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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 atomic_t inuse; /* active user-space update or lookup */
82
83 char *name;
84 void (*cache_put)(struct kref *);
85
86 int (*cache_upcall)(struct cache_detail *,
87 struct cache_head *);
88
89 void (*cache_request)(struct cache_detail *cd,
90 struct cache_head *ch,
91 char **bpp, int *blen);
92
93 int (*cache_parse)(struct cache_detail *,
94 char *buf, int len);
95
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,
100 int has_died);
101
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);
106
107 /* fields below this comment are for internal use
108 * and should not be touched by cache owners
109 */
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
114 * than this.
115 */
116 struct list_head others;
117 time_t nextcheck;
118 int entries;
119
120 /* fields for communication over channel */
121 struct list_head queue;
122
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 */
126
127 union {
128 struct cache_detail_procfs procfs;
129 struct cache_detail_pipefs pipefs;
130 } u;
131 struct net *net;
132};
133
134
135/* this must be embedded in any request structure that
136 * identifies an object that will want a callback on
137 * a cache fill
138 */
139struct cache_req {
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.
143 */
144};
145/* this must be embedded in a deferred_request that is being
146 * delayed awaiting cache-fill
147 */
148struct 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,
155 int too_many);
156};
157
158/*
159 * timestamps kept in the cache are expressed in seconds
160 * since boot. This is the best for measuring differences in
161 * real time.
162 */
163static inline time_t seconds_since_boot(void)
164{
165 struct timespec boot;
166 getboottime(&boot);
167 return get_seconds() - boot.tv_sec;
168}
169
170static inline time_t convert_to_wallclock(time_t sinceboot)
171{
172 struct timespec boot;
173 getboottime(&boot);
174 return boot.tv_sec + sinceboot;
175}
176
177extern const struct file_operations cache_file_operations_pipefs;
178extern const struct file_operations content_file_operations_pipefs;
179extern const struct file_operations cache_flush_operations_pipefs;
180
181extern struct cache_head *
182sunrpc_cache_lookup(struct cache_detail *detail,
183 struct cache_head *key, int hash);
184extern struct cache_head *
185sunrpc_cache_update(struct cache_detail *detail,
186 struct cache_head *new, struct cache_head *old, int hash);
187
188extern int
189sunrpc_cache_pipe_upcall(struct cache_detail *detail, struct cache_head *h);
190
191
192extern void cache_clean_deferred(void *owner);
193
194static inline struct cache_head *cache_get(struct cache_head *h)
195{
196 kref_get(&h->ref);
197 return h;
198}
199
200
201static inline void cache_put(struct cache_head *h, struct cache_detail *cd)
202{
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);
207}
208
209static inline int cache_is_expired(struct cache_detail *detail, struct cache_head *h)
210{
211 return (h->expiry_time < seconds_since_boot()) ||
212 (detail->flush_time >= h->last_refresh);
213}
214
215extern int cache_check(struct cache_detail *detail,
216 struct cache_head *h, struct cache_req *rqstp);
217extern void cache_flush(void);
218extern void cache_purge(struct cache_detail *detail);
219#define NEVER (0x7FFFFFFF)
220extern void __init cache_initialize(void);
221extern int cache_register_net(struct cache_detail *cd, struct net *net);
222extern void cache_unregister_net(struct cache_detail *cd, struct net *net);
223
224extern struct cache_detail *cache_create_net(struct cache_detail *tmpl, struct net *net);
225extern void cache_destroy_net(struct cache_detail *cd, struct net *net);
226
227extern void sunrpc_init_cache_detail(struct cache_detail *cd);
228extern void sunrpc_destroy_cache_detail(struct cache_detail *cd);
229extern int sunrpc_cache_register_pipefs(struct dentry *parent, const char *,
230 umode_t, struct cache_detail *);
231extern void sunrpc_cache_unregister_pipefs(struct cache_detail *);
232
233/* Must store cache_detail in seq_file->private if using next three functions */
234extern void *cache_seq_start(struct seq_file *file, loff_t *pos);
235extern void *cache_seq_next(struct seq_file *file, void *p, loff_t *pos);
236extern void cache_seq_stop(struct seq_file *file, void *p);
237
238extern void qword_add(char **bpp, int *lp, char *str);
239extern void qword_addhex(char **bpp, int *lp, char *buf, int blen);
240extern int qword_get(char **bpp, char *dest, int bufsize);
241
242static inline int get_int(char **bpp, int *anint)
243{
244 char buf[50];
245 char *ep;
246 int rv;
247 int len = qword_get(bpp, buf, sizeof(buf));
248
249 if (len < 0)
250 return -EINVAL;
251 if (len == 0)
252 return -ENOENT;
253
254 rv = simple_strtol(buf, &ep, 0);
255 if (*ep)
256 return -EINVAL;
257
258 *anint = rv;
259 return 0;
260}
261
262static inline int get_uint(char **bpp, unsigned int *anint)
263{
264 char buf[50];
265 int len = qword_get(bpp, buf, sizeof(buf));
266
267 if (len < 0)
268 return -EINVAL;
269 if (len == 0)
270 return -ENOENT;
271
272 if (kstrtouint(buf, 0, anint))
273 return -EINVAL;
274
275 return 0;
276}
277
278static inline int get_time(char **bpp, time_t *time)
279{
280 char buf[50];
281 long long ll;
282 int len = qword_get(bpp, buf, sizeof(buf));
283
284 if (len < 0)
285 return -EINVAL;
286 if (len == 0)
287 return -ENOENT;
288
289 if (kstrtoll(buf, 0, &ll))
290 return -EINVAL;
291
292 *time = (time_t)ll;
293 return 0;
294}
295
296static inline time_t get_expiry(char **bpp)
297{
298 time_t rv;
299 struct timespec boot;
300
301 if (get_time(bpp, &rv))
302 return 0;
303 if (rv < 0)
304 return 0;
305 getboottime(&boot);
306 return rv - boot.tv_sec;
307}
308
309#endif /* _LINUX_SUNRPC_CACHE_H_ */