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 expiry_time, don't use
  49                                         * the data */
  50        time64_t        last_refresh;   /* If CACHE_PENDING, this is when upcall was
  51                                         * sent, else this is when update was
  52                                         * received, though it is alway set to
  53                                         * be *after* ->flush_time.
  54                                         */
  55        struct kref     ref;
  56        unsigned long   flags;
  57};
  58#define CACHE_VALID     0       /* Entry contains valid data */
  59#define CACHE_NEGATIVE  1       /* Negative entry - there is no match for the key */
  60#define CACHE_PENDING   2       /* An upcall has been sent but no reply received yet*/
  61#define CACHE_CLEANED   3       /* Entry has been cleaned from cache */
  62
  63#define CACHE_NEW_EXPIRY 120    /* keep new things pending confirmation for 120 seconds */
  64
  65struct cache_detail {
  66        struct module *         owner;
  67        int                     hash_size;
  68        struct hlist_head *     hash_table;
  69        spinlock_t              hash_lock;
  70
  71        char                    *name;
  72        void                    (*cache_put)(struct kref *);
  73
  74        int                     (*cache_upcall)(struct cache_detail *,
  75                                                struct cache_head *);
  76
  77        void                    (*cache_request)(struct cache_detail *cd,
  78                                                 struct cache_head *ch,
  79                                                 char **bpp, int *blen);
  80
  81        int                     (*cache_parse)(struct cache_detail *,
  82                                               char *buf, int len);
  83
  84        int                     (*cache_show)(struct seq_file *m,
  85                                              struct cache_detail *cd,
  86                                              struct cache_head *h);
  87        void                    (*warn_no_listener)(struct cache_detail *cd,
  88                                              int has_died);
  89
  90        struct cache_head *     (*alloc)(void);
  91        void                    (*flush)(void);
  92        int                     (*match)(struct cache_head *orig, struct cache_head *new);
  93        void                    (*init)(struct cache_head *orig, struct cache_head *new);
  94        void                    (*update)(struct cache_head *orig, struct cache_head *new);
  95
  96        /* fields below this comment are for internal use
  97         * and should not be touched by cache owners
  98         */
  99        time64_t                flush_time;             /* flush all cache items with
 100                                                         * last_refresh at or earlier
 101                                                         * than this.  last_refresh
 102                                                         * is never set at or earlier
 103                                                         * than this.
 104                                                         */
 105        struct list_head        others;
 106        time64_t                nextcheck;
 107        int                     entries;
 108
 109        /* fields for communication over channel */
 110        struct list_head        queue;
 111
 112        atomic_t                writers;                /* how many time is /channel open */
 113        time64_t                last_close;             /* if no writers, when did last close */
 114        time64_t                last_warn;              /* when we last warned about no writers */
 115
 116        union {
 117                struct proc_dir_entry   *procfs;
 118                struct dentry           *pipefs;
 119        };
 120        struct net              *net;
 121};
 122
 123
 124/* this must be embedded in any request structure that
 125 * identifies an object that will want a callback on
 126 * a cache fill
 127 */
 128struct cache_req {
 129        struct cache_deferred_req *(*defer)(struct cache_req *req);
 130        int thread_wait;  /* How long (jiffies) we can block the
 131                           * current thread to wait for updates.
 132                           */
 133};
 134/* this must be embedded in a deferred_request that is being
 135 * delayed awaiting cache-fill
 136 */
 137struct cache_deferred_req {
 138        struct hlist_node       hash;   /* on hash chain */
 139        struct list_head        recent; /* on fifo */
 140        struct cache_head       *item;  /* cache item we wait on */
 141        void                    *owner; /* we might need to discard all defered requests
 142                                         * owned by someone */
 143        void                    (*revisit)(struct cache_deferred_req *req,
 144                                           int too_many);
 145};
 146
 147/*
 148 * timestamps kept in the cache are expressed in seconds
 149 * since boot.  This is the best for measuring differences in
 150 * real time.
 151 * This reimplemnts ktime_get_boottime_seconds() in a slightly
 152 * faster but less accurate way. When we end up converting
 153 * back to wallclock (CLOCK_REALTIME), that error often
 154 * cancels out during the reverse operation.
 155 */
 156static inline time64_t seconds_since_boot(void)
 157{
 158        struct timespec64 boot;
 159        getboottime64(&boot);
 160        return ktime_get_real_seconds() - boot.tv_sec;
 161}
 162
 163static inline time64_t convert_to_wallclock(time64_t sinceboot)
 164{
 165        struct timespec64 boot;
 166        getboottime64(&boot);
 167        return boot.tv_sec + sinceboot;
 168}
 169
 170extern const struct file_operations cache_file_operations_pipefs;
 171extern const struct file_operations content_file_operations_pipefs;
 172extern const struct file_operations cache_flush_operations_pipefs;
 173
 174extern struct cache_head *
 175sunrpc_cache_lookup_rcu(struct cache_detail *detail,
 176                        struct cache_head *key, int hash);
 177extern struct cache_head *
 178sunrpc_cache_update(struct cache_detail *detail,
 179                    struct cache_head *new, struct cache_head *old, int hash);
 180
 181extern int
 182sunrpc_cache_pipe_upcall(struct cache_detail *detail, struct cache_head *h);
 183extern int
 184sunrpc_cache_pipe_upcall_timeout(struct cache_detail *detail,
 185                                 struct cache_head *h);
 186
 187
 188extern void cache_clean_deferred(void *owner);
 189
 190static inline struct cache_head  *cache_get(struct cache_head *h)
 191{
 192        kref_get(&h->ref);
 193        return h;
 194}
 195
 196static inline struct cache_head  *cache_get_rcu(struct cache_head *h)
 197{
 198        if (kref_get_unless_zero(&h->ref))
 199                return h;
 200        return NULL;
 201}
 202
 203static inline void cache_put(struct cache_head *h, struct cache_detail *cd)
 204{
 205        if (kref_read(&h->ref) <= 2 &&
 206            h->expiry_time < cd->nextcheck)
 207                cd->nextcheck = h->expiry_time;
 208        kref_put(&h->ref, cd->cache_put);
 209}
 210
 211static inline bool cache_is_expired(struct cache_detail *detail, struct cache_head *h)
 212{
 213        if (h->expiry_time < seconds_since_boot())
 214                return true;
 215        if (!test_bit(CACHE_VALID, &h->flags))
 216                return false;
 217        return detail->flush_time >= h->last_refresh;
 218}
 219
 220extern int cache_check(struct cache_detail *detail,
 221                       struct cache_head *h, struct cache_req *rqstp);
 222extern void cache_flush(void);
 223extern void cache_purge(struct cache_detail *detail);
 224#define NEVER (0x7FFFFFFF)
 225extern void __init cache_initialize(void);
 226extern int cache_register_net(struct cache_detail *cd, struct net *net);
 227extern void cache_unregister_net(struct cache_detail *cd, struct net *net);
 228
 229extern struct cache_detail *cache_create_net(const struct cache_detail *tmpl, struct net *net);
 230extern void cache_destroy_net(struct cache_detail *cd, struct net *net);
 231
 232extern void sunrpc_init_cache_detail(struct cache_detail *cd);
 233extern void sunrpc_destroy_cache_detail(struct cache_detail *cd);
 234extern int sunrpc_cache_register_pipefs(struct dentry *parent, const char *,
 235                                        umode_t, struct cache_detail *);
 236extern void sunrpc_cache_unregister_pipefs(struct cache_detail *);
 237extern void sunrpc_cache_unhash(struct cache_detail *, struct cache_head *);
 238
 239/* Must store cache_detail in seq_file->private if using next three functions */
 240extern void *cache_seq_start_rcu(struct seq_file *file, loff_t *pos);
 241extern void *cache_seq_next_rcu(struct seq_file *file, void *p, loff_t *pos);
 242extern void cache_seq_stop_rcu(struct seq_file *file, void *p);
 243
 244extern void qword_add(char **bpp, int *lp, char *str);
 245extern void qword_addhex(char **bpp, int *lp, char *buf, int blen);
 246extern int qword_get(char **bpp, char *dest, int bufsize);
 247
 248static inline int get_int(char **bpp, int *anint)
 249{
 250        char buf[50];
 251        char *ep;
 252        int rv;
 253        int len = qword_get(bpp, buf, sizeof(buf));
 254
 255        if (len < 0)
 256                return -EINVAL;
 257        if (len == 0)
 258                return -ENOENT;
 259
 260        rv = simple_strtol(buf, &ep, 0);
 261        if (*ep)
 262                return -EINVAL;
 263
 264        *anint = rv;
 265        return 0;
 266}
 267
 268static inline int get_uint(char **bpp, unsigned int *anint)
 269{
 270        char buf[50];
 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 (kstrtouint(buf, 0, anint))
 279                return -EINVAL;
 280
 281        return 0;
 282}
 283
 284static inline int get_time(char **bpp, time64_t *time)
 285{
 286        char buf[50];
 287        long long ll;
 288        int len = qword_get(bpp, buf, sizeof(buf));
 289
 290        if (len < 0)
 291                return -EINVAL;
 292        if (len == 0)
 293                return -ENOENT;
 294
 295        if (kstrtoll(buf, 0, &ll))
 296                return -EINVAL;
 297
 298        *time = ll;
 299        return 0;
 300}
 301
 302static inline time64_t get_expiry(char **bpp)
 303{
 304        time64_t rv;
 305        struct timespec64 boot;
 306
 307        if (get_time(bpp, &rv))
 308                return 0;
 309        if (rv < 0)
 310                return 0;
 311        getboottime64(&boot);
 312        return rv - boot.tv_sec;
 313}
 314
 315#endif /*  _LINUX_SUNRPC_CACHE_H_ */
 316