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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 */
48struct 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
64struct cache_detail_procfs {
65 struct proc_dir_entry *proc_ent;
66 struct proc_dir_entry *flush_ent, *channel_ent, *content_ent;
67};
68
69struct cache_detail_pipefs {
70 struct dentry *dir;
71};
72
73struct 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 */
133struct 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 */
142struct 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 */
157static inline time_t seconds_since_boot(void)
158{
159 struct timespec boot;
160 getboottime(&boot);
161 return get_seconds() - boot.tv_sec;
162}
163
164static 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
171extern const struct file_operations cache_file_operations_pipefs;
172extern const struct file_operations content_file_operations_pipefs;
173extern const struct file_operations cache_flush_operations_pipefs;
174
175extern struct cache_head *
176sunrpc_cache_lookup(struct cache_detail *detail,
177 struct cache_head *key, int hash);
178extern struct cache_head *
179sunrpc_cache_update(struct cache_detail *detail,
180 struct cache_head *new, struct cache_head *old, int hash);
181
182extern int
183sunrpc_cache_pipe_upcall(struct cache_detail *detail, struct cache_head *h);
184
185
186extern void cache_clean_deferred(void *owner);
187
188static inline struct cache_head *cache_get(struct cache_head *h)
189{
190 kref_get(&h->ref);
191 return h;
192}
193
194
195static 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
203static 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
209extern int cache_check(struct cache_detail *detail,
210 struct cache_head *h, struct cache_req *rqstp);
211extern void cache_flush(void);
212extern void cache_purge(struct cache_detail *detail);
213#define NEVER (0x7FFFFFFF)
214extern void __init cache_initialize(void);
215extern int cache_register_net(struct cache_detail *cd, struct net *net);
216extern void cache_unregister_net(struct cache_detail *cd, struct net *net);
217
218extern struct cache_detail *cache_create_net(struct cache_detail *tmpl, struct net *net);
219extern void cache_destroy_net(struct cache_detail *cd, struct net *net);
220
221extern void sunrpc_init_cache_detail(struct cache_detail *cd);
222extern void sunrpc_destroy_cache_detail(struct cache_detail *cd);
223extern int sunrpc_cache_register_pipefs(struct dentry *parent, const char *,
224 umode_t, struct cache_detail *);
225extern void sunrpc_cache_unregister_pipefs(struct cache_detail *);
226
227extern void qword_add(char **bpp, int *lp, char *str);
228extern void qword_addhex(char **bpp, int *lp, char *buf, int blen);
229extern int qword_get(char **bpp, char *dest, int bufsize);
230
231static 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
251static 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
267static inline int get_time(char **bpp, time_t *time)
268{
269 char buf[50];
270 long long ll;
271 int len = qword_get(bpp, buf, sizeof(buf));
272
273 if (len < 0)
274 return -EINVAL;
275 if (len == 0)
276 return -ENOENT;
277
278 if (kstrtoll(buf, 0, &ll))
279 return -EINVAL;
280
281 *time = (time_t)ll;
282 return 0;
283}
284
285static inline time_t get_expiry(char **bpp)
286{
287 time_t rv;
288 struct timespec boot;
289
290 if (get_time(bpp, &rv))
291 return 0;
292 if (rv < 0)
293 return 0;
294 getboottime(&boot);
295 return rv - boot.tv_sec;
296}
297
298#endif /* _LINUX_SUNRPC_CACHE_H_ */