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/kstrtox.h>
  18#include <linux/proc_fs.h>
  19
  20/*
  21 * Each cache requires:
  22 *  - A 'struct cache_detail' which contains information specific to the cache
  23 *    for common code to use.
  24 *  - An item structure that must contain a "struct cache_head"
  25 *  - A lookup function defined using DefineCacheLookup
  26 *  - A 'put' function that can release a cache item. It will only
  27 *    be called after cache_put has succeed, so there are guarantee
  28 *    to be no references.
  29 *  - A function to calculate a hash of an item's key.
  30 *
  31 * as well as assorted code fragments (e.g. compare keys) and numbers
  32 * (e.g. hash size, goal_age, etc).
  33 *
  34 * Each cache must be registered so that it can be cleaned regularly.
  35 * When the cache is unregistered, it is flushed completely.
  36 *
  37 * Entries have a ref count and a 'hashed' flag which counts the existence
  38 * in the hash table.
  39 * We only expire entries when refcount is zero.
  40 * Existence in the cache is counted  the refcount.
  41 */
  42
  43/* Every cache item has a common header that is used
  44 * for expiring and refreshing entries.
  45 * 
  46 */
  47struct cache_head {
  48        struct hlist_node       cache_list;
  49        time64_t        expiry_time;    /* After time expiry_time, don't use
  50                                         * the data */
  51        time64_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 {
  67        struct module *         owner;
  68        int                     hash_size;
  69        struct hlist_head *     hash_table;
  70        spinlock_t              hash_lock;
  71
  72        char                    *name;
  73        void                    (*cache_put)(struct kref *);
  74
  75        int                     (*cache_upcall)(struct cache_detail *,
  76                                                struct cache_head *);
  77
  78        void                    (*cache_request)(struct cache_detail *cd,
  79                                                 struct cache_head *ch,
  80                                                 char **bpp, int *blen);
  81
  82        int                     (*cache_parse)(struct cache_detail *,
  83                                               char *buf, int len);
  84
  85        int                     (*cache_show)(struct seq_file *m,
  86                                              struct cache_detail *cd,
  87                                              struct cache_head *h);
  88        void                    (*warn_no_listener)(struct cache_detail *cd,
  89                                              int has_died);
  90
  91        struct cache_head *     (*alloc)(void);
  92        void                    (*flush)(void);
  93        int                     (*match)(struct cache_head *orig, struct cache_head *new);
  94        void                    (*init)(struct cache_head *orig, struct cache_head *new);
  95        void                    (*update)(struct cache_head *orig, struct cache_head *new);
  96
  97        /* fields below this comment are for internal use
  98         * and should not be touched by cache owners
  99         */
 100        time64_t                flush_time;             /* flush all cache items with
 101                                                         * last_refresh at or earlier
 102                                                         * than this.  last_refresh
 103                                                         * is never set at or earlier
 104                                                         * than this.
 105                                                         */
 106        struct list_head        others;
 107        time64_t                nextcheck;
 108        int                     entries;
 109
 110        /* fields for communication over channel */
 111        struct list_head        queue;
 112
 113        atomic_t                writers;                /* how many time is /channel open */
 114        time64_t                last_close;             /* if no writers, when did last close */
 115        time64_t                last_warn;              /* when we last warned about no writers */
 116
 117        union {
 118                struct proc_dir_entry   *procfs;
 119                struct dentry           *pipefs;
 120        };
 121        struct net              *net;
 122};
 123
 124
 125/* this must be embedded in any request structure that
 126 * identifies an object that will want a callback on
 127 * a cache fill
 128 */
 129struct cache_req {
 130        struct cache_deferred_req *(*defer)(struct cache_req *req);
 131        int thread_wait;  /* How long (jiffies) we can block the
 132                           * current thread to wait for updates.
 133                           */
 134};
 135/* this must be embedded in a deferred_request that is being
 136 * delayed awaiting cache-fill
 137 */
 138struct cache_deferred_req {
 139        struct hlist_node       hash;   /* on hash chain */
 140        struct list_head        recent; /* on fifo */
 141        struct cache_head       *item;  /* cache item we wait on */
 142        void                    *owner; /* we might need to discard all defered requests
 143                                         * owned by someone */
 144        void                    (*revisit)(struct cache_deferred_req *req,
 145                                           int too_many);
 146};
 147
 148/*
 149 * timestamps kept in the cache are expressed in seconds
 150 * since boot.  This is the best for measuring differences in
 151 * real time.
 152 * This reimplemnts ktime_get_boottime_seconds() in a slightly
 153 * faster but less accurate way. When we end up converting
 154 * back to wallclock (CLOCK_REALTIME), that error often
 155 * cancels out during the reverse operation.
 156 */
 157static inline time64_t seconds_since_boot(void)
 158{
 159        struct timespec64 boot;
 160        getboottime64(&boot);
 161        return ktime_get_real_seconds() - boot.tv_sec;
 162}
 163
 164static inline time64_t convert_to_wallclock(time64_t sinceboot)
 165{
 166        struct timespec64 boot;
 167        getboottime64(&boot);
 168        return boot.tv_sec + sinceboot;
 169}
 170
 171extern const struct file_operations cache_file_operations_pipefs;
 172extern const struct file_operations content_file_operations_pipefs;
 173extern const struct file_operations cache_flush_operations_pipefs;
 174
 175extern struct cache_head *
 176sunrpc_cache_lookup_rcu(struct cache_detail *detail,
 177                        struct cache_head *key, int hash);
 178extern struct cache_head *
 179sunrpc_cache_update(struct cache_detail *detail,
 180                    struct cache_head *new, struct cache_head *old, int hash);
 181
 182extern int
 183sunrpc_cache_pipe_upcall(struct cache_detail *detail, struct cache_head *h);
 184extern int
 185sunrpc_cache_pipe_upcall_timeout(struct cache_detail *detail,
 186                                 struct cache_head *h);
 187
 188
 189extern void cache_clean_deferred(void *owner);
 190
 191static inline struct cache_head  *cache_get(struct cache_head *h)
 192{
 193        kref_get(&h->ref);
 194        return h;
 195}
 196
 197static inline struct cache_head  *cache_get_rcu(struct cache_head *h)
 198{
 199        if (kref_get_unless_zero(&h->ref))
 200                return h;
 201        return NULL;
 202}
 203
 204static inline void cache_put(struct cache_head *h, struct cache_detail *cd)
 205{
 206        if (kref_read(&h->ref) <= 2 &&
 207            h->expiry_time < cd->nextcheck)
 208                cd->nextcheck = h->expiry_time;
 209        kref_put(&h->ref, cd->cache_put);
 210}
 211
 212static inline bool cache_is_expired(struct cache_detail *detail, struct cache_head *h)
 213{
 214        if (h->expiry_time < seconds_since_boot())
 215                return true;
 216        if (!test_bit(CACHE_VALID, &h->flags))
 217                return false;
 218        return detail->flush_time >= h->last_refresh;
 219}
 220
 221extern int cache_check(struct cache_detail *detail,
 222                       struct cache_head *h, struct cache_req *rqstp);
 223extern void cache_flush(void);
 224extern void cache_purge(struct cache_detail *detail);
 225#define NEVER (0x7FFFFFFF)
 226extern void __init cache_initialize(void);
 227extern int cache_register_net(struct cache_detail *cd, struct net *net);
 228extern void cache_unregister_net(struct cache_detail *cd, struct net *net);
 229
 230extern struct cache_detail *cache_create_net(const struct cache_detail *tmpl, struct net *net);
 231extern void cache_destroy_net(struct cache_detail *cd, struct net *net);
 232
 233extern void sunrpc_init_cache_detail(struct cache_detail *cd);
 234extern void sunrpc_destroy_cache_detail(struct cache_detail *cd);
 235extern int sunrpc_cache_register_pipefs(struct dentry *parent, const char *,
 236                                        umode_t, struct cache_detail *);
 237extern void sunrpc_cache_unregister_pipefs(struct cache_detail *);
 238extern void sunrpc_cache_unhash(struct cache_detail *, struct cache_head *);
 239
 240/* Must store cache_detail in seq_file->private if using next three functions */
 241extern void *cache_seq_start_rcu(struct seq_file *file, loff_t *pos);
 242extern void *cache_seq_next_rcu(struct seq_file *file, void *p, loff_t *pos);
 243extern void cache_seq_stop_rcu(struct seq_file *file, void *p);
 244
 245extern void qword_add(char **bpp, int *lp, char *str);
 246extern void qword_addhex(char **bpp, int *lp, char *buf, int blen);
 247extern int qword_get(char **bpp, char *dest, int bufsize);
 248
 249static inline int get_int(char **bpp, int *anint)
 250{
 251        char buf[50];
 252        char *ep;
 253        int rv;
 254        int len = qword_get(bpp, buf, sizeof(buf));
 255
 256        if (len < 0)
 257                return -EINVAL;
 258        if (len == 0)
 259                return -ENOENT;
 260
 261        rv = simple_strtol(buf, &ep, 0);
 262        if (*ep)
 263                return -EINVAL;
 264
 265        *anint = rv;
 266        return 0;
 267}
 268
 269static inline int get_uint(char **bpp, unsigned int *anint)
 270{
 271        char buf[50];
 272        int len = qword_get(bpp, buf, sizeof(buf));
 273
 274        if (len < 0)
 275                return -EINVAL;
 276        if (len == 0)
 277                return -ENOENT;
 278
 279        if (kstrtouint(buf, 0, anint))
 280                return -EINVAL;
 281
 282        return 0;
 283}
 284
 285static inline int get_time(char **bpp, time64_t *time)
 286{
 287        char buf[50];
 288        long long ll;
 289        int len = qword_get(bpp, buf, sizeof(buf));
 290
 291        if (len < 0)
 292                return -EINVAL;
 293        if (len == 0)
 294                return -ENOENT;
 295
 296        if (kstrtoll(buf, 0, &ll))
 297                return -EINVAL;
 298
 299        *time = ll;
 300        return 0;
 301}
 302
 303static inline time64_t get_expiry(char **bpp)
 304{
 305        time64_t rv;
 306        struct timespec64 boot;
 307
 308        if (get_time(bpp, &rv))
 309                return 0;
 310        if (rv < 0)
 311                return 0;
 312        getboottime64(&boot);
 313        return rv - boot.tv_sec;
 314}
 315
 316#endif /*  _LINUX_SUNRPC_CACHE_H_ */
 317