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 counted the refcount.
43 /* Every cache item has a common header that is used
44 * for expiring and refreshing entries.
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
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*/
60 #define CACHE_NEW_EXPIRY 120 /* keep new things pending confirmation for 120 seconds */
62 struct cache_detail_procfs {
63 struct proc_dir_entry *proc_ent;
64 struct proc_dir_entry *flush_ent, *channel_ent, *content_ent;
68 struct module * owner;
70 struct cache_head ** hash_table;
73 atomic_t inuse; /* active user-space update or lookup */
76 void (*cache_put)(struct kref *);
78 int (*cache_upcall)(struct cache_detail *,
81 int (*cache_parse)(struct cache_detail *,
84 int (*cache_show)(struct seq_file *m,
85 struct cache_detail *cd,
86 struct cache_head *h);
87 void (*warn_no_listener)(struct cache_detail *cd,
90 struct cache_head * (*alloc)(void);
91 int (*match)(struct cache_head *orig, struct cache_head *new);
92 void (*init)(struct cache_head *orig, struct cache_head *new);
93 void (*update)(struct cache_head *orig, struct cache_head *new);
95 /* fields below this comment are for internal use
96 * and should not be touched by cache owners
98 time_t flush_time; /* flush all cache items with last_refresh
99 * earlier than this */
100 struct list_head others;
104 /* fields for communication over channel */
105 struct list_head queue;
107 atomic_t readers; /* how many time is /chennel open */
108 time_t last_close; /* if no readers, when did last close */
109 time_t last_warn; /* when we last warned about no readers */
112 struct cache_detail_procfs procfs;
117 /* this must be embedded in any request structure that
118 * identifies an object that will want a callback on
122 struct cache_deferred_req *(*defer)(struct cache_req *req);
124 /* this must be embedded in a deferred_request that is being
125 * delayed awaiting cache-fill
127 struct cache_deferred_req {
128 struct list_head hash; /* on hash chain */
129 struct list_head recent; /* on fifo */
130 struct cache_head *item; /* cache item we wait on */
131 void *owner; /* we might need to discard all defered requests
132 * owned by someone */
133 void (*revisit)(struct cache_deferred_req *req,
138 extern struct cache_head *
139 sunrpc_cache_lookup(struct cache_detail *detail,
140 struct cache_head *key, int hash);
141 extern struct cache_head *
142 sunrpc_cache_update(struct cache_detail *detail,
143 struct cache_head *new, struct cache_head *old, int hash);
146 sunrpc_cache_pipe_upcall(struct cache_detail *detail, struct cache_head *h,
147 void (*cache_request)(struct cache_detail *,
153 extern void cache_clean_deferred(void *owner);
155 static inline struct cache_head *cache_get(struct cache_head *h)
162 static inline void cache_put(struct cache_head *h, struct cache_detail *cd)
164 if (atomic_read(&h->ref.refcount) <= 2 &&
165 h->expiry_time < cd->nextcheck)
166 cd->nextcheck = h->expiry_time;
167 kref_put(&h->ref, cd->cache_put);
170 static inline int cache_valid(struct cache_head *h)
172 /* If an item has been unhashed pending removal when
173 * the refcount drops to 0, the expiry_time will be
174 * set to 0. We don't want to consider such items
175 * valid in this context even though CACHE_VALID is
178 return (h->expiry_time != 0 && test_bit(CACHE_VALID, &h->flags));
181 extern int cache_check(struct cache_detail *detail,
182 struct cache_head *h, struct cache_req *rqstp);
183 extern void cache_flush(void);
184 extern void cache_purge(struct cache_detail *detail);
185 #define NEVER (0x7FFFFFFF)
186 extern int cache_register(struct cache_detail *cd);
187 extern void cache_unregister(struct cache_detail *cd);
189 extern void qword_add(char **bpp, int *lp, char *str);
190 extern void qword_addhex(char **bpp, int *lp, char *buf, int blen);
191 extern int qword_get(char **bpp, char *dest, int bufsize);
193 static inline int get_int(char **bpp, int *anint)
198 int len = qword_get(bpp, buf, 50);
199 if (len < 0) return -EINVAL;
200 if (len ==0) return -ENOENT;
201 rv = simple_strtol(buf, &ep, 0);
202 if (*ep) return -EINVAL;
207 static inline time_t get_expiry(char **bpp)
210 if (get_int(bpp, &rv))
217 #endif /* _LINUX_SUNRPC_CACHE_H_ */