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

   1/* SPDX-License-Identifier: GPL-2.0-only */
   2/*
   3 * include/linux/sunrpc/cache.h
   4 *
   5 * Generic code for various authentication-related caches
   6 * used by sunrpc clients and servers.
   7 *
   8 * Copyright (C) 2002 Neil Brown <neilb@cse.unsw.edu.au>
   9 */
  10
  11#ifndef _LINUX_SUNRPC_CACHE_H_
  12#define _LINUX_SUNRPC_CACHE_H_
  13
  14#include <linux/kref.h>
  15#include <linux/slab.h>
  16#include <linux/atomic.h>
  17#include <linux/proc_fs.h>
  18
  19/*
  20 * Each cache requires:
  21 *  - A 'struct cache_detail' which contains information specific to the cache
  22 *    for common code to use.
  23 *  - An item structure that must contain a "struct cache_head"
  24 *  - A lookup function defined using DefineCacheLookup
  25 *  - A 'put' function that can release a cache item. It will only
  26 *    be called after cache_put has succeed, so there are guarantee
  27 *    to be no references.
  28 *  - A function to calculate a hash of an item's key.
  29 *
  30 * as well as assorted code fragments (e.g. compare keys) and numbers
  31 * (e.g. hash size, goal_age, etc).
  32 *
  33 * Each cache must be registered so that it can be cleaned regularly.
  34 * When the cache is unregistered, it is flushed completely.
  35 *
  36 * Entries have a ref count and a 'hashed' flag which counts the existence
  37 * in the hash table.
  38 * We only expire entries when refcount is zero.
  39 * Existence in the cache is counted  the refcount.
  40 */
  41
  42/* Every cache item has a common header that is used
  43 * for expiring and refreshing entries.
  44 * 
  45 */
  46struct cache_head {
  47        struct hlist_node       cache_list;
  48        time_t          expiry_time;    /* After time time, don't use the data */
  49        time_t          last_refresh;   /* If CACHE_PENDING, this is when upcall was
  50                                         * sent, else this is when update was
  51                                         * received, though it is alway set to
  52                                         * be *after* ->flush_time.
  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 {
  65        struct module *         owner;
  66        int                     hash_size;
  67        struct hlist_head *     hash_table;
  68        spinlock_t              hash_lock;
  69
  70        char                    *name;
  71        void                    (*cache_put)(struct kref *);
  72
  73        int                     (*cache_upcall)(struct cache_detail *,
  74                                                struct cache_head *);
  75
  76        void                    (*cache_request)(struct cache_detail *cd,
  77                                                 struct cache_head *ch,
  78                                                 char **bpp, int *blen);
  79
  80        int                     (*cache_parse)(struct cache_detail *,
  81                                               char *buf, int len);
  82
  83        int                     (*cache_show)(struct seq_file *m,
  84                                              struct cache_detail *cd,
  85                                              struct cache_head *h);
  86        void                    (*warn_no_listener)(struct cache_detail *cd,
  87                                              int has_died);
  88
  89        struct cache_head *     (*alloc)(void);
  90        int                     (*match)(struct cache_head *orig, struct cache_head *new);
  91        void                    (*init)(struct cache_head *orig, struct cache_head *new);
  92        void                    (*update)(struct cache_head *orig, struct cache_head *new);
  93
  94        /* fields below this comment are for internal use
  95         * and should not be touched by cache owners
  96         */
  97        time_t                  flush_time;             /* flush all cache items with
  98                                                         * last_refresh at or earlier
  99                                                         * than this.  last_refresh
 100                                                         * is never set at or earlier
 101                                                         * than this.
 102                                                         */
 103        struct list_head        others;
 104        time_t                  nextcheck;
 105        int                     entries;
 106
 107        /* fields for communication over channel */
 108        struct list_head        queue;
 109
 110        atomic_t                readers;                /* how many time is /chennel open */
 111        time_t                  last_close;             /* if no readers, when did last close */
 112        time_t                  last_warn;              /* when we last warned about no readers */
 113
 114        union {
 115                struct proc_dir_entry   *procfs;
 116                struct dentry           *pipefs;
 117        };
 118        struct net              *net;
 119};
 120
 121
 122/* this must be embedded in any request structure that
 123 * identifies an object that will want a callback on
 124 * a cache fill
 125 */
 126struct cache_req {
 127        struct cache_deferred_req *(*defer)(struct cache_req *req);
 128        int thread_wait;  /* How long (jiffies) we can block the
 129                           * current thread to wait for updates.
 130                           */
 131};
 132/* this must be embedded in a deferred_request that is being
 133 * delayed awaiting cache-fill
 134 */
 135struct cache_deferred_req {
 136        struct hlist_node       hash;   /* on hash chain */
 137        struct list_head        recent; /* on fifo */
 138        struct cache_head       *item;  /* cache item we wait on */
 139        void                    *owner; /* we might need to discard all defered requests
 140                                         * owned by someone */
 141        void                    (*revisit)(struct cache_deferred_req *req,
 142                                           int too_many);
 143};
 144
 145/*
 146 * timestamps kept in the cache are expressed in seconds
 147 * since boot.  This is the best for measuring differences in
 148 * real time.
 149 */
 150static inline time_t seconds_since_boot(void)
 151{
 152        struct timespec boot;
 153        getboottime(&boot);
 154        return get_seconds() - boot.tv_sec;
 155}
 156
 157static inline time_t convert_to_wallclock(time_t sinceboot)
 158{
 159        struct timespec boot;
 160        getboottime(&boot);
 161        return boot.tv_sec + sinceboot;
 162}
 163
 164extern const struct file_operations cache_file_operations_pipefs;
 165extern const struct file_operations content_file_operations_pipefs;
 166extern const struct file_operations cache_flush_operations_pipefs;
 167
 168extern struct cache_head *
 169sunrpc_cache_lookup_rcu(struct cache_detail *detail,
 170                        struct cache_head *key, int hash);
 171extern struct cache_head *
 172sunrpc_cache_update(struct cache_detail *detail,
 173                    struct cache_head *new, struct cache_head *old, int hash);
 174
 175extern int
 176sunrpc_cache_pipe_upcall(struct cache_detail *detail, struct cache_head *h);
 177
 178
 179extern void cache_clean_deferred(void *owner);
 180
 181static inline struct cache_head  *cache_get(struct cache_head *h)
 182{
 183        kref_get(&h->ref);
 184        return h;
 185}
 186
 187static inline struct cache_head  *cache_get_rcu(struct cache_head *h)
 188{
 189        if (kref_get_unless_zero(&h->ref))
 190                return h;
 191        return NULL;
 192}
 193
 194static inline void cache_put(struct cache_head *h, struct cache_detail *cd)
 195{
 196        if (kref_read(&h->ref) <= 2 &&
 197            h->expiry_time < cd->nextcheck)
 198                cd->nextcheck = h->expiry_time;
 199        kref_put(&h->ref, cd->cache_put);
 200}
 201
 202static inline bool cache_is_expired(struct cache_detail *detail, struct cache_head *h)
 203{
 204        if (!test_bit(CACHE_VALID, &h->flags))
 205                return false;
 206
 207        return  (h->expiry_time < seconds_since_boot()) ||
 208                (detail->flush_time >= h->last_refresh);
 209}
 210
 211extern int cache_check(struct cache_detail *detail,
 212                       struct cache_head *h, struct cache_req *rqstp);
 213extern void cache_flush(void);
 214extern void cache_purge(struct cache_detail *detail);
 215#define NEVER (0x7FFFFFFF)
 216extern void __init cache_initialize(void);
 217extern int cache_register_net(struct cache_detail *cd, struct net *net);
 218extern void cache_unregister_net(struct cache_detail *cd, struct net *net);
 219
 220extern struct cache_detail *cache_create_net(const struct cache_detail *tmpl, struct net *net);
 221extern void cache_destroy_net(struct cache_detail *cd, struct net *net);
 222
 223extern void sunrpc_init_cache_detail(struct cache_detail *cd);
 224extern void sunrpc_destroy_cache_detail(struct cache_detail *cd);
 225extern int sunrpc_cache_register_pipefs(struct dentry *parent, const char *,
 226                                        umode_t, struct cache_detail *);
 227extern void sunrpc_cache_unregister_pipefs(struct cache_detail *);
 228extern void sunrpc_cache_unhash(struct cache_detail *, struct cache_head *);
 229
 230/* Must store cache_detail in seq_file->private if using next three functions */
 231extern void *cache_seq_start_rcu(struct seq_file *file, loff_t *pos);
 232extern void *cache_seq_next_rcu(struct seq_file *file, void *p, loff_t *pos);
 233extern void cache_seq_stop_rcu(struct seq_file *file, void *p);
 234
 235extern void qword_add(char **bpp, int *lp, char *str);
 236extern void qword_addhex(char **bpp, int *lp, char *buf, int blen);
 237extern int qword_get(char **bpp, char *dest, int bufsize);
 238
 239static inline int get_int(char **bpp, int *anint)
 240{
 241        char buf[50];
 242        char *ep;
 243        int rv;
 244        int len = qword_get(bpp, buf, sizeof(buf));
 245
 246        if (len < 0)
 247                return -EINVAL;
 248        if (len == 0)
 249                return -ENOENT;
 250
 251        rv = simple_strtol(buf, &ep, 0);
 252        if (*ep)
 253                return -EINVAL;
 254
 255        *anint = rv;
 256        return 0;
 257}
 258
 259static inline int get_uint(char **bpp, unsigned int *anint)
 260{
 261        char buf[50];
 262        int len = qword_get(bpp, buf, sizeof(buf));
 263
 264        if (len < 0)
 265                return -EINVAL;
 266        if (len == 0)
 267                return -ENOENT;
 268
 269        if (kstrtouint(buf, 0, anint))
 270                return -EINVAL;
 271
 272        return 0;
 273}
 274
 275static inline int get_time(char **bpp, time_t *time)
 276{
 277        char buf[50];
 278        long long ll;
 279        int len = qword_get(bpp, buf, sizeof(buf));
 280
 281        if (len < 0)
 282                return -EINVAL;
 283        if (len == 0)
 284                return -ENOENT;
 285
 286        if (kstrtoll(buf, 0, &ll))
 287                return -EINVAL;
 288
 289        *time = (time_t)ll;
 290        return 0;
 291}
 292
 293static inline time_t get_expiry(char **bpp)
 294{
 295        time_t rv;
 296        struct timespec boot;
 297
 298        if (get_time(bpp, &rv))
 299                return 0;
 300        if (rv < 0)
 301                return 0;
 302        getboottime(&boot);
 303        return rv - boot.tv_sec;
 304}
 305
 306#endif /*  _LINUX_SUNRPC_CACHE_H_ */
 307