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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
61#define CACHE_NEW_EXPIRY 120 /* keep new things pending confirmation for 120 seconds */
62
63struct cache_detail_procfs {
64 struct proc_dir_entry *proc_ent;
65 struct proc_dir_entry *flush_ent, *channel_ent, *content_ent;
66};
67
68struct cache_detail_pipefs {
69 struct dentry *dir;
70};
71
72struct cache_detail {
73 struct module * owner;
74 int hash_size;
75 struct cache_head ** hash_table;
76 rwlock_t hash_lock;
77
78 atomic_t inuse; /* active user-space update or lookup */
79
80 char *name;
81 void (*cache_put)(struct kref *);
82
83 int (*cache_upcall)(struct cache_detail *,
84 struct cache_head *);
85
86 int (*cache_parse)(struct cache_detail *,
87 char *buf, int len);
88
89 int (*cache_show)(struct seq_file *m,
90 struct cache_detail *cd,
91 struct cache_head *h);
92 void (*warn_no_listener)(struct cache_detail *cd,
93 int has_died);
94
95 struct cache_head * (*alloc)(void);
96 int (*match)(struct cache_head *orig, struct cache_head *new);
97 void (*init)(struct cache_head *orig, struct cache_head *new);
98 void (*update)(struct cache_head *orig, struct cache_head *new);
99
100 /* fields below this comment are for internal use
101 * and should not be touched by cache owners
102 */
103 time_t flush_time; /* flush all cache items with last_refresh
104 * earlier than this */
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 cache_detail_procfs procfs;
118 struct cache_detail_pipefs pipefs;
119 } u;
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
148extern const struct file_operations cache_file_operations_pipefs;
149extern const struct file_operations content_file_operations_pipefs;
150extern const struct file_operations cache_flush_operations_pipefs;
151
152extern struct cache_head *
153sunrpc_cache_lookup(struct cache_detail *detail,
154 struct cache_head *key, int hash);
155extern struct cache_head *
156sunrpc_cache_update(struct cache_detail *detail,
157 struct cache_head *new, struct cache_head *old, int hash);
158
159extern int
160sunrpc_cache_pipe_upcall(struct cache_detail *detail, struct cache_head *h,
161 void (*cache_request)(struct cache_detail *,
162 struct cache_head *,
163 char **,
164 int *));
165
166
167extern void cache_clean_deferred(void *owner);
168
169static inline struct cache_head *cache_get(struct cache_head *h)
170{
171 kref_get(&h->ref);
172 return h;
173}
174
175
176static inline void cache_put(struct cache_head *h, struct cache_detail *cd)
177{
178 if (atomic_read(&h->ref.refcount) <= 2 &&
179 h->expiry_time < cd->nextcheck)
180 cd->nextcheck = h->expiry_time;
181 kref_put(&h->ref, cd->cache_put);
182}
183
184static inline int cache_valid(struct cache_head *h)
185{
186 /* If an item has been unhashed pending removal when
187 * the refcount drops to 0, the expiry_time will be
188 * set to 0. We don't want to consider such items
189 * valid in this context even though CACHE_VALID is
190 * set.
191 */
192 return (h->expiry_time != 0 && test_bit(CACHE_VALID, &h->flags));
193}
194
195extern int cache_check(struct cache_detail *detail,
196 struct cache_head *h, struct cache_req *rqstp);
197extern void cache_flush(void);
198extern void cache_purge(struct cache_detail *detail);
199#define NEVER (0x7FFFFFFF)
200extern void __init cache_initialize(void);
201extern int cache_register_net(struct cache_detail *cd, struct net *net);
202extern void cache_unregister_net(struct cache_detail *cd, struct net *net);
203
204extern struct cache_detail *cache_create_net(struct cache_detail *tmpl, struct net *net);
205extern void cache_destroy_net(struct cache_detail *cd, struct net *net);
206
207extern void sunrpc_init_cache_detail(struct cache_detail *cd);
208extern void sunrpc_destroy_cache_detail(struct cache_detail *cd);
209extern int sunrpc_cache_register_pipefs(struct dentry *parent, const char *,
210 umode_t, struct cache_detail *);
211extern void sunrpc_cache_unregister_pipefs(struct cache_detail *);
212
213extern void qword_add(char **bpp, int *lp, char *str);
214extern void qword_addhex(char **bpp, int *lp, char *buf, int blen);
215extern int qword_get(char **bpp, char *dest, int bufsize);
216
217static inline int get_int(char **bpp, int *anint)
218{
219 char buf[50];
220 int len = qword_get(bpp, buf, sizeof(buf));
221
222 if (len < 0)
223 return -EINVAL;
224 if (len == 0)
225 return -ENOENT;
226
227 if (kstrtoint(buf, 0, anint))
228 return -EINVAL;
229
230 return 0;
231}
232
233static inline int get_uint(char **bpp, unsigned int *anint)
234{
235 char buf[50];
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 if (kstrtouint(buf, 0, anint))
244 return -EINVAL;
245
246 return 0;
247}
248
249/*
250 * timestamps kept in the cache are expressed in seconds
251 * since boot. This is the best for measuring differences in
252 * real time.
253 */
254static inline time_t seconds_since_boot(void)
255{
256 struct timespec boot;
257 getboottime(&boot);
258 return get_seconds() - boot.tv_sec;
259}
260
261static inline time_t convert_to_wallclock(time_t sinceboot)
262{
263 struct timespec boot;
264 getboottime(&boot);
265 return boot.tv_sec + sinceboot;
266}
267
268static inline time_t get_expiry(char **bpp)
269{
270 int rv;
271 struct timespec boot;
272
273 if (get_int(bpp, &rv))
274 return 0;
275 if (rv < 0)
276 return 0;
277 getboottime(&boot);
278 return rv - boot.tv_sec;
279}
280
281#endif /* _LINUX_SUNRPC_CACHE_H_ */