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
  61 #define CACHE_NEW_EXPIRY 120    /* keep new things pending confirmation for 120 seconds */
  62
  63 struct cache_detail_procfs {
  64         struct proc_dir_entry   *proc_ent;
  65         struct proc_dir_entry   *flush_ent, *channel_ent, *content_ent;
  66 };
  67
  68 struct cache_detail_pipefs {
  69         struct dentry *dir;
  70 };
  71
  72 struct cache_detail {
  73         struct module *         owner;
  74         int                     hash_size;
  75         struct cache_head **    hash_table;
  76         rwlock_t                hash_lock;
  77
  78         atomic_t                inuse; /* active user-space update or lookup */
  79
  80         char                    *name;
  81         void                    (*cache_put)(struct kref *);
  82
  83         int                     (*cache_upcall)(struct cache_detail *,
  84                                                 struct cache_head *);
  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         int                     (*match)(struct cache_head *orig, struct cache_head *new);
  97         void                    (*init)(struct cache_head *orig, struct cache_head *new);
  98         void                    (*update)(struct cache_head *orig, struct cache_head *new);
  99
 100         /* fields below this comment are for internal use
 101          * and should not be touched by cache owners
 102          */
 103         time_t                  flush_time;             /* flush all cache items with last_refresh
 104                                                          * earlier than this */
 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 cache_detail_procfs procfs;
 118                 struct cache_detail_pipefs pipefs;
 119         } u;
 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 extern const struct file_operations cache_file_operations_pipefs;
 149 extern const struct file_operations content_file_operations_pipefs;
 150 extern const struct file_operations cache_flush_operations_pipefs;
 151
 152 extern struct cache_head *
 153 sunrpc_cache_lookup(struct cache_detail *detail,
 154                     struct cache_head *key, int hash);
 155 extern struct cache_head *
 156 sunrpc_cache_update(struct cache_detail *detail,
 157                     struct cache_head *new, struct cache_head *old, int hash);
 158
 159 extern int
 160 sunrpc_cache_pipe_upcall(struct cache_detail *detail, struct cache_head *h,
 161                 void (*cache_request)(struct cache_detail *,
 162                                       struct cache_head *,
 163                                       char **,
 164                                       int *));
 165
 166
 167 extern void cache_clean_deferred(void *owner);
 168
 169 static inline struct cache_head  *cache_get(struct cache_head *h)
 170 {
 171         kref_get(&h->ref);
 172         return h;
 173 }
 174
 175
 176 static inline void cache_put(struct cache_head *h, struct cache_detail *cd)
 177 {
 178         if (atomic_read(&h->ref.refcount) <= 2 &&
 179             h->expiry_time < cd->nextcheck)
 180                 cd->nextcheck = h->expiry_time;
 181         kref_put(&h->ref, cd->cache_put);
 182 }
 183
 184 static inline int cache_valid(struct cache_head *h)
 185 {
 186         /* If an item has been unhashed pending removal when
 187          * the refcount drops to 0, the expiry_time will be
 188          * set to 0.  We don't want to consider such items
 189          * valid in this context even though CACHE_VALID is
 190          * set.
 191          */
 192         return (h->expiry_time != 0 && test_bit(CACHE_VALID, &h->flags));
 193 }
 194
 195 extern int cache_check(struct cache_detail *detail,
 196                        struct cache_head *h, struct cache_req *rqstp);
 197 extern void cache_flush(void);
 198 extern void cache_purge(struct cache_detail *detail);
 199 #define NEVER (0x7FFFFFFF)
 200 extern void __init cache_initialize(void);
 201 extern int cache_register_net(struct cache_detail *cd, struct net *net);
 202 extern void cache_unregister_net(struct cache_detail *cd, struct net *net);
 203
 204 extern struct cache_detail *cache_create_net(struct cache_detail *tmpl, struct net *net);
 205 extern void cache_destroy_net(struct cache_detail *cd, struct net *net);
 206
 207 extern void sunrpc_init_cache_detail(struct cache_detail *cd);
 208 extern void sunrpc_destroy_cache_detail(struct cache_detail *cd);
 209 extern int sunrpc_cache_register_pipefs(struct dentry *parent, const char *,
 210                                         umode_t, struct cache_detail *);
 211 extern void sunrpc_cache_unregister_pipefs(struct cache_detail *);
 212
 213 extern void qword_add(char **bpp, int *lp, char *str);
 214 extern void qword_addhex(char **bpp, int *lp, char *buf, int blen);
 215 extern int qword_get(char **bpp, char *dest, int bufsize);
 216
 217 static inline int get_int(char **bpp, int *anint)
 218 {
 219         char buf[50];
 220         int len = qword_get(bpp, buf, sizeof(buf));
 221
 222         if (len < 0)
 223                 return -EINVAL;
 224         if (len == 0)
 225                 return -ENOENT;
 226
 227         if (kstrtoint(buf, 0, anint))
 228                 return -EINVAL;
 229
 230         return 0;
 231 }
 232
 233 static inline int get_uint(char **bpp, unsigned int *anint)
 234 {
 235         char buf[50];
 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         if (kstrtouint(buf, 0, anint))
 244                 return -EINVAL;
 245
 246         return 0;
 247 }
 248
 249 /*
 250  * timestamps kept in the cache are expressed in seconds
 251  * since boot.  This is the best for measuring differences in
 252  * real time.
 253  */
 254 static inline time_t seconds_since_boot(void)
 255 {
 256         struct timespec boot;
 257         getboottime(&boot);
 258         return get_seconds() - boot.tv_sec;
 259 }
 260
 261 static inline time_t convert_to_wallclock(time_t sinceboot)
 262 {
 263         struct timespec boot;
 264         getboottime(&boot);
 265         return boot.tv_sec + sinceboot;
 266 }
 267
 268 static inline time_t get_expiry(char **bpp)
 269 {
 270         int rv;
 271         struct timespec boot;
 272
 273         if (get_int(bpp, &rv))
 274                 return 0;
 275         if (rv < 0)
 276                 return 0;
 277         getboottime(&boot);
 278         return rv - boot.tv_sec;
 279 }
 280
 281 #endif /*  _LINUX_SUNRPC_CACHE_H_ */