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Linux/include/linux/sunrpc/cache.h

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  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_ */
281 

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