1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
|
/*
* include/linux/sunrpc/cache.h
*
* Generic code for various authentication-related caches
* used by sunrpc clients and servers.
*
* Copyright (C) 2002 Neil Brown <neilb@cse.unsw.edu.au>
*
* Released under terms in GPL version 2. See COPYING.
*
*/
#ifndef _LINUX_SUNRPC_CACHE_H_
#define _LINUX_SUNRPC_CACHE_H_
#include <linux/slab.h>
#include <asm/atomic.h>
#include <linux/proc_fs.h>
/*
* Each cache requires:
* - A 'struct cache_detail' which contains information specific to the cache
* for common code to use.
* - An item structure that must contain a "struct cache_head"
* - A lookup function defined using DefineCacheLookup
* - A 'put' function that can release a cache item. It will only
* be called after cache_put has succeed, so there are guarantee
* to be no references.
* - A function to calculate a hash of an item's key.
*
* as well as assorted code fragments (e.g. compare keys) and numbers
* (e.g. hash size, goal_age, etc).
*
* Each cache must be registered so that it can be cleaned regularly.
* When the cache is unregistered, it is flushed completely.
*
* Entries have a ref count and a 'hashed' flag which counts the existance
* in the hash table.
* We only expire entries when refcount is zero.
* Existance in the cache is counted the refcount.
*/
/* Every cache item has a common header that is used
* for expiring and refreshing entries.
*
*/
struct cache_head {
struct cache_head * next;
time_t expiry_time; /* After time time, don't use the data */
time_t last_refresh; /* If CACHE_PENDING, this is when upcall
* was sent, else this is when update was received
*/
struct kref ref;
unsigned long flags;
};
#define CACHE_VALID 0 /* Entry contains valid data */
#define CACHE_NEGATIVE 1 /* Negative entry - there is no match for the key */
#define CACHE_PENDING 2 /* An upcall has been sent but no reply received yet*/
#define CACHE_NEW_EXPIRY 120 /* keep new things pending confirmation for 120 seconds */
struct cache_detail {
struct module * owner;
int hash_size;
struct cache_head ** hash_table;
rwlock_t hash_lock;
atomic_t inuse; /* active user-space update or lookup */
char *name;
void (*cache_put)(struct kref *);
void (*cache_request)(struct cache_detail *cd,
struct cache_head *h,
char **bpp, int *blen);
int (*cache_parse)(struct cache_detail *,
char *buf, int len);
int (*cache_show)(struct seq_file *m,
struct cache_detail *cd,
struct cache_head *h);
struct cache_head * (*alloc)(void);
int (*match)(struct cache_head *orig, struct cache_head *new);
void (*init)(struct cache_head *orig, struct cache_head *new);
void (*update)(struct cache_head *orig, struct cache_head *new);
/* fields below this comment are for internal use
* and should not be touched by cache owners
*/
time_t flush_time; /* flush all cache items with last_refresh
* earlier than this */
struct list_head others;
time_t nextcheck;
int entries;
/* fields for communication over channel */
struct list_head queue;
struct proc_dir_entry *proc_ent;
struct proc_dir_entry *flush_ent, *channel_ent, *content_ent;
atomic_t readers; /* how many time is /chennel open */
time_t last_close; /* if no readers, when did last close */
time_t last_warn; /* when we last warned about no readers */
void (*warn_no_listener)(struct cache_detail *cd);
};
/* this must be embedded in any request structure that
* identifies an object that will want a callback on
* a cache fill
*/
struct cache_req {
struct cache_deferred_req *(*defer)(struct cache_req *req);
};
/* this must be embedded in a deferred_request that is being
* delayed awaiting cache-fill
*/
struct cache_deferred_req {
struct list_head hash; /* on hash chain */
struct list_head recent; /* on fifo */
struct cache_head *item; /* cache item we wait on */
void *owner; /* we might need to discard all defered requests
* owned by someone */
void (*revisit)(struct cache_deferred_req *req,
int too_many);
};
extern struct cache_head *
sunrpc_cache_lookup(struct cache_detail *detail,
struct cache_head *key, int hash);
extern struct cache_head *
sunrpc_cache_update(struct cache_detail *detail,
struct cache_head *new, struct cache_head *old, int hash);
extern void cache_clean_deferred(void *owner);
static inline struct cache_head *cache_get(struct cache_head *h)
{
kref_get(&h->ref);
return h;
}
static inline void cache_put(struct cache_head *h, struct cache_detail *cd)
{
if (atomic_read(&h->ref.refcount) <= 2 &&
h->expiry_time < cd->nextcheck)
cd->nextcheck = h->expiry_time;
kref_put(&h->ref, cd->cache_put);
}
static inline int cache_valid(struct cache_head *h)
{
/* If an item has been unhashed pending removal when
* the refcount drops to 0, the expiry_time will be
* set to 0. We don't want to consider such items
* valid in this context even though CACHE_VALID is
* set.
*/
return (h->expiry_time != 0 && test_bit(CACHE_VALID, &h->flags));
}
extern int cache_check(struct cache_detail *detail,
struct cache_head *h, struct cache_req *rqstp);
extern void cache_flush(void);
extern void cache_purge(struct cache_detail *detail);
#define NEVER (0x7FFFFFFF)
extern int cache_register(struct cache_detail *cd);
extern void cache_unregister(struct cache_detail *cd);
extern void qword_add(char **bpp, int *lp, char *str);
extern void qword_addhex(char **bpp, int *lp, char *buf, int blen);
extern int qword_get(char **bpp, char *dest, int bufsize);
static inline int get_int(char **bpp, int *anint)
{
char buf[50];
char *ep;
int rv;
int len = qword_get(bpp, buf, 50);
if (len < 0) return -EINVAL;
if (len ==0) return -ENOENT;
rv = simple_strtol(buf, &ep, 0);
if (*ep) return -EINVAL;
*anint = rv;
return 0;
}
static inline time_t get_expiry(char **bpp)
{
int rv;
if (get_int(bpp, &rv))
return 0;
if (rv < 0)
return 0;
return rv;
}
#endif /* _LINUX_SUNRPC_CACHE_H_ */
|
