2 * include/linux/sunrpc/cache.h
4 * Generic code for various authentication-related caches
5 * used by sunrpc clients and servers.
7 * Copyright (C) 2002 Neil Brown <neilb@cse.unsw.edu.au>
9 * Released under terms in GPL version 2. See COPYING.
13 #ifndef _LINUX_SUNRPC_CACHE_H_
14 #define _LINUX_SUNRPC_CACHE_H_
16 #include <linux/kref.h>
17 #include <linux/slab.h>
18 #include <linux/atomic.h>
19 #include <linux/proc_fs.h>
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.
32 * as well as assorted code fragments (e.g. compare keys) and numbers
33 * (e.g. hash size, goal_age, etc).
35 * Each cache must be registered so that it can be cleaned regularly.
36 * When the cache is unregistered, it is flushed completely.
38 * Entries have a ref count and a 'hashed' flag which counts the existence
40 * We only expire entries when refcount is zero.
41 * Existence in the cache is counted the refcount.
44 /* Every cache item has a common header that is used
45 * for expiring and refreshing entries.
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.
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 */
64 #define CACHE_NEW_EXPIRY 120 /* keep new things pending confirmation for 120 seconds */
66 struct cache_detail_procfs {
67 struct proc_dir_entry *proc_ent;
68 struct proc_dir_entry *flush_ent, *channel_ent, *content_ent;
71 struct cache_detail_pipefs {
76 struct module * owner;
78 struct hlist_head * hash_table;
81 atomic_t inuse; /* active user-space update or lookup */
84 void (*cache_put)(struct kref *);
86 int (*cache_upcall)(struct cache_detail *,
89 void (*cache_request)(struct cache_detail *cd,
90 struct cache_head *ch,
91 char **bpp, int *blen);
93 int (*cache_parse)(struct cache_detail *,
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,
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);
107 /* fields below this comment are for internal use
108 * and should not be touched by cache owners
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
116 struct list_head others;
120 /* fields for communication over channel */
121 struct list_head queue;
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 */
128 struct cache_detail_procfs procfs;
129 struct cache_detail_pipefs pipefs;
135 /* this must be embedded in any request structure that
136 * identifies an object that will want a callback on
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.
145 /* this must be embedded in a deferred_request that is being
146 * delayed awaiting cache-fill
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,
159 * timestamps kept in the cache are expressed in seconds
160 * since boot. This is the best for measuring differences in
163 static inline time_t seconds_since_boot(void)
165 struct timespec boot;
167 return get_seconds() - boot.tv_sec;
170 static inline time_t convert_to_wallclock(time_t sinceboot)
172 struct timespec boot;
174 return boot.tv_sec + sinceboot;
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;
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);
189 sunrpc_cache_pipe_upcall(struct cache_detail *detail, struct cache_head *h);
192 extern void cache_clean_deferred(void *owner);
194 static inline struct cache_head *cache_get(struct cache_head *h)
201 static inline void cache_put(struct cache_head *h, struct cache_detail *cd)
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);
209 static inline int cache_is_expired(struct cache_detail *detail, struct cache_head *h)
211 return (h->expiry_time < seconds_since_boot()) ||
212 (detail->flush_time >= h->last_refresh);
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);
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);
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 *);
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);
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);
242 static inline int get_int(char **bpp, int *anint)
247 int len = qword_get(bpp, buf, sizeof(buf));
254 rv = simple_strtol(buf, &ep, 0);
262 static inline int get_uint(char **bpp, unsigned int *anint)
265 int len = qword_get(bpp, buf, sizeof(buf));
272 if (kstrtouint(buf, 0, anint))
278 static inline int get_time(char **bpp, time_t *time)
282 int len = qword_get(bpp, buf, sizeof(buf));
289 if (kstrtoll(buf, 0, &ll))
296 static inline time_t get_expiry(char **bpp)
299 struct timespec boot;
301 if (get_time(bpp, &rv))
306 return rv - boot.tv_sec;
309 #endif /* _LINUX_SUNRPC_CACHE_H_ */