1/*
2 * include/linux/sunrpc/cache.h
3 *
4 * Generic code for various authentication-related caches
5 * used by sunrpc clients and servers.
6 *
7 * Copyright (C) 2002 Neil Brown <neilb@cse.unsw.edu.au>
8 *
9 * Released under terms in GPL version 2.  See COPYING.
10 *
11 */
12
13#ifndef _LINUX_SUNRPC_CACHE_H_
14#define _LINUX_SUNRPC_CACHE_H_
15
16#include <linux/kref.h>
17#include <linux/slab.h>
18#include <linux/atomic.h>
19#include <linux/proc_fs.h>
20
21/*
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.
31 *
32 * as well as assorted code fragments (e.g. compare keys) and numbers
33 * (e.g. hash size, goal_age, etc).
34 *
35 * Each cache must be registered so that it can be cleaned regularly.
36 * When the cache is unregistered, it is flushed completely.
37 *
38 * Entries have a ref count and a 'hashed' flag which counts the existence
39 * in the hash table.
40 * We only expire entries when refcount is zero.
41 * Existence in the cache is counted  the refcount.
42 */
43
44/* Every cache item has a common header that is used
45 * for expiring and refreshing entries.
46 *
47 */
48struct cache_head {
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
53					 */
54	struct kref	ref;
55	unsigned long	flags;
56};
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_CLEANED	3	/* Entry has been cleaned from cache */
61
62#define	CACHE_NEW_EXPIRY 120	/* keep new things pending confirmation for 120 seconds */
63
64struct cache_detail_procfs {
65	struct proc_dir_entry	*proc_ent;
66	struct proc_dir_entry   *flush_ent, *channel_ent, *content_ent;
67};
68
69struct cache_detail_pipefs {
70	struct dentry *dir;
71};
72
73struct cache_detail {
74	struct module *		owner;
75	int			hash_size;
76	struct cache_head **	hash_table;
77	rwlock_t		hash_lock;
78
79	atomic_t		inuse; /* active user-space update or lookup */
80
81	char			*name;
82	void			(*cache_put)(struct kref *);
83
84	int			(*cache_upcall)(struct cache_detail *,
85						struct cache_head *);
86
87	void			(*cache_request)(struct cache_detail *cd,
88						 struct cache_head *ch,
89						 char **bpp, int *blen);
90
91	int			(*cache_parse)(struct cache_detail *,
92					       char *buf, int len);
93
94	int			(*cache_show)(struct seq_file *m,
95					      struct cache_detail *cd,
96					      struct cache_head *h);
97	void			(*warn_no_listener)(struct cache_detail *cd,
98					      int has_died);
99
100	struct cache_head *	(*alloc)(void);
101	int			(*match)(struct cache_head *orig, struct cache_head *new);
102	void			(*init)(struct cache_head *orig, struct cache_head *new);
103	void			(*update)(struct cache_head *orig, struct cache_head *new);
104
105	/* fields below this comment are for internal use
106	 * and should not be touched by cache owners
107	 */
108	time_t			flush_time;		/* flush all cache items with last_refresh
109							 * earlier than this */
110	struct list_head	others;
111	time_t			nextcheck;
112	int			entries;
113
114	/* fields for communication over channel */
115	struct list_head	queue;
116
117	atomic_t		readers;		/* how many time is /chennel open */
118	time_t			last_close;		/* if no readers, when did last close */
119	time_t			last_warn;		/* when we last warned about no readers */
120
121	union {
122		struct cache_detail_procfs procfs;
123		struct cache_detail_pipefs pipefs;
124	} u;
125	struct net		*net;
126};
127
128
129/* this must be embedded in any request structure that
130 * identifies an object that will want a callback on
131 * a cache fill
132 */
133struct cache_req {
134	struct cache_deferred_req *(*defer)(struct cache_req *req);
135	int thread_wait;  /* How long (jiffies) we can block the
136			   * current thread to wait for updates.
137			   */
138};
139/* this must be embedded in a deferred_request that is being
140 * delayed awaiting cache-fill
141 */
142struct cache_deferred_req {
143	struct hlist_node	hash;	/* on hash chain */
144	struct list_head	recent; /* on fifo */
145	struct cache_head	*item;  /* cache item we wait on */
146	void			*owner; /* we might need to discard all defered requests
147					 * owned by someone */
148	void			(*revisit)(struct cache_deferred_req *req,
149					   int too_many);
150};
151
152/*
153 * timestamps kept in the cache are expressed in seconds
154 * since boot.  This is the best for measuring differences in
155 * real time.
156 */
157static inline time_t seconds_since_boot(void)
158{
159	struct timespec boot;
160	getboottime(&boot);
161	return get_seconds() - boot.tv_sec;
162}
163
164static inline time_t convert_to_wallclock(time_t sinceboot)
165{
166	struct timespec boot;
167	getboottime(&boot);
168	return boot.tv_sec + sinceboot;
169}
170
171extern const struct file_operations cache_file_operations_pipefs;
172extern const struct file_operations content_file_operations_pipefs;
173extern const struct file_operations cache_flush_operations_pipefs;
174
175extern struct cache_head *
176sunrpc_cache_lookup(struct cache_detail *detail,
177		    struct cache_head *key, int hash);
178extern struct cache_head *
179sunrpc_cache_update(struct cache_detail *detail,
180		    struct cache_head *new, struct cache_head *old, int hash);
181
182extern int
183sunrpc_cache_pipe_upcall(struct cache_detail *detail, struct cache_head *h);
184
185
186extern void cache_clean_deferred(void *owner);
187
188static inline struct cache_head  *cache_get(struct cache_head *h)
189{
190	kref_get(&h->ref);
191	return h;
192}
193
194
195static inline void cache_put(struct cache_head *h, struct cache_detail *cd)
196{
197	if (atomic_read(&h->ref.refcount) <= 2 &&
198	    h->expiry_time < cd->nextcheck)
199		cd->nextcheck = h->expiry_time;
200	kref_put(&h->ref, cd->cache_put);
201}
202
203static inline int cache_is_expired(struct cache_detail *detail, struct cache_head *h)
204{
205	return  (h->expiry_time < seconds_since_boot()) ||
206		(detail->flush_time > h->last_refresh);
207}
208
209extern int cache_check(struct cache_detail *detail,
210		       struct cache_head *h, struct cache_req *rqstp);
211extern void cache_flush(void);
212extern void cache_purge(struct cache_detail *detail);
213#define NEVER (0x7FFFFFFF)
214extern void __init cache_initialize(void);
215extern int cache_register_net(struct cache_detail *cd, struct net *net);
216extern void cache_unregister_net(struct cache_detail *cd, struct net *net);
217
218extern struct cache_detail *cache_create_net(struct cache_detail *tmpl, struct net *net);
219extern void cache_destroy_net(struct cache_detail *cd, struct net *net);
220
221extern void sunrpc_init_cache_detail(struct cache_detail *cd);
222extern void sunrpc_destroy_cache_detail(struct cache_detail *cd);
223extern int sunrpc_cache_register_pipefs(struct dentry *parent, const char *,
224					umode_t, struct cache_detail *);
225extern void sunrpc_cache_unregister_pipefs(struct cache_detail *);
226
227extern void qword_add(char **bpp, int *lp, char *str);
228extern void qword_addhex(char **bpp, int *lp, char *buf, int blen);
229extern int qword_get(char **bpp, char *dest, int bufsize);
230
231static inline int get_int(char **bpp, int *anint)
232{
233	char buf[50];
234	char *ep;
235	int rv;
236	int len = qword_get(bpp, buf, sizeof(buf));
237
238	if (len < 0)
239		return -EINVAL;
240	if (len == 0)
241		return -ENOENT;
242
243	rv = simple_strtol(buf, &ep, 0);
244	if (*ep)
245		return -EINVAL;
246
247	*anint = rv;
248	return 0;
249}
250
251static inline int get_uint(char **bpp, unsigned int *anint)
252{
253	char buf[50];
254	int len = qword_get(bpp, buf, sizeof(buf));
255
256	if (len < 0)
257		return -EINVAL;
258	if (len == 0)
259		return -ENOENT;
260
261	if (kstrtouint(buf, 0, anint))
262		return -EINVAL;
263
264	return 0;
265}
266
267static inline int get_time(char **bpp, time_t *time)
268{
269	char buf[50];
270	long long ll;
271	int len = qword_get(bpp, buf, sizeof(buf));
272
273	if (len < 0)
274		return -EINVAL;
275	if (len == 0)
276		return -ENOENT;
277
278	if (kstrtoll(buf, 0, &ll))
279		return -EINVAL;
280
281	*time = (time_t)ll;
282	return 0;
283}
284
285static inline time_t get_expiry(char **bpp)
286{
287	time_t rv;
288	struct timespec boot;
289
290	if (get_time(bpp, &rv))
291		return 0;
292	if (rv < 0)
293		return 0;
294	getboottime(&boot);
295	return rv - boot.tv_sec;
296}
297
298#endif /*  _LINUX_SUNRPC_CACHE_H_ */
299