2 * include/linux/sunrpc/cache.h
4 * Generic code for various authentication-related caches
5 * used by sunrpc clients and servers.
7 * Copyright (C) 2002 Neil Brown <neilb@cse.unsw.edu.au>
9 * Released under terms in GPL version 2. See COPYING.
13 #ifndef _LINUX_SUNRPC_CACHE_H_
14 #define _LINUX_SUNRPC_CACHE_H_
16 #include <linux/slab.h>
17 #include <asm/atomic.h>
18 #include <linux/proc_fs.h>
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.
31 * as well as assorted code fragments (e.g. compare keys) and numbers
32 * (e.g. hash size, goal_age, etc).
34 * Each cache must be registered so that it can be cleaned regularly.
35 * When the cache is unregistered, it is flushed completely.
37 * Entries have a ref count and a 'hashed' flag which counts the existance
39 * We only expire entries when refcount is zero.
40 * Existance in the cache is not measured in refcount but rather in
44 /* Every cache item has a common header that is used
45 * for expiring and refreshing entries.
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
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 #define CACHE_HASHED 3 /* Entry is in a hash table */
62 #define CACHE_NEW_EXPIRY 120 /* keep new things pending confirmation for 120 seconds */
66 struct cache_head ** hash_table;
69 atomic_t inuse; /* active user-space update or lookup */
72 void (*cache_put)(struct cache_head *,
73 struct cache_detail*);
75 void (*cache_request)(struct cache_detail *cd,
77 char **bpp, int *blen);
78 int (*cache_parse)(struct cache_detail *,
81 int (*cache_show)(struct seq_file *m,
82 struct cache_detail *cd,
83 struct cache_head *h);
85 /* fields below this comment are for internal use
86 * and should not be touched by cache owners
88 time_t flush_time; /* flush all cache items with last_refresh
89 * earlier than this */
90 struct list_head others;
94 /* fields for communication over channel */
95 struct list_head queue;
96 struct proc_dir_entry *proc_ent;
97 struct proc_dir_entry *flush_ent, *channel_ent, *content_ent;
99 atomic_t readers; /* how many time is /chennel open */
100 time_t last_close; /* if no readers, when did last close */
101 time_t last_warn; /* when we last warned about no readers */
102 void (*warn_no_listener)(struct cache_detail *cd);
106 /* this must be embedded in any request structure that
107 * identifies an object that will want a callback on
111 struct cache_deferred_req *(*defer)(struct cache_req *req);
113 /* this must be embedded in a deferred_request that is being
114 * delayed awaiting cache-fill
116 struct cache_deferred_req {
117 struct list_head hash; /* on hash chain */
118 struct list_head recent; /* on fifo */
119 struct cache_head *item; /* cache item we wait on */
121 void *owner; /* we might need to discard all defered requests
122 * owned by someone */
123 void (*revisit)(struct cache_deferred_req *req,
128 * just like a template in C++, this macro does cache lookup
130 * The function is passed some sort of HANDLE from which a cache_detail
131 * structure can be determined (via SETUP, DETAIL), a template
132 * cache entry (type RTN*), and a "set" flag. Using the HASHFN and the
133 * TEST, the function will try to find a matching cache entry in the cache.
135 * If an entry is found, it is returned
136 * If no entry is found, a new non-VALID entry is created.
137 * If "set" == 1 and INPLACE == 0 :
138 * If no entry is found a new one is inserted with data from "template"
139 * If a non-CACHE_VALID entry is found, it is updated from template using UPDATE
140 * If a CACHE_VALID entry is found, a new entry is swapped in with data
142 * If set == 1, and INPLACE == 1 :
143 * As above, except that if a CACHE_VALID entry is found, we UPDATE in place
144 * instead of swapping in a new entry.
146 * If the passed handle has the CACHE_NEGATIVE flag set, then UPDATE is not
147 * run but insteead CACHE_NEGATIVE is set in any new item.
149 * In any case, the new entry is returned with a reference count.
152 * RTN is a struct type for a cache entry
153 * MEMBER is the member of the cache which is cache_head, which must be first
154 * FNAME is the name for the function
155 * ARGS are arguments to function and must contain RTN *item, int set. May
156 * also contain something to be usedby SETUP or DETAIL to find cache_detail.
157 * SETUP locates the cache detail and makes it available as...
158 * DETAIL identifies the cache detail, possibly set up by SETUP
159 * HASHFN returns a hash value of the cache entry "item"
160 * TEST tests if "tmp" matches "item"
161 * INIT copies key information from "item" to "new"
162 * UPDATE copies content information from "item" to "tmp"
163 * INPLACE is true if updates can happen inplace rather than allocating a new structure
165 #define DefineCacheLookup(RTN,MEMBER,FNAME,ARGS,SETUP,DETAIL,HASHFN,TEST,INIT,UPDATE,INPLACE) \
168 RTN *tmp, *new=NULL; \
169 struct cache_head **hp, **head; \
171 head = &(DETAIL)->hash_table[HASHFN]; \
173 if (set||new) write_lock(&(DETAIL)->hash_lock); \
174 else read_lock(&(DETAIL)->hash_lock); \
175 for(hp=head; *hp != NULL; hp = &tmp->MEMBER.next) { \
176 tmp = container_of(*hp, RTN, MEMBER); \
177 if (TEST) { /* found a match */ \
179 if (set && !INPLACE && test_bit(CACHE_VALID, &tmp->MEMBER.flags) && !new) \
184 cache_get(&tmp->MEMBER); \
186 if (!INPLACE && test_bit(CACHE_VALID, &tmp->MEMBER.flags))\
187 { /* need to swap in new */ \
190 new->MEMBER.next = tmp->MEMBER.next; \
191 *hp = &new->MEMBER; \
192 tmp->MEMBER.next = NULL; \
193 set_bit(CACHE_HASHED, &new->MEMBER.flags); \
194 clear_bit(CACHE_HASHED, &tmp->MEMBER.flags); \
195 t2 = tmp; tmp = new; new = t2; \
197 if (test_bit(CACHE_NEGATIVE, &item->MEMBER.flags)) \
198 set_bit(CACHE_NEGATIVE, &tmp->MEMBER.flags); \
201 clear_bit(CACHE_NEGATIVE, &tmp->MEMBER.flags); \
204 if (set||new) write_unlock(&(DETAIL)->hash_lock); \
205 else read_unlock(&(DETAIL)->hash_lock); \
207 cache_fresh(DETAIL, &tmp->MEMBER, item->MEMBER.expiry_time); \
208 if (set && !INPLACE && new) cache_fresh(DETAIL, &new->MEMBER, 0); \
209 if (new) (DETAIL)->cache_put(&new->MEMBER, DETAIL); \
213 /* Didn't find anything */ \
216 new->MEMBER.next = *head; \
217 *head = &new->MEMBER; \
218 (DETAIL)->entries ++; \
219 set_bit(CACHE_HASHED, &new->MEMBER.flags); \
222 if (test_bit(CACHE_NEGATIVE, &item->MEMBER.flags)) \
223 set_bit(CACHE_NEGATIVE, &tmp->MEMBER.flags); \
227 if (set||new) write_unlock(&(DETAIL)->hash_lock); \
228 else read_unlock(&(DETAIL)->hash_lock); \
230 cache_fresh(DETAIL, &new->MEMBER, item->MEMBER.expiry_time); \
233 new = kmalloc(sizeof(*new), GFP_KERNEL); \
235 cache_init(&new->MEMBER); \
236 cache_get(&new->MEMBER); \
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)
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--;}); \
251 for (pos = container_of((detail)->hash_table[index], typeof(*pos), member); \
253 pos = container_of(pos->member.next, typeof(*pos), member))
257 extern void cache_defer_req(struct cache_req *req, struct cache_head *item);
258 extern void cache_revisit_request(struct cache_head *item);
259 extern void cache_clean_deferred(void *owner);
261 static inline struct cache_head *cache_get(struct cache_head *h)
263 atomic_inc(&h->refcnt);
268 static inline int cache_put(struct cache_head *h, struct cache_detail *cd)
270 atomic_dec(&h->refcnt);
271 if (!atomic_read(&h->refcnt) &&
272 h->expiry_time < cd->nextcheck)
273 cd->nextcheck = h->expiry_time;
274 if (!test_bit(CACHE_HASHED, &h->flags) &&
275 !atomic_read(&h->refcnt))
281 extern void cache_init(struct cache_head *h);
282 extern void cache_fresh(struct cache_detail *detail,
283 struct cache_head *head, time_t expiry);
284 extern int cache_check(struct cache_detail *detail,
285 struct cache_head *h, struct cache_req *rqstp);
286 extern int cache_clean(void);
287 extern void cache_flush(void);
288 extern void cache_purge(struct cache_detail *detail);
289 #define NEVER (0x7FFFFFFF)
290 extern void cache_register(struct cache_detail *cd);
291 extern int cache_unregister(struct cache_detail *cd);
292 extern struct cache_detail *cache_find(char *name);
293 extern void cache_drop(struct cache_detail *detail);
295 extern void qword_add(char **bpp, int *lp, char *str);
296 extern void qword_addhex(char **bpp, int *lp, char *buf, int blen);
297 extern int qword_get(char **bpp, char *dest, int bufsize);
299 static inline int get_int(char **bpp, int *anint)
304 int len = qword_get(bpp, buf, 50);
305 if (len < 0) return -EINVAL;
306 if (len ==0) return -ENOENT;
307 rv = simple_strtol(buf, &ep, 0);
308 if (*ep) return -EINVAL;
313 static inline time_t get_expiry(char **bpp)
316 if (get_int(bpp, &rv))
323 #endif /* _LINUX_SUNRPC_CACHE_H_ */