void *cache_seq_start(struct seq_file *file, loff_t *pos);
 235extern void *cache_seq_next(struct seq_file *file, void *p, loff_t *pos);
 236extern void cache_seq_stop(struct seq_file *file, void *p);
 237
 238extern void qword_add(char **bpp, int *lp, char *str);
 239extern void qword_addhex(char **bpp, int *lp, char *buf, int blen);
 240extern int qword_get(char **bpp, char *dest, int bufsize);
 241
 242static inline int get_int(char **bpp, int *anint)
 243{
 244        char buf[50];
 245        char *ep;
 246        int rv;
 247        int len = qword_get(bpp, buf, sizeof(buf));
 248
 249        if (len < 0)
 250                return -EINVAL;
 251        if (len == 0)
 252                return -ENOENT;
 253
 254        rv = simple_strtol(buf, &ep, 0);
 255        if (*ep)
 256                return -EINVAL;
 257
 258        *anint = rv;
 259        return 0;
 260}
 261
 262static inline int get_uint(char **bpp, unsigned int *anint)
 263{
 264        char buf[50];
 265        int len = qword_get(bpp, buf, sizeof(buf));
 266
 267        if (len < 0)
 268                return -EINVAL;
 269        if (len == 0)
 270                return -ENOENT;
 271
 272        if (kstrtouint(buf, 0, anint))
 273                return -EINVAL;
 274
 275        return 0;
 276}
 277
 278static inline int get_time(char **bpp, time_t *time)
 279{
 280        char buf[50];
 281        long long ll;
 282        int len = qword_get(bpp, buf, sizeof(buf));
 283
 284        if (len < 0)
 285                return -EINVAL;
 286        if (len == 0)
 287                return -ENOENT;
 288
 289        if (kstrtoll(buf, 0, &ll))
 290                return -EINVAL;
 291
 292        *time = (time_t)ll;
 293        return 0;
 294}
 295
 296static inline time_t get_expiry(char **bpp)
 297{
 298        time_t rv;
 299        struct timespec boot;
 300
 301        if (get_time(bpp, &rv))
 302                return 0;
 303        if (rv < 0)
 304                return 0;
 305        getboottime(&boot);
 306        return rv - boot.tv_sec;
 307}
 308
 309#endif /*  _LINUX_SUNRPC_CACHE_H_ */
 310