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 */
47struct 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 */
61enum {
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
70struct 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 */
132struct 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 */
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 * 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 */
161static inline time64_t seconds_since_boot(void)
162{
163 struct timespec64 boot;
164 getboottime64(ts: &boot);
165 return ktime_get_real_seconds() - boot.tv_sec;
166}
167
168static inline time64_t convert_to_wallclock(time64_t sinceboot)
169{
170 struct timespec64 boot;
171 getboottime64(ts: &boot);
172 return boot.tv_sec + sinceboot;
173}
174
175extern const struct file_operations cache_file_operations_pipefs;
176extern const struct file_operations content_file_operations_pipefs;
177extern const struct file_operations cache_flush_operations_pipefs;
178
179extern struct cache_head *
180sunrpc_cache_lookup_rcu(struct cache_detail *detail,
181 struct cache_head *key, int hash);
182extern struct cache_head *
183sunrpc_cache_update(struct cache_detail *detail,
184 struct cache_head *new, struct cache_head *old, int hash);
185
186extern int
187sunrpc_cache_pipe_upcall(struct cache_detail *detail, struct cache_head *h);
188extern int
189sunrpc_cache_pipe_upcall_timeout(struct cache_detail *detail,
190 struct cache_head *h);
191
192
193extern void cache_clean_deferred(void *owner);
194
195static inline struct cache_head *cache_get(struct cache_head *h)
196{
197 kref_get(kref: &h->ref);
198 return h;
199}
200
201static inline struct cache_head *cache_get_rcu(struct cache_head *h)
202{
203 if (kref_get_unless_zero(kref: &h->ref))
204 return h;
205 return NULL;
206}
207
208static inline void cache_put(struct cache_head *h, struct cache_detail *cd)
209{
210 if (kref_read(kref: &h->ref) <= 2 &&
211 h->expiry_time < cd->nextcheck)
212 cd->nextcheck = h->expiry_time;
213 kref_put(kref: &h->ref, release: cd->cache_put);
214}
215
216static 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
225extern int cache_check_rcu(struct cache_detail *detail,
226 struct cache_head *h, struct cache_req *rqstp);
227extern int cache_check(struct cache_detail *detail,
228 struct cache_head *h, struct cache_req *rqstp);
229extern void cache_flush(void);
230extern void cache_purge(struct cache_detail *detail);
231#define NEVER (0x7FFFFFFF)
232extern void __init cache_initialize(void);
233extern int cache_register_net(struct cache_detail *cd, struct net *net);
234extern void cache_unregister_net(struct cache_detail *cd, struct net *net);
235
236extern struct cache_detail *cache_create_net(const struct cache_detail *tmpl, struct net *net);
237extern void cache_destroy_net(struct cache_detail *cd, struct net *net);
238
239extern void sunrpc_init_cache_detail(struct cache_detail *cd);
240extern void sunrpc_destroy_cache_detail(struct cache_detail *cd);
241extern int sunrpc_cache_register_pipefs(struct dentry *parent, const char *,
242 umode_t, struct cache_detail *);
243extern void sunrpc_cache_unregister_pipefs(struct cache_detail *);
244extern 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 */
247extern void *cache_seq_start_rcu(struct seq_file *file, loff_t *pos);
248extern void *cache_seq_next_rcu(struct seq_file *file, void *p, loff_t *pos);
249extern void cache_seq_stop_rcu(struct seq_file *file, void *p);
250
251extern void qword_add(char **bpp, int *lp, char *str);
252extern void qword_addhex(char **bpp, int *lp, char *buf, int blen);
253extern int qword_get(char **bpp, char *dest, int bufsize);
254
255static 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, dest: buf, bufsize: 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
275static inline int get_uint(char **bpp, unsigned int *anint)
276{
277 char buf[50];
278 int len = qword_get(bpp, dest: buf, bufsize: sizeof(buf));
279
280 if (len < 0)
281 return -EINVAL;
282 if (len == 0)
283 return -ENOENT;
284
285 if (kstrtouint(s: buf, base: 0, res: anint))
286 return -EINVAL;
287
288 return 0;
289}
290
291static inline int get_time(char **bpp, time64_t *time)
292{
293 char buf[50];
294 long long ll;
295 int len = qword_get(bpp, dest: buf, bufsize: sizeof(buf));
296
297 if (len < 0)
298 return -EINVAL;
299 if (len == 0)
300 return -ENOENT;
301
302 if (kstrtoll(s: buf, base: 0, res: &ll))
303 return -EINVAL;
304
305 *time = ll;
306 return 0;
307}
308
309static inline int get_expiry(char **bpp, time64_t *rvp)
310{
311 int error;
312 struct timespec64 boot;
313
314 error = get_time(bpp, time: rvp);
315 if (error)
316 return error;
317
318 getboottime64(ts: &boot);
319 (*rvp) -= boot.tv_sec;
320 return 0;
321}
322
323#endif /* _LINUX_SUNRPC_CACHE_H_ */
324

source code of linux/include/linux/sunrpc/cache.h

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