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 */
48 struct 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
63 struct cache_detail_procfs {
64 struct proc_dir_entry *proc_ent;
65 struct proc_dir_entry *flush_ent, *channel_ent, *content_ent;
66 };
67
68 struct cache_detail_pipefs {
69 struct dentry *dir;
70 };
71
72 struct 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 */
128 struct 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 */
137 struct 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 extern const struct file_operations cache_file_operations_pipefs;
149 extern const struct file_operations content_file_operations_pipefs;
150 extern const struct file_operations cache_flush_operations_pipefs;
151
152 extern struct cache_head *
153 sunrpc_cache_lookup(struct cache_detail *detail,
154 struct cache_head *key, int hash);
155 extern struct cache_head *
156 sunrpc_cache_update(struct cache_detail *detail,
157 struct cache_head *new, struct cache_head *old, int hash);
158
159 extern int
160 sunrpc_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
167 extern void cache_clean_deferred(void *owner);
168
cache_get(struct cache_head * h)169 static inline struct cache_head *cache_get(struct cache_head *h)
170 {
171 kref_get(&h->ref);
172 return h;
173 }
174
175
cache_put(struct cache_head * h,struct cache_detail * cd)176 static 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
cache_valid(struct cache_head * h)184 static 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
195 extern int cache_check(struct cache_detail *detail,
196 struct cache_head *h, struct cache_req *rqstp);
197 extern void cache_flush(void);
198 extern void cache_purge(struct cache_detail *detail);
199 #define NEVER (0x7FFFFFFF)
200 extern void __init cache_initialize(void);
201 extern int cache_register_net(struct cache_detail *cd, struct net *net);
202 extern void cache_unregister_net(struct cache_detail *cd, struct net *net);
203
204 extern struct cache_detail *cache_create_net(struct cache_detail *tmpl, struct net *net);
205 extern void cache_destroy_net(struct cache_detail *cd, struct net *net);
206
207 extern void sunrpc_init_cache_detail(struct cache_detail *cd);
208 extern void sunrpc_destroy_cache_detail(struct cache_detail *cd);
209 extern int sunrpc_cache_register_pipefs(struct dentry *parent, const char *,
210 umode_t, struct cache_detail *);
211 extern void sunrpc_cache_unregister_pipefs(struct cache_detail *);
212
213 extern void qword_add(char **bpp, int *lp, char *str);
214 extern void qword_addhex(char **bpp, int *lp, char *buf, int blen);
215 extern int qword_get(char **bpp, char *dest, int bufsize);
216
get_int(char ** bpp,int * anint)217 static inline int get_int(char **bpp, int *anint)
218 {
219 char buf[50];
220 char *ep;
221 int rv;
222 int len = qword_get(bpp, buf, 50);
223 if (len < 0) return -EINVAL;
224 if (len ==0) return -ENOENT;
225 rv = simple_strtol(buf, &ep, 0);
226 if (*ep) return -EINVAL;
227 *anint = rv;
228 return 0;
229 }
230
get_uint(char ** bpp,unsigned int * anint)231 static inline int get_uint(char **bpp, unsigned int *anint)
232 {
233 char buf[50];
234 int len = qword_get(bpp, buf, sizeof(buf));
235
236 if (len < 0)
237 return -EINVAL;
238 if (len == 0)
239 return -ENOENT;
240
241 if (kstrtouint(buf, 0, anint))
242 return -EINVAL;
243
244 return 0;
245 }
246
247 /*
248 * timestamps kept in the cache are expressed in seconds
249 * since boot. This is the best for measuring differences in
250 * real time.
251 */
seconds_since_boot(void)252 static inline time_t seconds_since_boot(void)
253 {
254 struct timespec boot;
255 getboottime(&boot);
256 return get_seconds() - boot.tv_sec;
257 }
258
convert_to_wallclock(time_t sinceboot)259 static inline time_t convert_to_wallclock(time_t sinceboot)
260 {
261 struct timespec boot;
262 getboottime(&boot);
263 return boot.tv_sec + sinceboot;
264 }
265
get_expiry(char ** bpp)266 static inline time_t get_expiry(char **bpp)
267 {
268 int rv;
269 struct timespec boot;
270
271 if (get_int(bpp, &rv))
272 return 0;
273 if (rv < 0)
274 return 0;
275 getboottime(&boot);
276 return rv - boot.tv_sec;
277 }
278
279 #endif /* _LINUX_SUNRPC_CACHE_H_ */
280