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  */
  47 struct 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
  60 /* cache_head.flags */
  61 enum {
  62         CACHE_VALID,            /* Entry contains valid data */
  63         CACHE_NEGATIVE,         /* Negative entry - there is no match for the key */
  64         CACHE_PENDING,          /* An upcall has been sent but no reply received yet*/
  65         CACHE_CLEANED,          /* Entry has been cleaned from cache */
  66 };
  67
  68 #define CACHE_NEW_EXPIRY 120    /* keep new things pending confirmation for 120 seconds */
  69
  70 struct cache_detail {
  71         struct module *         owner;
  72         int                     hash_size;
  73         struct hlist_head *     hash_table;
  74         spinlock_t              hash_lock;
  75
  76         char                    *name;
  77         void                    (*cache_put)(struct kref *);
  78
  79         int                     (*cache_upcall)(struct cache_detail *,
  80                                                 struct cache_head *);
  81
  82         void                    (*cache_request)(struct cache_detail *cd,
  83                                                  struct cache_head *ch,
  84                                                  char **bpp, int *blen);
  85
  86         int                     (*cache_parse)(struct cache_detail *,
  87                                                char *buf, int len);
  88
  89         int                     (*cache_show)(struct seq_file *m,
  90                                               struct cache_detail *cd,
  91                                               struct cache_head *h);
  92         void                    (*warn_no_listener)(struct cache_detail *cd,
  93                                               int has_died);
  94
  95         struct cache_head *     (*alloc)(void);
  96         void                    (*flush)(void);
  97         int                     (*match)(struct cache_head *orig, struct cache_head *new);
  98         void                    (*init)(struct cache_head *orig, struct cache_head *new);
  99         void                    (*update)(struct cache_head *orig, struct cache_head *new);
 100
 101         /* fields below this comment are for internal use
 102          * and should not be touched by cache owners
 103          */
 104         time64_t                flush_time;             /* flush all cache items with
 105                                                          * last_refresh at or earlier
 106                                                          * than this.  last_refresh
 107                                                          * is never set at or earlier
 108                                                          * than this.
 109                                                          */
 110         struct list_head        others;
 111         time64_t                nextcheck;
 112         int                     entries;
 113
 114         /* fields for communication over channel */
 115         struct list_head        queue;
 116
 117         atomic_t                writers;                /* how many time is /channel open */
 118         time64_t                last_close;             /* if no writers, when did last close */
 119         time64_t                last_warn;              /* when we last warned about no writers */
 120
 121         union {
 122                 struct proc_dir_entry   *procfs;
 123                 struct dentry           *pipefs;
 124         };
 125         struct net              *net;
 126 };
 127
 128 /* this must be embedded in any request structure that
 129  * identifies an object that will want a callback on
 130  * a cache fill
 131  */
 132 struct cache_req {
 133         struct cache_deferred_req *(*defer)(struct cache_req *req);
 134         unsigned long   thread_wait;    /* How long (jiffies) we can block the
 135                                          * current thread to wait for updates.
 136                                          */
 137 };
 138
 139 /* this must be embedded in a deferred_request that is being
 140  * delayed awaiting cache-fill
 141  */
 142 struct cache_deferred_req {
 143         struct hlist_node       hash;   /* on hash chain */
 144         struct list_head        recent; /* on fifo */
 145         struct cache_head       *item;  /* cache item we wait on */
 146         void                    *owner; /* we might need to discard all defered requests
 147                                          * owned by someone */
 148         void                    (*revisit)(struct cache_deferred_req *req,
 149                                            int too_many);
 150 };
 151
 152 /*
 153  * timestamps kept in the cache are expressed in seconds
 154  * since boot.  This is the best for measuring differences in
 155  * real time.
 156  * This reimplemnts ktime_get_boottime_seconds() in a slightly
 157  * faster but less accurate way. When we end up converting
 158  * back to wallclock (CLOCK_REALTIME), that error often
 159  * cancels out during the reverse operation.
 160  */
 161 static inline time64_t seconds_since_boot(void)
 162 {
 163         struct timespec64 boot;
 164         getboottime64(&boot);
 165         return ktime_get_real_seconds() - boot.tv_sec;
 166 }
 167
 168 static inline time64_t convert_to_wallclock(time64_t sinceboot)
 169 {
 170         struct timespec64 boot;
 171         getboottime64(&boot);
 172         return boot.tv_sec + sinceboot;
 173 }
 174
 175 extern const struct file_operations cache_file_operations_pipefs;
 176 extern const struct file_operations content_file_operations_pipefs;
 177 extern const struct file_operations cache_flush_operations_pipefs;
 178
 179 extern struct cache_head *
 180 sunrpc_cache_lookup_rcu(struct cache_detail *detail,
 181                         struct cache_head *key, int hash);
 182 extern struct cache_head *
 183 sunrpc_cache_update(struct cache_detail *detail,
 184                     struct cache_head *new, struct cache_head *old, int hash);
 185
 186 extern int
 187 sunrpc_cache_pipe_upcall(struct cache_detail *detail, struct cache_head *h);
 188 extern int
 189 sunrpc_cache_pipe_upcall_timeout(struct cache_detail *detail,
 190                                  struct cache_head *h);
 191
 192
 193 extern void cache_clean_deferred(void *owner);
 194
 195 static inline struct cache_head  *cache_get(struct cache_head *h)
 196 {
 197         kref_get(&h->ref);
 198         return h;
 199 }
 200
 201 static inline struct cache_head  *cache_get_rcu(struct cache_head *h)
 202 {
 203         if (kref_get_unless_zero(&h->ref))
 204                 return h;
 205         return NULL;
 206 }
 207
 208 static inline void cache_put(struct cache_head *h, struct cache_detail *cd)
 209 {
 210         if (kref_read(&h->ref) <= 2 &&
 211             h->expiry_time < cd->nextcheck)
 212                 cd->nextcheck = h->expiry_time;
 213         kref_put(&h->ref, cd->cache_put);
 214 }
 215
 216 static inline bool cache_is_expired(struct cache_detail *detail, struct cache_head *h)
 217 {
 218         if (h->expiry_time < seconds_since_boot())
 219                 return true;
 220         if (!test_bit(CACHE_VALID, &h->flags))
 221                 return false;
 222         return detail->flush_time >= h->last_refresh;
 223 }
 224
 225 extern int cache_check(struct cache_detail *detail,
 226                        struct cache_head *h, struct cache_req *rqstp);
 227 extern void cache_flush(void);
 228 extern void cache_purge(struct cache_detail *detail);
 229 #define NEVER (0x7FFFFFFF)
 230 extern void __init cache_initialize(void);
 231 extern int cache_register_net(struct cache_detail *cd, struct net *net);
 232 extern void cache_unregister_net(struct cache_detail *cd, struct net *net);
 233
 234 extern struct cache_detail *cache_create_net(const struct cache_detail *tmpl, struct net *net);
 235 extern void cache_destroy_net(struct cache_detail *cd, struct net *net);
 236
 237 extern void sunrpc_init_cache_detail(struct cache_detail *cd);
 238 extern void sunrpc_destroy_cache_detail(struct cache_detail *cd);
 239 extern int sunrpc_cache_register_pipefs(struct dentry *parent, const char *,
 240                                         umode_t, struct cache_detail *);
 241 extern void sunrpc_cache_unregister_pipefs(struct cache_detail *);
 242 extern void sunrpc_cache_unhash(struct cache_detail *, struct cache_head *);
 243
 244 /* Must store cache_detail in seq_file->private if using next three functions */
 245 extern void *cache_seq_start_rcu(struct seq_file *file, loff_t *pos);
 246 extern void *cache_seq_next_rcu(struct seq_file *file, void *p, loff_t *pos);
 247 extern void cache_seq_stop_rcu(struct seq_file *file, void *p);
 248
 249 extern void qword_add(char **bpp, int *lp, char *str);
 250 extern void qword_addhex(char **bpp, int *lp, char *buf, int blen);
 251 extern int qword_get(char **bpp, char *dest, int bufsize);
 252
 253 static inline int get_int(char **bpp, int *anint)
 254 {
 255         char buf[50];
 256         char *ep;
 257         int rv;
 258         int len = qword_get(bpp, buf, sizeof(buf));
 259
 260         if (len < 0)
 261                 return -EINVAL;
 262         if (len == 0)
 263                 return -ENOENT;
 264
 265         rv = simple_strtol(buf, &ep, 0);
 266         if (*ep)
 267                 return -EINVAL;
 268
 269         *anint = rv;
 270         return 0;
 271 }
 272
 273 static inline int get_uint(char **bpp, unsigned int *anint)
 274 {
 275         char buf[50];
 276         int len = qword_get(bpp, buf, sizeof(buf));
 277
 278         if (len < 0)
 279                 return -EINVAL;
 280         if (len == 0)
 281                 return -ENOENT;
 282
 283         if (kstrtouint(buf, 0, anint))
 284                 return -EINVAL;
 285
 286         return 0;
 287 }
 288
 289 static inline int get_time(char **bpp, time64_t *time)
 290 {
 291         char buf[50];
 292         long long ll;
 293         int len = qword_get(bpp, buf, sizeof(buf));
 294
 295         if (len < 0)
 296                 return -EINVAL;
 297         if (len == 0)
 298                 return -ENOENT;
 299
 300         if (kstrtoll(buf, 0, &ll))
 301                 return -EINVAL;
 302
 303         *time = ll;
 304         return 0;
 305 }
 306
 307 static inline int get_expiry(char **bpp, time64_t *rvp)
 308 {
 309         int error;
 310         struct timespec64 boot;
 311
 312         error = get_time(bpp, rvp);
 313         if (error)
 314                 return error;
 315
 316         getboottime64(&boot);
 317         (*rvp) -= boot.tv_sec;
 318         return 0;
 319 }
 320
 321 #endif /*  _LINUX_SUNRPC_CACHE_H_ */