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_procfs {
  67         struct proc_dir_entry   *proc_ent;
  68         struct proc_dir_entry   *flush_ent, *channel_ent, *content_ent;
  69 };
  70
  71 struct cache_detail_pipefs {
  72         struct dentry *dir;
  73 };
  74
  75 struct cache_detail {
  76         struct module *         owner;
  77         int                     hash_size;
  78         struct hlist_head *     hash_table;
  79         rwlock_t                hash_lock;
  80
  81         char                    *name;
  82         void                    (*cache_put)(struct kref *);
  83
  84         int                     (*cache_upcall)(struct cache_detail *,
  85                                                 struct cache_head *);
  86
  87         void                    (*cache_request)(struct cache_detail *cd,
  88                                                  struct cache_head *ch,
  89                                                  char **bpp, int *blen);
  90
  91         int                     (*cache_parse)(struct cache_detail *,
  92                                                char *buf, int len);
  93
  94         int                     (*cache_show)(struct seq_file *m,
  95                                               struct cache_detail *cd,
  96                                               struct cache_head *h);
  97         void                    (*warn_no_listener)(struct cache_detail *cd,
  98                                               int has_died);
  99
 100         struct cache_head *     (*alloc)(void);
 101         int                     (*match)(struct cache_head *orig, struct cache_head *new);
 102         void                    (*init)(struct cache_head *orig, struct cache_head *new);
 103         void                    (*update)(struct cache_head *orig, struct cache_head *new);
 104
 105         /* fields below this comment are for internal use
 106          * and should not be touched by cache owners
 107          */
 108         time_t                  flush_time;             /* flush all cache items with
 109                                                          * last_refresh at or earlier
 110                                                          * than this.  last_refresh
 111                                                          * is never set at or earlier
 112                                                          * than this.
 113                                                          */
 114         struct list_head        others;
 115         time_t                  nextcheck;
 116         int                     entries;
 117
 118         /* fields for communication over channel */
 119         struct list_head        queue;
 120
 121         atomic_t                readers;                /* how many time is /chennel open */
 122         time_t                  last_close;             /* if no readers, when did last close */
 123         time_t                  last_warn;              /* when we last warned about no readers */
 124
 125         union {
 126                 struct cache_detail_procfs procfs;
 127                 struct cache_detail_pipefs pipefs;
 128         } u;
 129         struct net              *net;
 130 };
 131
 132
 133 /* this must be embedded in any request structure that
 134  * identifies an object that will want a callback on
 135  * a cache fill
 136  */
 137 struct cache_req {
 138         struct cache_deferred_req *(*defer)(struct cache_req *req);
 139         int thread_wait;  /* How long (jiffies) we can block the
 140                            * current thread to wait for updates.
 141                            */
 142 };
 143 /* this must be embedded in a deferred_request that is being
 144  * delayed awaiting cache-fill
 145  */
 146 struct cache_deferred_req {
 147         struct hlist_node       hash;   /* on hash chain */
 148         struct list_head        recent; /* on fifo */
 149         struct cache_head       *item;  /* cache item we wait on */
 150         void                    *owner; /* we might need to discard all defered requests
 151                                          * owned by someone */
 152         void                    (*revisit)(struct cache_deferred_req *req,
 153                                            int too_many);
 154 };
 155
 156 /*
 157  * timestamps kept in the cache are expressed in seconds
 158  * since boot.  This is the best for measuring differences in
 159  * real time.
 160  */
 161 static inline time_t seconds_since_boot(void)
 162 {
 163         struct timespec boot;
 164         getboottime(&boot);
 165         return get_seconds() - boot.tv_sec;
 166 }
 167
 168 static inline time_t convert_to_wallclock(time_t sinceboot)
 169 {
 170         struct timespec boot;
 171         getboottime(&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(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
 189
 190 extern void cache_clean_deferred(void *owner);
 191
 192 static inline struct cache_head  *cache_get(struct cache_head *h)
 193 {
 194         kref_get(&h->ref);
 195         return h;
 196 }
 197
 198
 199 static inline void cache_put(struct cache_head *h, struct cache_detail *cd)
 200 {
 201         if (atomic_read(&h->ref.refcount) <= 2 &&
 202             h->expiry_time < cd->nextcheck)
 203                 cd->nextcheck = h->expiry_time;
 204         kref_put(&h->ref, cd->cache_put);
 205 }
 206
 207 static inline int cache_is_expired(struct cache_detail *detail, struct cache_head *h)
 208 {
 209         return  (h->expiry_time < seconds_since_boot()) ||
 210                 (detail->flush_time >= h->last_refresh);
 211 }
 212
 213 extern int cache_check(struct cache_detail *detail,
 214                        struct cache_head *h, struct cache_req *rqstp);
 215 extern void cache_flush(void);
 216 extern void cache_purge(struct cache_detail *detail);
 217 #define NEVER (0x7FFFFFFF)
 218 extern void __init cache_initialize(void);
 219 extern int cache_register_net(struct cache_detail *cd, struct net *net);
 220 extern void cache_unregister_net(struct cache_detail *cd, struct net *net);
 221
 222 extern struct cache_detail *cache_create_net(struct cache_detail *tmpl, struct net *net);
 223 extern void cache_destroy_net(struct cache_detail *cd, struct net *net);
 224
 225 extern void sunrpc_init_cache_detail(struct cache_detail *cd);
 226 extern void sunrpc_destroy_cache_detail(struct cache_detail *cd);
 227 extern int sunrpc_cache_register_pipefs(struct dentry *parent, const char *,
 228                                         umode_t, struct cache_detail *);
 229 extern void sunrpc_cache_unregister_pipefs(struct cache_detail *);
 230
 231 /* Must store cache_detail in seq_file->private if using next three functions */
 232 extern void *cache_seq_start(struct seq_file *file, loff_t *pos);
 233 extern void *cache_seq_next(struct seq_file *file, void *p, loff_t *pos);
 234 extern void cache_seq_stop(struct seq_file *file, void *p);
 235
 236 extern void qword_add(char **bpp, int *lp, char *str);
 237 extern void qword_addhex(char **bpp, int *lp, char *buf, int blen);
 238 extern int qword_get(char **bpp, char *dest, int bufsize);
 239
 240 static inline int get_int(char **bpp, int *anint)
 241 {
 242         char buf[50];
 243         char *ep;
 244         int rv;
 245         int len = qword_get(bpp, buf, sizeof(buf));
 246
 247         if (len < 0)
 248                 return -EINVAL;
 249         if (len == 0)
 250                 return -ENOENT;
 251
 252         rv = simple_strtol(buf, &ep, 0);
 253         if (*ep)
 254                 return -EINVAL;
 255
 256         *anint = rv;
 257         return 0;
 258 }
 259
 260 static inline int get_uint(char **bpp, unsigned int *anint)
 261 {
 262         char buf[50];
 263         int len = qword_get(bpp, buf, sizeof(buf));
 264
 265         if (len < 0)
 266                 return -EINVAL;
 267         if (len == 0)
 268                 return -ENOENT;
 269
 270         if (kstrtouint(buf, 0, anint))
 271                 return -EINVAL;
 272
 273         return 0;
 274 }
 275
 276 static inline int get_time(char **bpp, time_t *time)
 277 {
 278         char buf[50];
 279         long long ll;
 280         int len = qword_get(bpp, buf, sizeof(buf));
 281
 282         if (len < 0)
 283                 return -EINVAL;
 284         if (len == 0)
 285                 return -ENOENT;
 286
 287         if (kstrtoll(buf, 0, &ll))
 288                 return -EINVAL;
 289
 290         *time = (time_t)ll;
 291         return 0;
 292 }
 293
 294 static inline time_t get_expiry(char **bpp)
 295 {
 296         time_t rv;
 297         struct timespec boot;
 298
 299         if (get_time(bpp, &rv))
 300                 return 0;
 301         if (rv < 0)
 302                 return 0;
 303         getboottime(&boot);
 304         return rv - boot.tv_sec;
 305 }
 306
 307 #endif /*  _LINUX_SUNRPC_CACHE_H_ */