summaryrefslogtreecommitdiffstats
path: root/include/linux/sunrpc/cache.h
blob: 6864063d1b9f0c6638a2c7fa94f525536179e522 (plain)
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
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
/*
 * 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
					 */
	atomic_t 	refcnt;
	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 {
	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 cache_head *,
					     struct cache_detail*);

	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);

	/* 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 */
	time_t			recv_time;
	void			*owner; /* we might need to discard all defered requests
					 * owned by someone */
	void			(*revisit)(struct cache_deferred_req *req,
					   int too_many);
};

/*
 * just like a template in C++, this macro does cache lookup
 * for us.
 * The function is passed some sort of HANDLE from which a cache_detail
 * structure can be determined (via SETUP, DETAIL), a template
 * cache entry (type RTN*), and a "set" flag.  Using the HASHFN and the 
 * TEST, the function will try to find a matching cache entry in the cache.
 * If "set" == 0 :
 *    If an entry is found, it is returned
 *    If no entry is found, a new non-VALID entry is created.
 * If "set" == 1 and INPLACE == 0 :
 *    If no entry is found a new one is inserted with data from "template"
 *    If a non-CACHE_VALID entry is found, it is updated from template using UPDATE
 *    If a CACHE_VALID entry is found, a new entry is swapped in with data
 *       from "template"
 * If set == 1, and INPLACE == 1 :
 *    As above, except that if a CACHE_VALID entry is found, we UPDATE in place
 *       instead of swapping in a new entry.
 *
 * If the passed handle has the CACHE_NEGATIVE flag set, then UPDATE is not
 * run but insteead CACHE_NEGATIVE is set in any new item.

 *  In any case, the new entry is returned with a reference count.
 *
 *    
 * RTN is a struct type for a cache entry
 * MEMBER is the member of the cache which is cache_head, which must be first
 * FNAME is the name for the function	
 * ARGS are arguments to function and must contain RTN *item, int set.  May
 *   also contain something to be usedby SETUP or DETAIL to find cache_detail.
 * SETUP  locates the cache detail and makes it available as...
 * DETAIL identifies the cache detail, possibly set up by SETUP
 * HASHFN returns a hash value of the cache entry "item"
 * TEST  tests if "tmp" matches "item"
 * INIT copies key information from "item" to "new"
 * UPDATE copies content information from "item" to "tmp"
 * INPLACE is true if updates can happen inplace rather than allocating a new structure
 *
 * WARNING: any substantial changes to this must be reflected in
 *   net/sunrpc/svcauth.c(auth_domain_lookup)
 *  which is a similar routine that is open-coded.
 */
#define DefineCacheLookup(RTN,MEMBER,FNAME,ARGS,SETUP,DETAIL,HASHFN,TEST,INIT,UPDATE,INPLACE)	\
RTN *FNAME ARGS										\
{											\
	RTN *tmp, *new=NULL;								\
	struct cache_head **hp, **head;							\
	SETUP;										\
	head = &(DETAIL)->hash_table[HASHFN];						\
 retry:											\
	if (set||new) write_lock(&(DETAIL)->hash_lock);					\
	else read_lock(&(DETAIL)->hash_lock);						\
	for(hp=head; *hp != NULL; hp = &tmp->MEMBER.next) {				\
		tmp = container_of(*hp, RTN, MEMBER);					\
		if (TEST) { /* found a match */						\
											\
			if (set && !INPLACE && test_bit(CACHE_VALID, &tmp->MEMBER.flags) && !new) \
				break;							\
											\
			if (new)							\
				{INIT;}							\
			if (set) {							\
				if (!INPLACE && test_bit(CACHE_VALID, &tmp->MEMBER.flags))\
				{ /* need to swap in new */				\
					RTN *t2;					\
											\
					new->MEMBER.next = tmp->MEMBER.next;		\
					*hp = &new->MEMBER;				\
					tmp->MEMBER.next = NULL;			\
					t2 = tmp; tmp = new; new = t2;			\
				}							\
				if (test_bit(CACHE_NEGATIVE,  &item->MEMBER.flags))	\
					set_bit(CACHE_NEGATIVE, &tmp->MEMBER.flags);	\
				else {							\
					UPDATE;						\
					clear_bit(CACHE_NEGATIVE, &tmp->MEMBER.flags);	\
				}							\
			}								\
			cache_get(&tmp->MEMBER);					\
			if (set||new) write_unlock(&(DETAIL)->hash_lock);		\
			else read_unlock(&(DETAIL)->hash_lock);				\
			if (set)							\
				cache_fresh(DETAIL, &tmp->MEMBER, item->MEMBER.expiry_time); \
			if (set && !INPLACE && new) cache_fresh(DETAIL, &new->MEMBER, 0);	\
			if (new) (DETAIL)->cache_put(&new->MEMBER, DETAIL);		\
			return tmp;							\
		}									\
	}										\
	/* Didn't find anything */							\
	if (new) {									\
		INIT;									\
		new->MEMBER.next = *head;						\
		*head = &new->MEMBER;							\
		(DETAIL)->entries ++;							\
		cache_get(&new->MEMBER);						\
		if (set) {								\
			tmp = new;							\
			if (test_bit(CACHE_NEGATIVE, &item->MEMBER.flags))		\
				set_bit(CACHE_NEGATIVE, &tmp->MEMBER.flags);		\
			else {UPDATE;}							\
		}									\
	}										\
	if (set||new) write_unlock(&(DETAIL)->hash_lock);				\
	else read_unlock(&(DETAIL)->hash_lock);						\
	if (new && set)									\
		cache_fresh(DETAIL, &new->MEMBER, item->MEMBER.expiry_time);		\
	if (new)				       					\
		return new;								\
	new = kmalloc(sizeof(*new), GFP_KERNEL);					\
	if (new) {									\
		cache_init(&new->MEMBER);						\
		goto retry;								\
	}										\
	return NULL;									\
}

#define DefineSimpleCacheLookup(STRUCT,INPLACE)	\
	DefineCacheLookup(struct STRUCT, h, STRUCT##_lookup, (struct STRUCT *item, int set), /*no setup */,	\
			  & STRUCT##_cache, STRUCT##_hash(item), STRUCT##_match(item, tmp),\
			  STRUCT##_init(new, item), STRUCT##_update(tmp, item),INPLACE)

#define cache_for_each(pos, detail, index, member) 						\
	for (({read_lock(&(detail)->hash_lock); index = (detail)->hash_size;}) ;		\
	     ({if (index==0)read_unlock(&(detail)->hash_lock); index--;});			\
		)										\
		for (pos = container_of((detail)->hash_table[index], typeof(*pos), member);	\
		     &pos->member;								\
		     pos = container_of(pos->member.next, typeof(*pos), member))

	     

extern void cache_clean_deferred(void *owner);

static inline struct cache_head  *cache_get(struct cache_head *h)
{
	atomic_inc(&h->refcnt);
	return h;
}


static inline int cache_put(struct cache_head *h, struct cache_detail *cd)
{
	if (atomic_read(&h->refcnt) <= 2 &&
	    h->expiry_time < cd->nextcheck)
		cd->nextcheck = h->expiry_time;
	return atomic_dec_and_test(&h->refcnt);
}

extern void cache_init(struct cache_head *h);
extern void cache_fresh(struct cache_detail *detail,
			struct cache_head *head, time_t expiry);
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 void cache_register(struct cache_detail *cd);
extern int 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_ */
OpenPOWER on IntegriCloud