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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/proc_fs.h>
18
19/*
20 * Each cache requires:
21 * - A 'struct cache_detail' which contains information specific to the cache
22 * for common code to use.
23 * - An item structure that must contain a "struct cache_head"
24 * - A lookup function defined using DefineCacheLookup
25 * - A 'put' function that can release a cache item. It will only
26 * be called after cache_put has succeed, so there are guarantee
27 * to be no references.
28 * - A function to calculate a hash of an item's key.
29 *
30 * as well as assorted code fragments (e.g. compare keys) and numbers
31 * (e.g. hash size, goal_age, etc).
32 *
33 * Each cache must be registered so that it can be cleaned regularly.
34 * When the cache is unregistered, it is flushed completely.
35 *
36 * Entries have a ref count and a 'hashed' flag which counts the existence
37 * in the hash table.
38 * We only expire entries when refcount is zero.
39 * Existence in the cache is counted the refcount.
40 */
41
42/* Every cache item has a common header that is used
43 * for expiring and refreshing entries.
44 *
45 */
46struct cache_head {
47 struct hlist_node cache_list;
48 time64_t expiry_time; /* After time time, don't use the data */
49 time64_t last_refresh; /* If CACHE_PENDING, this is when upcall was
50 * sent, else this is when update was
51 * received, though it is alway set to
52 * be *after* ->flush_time.
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 {
65 struct module * owner;
66 int hash_size;
67 struct hlist_head * hash_table;
68 spinlock_t hash_lock;
69
70 char *name;
71 void (*cache_put)(struct kref *);
72
73 int (*cache_upcall)(struct cache_detail *,
74 struct cache_head *);
75
76 void (*cache_request)(struct cache_detail *cd,
77 struct cache_head *ch,
78 char **bpp, int *blen);
79
80 int (*cache_parse)(struct cache_detail *,
81 char *buf, int len);
82
83 int (*cache_show)(struct seq_file *m,
84 struct cache_detail *cd,
85 struct cache_head *h);
86 void (*warn_no_listener)(struct cache_detail *cd,
87 int has_died);
88
89 struct cache_head * (*alloc)(void);
90 void (*flush)(void);
91 int (*match)(struct cache_head *orig, struct cache_head *new);
92 void (*init)(struct cache_head *orig, struct cache_head *new);
93 void (*update)(struct cache_head *orig, struct cache_head *new);
94
95 /* fields below this comment are for internal use
96 * and should not be touched by cache owners
97 */
98 time64_t flush_time; /* flush all cache items with
99 * last_refresh at or earlier
100 * than this. last_refresh
101 * is never set at or earlier
102 * than this.
103 */
104 struct list_head others;
105 time64_t nextcheck;
106 int entries;
107
108 /* fields for communication over channel */
109 struct list_head queue;
110
111 atomic_t writers; /* how many time is /channel open */
112 time64_t last_close; /* if no writers, when did last close */
113 time64_t last_warn; /* when we last warned about no writers */
114
115 union {
116 struct proc_dir_entry *procfs;
117 struct dentry *pipefs;
118 };
119 struct net *net;
120};
121
122
123/* this must be embedded in any request structure that
124 * identifies an object that will want a callback on
125 * a cache fill
126 */
127struct cache_req {
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.
131 */
132};
133/* this must be embedded in a deferred_request that is being
134 * delayed awaiting cache-fill
135 */
136struct 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,
143 int too_many);
144};
145
146/*
147 * timestamps kept in the cache are expressed in seconds
148 * since boot. This is the best for measuring differences in
149 * real time.
150 * This reimplemnts ktime_get_boottime_seconds() in a slightly
151 * faster but less accurate way. When we end up converting
152 * back to wallclock (CLOCK_REALTIME), that error often
153 * cancels out during the reverse operation.
154 */
155static inline time64_t seconds_since_boot(void)
156{
157 struct timespec64 boot;
158 getboottime64(&boot);
159 return ktime_get_real_seconds() - boot.tv_sec;
160}
161
162static inline time64_t convert_to_wallclock(time64_t sinceboot)
163{
164 struct timespec64 boot;
165 getboottime64(&boot);
166 return boot.tv_sec + sinceboot;
167}
168
169extern const struct file_operations cache_file_operations_pipefs;
170extern const struct file_operations content_file_operations_pipefs;
171extern const struct file_operations cache_flush_operations_pipefs;
172
173extern struct cache_head *
174sunrpc_cache_lookup_rcu(struct cache_detail *detail,
175 struct cache_head *key, int hash);
176extern struct cache_head *
177sunrpc_cache_update(struct cache_detail *detail,
178 struct cache_head *new, struct cache_head *old, int hash);
179
180extern int
181sunrpc_cache_pipe_upcall(struct cache_detail *detail, struct cache_head *h);
182
183
184extern void cache_clean_deferred(void *owner);
185
186static inline struct cache_head *cache_get(struct cache_head *h)
187{
188 kref_get(&h->ref);
189 return h;
190}
191
192static inline struct cache_head *cache_get_rcu(struct cache_head *h)
193{
194 if (kref_get_unless_zero(&h->ref))
195 return h;
196 return NULL;
197}
198
199static inline void cache_put(struct cache_head *h, struct cache_detail *cd)
200{
201 if (kref_read(&h->ref) <= 2 &&
202 h->expiry_time < cd->nextcheck)
203 cd->nextcheck = h->expiry_time;
204 kref_put(&h->ref, cd->cache_put);
205}
206
207static inline bool cache_is_expired(struct cache_detail *detail, struct cache_head *h)
208{
209 if (!test_bit(CACHE_VALID, &h->flags))
210 return false;
211
212 return (h->expiry_time < seconds_since_boot()) ||
213 (detail->flush_time >= h->last_refresh);
214}
215
216extern int cache_check(struct cache_detail *detail,
217 struct cache_head *h, struct cache_req *rqstp);
218extern void cache_flush(void);
219extern void cache_purge(struct cache_detail *detail);
220#define NEVER (0x7FFFFFFF)
221extern void __init cache_initialize(void);
222extern int cache_register_net(struct cache_detail *cd, struct net *net);
223extern void cache_unregister_net(struct cache_detail *cd, struct net *net);
224
225extern struct cache_detail *cache_create_net(const struct cache_detail *tmpl, struct net *net);
226extern void cache_destroy_net(struct cache_detail *cd, struct net *net);
227
228extern void sunrpc_init_cache_detail(struct cache_detail *cd);
229extern void sunrpc_destroy_cache_detail(struct cache_detail *cd);
230extern int sunrpc_cache_register_pipefs(struct dentry *parent, const char *,
231 umode_t, struct cache_detail *);
232extern void sunrpc_cache_unregister_pipefs(struct cache_detail *);
233extern void sunrpc_cache_unhash(struct cache_detail *, struct cache_head *);
234
235/* Must store cache_detail in seq_file->private if using next three functions */
236extern void *cache_seq_start_rcu(struct seq_file *file, loff_t *pos);
237extern void *cache_seq_next_rcu(struct seq_file *file, void *p, loff_t *pos);
238extern void cache_seq_stop_rcu(struct seq_file *file, void *p);
239
240extern void qword_add(char **bpp, int *lp, char *str);
241extern void qword_addhex(char **bpp, int *lp, char *buf, int blen);
242extern int qword_get(char **bpp, char *dest, int bufsize);
243
244static inline int get_int(char **bpp, int *anint)
245{
246 char buf[50];
247 char *ep;
248 int rv;
249 int len = qword_get(bpp, buf, sizeof(buf));
250
251 if (len < 0)
252 return -EINVAL;
253 if (len == 0)
254 return -ENOENT;
255
256 rv = simple_strtol(buf, &ep, 0);
257 if (*ep)
258 return -EINVAL;
259
260 *anint = rv;
261 return 0;
262}
263
264static inline int get_uint(char **bpp, unsigned int *anint)
265{
266 char buf[50];
267 int len = qword_get(bpp, buf, sizeof(buf));
268
269 if (len < 0)
270 return -EINVAL;
271 if (len == 0)
272 return -ENOENT;
273
274 if (kstrtouint(buf, 0, anint))
275 return -EINVAL;
276
277 return 0;
278}
279
280static inline int get_time(char **bpp, time64_t *time)
281{
282 char buf[50];
283 long long ll;
284 int len = qword_get(bpp, buf, sizeof(buf));
285
286 if (len < 0)
287 return -EINVAL;
288 if (len == 0)
289 return -ENOENT;
290
291 if (kstrtoll(buf, 0, &ll))
292 return -EINVAL;
293
294 *time = ll;
295 return 0;
296}
297
298static inline time64_t get_expiry(char **bpp)
299{
300 time64_t rv;
301 struct timespec64 boot;
302
303 if (get_time(bpp, &rv))
304 return 0;
305 if (rv < 0)
306 return 0;
307 getboottime64(&boot);
308 return rv - boot.tv_sec;
309}
310
311#endif /* _LINUX_SUNRPC_CACHE_H_ */