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/kref.h>
17 #include <linux/slab.h>
18 #include <asm/atomic.h>
19 #include <linux/proc_fs.h>
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.
32 * as well as assorted code fragments (e.g. compare keys) and numbers
33 * (e.g. hash size, goal_age, etc).
35 * Each cache must be registered so that it can be cleaned regularly.
36 * When the cache is unregistered, it is flushed completely.
38 * Entries have a ref count and a 'hashed' flag which counts the existence
40 * We only expire entries when refcount is zero.
41 * Existence in the cache is counted the refcount.
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*/
61 #define CACHE_NEW_EXPIRY 120 /* keep new things pending confirmation for 120 seconds */
63 struct cache_detail_procfs
{
64 struct proc_dir_entry
*proc_ent
;
65 struct proc_dir_entry
*flush_ent
, *channel_ent
, *content_ent
;
68 struct cache_detail_pipefs
{
73 struct module
* owner
;
75 struct cache_head
** hash_table
;
78 atomic_t inuse
; /* active user-space update or lookup */
81 void (*cache_put
)(struct kref
*);
83 int (*cache_upcall
)(struct cache_detail
*,
86 int (*cache_parse
)(struct cache_detail
*,
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
,
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);
100 /* fields below this comment are for internal use
101 * and should not be touched by cache owners
103 time_t flush_time
; /* flush all cache items with last_refresh
104 * earlier than this */
105 struct list_head others
;
109 /* fields for communication over channel */
110 struct list_head queue
;
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 */
117 struct cache_detail_procfs procfs
;
118 struct cache_detail_pipefs pipefs
;
123 /* this must be embedded in any request structure that
124 * identifies an object that will want a callback on
128 struct cache_deferred_req
*(*defer
)(struct cache_req
*req
);
129 int thread_wait
; /* How long (jiffies) we can block the
130 * current thread to wait for updates.
133 /* this must be embedded in a deferred_request that is being
134 * delayed awaiting cache-fill
136 struct cache_deferred_req
{
137 struct hlist_node hash
; /* on hash chain */
138 struct list_head recent
; /* on fifo */
139 struct cache_head
*item
; /* cache item we wait on */
140 void *owner
; /* we might need to discard all defered requests
141 * owned by someone */
142 void (*revisit
)(struct cache_deferred_req
*req
,
147 extern const struct file_operations cache_file_operations_pipefs
;
148 extern const struct file_operations content_file_operations_pipefs
;
149 extern const struct file_operations cache_flush_operations_pipefs
;
151 extern struct cache_head
*
152 sunrpc_cache_lookup(struct cache_detail
*detail
,
153 struct cache_head
*key
, int hash
);
154 extern struct cache_head
*
155 sunrpc_cache_update(struct cache_detail
*detail
,
156 struct cache_head
*new, struct cache_head
*old
, int hash
);
159 sunrpc_cache_pipe_upcall(struct cache_detail
*detail
, struct cache_head
*h
,
160 void (*cache_request
)(struct cache_detail
*,
166 extern void cache_clean_deferred(void *owner
);
168 static inline struct cache_head
*cache_get(struct cache_head
*h
)
175 static inline void cache_put(struct cache_head
*h
, struct cache_detail
*cd
)
177 if (atomic_read(&h
->ref
.refcount
) <= 2 &&
178 h
->expiry_time
< cd
->nextcheck
)
179 cd
->nextcheck
= h
->expiry_time
;
180 kref_put(&h
->ref
, cd
->cache_put
);
183 static inline int cache_valid(struct cache_head
*h
)
185 /* If an item has been unhashed pending removal when
186 * the refcount drops to 0, the expiry_time will be
187 * set to 0. We don't want to consider such items
188 * valid in this context even though CACHE_VALID is
191 return (h
->expiry_time
!= 0 && test_bit(CACHE_VALID
, &h
->flags
));
194 extern int cache_check(struct cache_detail
*detail
,
195 struct cache_head
*h
, struct cache_req
*rqstp
);
196 extern void cache_flush(void);
197 extern void cache_purge(struct cache_detail
*detail
);
198 #define NEVER (0x7FFFFFFF)
199 extern void __init
cache_initialize(void);
200 extern int cache_register(struct cache_detail
*cd
);
201 extern int cache_register_net(struct cache_detail
*cd
, struct net
*net
);
202 extern void cache_unregister(struct cache_detail
*cd
);
203 extern void cache_unregister_net(struct cache_detail
*cd
, struct net
*net
);
205 extern int sunrpc_cache_register_pipefs(struct dentry
*parent
, const char *,
206 mode_t
, struct cache_detail
*);
207 extern void sunrpc_cache_unregister_pipefs(struct cache_detail
*);
209 extern void qword_add(char **bpp
, int *lp
, char *str
);
210 extern void qword_addhex(char **bpp
, int *lp
, char *buf
, int blen
);
211 extern int qword_get(char **bpp
, char *dest
, int bufsize
);
213 static inline int get_int(char **bpp
, int *anint
)
218 int len
= qword_get(bpp
, buf
, 50);
219 if (len
< 0) return -EINVAL
;
220 if (len
==0) return -ENOENT
;
221 rv
= simple_strtol(buf
, &ep
, 0);
222 if (*ep
) return -EINVAL
;
228 * timestamps kept in the cache are expressed in seconds
229 * since boot. This is the best for measuring differences in
232 static inline time_t seconds_since_boot(void)
234 struct timespec boot
;
236 return get_seconds() - boot
.tv_sec
;
239 static inline time_t convert_to_wallclock(time_t sinceboot
)
241 struct timespec boot
;
243 return boot
.tv_sec
+ sinceboot
;
246 static inline time_t get_expiry(char **bpp
)
249 struct timespec boot
;
251 if (get_int(bpp
, &rv
))
256 return rv
- boot
.tv_sec
;
259 #ifdef CONFIG_NFSD_DEPRECATED
260 static inline void sunrpc_invalidate(struct cache_head
*h
,
261 struct cache_detail
*detail
)
263 h
->expiry_time
= seconds_since_boot() - 1;
264 detail
->nextcheck
= seconds_since_boot();
266 #endif /* CONFIG_NFSD_DEPRECATED */
268 #endif /* _LINUX_SUNRPC_CACHE_H_ */