include/linux/sunrpc/cache.h

   1 /*
   2  * include/linux/sunrpc/cache.h
   3  *
   4  * Generic code for various authentication-related caches
   5  * used by sunrpc clients and servers.
   6  *
   7  * Copyright (C) 2002 Neil Brown <neilb@cse.unsw.edu.au>
   8  *
   9  * Released under terms in GPL version 2.  See COPYING.
  10  *
  11  */
  12
  13 #ifndef _LINUX_SUNRPC_CACHE_H_
  14 #define _LINUX_SUNRPC_CACHE_H_
  15
  16 #include <linux/kref.h>
  17 #include <linux/slab.h>
  18 #include <linux/atomic.h>
  19 #include <linux/proc_fs.h>
  20
  21 /*
  22  * Each cache requires:
  23  *  - A 'struct cache_detail' which contains information specific to the cache
  24  *    for common code to use.
  25  *  - An item structure that must contain a "struct cache_head"
  26  *  - A lookup function defined using DefineCacheLookup
  27  *  - A 'put' function that can release a cache item. It will only
  28  *    be called after cache_put has succeed, so there are guarantee
  29  *    to be no references.
  30  *  - A function to calculate a hash of an item's key.
  31  *
  32  * as well as assorted code fragments (e.g. compare keys) and numbers
  33  * (e.g. hash size, goal_age, etc).
  34  *
  35  * Each cache must be registered so that it can be cleaned regularly.
  36  * When the cache is unregistered, it is flushed completely.
  37  *
  38  * Entries have a ref count and a 'hashed' flag which counts the existence
  39  * in the hash table.
  40  * We only expire entries when refcount is zero.
  41  * Existence in the cache is counted  the refcount.
  42  */
  43
  44 /* Every cache item has a common header that is used
  45  * for expiring and refreshing entries.
  46  *
  47  */
  48 struct cache_head {
  49         struct hlist_node       cache_list;
  50         time_t          expiry_time;    /* After time time, don't use the data */
  51         time_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
  66 struct cache_detail {
  67         struct module *         owner;
  68         int                     hash_size;
  69         struct hlist_head *     hash_table;
  70         rwlock_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         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         time_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         time_t                  nextcheck;
 107         int                     entries;
 108
 109         /* fields for communication over channel */
 110         struct list_head        queue;
 111
 112         atomic_t                readers;                /* how many time is /chennel open */
 113         time_t                  last_close;             /* if no readers, when did last close */
 114         time_t                  last_warn;              /* when we last warned about no readers */
 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  */
 128 struct 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  */
 137 struct 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  */
 152 static inline time_t seconds_since_boot(void)
 153 {
 154         struct timespec boot;
 155         getboottime(&boot);
 156         return get_seconds() - boot.tv_sec;
 157 }
 158
 159 static inline time_t convert_to_wallclock(time_t sinceboot)
 160 {
 161         struct timespec boot;
 162         getboottime(&boot);
 163         return boot.tv_sec + sinceboot;
 164 }
 165
 166 extern const struct file_operations cache_file_operations_pipefs;
 167 extern const struct file_operations content_file_operations_pipefs;
 168 extern const struct file_operations cache_flush_operations_pipefs;
 169
 170 extern struct cache_head *
 171 sunrpc_cache_lookup(struct cache_detail *detail,
 172                     struct cache_head *key, int hash);
 173 extern struct cache_head *
 174 sunrpc_cache_update(struct cache_detail *detail,
 175                     struct cache_head *new, struct cache_head *old, int hash);
 176
 177 extern int
 178 sunrpc_cache_pipe_upcall(struct cache_detail *detail, struct cache_head *h);
 179
 180
 181 extern void cache_clean_deferred(void *owner);
 182
 183 static inline struct cache_head  *cache_get(struct cache_head *h)
 184 {
 185         kref_get(&h->ref);
 186         return h;
 187 }
 188
 189
 190 static inline void cache_put(struct cache_head *h, struct cache_detail *cd)
 191 {
 192         if (kref_read(&h->ref) <= 2 &&
 193             h->expiry_time < cd->nextcheck)
 194                 cd->nextcheck = h->expiry_time;
 195         kref_put(&h->ref, cd->cache_put);
 196 }
 197
 198 static inline bool cache_is_expired(struct cache_detail *detail, struct cache_head *h)
 199 {
 200         if (!test_bit(CACHE_VALID, &h->flags))
 201                 return false;
 202
 203         return  (h->expiry_time < seconds_since_boot()) ||
 204                 (detail->flush_time >= h->last_refresh);
 205 }
 206
 207 extern int cache_check(struct cache_detail *detail,
 208                        struct cache_head *h, struct cache_req *rqstp);
 209 extern void cache_flush(void);
 210 extern void cache_purge(struct cache_detail *detail);
 211 #define NEVER (0x7FFFFFFF)
 212 extern void __init cache_initialize(void);
 213 extern int cache_register_net(struct cache_detail *cd, struct net *net);
 214 extern void cache_unregister_net(struct cache_detail *cd, struct net *net);
 215
 216 extern struct cache_detail *cache_create_net(struct cache_detail *tmpl, struct net *net);
 217 extern void cache_destroy_net(struct cache_detail *cd, struct net *net);
 218
 219 extern void sunrpc_init_cache_detail(struct cache_detail *cd);
 220 extern void sunrpc_destroy_cache_detail(struct cache_detail *cd);
 221 extern int sunrpc_cache_register_pipefs(struct dentry *parent, const char *,
 222                                         umode_t, struct cache_detail *);
 223 extern void sunrpc_cache_unregister_pipefs(struct cache_detail *);
 224 extern void sunrpc_cache_unhash(struct cache_detail *, struct cache_head *);
 225
 226 /* Must store cache_detail in seq_file->private if using next three functions */
 227 extern void *cache_seq_start(struct seq_file *file, loff_t *pos);
 228 extern void *cache_seq_next(struct seq_file *file, void *p, loff_t *pos);
 229 extern void cache_seq_stop(struct seq_file *file, void *p);
 230
 231 extern void qword_add(char **bpp, int *lp, char *str);
 232 extern void qword_addhex(char **bpp, int *lp, char *buf, int blen);
 233 extern int qword_get(char **bpp, char *dest, int bufsize);
 234
 235 static inline int get_int(char **bpp, int *anint)
 236 {
 237         char buf[50];
 238         char *ep;
 239         int rv;
 240         int len = qword_get(bpp, buf, sizeof(buf));
 241
 242         if (len < 0)
 243                 return -EINVAL;
 244         if (len == 0)
 245                 return -ENOENT;
 246
 247         rv = simple_strtol(buf, &ep, 0);
 248         if (*ep)
 249                 return -EINVAL;
 250
 251         *anint = rv;
 252         return 0;
 253 }
 254
 255 static inline int get_uint(char **bpp, unsigned int *anint)
 256 {
 257         char buf[50];
 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         if (kstrtouint(buf, 0, anint))
 266                 return -EINVAL;
 267
 268         return 0;
 269 }
 270
 271 static inline int get_time(char **bpp, time_t *time)
 272 {
 273         char buf[50];
 274         long long ll;
 275         int len = qword_get(bpp, buf, sizeof(buf));
 276
 277         if (len < 0)
 278                 return -EINVAL;
 279         if (len == 0)
 280                 return -ENOENT;
 281
 282         if (kstrtoll(buf, 0, &ll))
 283                 return -EINVAL;
 284
 285         *time = (time_t)ll;
 286         return 0;
 287 }
 288
 289 static inline time_t get_expiry(char **bpp)
 290 {
 291         time_t rv;
 292         struct timespec boot;
 293
 294         if (get_time(bpp, &rv))
 295                 return 0;
 296         if (rv < 0)
 297                 return 0;
 298         getboottime(&boot);
 299         return rv - boot.tv_sec;
 300 }
 301
 302 #endif /*  _LINUX_SUNRPC_CACHE_H_ */