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        time64_t        expiry_time;    /* After time time, don't use the data */
  49        time64_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        void                    (*flush)(void);
  91        int                     (*match)(struct cache_head *orig, struct cache_head *new);
  92        void                    (*init)(struct cache_head *orig, struct cache_head *new);
  93        void                    (*update)(struct cache_head *orig, struct cache_head *new);
  94
  95        /* fields below this comment are for internal use
  96         * and should not be touched by cache owners
  97         */
  98        time64_t                flush_time;             /* flush all cache items with
  99                                                         * last_refresh at or earlier
 100                                                         * than this.  last_refresh
 101                                                         * is never set at or earlier
 102                                                         * than this.
 103                                                         */
 104        struct list_head        others;
 105        time64_t                nextcheck;
 106        int                     entries;
 107
 108        /* fields for communication over channel */
 109        struct list_head        queue;
 110
 111        atomic_t                writers;                /* how many time is /channel open */
 112        time64_t                last_close;             /* if no writers, when did last close */
 113        time64_t                last_warn;              /* when we last warned about no writers */
 114
 115        union {
 116                struct proc_dir_entry   *procfs;
 117                struct dentry           *pipefs;
 118        };
 119        struct net              *net;
 120};
 121
 122
 123/* this must be embedded in any request structure that
 124 * identifies an object that will want a callback on
 125 * a cache fill
 126 */
 127struct cache_req {
 128        struct cache_deferred_req *(*defer)(struct cache_req *req);
 129        int thread_wait;  /* How long (jiffies) we can block the
 130                           * current thread to wait for updates.
 131                           */
 132};
 133/* this must be embedded in a deferred_request that is being
 134 * delayed awaiting cache-fill
 135 */
 136struct cache_deferred_req {
 137        struct hlist_node       hash;   /* on hash chain */
 138        struct list_head        recent; /* on fifo */
 139        struct cache_head       *item;  /* cache item we wait on */
 140        void                    *owner; /* we might need to discard all defered requests
 141                                         * owned by someone */
 142        void                    (*revisit)(struct cache_deferred_req *req,
 143                                           int too_many);
 144};
 145
 146/*
 147 * timestamps kept in the cache are expressed in seconds
 148 * since boot.  This is the best for measuring differences in
 149 * real time.
 150 * This reimplemnts ktime_get_boottime_seconds() in a slightly
 151 * faster but less accurate way. When we end up converting
 152 * back to wallclock (CLOCK_REALTIME), that error often
 153 * cancels out during the reverse operation.
 154 */
 155static inline time64_t seconds_since_boot(void)
 156{
 157        struct timespec64 boot;
 158        getboottime64(&boot);
 159        return ktime_get_real_seconds() - boot.tv_sec;
 160}
 161
 162static inline time64_t convert_to_wallclock(time64_t sinceboot)
 163{
 164        struct timespec64 boot;
 165        getboottime64(&boot);
 166        return boot.tv_sec + sinceboot;
 167}
 168
 169extern const struct file_operations cache_file_operations_pipefs;
 170extern const struct file_operations content_file_operations_pipefs;
 171extern const struct file_operations cache_flush_operations_pipefs;
 172
 173extern struct cache_head *
 174sunrpc_cache_lookup_rcu(struct cache_detail *detail,
 175                        struct cache_head *key, int hash);
 176extern struct cache_head *
 177sunrpc_cache_update(struct cache_detail *detail,
 178                    struct cache_head *new, struct cache_head *old, int hash);
 179
 180extern int
 181sunrpc_cache_pipe_upcall(struct cache_detail *detail, struct cache_head *h);
 182extern int
 183sunrpc_cache_pipe_upcall_timeout(struct cache_detail *detail,
 184                                 struct cache_head *h);
 185
 186
 187extern void cache_clean_deferred(void *owner);
 188
 189static inline struct cache_head  *cache_get(struct cache_head *h)
 190{
 191        kref_get(&h->ref);
 192        return h;
 193}
 194
 195static inline struct cache_head  *cache_get_rcu(struct cache_head *h)
 196{
 197        if (kref_get_unless_zero(&h->ref))
 198                return h;
 199        return NULL;
 200}
 201
 202static inline void cache_put(struct cache_head *h, struct cache_detail *cd)
 203{
 204        if (kref_read(&h->ref) <= 2 &&
 205            h->expiry_time < cd->nextcheck)
 206                cd->nextcheck = h->expiry_time;
 207        kref_put(&h->ref, cd->cache_put);
 208}
 209
 210static inline bool cache_is_expired(struct cache_detail *detail, struct cache_head *h)
 211{
 212        if (h->expiry_time < seconds_since_boot())
 213                return true;
 214        if (!test_bit(CACHE_VALID, &h->flags))
 215                return false;
 216        return detail->flush_time >= h->last_refresh;
 217}
 218
 219extern int cache_check(struct cache_detail *detail,
 220                       struct cache_head *h, struct cache_req *rqstp);
 221extern void cache_flush(void);
 222extern void cache_purge(struct cache_detail *detail);
 223#define NEVER (0x7FFFFFFF)
 224extern void __init cache_initialize(void);
 225extern int cache_register_net(struct cache_detail *cd, struct net *net);
 226extern void cache_unregister_net(struct cache_detail *cd, struct net *net);
 227
 228extern struct cache_detail *cache_create_net(const struct cache_detail *tmpl, struct net *net);
 229extern void cache_destroy_net(struct cache_detail *cd, struct net *net);
 230
 231extern void sunrpc_init_cache_detail(struct cache_detail *cd);
 232extern void sunrpc_destroy_cache_detail(struct cache_detail *cd);
 233extern int sunrpc_cache_register_pipefs(struct dentry *parent, const char *,
 234                                        umode_t, struct cache_detail *);
 235extern void sunrpc_cache_unregister_pipefs(struct cache_detail *);
 236extern void sunrpc_cache_unhash(struct cache_detail *, struct cache_head *);
 237
 238/* Must store cache_detail in seq_file->private if using next three functions */
 239extern void *cache_seq_start_rcu(struct seq_file *file, loff_t *pos);
 240extern void *cache_seq_next_rcu(struct seq_file *file, void *p, loff_t *pos);
 241extern void cache_seq_stop_rcu(struct seq_file *file, void *p);
 242
 243extern void qword_add(char **bpp, int *lp, char *str);
 244extern void qword_addhex(char **bpp, int *lp, char *buf, int blen);
 245extern int qword_get(char **bpp, char *dest, int bufsize);
 246
 247static inline int get_int(char **bpp, int *anint)
 248{
 249        char buf[50];
 250        char *ep;
 251        int rv;
 252        int len = qword_get(bpp, buf, sizeof(buf));
 253
 254        if (len < 0)
 255                return -EINVAL;
 256        if (len == 0)
 257                return -ENOENT;
 258
 259        rv = simple_strtol(buf, &ep, 0);
 260        if (*ep)
 261                return -EINVAL;
 262
 263        *anint = rv;
 264        return 0;
 265}
 266
 267static inline int get_uint(char **bpp, unsigned int *anint)
 268{
 269        char buf[50];
 270        int len = qword_get(bpp, buf, sizeof(buf));
 271
 272        if (len < 0)
 273                return -EINVAL;
 274        if (len == 0)
 275                return -ENOENT;
 276
 277        if (kstrtouint(buf, 0, anint))
 278                return -EINVAL;
 279
 280        return 0;
 281}
 282
 283static inline int get_time(char **bpp, time64_t *time)
 284{
 285        char buf[50];
 286        long long ll;
 287        int len = qword_get(bpp, buf, sizeof(buf));
 288
 289        if (len < 0)
 290                return -EINVAL;
 291        if (len == 0)
 292                return -ENOENT;
 293
 294        if (kstrtoll(buf, 0, &ll))
 295                return -EINVAL;
 296
 297        *time = ll;
 298        return 0;
 299}
 300
 301static inline time64_t get_expiry(char **bpp)
 302{
 303        time64_t rv;
 304        struct timespec64 boot;
 305
 306        if (get_time(bpp, &rv))
 307                return 0;
 308        if (rv < 0)
 309                return 0;
 310        getboottime64(&boot);
 311        return rv - boot.tv_sec;
 312}
 313
 314#endif /*  _LINUX_SUNRPC_CACHE_H_ */
 315