xref: /linux/include/linux/sunrpc/cache.h (revision f34b580514c9816a317764e6b138ec66a4adab25)
1 /* SPDX-License-Identifier: GPL-2.0-only */
2 /*
3  * include/linux/sunrpc/cache.h
4  *
5  * Generic code for various authentication-related caches
6  * used by sunrpc clients and servers.
7  *
8  * Copyright (C) 2002 Neil Brown <neilb@cse.unsw.edu.au>
9  */
10 
11 #ifndef _LINUX_SUNRPC_CACHE_H_
12 #define _LINUX_SUNRPC_CACHE_H_
13 
14 #include <linux/kref.h>
15 #include <linux/slab.h>
16 #include <linux/atomic.h>
17 #include <linux/kstrtox.h>
18 #include <linux/proc_fs.h>
19 
20 /*
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.
30  *
31  * as well as assorted code fragments (e.g. compare keys) and numbers
32  * (e.g. hash size, goal_age, etc).
33  *
34  * Each cache must be registered so that it can be cleaned regularly.
35  * When the cache is unregistered, it is flushed completely.
36  *
37  * Entries have a ref count and a 'hashed' flag which counts the existence
38  * in the hash table.
39  * We only expire entries when refcount is zero.
40  * Existence in the cache is counted  the refcount.
41  */
42 
43 /* Every cache item has a common header that is used
44  * for expiring and refreshing entries.
45  *
46  */
47 struct cache_head {
48 	struct hlist_node	cache_list;
49 	time64_t	expiry_time;	/* After time expiry_time, don't use
50 					 * the data */
51 	time64_t	last_refresh;   /* If CACHE_PENDING, this is when upcall was
52 					 * sent, else this is when update was
53 					 * received, though it is alway set to
54 					 * be *after* ->flush_time.
55 					 */
56 	struct kref	ref;
57 	unsigned long	flags;
58 };
59 
60 /* cache_head.flags */
61 enum {
62 	CACHE_VALID,		/* Entry contains valid data */
63 	CACHE_NEGATIVE,		/* Negative entry - there is no match for the key */
64 	CACHE_PENDING,		/* An upcall has been sent but no reply received yet*/
65 	CACHE_CLEANED,		/* Entry has been cleaned from cache */
66 };
67 
68 #define	CACHE_NEW_EXPIRY 120	/* keep new things pending confirmation for 120 seconds */
69 
70 struct cache_detail {
71 	struct module *		owner;
72 	int			hash_size;
73 	struct hlist_head *	hash_table;
74 	spinlock_t		hash_lock;
75 
76 	char			*name;
77 	void			(*cache_put)(struct kref *);
78 
79 	int			(*cache_upcall)(struct cache_detail *,
80 						struct cache_head *);
81 
82 	void			(*cache_request)(struct cache_detail *cd,
83 						 struct cache_head *ch,
84 						 char **bpp, int *blen);
85 
86 	int			(*cache_parse)(struct cache_detail *,
87 					       char *buf, int len);
88 
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,
93 					      int has_died);
94 
95 	struct cache_head *	(*alloc)(void);
96 	void			(*flush)(void);
97 	int			(*match)(struct cache_head *orig, struct cache_head *new);
98 	void			(*init)(struct cache_head *orig, struct cache_head *new);
99 	void			(*update)(struct cache_head *orig, struct cache_head *new);
100 
101 	/* fields below this comment are for internal use
102 	 * and should not be touched by cache owners
103 	 */
104 	time64_t		flush_time;		/* flush all cache items with
105 							 * last_refresh at or earlier
106 							 * than this.  last_refresh
107 							 * is never set at or earlier
108 							 * than this.
109 							 */
110 	struct list_head	others;
111 	time64_t		nextcheck;
112 	int			entries;
113 
114 	/* fields for communication over channel */
115 	struct list_head	queue;
116 
117 	atomic_t		writers;		/* how many time is /channel open */
118 	time64_t		last_close;		/* if no writers, when did last close */
119 	time64_t		last_warn;		/* when we last warned about no writers */
120 
121 	union {
122 		struct proc_dir_entry	*procfs;
123 		struct dentry		*pipefs;
124 	};
125 	struct net		*net;
126 };
127 
128 /* this must be embedded in any request structure that
129  * identifies an object that will want a callback on
130  * a cache fill
131  */
132 struct cache_req {
133 	struct cache_deferred_req *(*defer)(struct cache_req *req);
134 	unsigned long	thread_wait;	/* How long (jiffies) we can block the
135 					 * current thread to wait for updates.
136 					 */
137 };
138 
139 /* this must be embedded in a deferred_request that is being
140  * delayed awaiting cache-fill
141  */
142 struct 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  * This reimplemnts ktime_get_boottime_seconds() in a slightly
157  * faster but less accurate way. When we end up converting
158  * back to wallclock (CLOCK_REALTIME), that error often
159  * cancels out during the reverse operation.
160  */
161 static inline time64_t seconds_since_boot(void)
162 {
163 	struct timespec64 boot;
164 	getboottime64(&boot);
165 	return ktime_get_real_seconds() - boot.tv_sec;
166 }
167 
168 static inline time64_t convert_to_wallclock(time64_t sinceboot)
169 {
170 	struct timespec64 boot;
171 	getboottime64(&boot);
172 	return boot.tv_sec + sinceboot;
173 }
174 
175 extern const struct file_operations cache_file_operations_pipefs;
176 extern const struct file_operations content_file_operations_pipefs;
177 extern const struct file_operations cache_flush_operations_pipefs;
178 
179 extern struct cache_head *
180 sunrpc_cache_lookup_rcu(struct cache_detail *detail,
181 			struct cache_head *key, int hash);
182 extern struct cache_head *
183 sunrpc_cache_update(struct cache_detail *detail,
184 		    struct cache_head *new, struct cache_head *old, int hash);
185 
186 extern int
187 sunrpc_cache_pipe_upcall(struct cache_detail *detail, struct cache_head *h);
188 extern int
189 sunrpc_cache_pipe_upcall_timeout(struct cache_detail *detail,
190 				 struct cache_head *h);
191 
192 
193 extern void cache_clean_deferred(void *owner);
194 
195 static inline struct cache_head  *cache_get(struct cache_head *h)
196 {
197 	kref_get(&h->ref);
198 	return h;
199 }
200 
201 static inline struct cache_head  *cache_get_rcu(struct cache_head *h)
202 {
203 	if (kref_get_unless_zero(&h->ref))
204 		return h;
205 	return NULL;
206 }
207 
208 static inline void cache_put(struct cache_head *h, struct cache_detail *cd)
209 {
210 	if (kref_read(&h->ref) <= 2 &&
211 	    h->expiry_time < cd->nextcheck)
212 		cd->nextcheck = h->expiry_time;
213 	kref_put(&h->ref, cd->cache_put);
214 }
215 
216 static inline bool cache_is_expired(struct cache_detail *detail, struct cache_head *h)
217 {
218 	if (h->expiry_time < seconds_since_boot())
219 		return true;
220 	if (!test_bit(CACHE_VALID, &h->flags))
221 		return false;
222 	return detail->flush_time >= h->last_refresh;
223 }
224 
225 extern int cache_check_rcu(struct cache_detail *detail,
226 		       struct cache_head *h, struct cache_req *rqstp);
227 extern int cache_check(struct cache_detail *detail,
228 		       struct cache_head *h, struct cache_req *rqstp);
229 extern void cache_flush(void);
230 extern void cache_purge(struct cache_detail *detail);
231 #define NEVER (0x7FFFFFFF)
232 extern void __init cache_initialize(void);
233 extern int cache_register_net(struct cache_detail *cd, struct net *net);
234 extern void cache_unregister_net(struct cache_detail *cd, struct net *net);
235 
236 extern struct cache_detail *cache_create_net(const struct cache_detail *tmpl, struct net *net);
237 extern void cache_destroy_net(struct cache_detail *cd, struct net *net);
238 
239 extern void sunrpc_init_cache_detail(struct cache_detail *cd);
240 extern void sunrpc_destroy_cache_detail(struct cache_detail *cd);
241 extern int sunrpc_cache_register_pipefs(struct dentry *parent, const char *,
242 					umode_t, struct cache_detail *);
243 extern void sunrpc_cache_unregister_pipefs(struct cache_detail *);
244 extern void sunrpc_cache_unhash(struct cache_detail *, struct cache_head *);
245 
246 /* Must store cache_detail in seq_file->private if using next three functions */
247 extern void *cache_seq_start_rcu(struct seq_file *file, loff_t *pos);
248 extern void *cache_seq_next_rcu(struct seq_file *file, void *p, loff_t *pos);
249 extern void cache_seq_stop_rcu(struct seq_file *file, void *p);
250 
251 extern void qword_add(char **bpp, int *lp, char *str);
252 extern void qword_addhex(char **bpp, int *lp, char *buf, int blen);
253 extern int qword_get(char **bpp, char *dest, int bufsize);
254 
255 static inline int get_int(char **bpp, int *anint)
256 {
257 	char buf[50];
258 	char *ep;
259 	int rv;
260 	int len = qword_get(bpp, buf, sizeof(buf));
261 
262 	if (len < 0)
263 		return -EINVAL;
264 	if (len == 0)
265 		return -ENOENT;
266 
267 	rv = simple_strtol(buf, &ep, 0);
268 	if (*ep)
269 		return -EINVAL;
270 
271 	*anint = rv;
272 	return 0;
273 }
274 
275 static inline int get_uint(char **bpp, unsigned int *anint)
276 {
277 	char buf[50];
278 	int len = qword_get(bpp, buf, sizeof(buf));
279 
280 	if (len < 0)
281 		return -EINVAL;
282 	if (len == 0)
283 		return -ENOENT;
284 
285 	if (kstrtouint(buf, 0, anint))
286 		return -EINVAL;
287 
288 	return 0;
289 }
290 
291 static inline int get_time(char **bpp, time64_t *time)
292 {
293 	char buf[50];
294 	long long ll;
295 	int len = qword_get(bpp, buf, sizeof(buf));
296 
297 	if (len < 0)
298 		return -EINVAL;
299 	if (len == 0)
300 		return -ENOENT;
301 
302 	if (kstrtoll(buf, 0, &ll))
303 		return -EINVAL;
304 
305 	*time = ll;
306 	return 0;
307 }
308 
309 static inline int get_expiry(char **bpp, time64_t *rvp)
310 {
311 	int error;
312 	struct timespec64 boot;
313 
314 	error = get_time(bpp, rvp);
315 	if (error)
316 		return error;
317 
318 	getboottime64(&boot);
319 	(*rvp) -= boot.tv_sec;
320 	return 0;
321 }
322 
323 #endif /*  _LINUX_SUNRPC_CACHE_H_ */
324