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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 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
66struct cache_detail {
67 struct module * owner;
68 int hash_size;
69 struct hlist_head * hash_table;
70 rwlock_t hash_lock;
71
72 char *name;
73 void (*cache_put)(struct kref *);
74
75 int (*cache_upcall)(struct cache_detail *,
76 struct cache_head *);
77
78 void (*cache_request)(struct cache_detail *cd,
79 struct cache_head *ch,
80 char **bpp, int *blen);
81
82 int (*cache_parse)(struct cache_detail *,
83 char *buf, int len);
84
85 int (*cache_show)(struct seq_file *m,
86 struct cache_detail *cd,
87 struct cache_head *h);
88 void (*warn_no_listener)(struct cache_detail *cd,
89 int has_died);
90
91 struct cache_head * (*alloc)(void);
92 int (*match)(struct cache_head *orig, struct cache_head *new);
93 void (*init)(struct cache_head *orig, struct cache_head *new);
94 void (*update)(struct cache_head *orig, struct cache_head *new);
95
96 /* fields below this comment are for internal use
97 * and should not be touched by cache owners
98 */
99 time_t flush_time; /* flush all cache items with
100 * last_refresh at or earlier
101 * than this. last_refresh
102 * is never set at or earlier
103 * than this.
104 */
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 proc_dir_entry *procfs;
118 struct dentry *pipefs;
119 };
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 */
128struct 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 */
137struct 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 * timestamps kept in the cache are expressed in seconds
149 * since boot. This is the best for measuring differences in
150 * real time.
151 */
152static inline time_t seconds_since_boot(void)
153{
154 struct timespec boot;
155 getboottime(&boot);
156 return get_seconds() - boot.tv_sec;
157}
158
159static inline time_t convert_to_wallclock(time_t sinceboot)
160{
161 struct timespec boot;
162 getboottime(&boot);
163 return boot.tv_sec + sinceboot;
164}
165
166extern const struct file_operations cache_file_operations_pipefs;
167extern const struct file_operations content_file_operations_pipefs;
168extern const struct file_operations cache_flush_operations_pipefs;
169
170extern struct cache_head *
171sunrpc_cache_lookup(struct cache_detail *detail,
172 struct cache_head *key, int hash);
173extern struct cache_head *
174sunrpc_cache_update(struct cache_detail *detail,
175 struct cache_head *new, struct cache_head *old, int hash);
176
177extern int
178sunrpc_cache_pipe_upcall(struct cache_detail *detail, struct cache_head *h);
179
180
181extern void cache_clean_deferred(void *owner);
182
183static inline struct cache_head *cache_get(struct cache_head *h)
184{
185 kref_get(&h->ref);
186 return h;
187}
188
189
190static inline void cache_put(struct cache_head *h, struct cache_detail *cd)
191{
192 if (kref_read(&h->ref) <= 2 &&
193 h->expiry_time < cd->nextcheck)
194 cd->nextcheck = h->expiry_time;
195 kref_put(&h->ref, cd->cache_put);
196}
197
198static inline bool cache_is_expired(struct cache_detail *detail, struct cache_head *h)
199{
200 if (!test_bit(CACHE_VALID, &h->flags))
201 return false;
202
203 return (h->expiry_time < seconds_since_boot()) ||
204 (detail->flush_time >= h->last_refresh);
205}
206
207extern int cache_check(struct cache_detail *detail,
208 struct cache_head *h, struct cache_req *rqstp);
209extern void cache_flush(void);
210extern void cache_purge(struct cache_detail *detail);
211#define NEVER (0x7FFFFFFF)
212extern void __init cache_initialize(void);
213extern int cache_register_net(struct cache_detail *cd, struct net *net);
214extern void cache_unregister_net(struct cache_detail *cd, struct net *net);
215
216extern struct cache_detail *cache_create_net(const struct cache_detail *tmpl, struct net *net);
217extern void cache_destroy_net(struct cache_detail *cd, struct net *net);
218
219extern void sunrpc_init_cache_detail(struct cache_detail *cd);
220extern void sunrpc_destroy_cache_detail(struct cache_detail *cd);
221extern int sunrpc_cache_register_pipefs(struct dentry *parent, const char *,
222 umode_t, struct cache_detail *);
223extern void sunrpc_cache_unregister_pipefs(struct cache_detail *);
224extern void sunrpc_cache_unhash(struct cache_detail *, struct cache_head *);
225
226/* Must store cache_detail in seq_file->private if using next three functions */
227extern void *cache_seq_start(struct seq_file *file, loff_t *pos);
228extern void *cache_seq_next(struct seq_file *file, void *p, loff_t *pos);
229extern void cache_seq_stop(struct seq_file *file, void *p);
230
231extern void qword_add(char **bpp, int *lp, char *str);
232extern void qword_addhex(char **bpp, int *lp, char *buf, int blen);
233extern int qword_get(char **bpp, char *dest, int bufsize);
234
235static inline int get_int(char **bpp, int *anint)
236{
237 char buf[50];
238 char *ep;
239 int rv;
240 int len = qword_get(bpp, buf, sizeof(buf));
241
242 if (len < 0)
243 return -EINVAL;
244 if (len == 0)
245 return -ENOENT;
246
247 rv = simple_strtol(buf, &ep, 0);
248 if (*ep)
249 return -EINVAL;
250
251 *anint = rv;
252 return 0;
253}
254
255static inline int get_uint(char **bpp, unsigned int *anint)
256{
257 char buf[50];
258 int len = qword_get(bpp, buf, sizeof(buf));
259
260 if (len < 0)
261 return -EINVAL;
262 if (len == 0)
263 return -ENOENT;
264
265 if (kstrtouint(buf, 0, anint))
266 return -EINVAL;
267
268 return 0;
269}
270
271static inline int get_time(char **bpp, time_t *time)
272{
273 char buf[50];
274 long long ll;
275 int len = qword_get(bpp, buf, sizeof(buf));
276
277 if (len < 0)
278 return -EINVAL;
279 if (len == 0)
280 return -ENOENT;
281
282 if (kstrtoll(buf, 0, &ll))
283 return -EINVAL;
284
285 *time = (time_t)ll;
286 return 0;
287}
288
289static inline time_t get_expiry(char **bpp)
290{
291 time_t rv;
292 struct timespec boot;
293
294 if (get_time(bpp, &rv))
295 return 0;
296 if (rv < 0)
297 return 0;
298 getboottime(&boot);
299 return rv - boot.tv_sec;
300}
301
302#endif /* _LINUX_SUNRPC_CACHE_H_ */