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         atomic_t                inuse; /* active user-space update or lookup */
  82
  83         char                    *name;
  84         void                    (*cache_put)(struct kref *);
  85
  86         int                     (*cache_upcall)(struct cache_detail *,
  87                                                 struct cache_head *);
  88
  89         void                    (*cache_request)(struct cache_detail *cd,
  90                                                  struct cache_head *ch,
  91                                                  char **bpp, int *blen);
  92
  93         int                     (*cache_parse)(struct cache_detail *,
  94                                                char *buf, int len);
  95
  96         int                     (*cache_show)(struct seq_file *m,
  97                                               struct cache_detail *cd,
  98                                               struct cache_head *h);
  99         void                    (*warn_no_listener)(struct cache_detail *cd,
 100                                               int has_died);
 101
 102         struct cache_head *     (*alloc)(void);
 103         int                     (*match)(struct cache_head *orig, struct cache_head *new);
 104         void                    (*init)(struct cache_head *orig, struct cache_head *new);
 105         void                    (*update)(struct cache_head *orig, struct cache_head *new);
 106
 107         /* fields below this comment are for internal use
 108          * and should not be touched by cache owners
 109          */
 110         time_t                  flush_time;             /* flush all cache items with
 111                                                          * last_refresh at or earlier
 112                                                          * than this.  last_refresh
 113                                                          * is never set at or earlier
 114                                                          * than this.
 115                                                          */
 116         struct list_head        others;
 117         time_t                  nextcheck;
 118         int                     entries;
 119
 120         /* fields for communication over channel */
 121         struct list_head        queue;
 122
 123         atomic_t                readers;                /* how many time is /chennel open */
 124         time_t                  last_close;             /* if no readers, when did last close */
 125         time_t                  last_warn;              /* when we last warned about no readers */
 126
 127         union {
 128                 struct cache_detail_procfs procfs;
 129                 struct cache_detail_pipefs pipefs;
 130         } u;
 131         struct net              *net;
 132 };
 133
 134
 135 /* this must be embedded in any request structure that
 136  * identifies an object that will want a callback on
 137  * a cache fill
 138  */
 139 struct cache_req {
 140         struct cache_deferred_req *(*defer)(struct cache_req *req);
 141         int thread_wait;  /* How long (jiffies) we can block the
 142                            * current thread to wait for updates.
 143                            */
 144 };
 145 /* this must be embedded in a deferred_request that is being
 146  * delayed awaiting cache-fill
 147  */
 148 struct cache_deferred_req {
 149         struct hlist_node       hash;   /* on hash chain */
 150         struct list_head        recent; /* on fifo */
 151         struct cache_head       *item;  /* cache item we wait on */
 152         void                    *owner; /* we might need to discard all defered requests
 153                                          * owned by someone */
 154         void                    (*revisit)(struct cache_deferred_req *req,
 155                                            int too_many);
 156 };
 157
 158 /*
 159  * timestamps kept in the cache are expressed in seconds
 160  * since boot.  This is the best for measuring differences in
 161  * real time.
 162  */
 163 static inline time_t seconds_since_boot(void)
 164 {
 165         struct timespec boot;
 166         getboottime(&boot);
 167         return get_seconds() - boot.tv_sec;
 168 }
 169
 170 static inline time_t convert_to_wallclock(time_t sinceboot)
 171 {
 172         struct timespec boot;
 173         getboottime(&boot);
 174         return boot.tv_sec + sinceboot;
 175 }
 176
 177 extern const struct file_operations cache_file_operations_pipefs;
 178 extern const struct file_operations content_file_operations_pipefs;
 179 extern const struct file_operations cache_flush_operations_pipefs;
 180
 181 extern struct cache_head *
 182 sunrpc_cache_lookup(struct cache_detail *detail,
 183                     struct cache_head *key, int hash);
 184 extern struct cache_head *
 185 sunrpc_cache_update(struct cache_detail *detail,
 186                     struct cache_head *new, struct cache_head *old, int hash);
 187
 188 extern int
 189 sunrpc_cache_pipe_upcall(struct cache_detail *detail, struct cache_head *h);
 190
 191
 192 extern void cache_clean_deferred(void *owner);
 193
 194 static inline struct cache_head  *cache_get(struct cache_head *h)
 195 {
 196         kref_get(&h->ref);
 197         return h;
 198 }
 199
 200
 201 static inline void cache_put(struct cache_head *h, struct cache_detail *cd)
 202 {
 203         if (atomic_read(&h->ref.refcount) <= 2 &&
 204             h->expiry_time < cd->nextcheck)
 205                 cd->nextcheck = h->expiry_time;
 206         kref_put(&h->ref, cd->cache_put);
 207 }
 208
 209 static inline int cache_is_expired(struct cache_detail *detail, struct cache_head *h)
 210 {
 211         return  (h->expiry_time < seconds_since_boot()) ||
 212                 (detail->flush_time >= h->last_refresh);
 213 }
 214
 215 extern int cache_check(struct cache_detail *detail,
 216                        struct cache_head *h, struct cache_req *rqstp);
 217 extern void cache_flush(void);
 218 extern void cache_purge(struct cache_detail *detail);
 219 #define NEVER (0x7FFFFFFF)
 220 extern void __init cache_initialize(void);
 221 extern int cache_register_net(struct cache_detail *cd, struct net *net);
 222 extern void cache_unregister_net(struct cache_detail *cd, struct net *net);
 223
 224 extern struct cache_detail *cache_create_net(struct cache_detail *tmpl, struct net *net);
 225 extern void cache_destroy_net(struct cache_detail *cd, struct net *net);
 226
 227 extern void sunrpc_init_cache_detail(struct cache_detail *cd);
 228 extern void sunrpc_destroy_cache_detail(struct cache_detail *cd);
 229 extern int sunrpc_cache_register_pipefs(struct dentry *parent, const char *,
 230                                         umode_t, struct cache_detail *);
 231 extern void sunrpc_cache_unregister_pipefs(struct cache_detail *);
 232
 233 /* Must store cache_detail in seq_file->private if using next three functions */
 234 extern void *cache_seq_start(struct seq_file *file, loff_t *pos);
 235 extern void *cache_seq_next(struct seq_file *file, void *p, loff_t *pos);
 236 extern void cache_seq_stop(struct seq_file *file, void *p);
 237
 238 extern void qword_add(char **bpp, int *lp, char *str);
 239 extern void qword_addhex(char **bpp, int *lp, char *buf, int blen);
 240 extern int qword_get(char **bpp, char *dest, int bufsize);
 241
 242 static inline int get_int(char **bpp, int *anint)
 243 {
 244         char buf[50];
 245         char *ep;
 246         int rv;
 247         int len = qword_get(bpp, buf, sizeof(buf));
 248
 249         if (len < 0)
 250                 return -EINVAL;
 251         if (len == 0)
 252                 return -ENOENT;
 253
 254         rv = simple_strtol(buf, &ep, 0);
 255         if (*ep)
 256                 return -EINVAL;
 257
 258         *anint = rv;
 259         return 0;
 260 }
 261
 262 static inline int get_uint(char **bpp, unsigned int *anint)
 263 {
 264         char buf[50];
 265         int len = qword_get(bpp, buf, sizeof(buf));
 266
 267         if (len < 0)
 268                 return -EINVAL;
 269         if (len == 0)
 270                 return -ENOENT;
 271
 272         if (kstrtouint(buf, 0, anint))
 273                 return -EINVAL;
 274
 275         return 0;
 276 }
 277
 278 static inline int get_time(char **bpp, time_t *time)
 279 {
 280         char buf[50];
 281         long long ll;
 282         int len = qword_get(bpp, buf, sizeof(buf));
 283
 284         if (len < 0)
 285                 return -EINVAL;
 286         if (len == 0)
 287                 return -ENOENT;
 288
 289         if (kstrtoll(buf, 0, &ll))
 290                 return -EINVAL;
 291
 292         *time = (time_t)ll;
 293         return 0;
 294 }
 295
 296 static inline time_t get_expiry(char **bpp)
 297 {
 298         time_t rv;
 299         struct timespec boot;
 300
 301         if (get_time(bpp, &rv))
 302                 return 0;
 303         if (rv < 0)
 304                 return 0;
 305         getboottime(&boot);
 306         return rv - boot.tv_sec;
 307 }
 308
 309 #endif /*  _LINUX_SUNRPC_CACHE_H_ */