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Linux v2.6.15-rc7
[pohmelfs.git] / include / linux / sunrpc / cache.h
blobc4e3ea7cf1545e5da79e504c8fabddbc1f4a8d87
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/slab.h>
17 #include <asm/atomic.h>
18 #include <linux/proc_fs.h>
19
20 /*
21 * Each cache requires:
22 * - A 'struct cache_detail' which contains information specific to the cache
23 * for common code to use.
24 * - An item structure that must contain a "struct cache_head"
25 * - A lookup function defined using DefineCacheLookup
26 * - A 'put' function that can release a cache item. It will only
27 * be called after cache_put has succeed, so there are guarantee
28 * to be no references.
29 * - A function to calculate a hash of an item's key.
30 *
31 * as well as assorted code fragments (e.g. compare keys) and numbers
32 * (e.g. hash size, goal_age, etc).
33 *
34 * Each cache must be registered so that it can be cleaned regularly.
35 * When the cache is unregistered, it is flushed completely.
36 *
37 * Entries have a ref count and a 'hashed' flag which counts the existance
38 * in the hash table.
39 * We only expire entries when refcount is zero.
40 * Existance in the cache is counted the refcount.
41 */
42
43 /* Every cache item has a common header that is used
44 * for expiring and refreshing entries.
45 *
46 */
47 struct cache_head {
48 struct cache_head * next;
49 time_t expiry_time; /* After time time, don't use the data */
50 time_t last_refresh; /* If CACHE_PENDING, this is when upcall
51 * was sent, else this is when update was received
52 */
53 atomic_t refcnt;
54 unsigned long flags;
55 };
56 #define CACHE_VALID 0 /* Entry contains valid data */
57 #define CACHE_NEGATIVE 1 /* Negative entry - there is no match for the key */
58 #define CACHE_PENDING 2 /* An upcall has been sent but no reply received yet*/
59
60 #define CACHE_NEW_EXPIRY 120 /* keep new things pending confirmation for 120 seconds */
61
62 struct cache_detail {
63 struct module * owner;
64 int hash_size;
65 struct cache_head ** hash_table;
66 rwlock_t hash_lock;
67
68 atomic_t inuse; /* active user-space update or lookup */
69
70 char *name;
71 void (*cache_put)(struct cache_head *,
72 struct cache_detail*);
73
74 void (*cache_request)(struct cache_detail *cd,
75 struct cache_head *h,
76 char **bpp, int *blen);
77 int (*cache_parse)(struct cache_detail *,
78 char *buf, int len);
79
80 int (*cache_show)(struct seq_file *m,
81 struct cache_detail *cd,
82 struct cache_head *h);
83
84 /* fields below this comment are for internal use
85 * and should not be touched by cache owners
86 */
87 time_t flush_time; /* flush all cache items with last_refresh
88 * earlier than this */
89 struct list_head others;
90 time_t nextcheck;
91 int entries;
92
93 /* fields for communication over channel */
94 struct list_head queue;
95 struct proc_dir_entry *proc_ent;
96 struct proc_dir_entry *flush_ent, *channel_ent, *content_ent;
97
98 atomic_t readers; /* how many time is /chennel open */
99 time_t last_close; /* if no readers, when did last close */
100 time_t last_warn; /* when we last warned about no readers */
101 void (*warn_no_listener)(struct cache_detail *cd);
102 };
103
104
105 /* this must be embedded in any request structure that
106 * identifies an object that will want a callback on
107 * a cache fill
108 */
109 struct cache_req {
110 struct cache_deferred_req *(*defer)(struct cache_req *req);
111 };
112 /* this must be embedded in a deferred_request that is being
113 * delayed awaiting cache-fill
114 */
115 struct cache_deferred_req {
116 struct list_head hash; /* on hash chain */
117 struct list_head recent; /* on fifo */
118 struct cache_head *item; /* cache item we wait on */
119 time_t recv_time;
120 void *owner; /* we might need to discard all defered requests
121 * owned by someone */
122 void (*revisit)(struct cache_deferred_req *req,
123 int too_many);
124 };
125
126 /*
127 * just like a template in C++, this macro does cache lookup
128 * for us.
129 * The function is passed some sort of HANDLE from which a cache_detail
130 * structure can be determined (via SETUP, DETAIL), a template
131 * cache entry (type RTN*), and a "set" flag. Using the HASHFN and the
132 * TEST, the function will try to find a matching cache entry in the cache.
133 * If "set" == 0 :
134 * If an entry is found, it is returned
135 * If no entry is found, a new non-VALID entry is created.
136 * If "set" == 1 and INPLACE == 0 :
137 * If no entry is found a new one is inserted with data from "template"
138 * If a non-CACHE_VALID entry is found, it is updated from template using UPDATE
139 * If a CACHE_VALID entry is found, a new entry is swapped in with data
140 * from "template"
141 * If set == 1, and INPLACE == 1 :
142 * As above, except that if a CACHE_VALID entry is found, we UPDATE in place
143 * instead of swapping in a new entry.
144 *
145 * If the passed handle has the CACHE_NEGATIVE flag set, then UPDATE is not
146 * run but insteead CACHE_NEGATIVE is set in any new item.
147
148 * In any case, the new entry is returned with a reference count.
149 *
150 *
151 * RTN is a struct type for a cache entry
152 * MEMBER is the member of the cache which is cache_head, which must be first
153 * FNAME is the name for the function
154 * ARGS are arguments to function and must contain RTN *item, int set. May
155 * also contain something to be usedby SETUP or DETAIL to find cache_detail.
156 * SETUP locates the cache detail and makes it available as...
157 * DETAIL identifies the cache detail, possibly set up by SETUP
158 * HASHFN returns a hash value of the cache entry "item"
159 * TEST tests if "tmp" matches "item"
160 * INIT copies key information from "item" to "new"
161 * UPDATE copies content information from "item" to "tmp"
162 * INPLACE is true if updates can happen inplace rather than allocating a new structure
163 *
164 * WARNING: any substantial changes to this must be reflected in
165 * net/sunrpc/svcauth.c(auth_domain_lookup)
166 * which is a similar routine that is open-coded.
167 */
168 #define DefineCacheLookup(RTN,MEMBER,FNAME,ARGS,SETUP,DETAIL,HASHFN,TEST,INIT,UPDATE,INPLACE) \
169 RTN *FNAME ARGS \
170 { \
171 RTN *tmp, *new=NULL; \
172 struct cache_head **hp, **head; \
173 SETUP; \
174 head = &(DETAIL)->hash_table[HASHFN]; \
175 retry: \
176 if (set||new) write_lock(&(DETAIL)->hash_lock); \
177 else read_lock(&(DETAIL)->hash_lock); \
178 for(hp=head; *hp != NULL; hp = &tmp->MEMBER.next) { \
179 tmp = container_of(*hp, RTN, MEMBER); \
180 if (TEST) { /* found a match */ \
181 \
182 if (set && !INPLACE && test_bit(CACHE_VALID, &tmp->MEMBER.flags) && !new) \
183 break; \
184 \
185 if (new) \
186 {INIT;} \
187 if (set) { \
188 if (!INPLACE && test_bit(CACHE_VALID, &tmp->MEMBER.flags))\
189 { /* need to swap in new */ \
190 RTN *t2; \
191 \
192 new->MEMBER.next = tmp->MEMBER.next; \
193 *hp = &new->MEMBER; \
194 tmp->MEMBER.next = NULL; \
195 t2 = tmp; tmp = new; new = t2; \
196 } \
197 if (test_bit(CACHE_NEGATIVE, &item->MEMBER.flags)) \
198 set_bit(CACHE_NEGATIVE, &tmp->MEMBER.flags); \
199 else { \
200 UPDATE; \
201 clear_bit(CACHE_NEGATIVE, &tmp->MEMBER.flags); \
202 } \
203 } \
204 cache_get(&tmp->MEMBER); \
205 if (set||new) write_unlock(&(DETAIL)->hash_lock); \
206 else read_unlock(&(DETAIL)->hash_lock); \
207 if (set) \
208 cache_fresh(DETAIL, &tmp->MEMBER, item->MEMBER.expiry_time); \
209 if (set && !INPLACE && new) cache_fresh(DETAIL, &new->MEMBER, 0); \
210 if (new) (DETAIL)->cache_put(&new->MEMBER, DETAIL); \
211 return tmp; \
212 } \
213 } \
214 /* Didn't find anything */ \
215 if (new) { \
216 INIT; \
217 new->MEMBER.next = *head; \
218 *head = &new->MEMBER; \
219 (DETAIL)->entries ++; \
220 cache_get(&new->MEMBER); \
221 if (set) { \
222 tmp = new; \
223 if (test_bit(CACHE_NEGATIVE, &item->MEMBER.flags)) \
224 set_bit(CACHE_NEGATIVE, &tmp->MEMBER.flags); \
225 else {UPDATE;} \
226 } \
227 } \
228 if (set||new) write_unlock(&(DETAIL)->hash_lock); \
229 else read_unlock(&(DETAIL)->hash_lock); \
230 if (new && set) \
231 cache_fresh(DETAIL, &new->MEMBER, item->MEMBER.expiry_time); \
232 if (new) \
233 return new; \
234 new = kmalloc(sizeof(*new), GFP_KERNEL); \
235 if (new) { \
236 cache_init(&new->MEMBER); \
237 goto retry; \
238 } \
239 return NULL; \
240 }
241
242 #define DefineSimpleCacheLookup(STRUCT,INPLACE) \
243 DefineCacheLookup(struct STRUCT, h, STRUCT##_lookup, (struct STRUCT *item, int set), /*no setup */, \
244 & STRUCT##_cache, STRUCT##_hash(item), STRUCT##_match(item, tmp),\
245 STRUCT##_init(new, item), STRUCT##_update(tmp, item),INPLACE)
246
247 #define cache_for_each(pos, detail, index, member) \
248 for (({read_lock(&(detail)->hash_lock); index = (detail)->hash_size;}) ; \
249 ({if (index==0)read_unlock(&(detail)->hash_lock); index--;}); \
250 ) \
251 for (pos = container_of((detail)->hash_table[index], typeof(*pos), member); \
252 &pos->member; \
253 pos = container_of(pos->member.next, typeof(*pos), member))
254
255
256
257 extern void cache_clean_deferred(void *owner);
258
259 static inline struct cache_head *cache_get(struct cache_head *h)
260 {
261 atomic_inc(&h->refcnt);
262 return h;
263 }
264
265
266 static inline int cache_put(struct cache_head *h, struct cache_detail *cd)
267 {
268 if (atomic_read(&h->refcnt) <= 2 &&
269 h->expiry_time < cd->nextcheck)
270 cd->nextcheck = h->expiry_time;
271 return atomic_dec_and_test(&h->refcnt);
272 }
273
274 extern void cache_init(struct cache_head *h);
275 extern void cache_fresh(struct cache_detail *detail,
276 struct cache_head *head, time_t expiry);
277 extern int cache_check(struct cache_detail *detail,
278 struct cache_head *h, struct cache_req *rqstp);
279 extern void cache_flush(void);
280 extern void cache_purge(struct cache_detail *detail);
281 #define NEVER (0x7FFFFFFF)
282 extern void cache_register(struct cache_detail *cd);
283 extern int cache_unregister(struct cache_detail *cd);
284
285 extern void qword_add(char **bpp, int *lp, char *str);
286 extern void qword_addhex(char **bpp, int *lp, char *buf, int blen);
287 extern int qword_get(char **bpp, char *dest, int bufsize);
288
289 static inline int get_int(char **bpp, int *anint)
290 {
291 char buf[50];
292 char *ep;
293 int rv;
294 int len = qword_get(bpp, buf, 50);
295 if (len < 0) return -EINVAL;
296 if (len ==0) return -ENOENT;
297 rv = simple_strtol(buf, &ep, 0);
298 if (*ep) return -EINVAL;
299 *anint = rv;
300 return 0;
301 }
302
303 static inline time_t get_expiry(char **bpp)
304 {
305 int rv;
306 if (get_int(bpp, &rv))
307 return 0;
308 if (rv < 0)
309 return 0;
310 return rv;
311 }
312
313 #endif /* _LINUX_SUNRPC_CACHE_H_ */