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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_procfs {
67 struct proc_dir_entry *proc_ent;
68 struct proc_dir_entry *flush_ent, *channel_ent, *content_ent;
69};
70
71struct cache_detail_pipefs {
72 struct dentry *dir;
73};
74
75struct cache_detail {
76 struct module * owner;
77 int hash_size;
78 struct hlist_head * hash_table;
79 rwlock_t hash_lock;
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
109 * last_refresh at or earlier
110 * than this. last_refresh
111 * is never set at or earlier
112 * than this.
113 */
114 struct list_head others;
115 time_t nextcheck;
116 int entries;
117
118 /* fields for communication over channel */
119 struct list_head queue;
120
121 atomic_t readers; /* how many time is /chennel open */
122 time_t last_close; /* if no readers, when did last close */
123 time_t last_warn; /* when we last warned about no readers */
124
125 union {
126 struct cache_detail_procfs procfs;
127 struct cache_detail_pipefs pipefs;
128 } u;
129 struct net *net;
130};
131
132
133/* this must be embedded in any request structure that
134 * identifies an object that will want a callback on
135 * a cache fill
136 */
137struct cache_req {
138 struct cache_deferred_req *(*defer)(struct cache_req *req);
139 int thread_wait; /* How long (jiffies) we can block the
140 * current thread to wait for updates.
141 */
142};
143/* this must be embedded in a deferred_request that is being
144 * delayed awaiting cache-fill
145 */
146struct cache_deferred_req {
147 struct hlist_node hash; /* on hash chain */
148 struct list_head recent; /* on fifo */
149 struct cache_head *item; /* cache item we wait on */
150 void *owner; /* we might need to discard all defered requests
151 * owned by someone */
152 void (*revisit)(struct cache_deferred_req *req,
153 int too_many);
154};
155
156/*
157 * timestamps kept in the cache are expressed in seconds
158 * since boot. This is the best for measuring differences in
159 * real time.
160 */
161static inline time_t seconds_since_boot(void)
162{
163 struct timespec boot;
164 getboottime(&boot);
165 return get_seconds() - boot.tv_sec;
166}
167
168static inline time_t convert_to_wallclock(time_t sinceboot)
169{
170 struct timespec boot;
171 getboottime(&boot);
172 return boot.tv_sec + sinceboot;
173}
174
175extern const struct file_operations cache_file_operations_pipefs;
176extern const struct file_operations content_file_operations_pipefs;
177extern const struct file_operations cache_flush_operations_pipefs;
178
179extern struct cache_head *
180sunrpc_cache_lookup(struct cache_detail *detail,
181 struct cache_head *key, int hash);
182extern struct cache_head *
183sunrpc_cache_update(struct cache_detail *detail,
184 struct cache_head *new, struct cache_head *old, int hash);
185
186extern int
187sunrpc_cache_pipe_upcall(struct cache_detail *detail, struct cache_head *h);
188
189
190extern void cache_clean_deferred(void *owner);
191
192static inline struct cache_head *cache_get(struct cache_head *h)
193{
194 kref_get(&h->ref);
195 return h;
196}
197
198
199static inline void cache_put(struct cache_head *h, struct cache_detail *cd)
200{
201 if (atomic_read(&h->ref.refcount) <= 2 &&
202 h->expiry_time < cd->nextcheck)
203 cd->nextcheck = h->expiry_time;
204 kref_put(&h->ref, cd->cache_put);
205}
206
207static inline int cache_is_expired(struct cache_detail *detail, struct cache_head *h)
208{
209 return (h->expiry_time < seconds_since_boot()) ||
210 (detail->flush_time >= h->last_refresh);
211}
212
213extern int cache_check(struct cache_detail *detail,
214 struct cache_head *h, struct cache_req *rqstp);
215extern void cache_flush(void);
216extern void cache_purge(struct cache_detail *detail);
217#define NEVER (0x7FFFFFFF)
218extern void __init cache_initialize(void);
219extern int cache_register_net(struct cache_detail *cd, struct net *net);
220extern void cache_unregister_net(struct cache_detail *cd, struct net *net);
221
222extern struct cache_detail *cache_create_net(struct cache_detail *tmpl, struct net *net);
223extern void cache_destroy_net(struct cache_detail *cd, struct net *net);
224
225extern void sunrpc_init_cache_detail(struct cache_detail *cd);
226extern void sunrpc_destroy_cache_detail(struct cache_detail *cd);
227extern int sunrpc_cache_register_pipefs(struct dentry *parent, const char *,
228 umode_t, struct cache_detail *);
229extern void sunrpc_cache_unregister_pipefs(struct cache_detail *);
230
231/* Must store cache_detail in seq_file->private if using next three functions */
232extern void *cache_seq_start(struct seq_file *file, loff_t *pos);
233extern void *cache_seq_next(struct seq_file *file, void *p, loff_t *pos);
234extern void cache_seq_stop(struct seq_file *file, void *p);
235
236extern void qword_add(char **bpp, int *lp, char *str);
237extern void qword_addhex(char **bpp, int *lp, char *buf, int blen);
238extern int qword_get(char **bpp, char *dest, int bufsize);
239
240static inline int get_int(char **bpp, int *anint)
241{
242 char buf[50];
243 char *ep;
244 int rv;
245 int len = qword_get(bpp, buf, sizeof(buf));
246
247 if (len < 0)
248 return -EINVAL;
249 if (len == 0)
250 return -ENOENT;
251
252 rv = simple_strtol(buf, &ep, 0);
253 if (*ep)
254 return -EINVAL;
255
256 *anint = rv;
257 return 0;
258}
259
260static inline int get_uint(char **bpp, unsigned int *anint)
261{
262 char buf[50];
263 int len = qword_get(bpp, buf, sizeof(buf));
264
265 if (len < 0)
266 return -EINVAL;
267 if (len == 0)
268 return -ENOENT;
269
270 if (kstrtouint(buf, 0, anint))
271 return -EINVAL;
272
273 return 0;
274}
275
276static inline int get_time(char **bpp, time_t *time)
277{
278 char buf[50];
279 long long ll;
280 int len = qword_get(bpp, buf, sizeof(buf));
281
282 if (len < 0)
283 return -EINVAL;
284 if (len == 0)
285 return -ENOENT;
286
287 if (kstrtoll(buf, 0, &ll))
288 return -EINVAL;
289
290 *time = (time_t)ll;
291 return 0;
292}
293
294static inline time_t get_expiry(char **bpp)
295{
296 time_t rv;
297 struct timespec boot;
298
299 if (get_time(bpp, &rv))
300 return 0;
301 if (rv < 0)
302 return 0;
303 getboottime(&boot);
304 return rv - boot.tv_sec;
305}
306
307#endif /* _LINUX_SUNRPC_CACHE_H_ */