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 cache_head * next;
  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
  52                                          * was sent, else this is when update was received
  53                                          */
  54         struct kref     ref;
  55         unsigned long   flags;
  56 };
  57 #define CACHE_VALID     0       /* Entry contains valid data */
  58 #define CACHE_NEGATIVE  1       /* Negative entry - there is no match for the key */
  59 #define CACHE_PENDING   2       /* An upcall has been sent but no reply received yet*/
  60 #define CACHE_CLEANED   3       /* Entry has been cleaned from cache */
  61
  62 #define CACHE_NEW_EXPIRY 120    /* keep new things pending confirmation for 120 seconds */
  63
  64 struct cache_detail_procfs {
  65         struct proc_dir_entry   *proc_ent;
  66         struct proc_dir_entry   *flush_ent, *channel_ent, *content_ent;
  67 };
  68
  69 struct cache_detail_pipefs {
  70         struct dentry *dir;
  71 };
  72
  73 struct cache_detail {
  74         struct module *         owner;
  75         int                     hash_size;
  76         struct cache_head **    hash_table;
  77         rwlock_t                hash_lock;
  78
  79         atomic_t                inuse; /* active user-space update or lookup */
  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 last_refresh
 109                                                          * earlier than this */
 110         struct list_head        others;
 111         time_t                  nextcheck;
 112         int                     entries;
 113
 114         /* fields for communication over channel */
 115         struct list_head        queue;
 116
 117         atomic_t                readers;                /* how many time is /chennel open */
 118         time_t                  last_close;             /* if no readers, when did last close */
 119         time_t                  last_warn;              /* when we last warned about no readers */
 120
 121         union {
 122                 struct cache_detail_procfs procfs;
 123                 struct cache_detail_pipefs pipefs;
 124         } u;
 125         struct net              *net;
 126 };
 127
 128
 129 /* this must be embedded in any request structure that
 130  * identifies an object that will want a callback on
 131  * a cache fill
 132  */
 133 struct cache_req {
 134         struct cache_deferred_req *(*defer)(struct cache_req *req);
 135         int thread_wait;  /* How long (jiffies) we can block the
 136                            * current thread to wait for updates.
 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  */
 157 static inline time_t seconds_since_boot(void)
 158 {
 159         struct timespec boot;
 160         getboottime(&boot);
 161         return get_seconds() - boot.tv_sec;
 162 }
 163
 164 static inline time_t convert_to_wallclock(time_t sinceboot)
 165 {
 166         struct timespec boot;
 167         getboottime(&boot);
 168         return boot.tv_sec + sinceboot;
 169 }
 170
 171 extern const struct file_operations cache_file_operations_pipefs;
 172 extern const struct file_operations content_file_operations_pipefs;
 173 extern const struct file_operations cache_flush_operations_pipefs;
 174
 175 extern struct cache_head *
 176 sunrpc_cache_lookup(struct cache_detail *detail,
 177                     struct cache_head *key, int hash);
 178 extern struct cache_head *
 179 sunrpc_cache_update(struct cache_detail *detail,
 180                     struct cache_head *new, struct cache_head *old, int hash);
 181
 182 extern int
 183 sunrpc_cache_pipe_upcall(struct cache_detail *detail, struct cache_head *h);
 184
 185
 186 extern void cache_clean_deferred(void *owner);
 187
 188 static inline struct cache_head  *cache_get(struct cache_head *h)
 189 {
 190         kref_get(&h->ref);
 191         return h;
 192 }
 193
 194
 195 static inline void cache_put(struct cache_head *h, struct cache_detail *cd)
 196 {
 197         if (atomic_read(&h->ref.refcount) <= 2 &&
 198             h->expiry_time < cd->nextcheck)
 199                 cd->nextcheck = h->expiry_time;
 200         kref_put(&h->ref, cd->cache_put);
 201 }
 202
 203 static inline int cache_is_expired(struct cache_detail *detail, struct cache_head *h)
 204 {
 205         return  (h->expiry_time < seconds_since_boot()) ||
 206                 (detail->flush_time > h->last_refresh);
 207 }
 208
 209 extern int cache_check(struct cache_detail *detail,
 210                        struct cache_head *h, struct cache_req *rqstp);
 211 extern void cache_flush(void);
 212 extern void cache_purge(struct cache_detail *detail);
 213 #define NEVER (0x7FFFFFFF)
 214 extern void __init cache_initialize(void);
 215 extern int cache_register_net(struct cache_detail *cd, struct net *net);
 216 extern void cache_unregister_net(struct cache_detail *cd, struct net *net);
 217
 218 extern struct cache_detail *cache_create_net(struct cache_detail *tmpl, struct net *net);
 219 extern void cache_destroy_net(struct cache_detail *cd, struct net *net);
 220
 221 extern void sunrpc_init_cache_detail(struct cache_detail *cd);
 222 extern void sunrpc_destroy_cache_detail(struct cache_detail *cd);
 223 extern int sunrpc_cache_register_pipefs(struct dentry *parent, const char *,
 224                                         umode_t, struct cache_detail *);
 225 extern void sunrpc_cache_unregister_pipefs(struct cache_detail *);
 226
 227 extern void qword_add(char **bpp, int *lp, char *str);
 228 extern void qword_addhex(char **bpp, int *lp, char *buf, int blen);
 229 extern int qword_get(char **bpp, char *dest, int bufsize);
 230
 231 static inline int get_int(char **bpp, int *anint)
 232 {
 233         char buf[50];
 234         char *ep;
 235         int rv;
 236         int len = qword_get(bpp, buf, sizeof(buf));
 237
 238         if (len < 0)
 239                 return -EINVAL;
 240         if (len == 0)
 241                 return -ENOENT;
 242
 243         rv = simple_strtol(buf, &ep, 0);
 244         if (*ep)
 245                 return -EINVAL;
 246
 247         *anint = rv;
 248         return 0;
 249 }
 250
 251 static inline int get_uint(char **bpp, unsigned int *anint)
 252 {
 253         char buf[50];
 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         if (kstrtouint(buf, 0, anint))
 262                 return -EINVAL;
 263
 264         return 0;
 265 }
 266
 267 static inline time_t get_expiry(char **bpp)
 268 {
 269         int rv;
 270         struct timespec boot;
 271
 272         if (get_int(bpp, &rv))
 273                 return 0;
 274         if (rv < 0)
 275                 return 0;
 276         getboottime(&boot);
 277         return rv - boot.tv_sec;
 278 }
 279
 280 #endif /*  _LINUX_SUNRPC_CACHE_H_ */