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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 expiry_time, don't use
49 * the data */
50 time64_t last_refresh; /* If CACHE_PENDING, this is when upcall was
51 * sent, else this is when update was
52 * received, though it is alway set to
53 * be *after* ->flush_time.
54 */
55 struct kref ref;
56 unsigned long flags;
57};
58#define CACHE_VALID 0 /* Entry contains valid data */
59#define CACHE_NEGATIVE 1 /* Negative entry - there is no match for the key */
60#define CACHE_PENDING 2 /* An upcall has been sent but no reply received yet*/
61#define CACHE_CLEANED 3 /* Entry has been cleaned from cache */
62
63#define CACHE_NEW_EXPIRY 120 /* keep new things pending confirmation for 120 seconds */
64
65struct cache_detail {
66 struct module * owner;
67 int hash_size;
68 struct hlist_head * hash_table;
69 spinlock_t hash_lock;
70
71 char *name;
72 void (*cache_put)(struct kref *);
73
74 int (*cache_upcall)(struct cache_detail *,
75 struct cache_head *);
76
77 void (*cache_request)(struct cache_detail *cd,
78 struct cache_head *ch,
79 char **bpp, int *blen);
80
81 int (*cache_parse)(struct cache_detail *,
82 char *buf, int len);
83
84 int (*cache_show)(struct seq_file *m,
85 struct cache_detail *cd,
86 struct cache_head *h);
87 void (*warn_no_listener)(struct cache_detail *cd,
88 int has_died);
89
90 struct cache_head * (*alloc)(void);
91 void (*flush)(void);
92 int (*match)(struct cache_head *orig, struct cache_head *new);
93 void (*init)(struct cache_head *orig, struct cache_head *new);
94 void (*update)(struct cache_head *orig, struct cache_head *new);
95
96 /* fields below this comment are for internal use
97 * and should not be touched by cache owners
98 */
99 time64_t flush_time; /* flush all cache items with
100 * last_refresh at or earlier
101 * than this. last_refresh
102 * is never set at or earlier
103 * than this.
104 */
105 struct list_head others;
106 time64_t nextcheck;
107 int entries;
108
109 /* fields for communication over channel */
110 struct list_head queue;
111
112 atomic_t writers; /* how many time is /channel open */
113 time64_t last_close; /* if no writers, when did last close */
114 time64_t last_warn; /* when we last warned about no writers */
115
116 union {
117 struct proc_dir_entry *procfs;
118 struct dentry *pipefs;
119 };
120 struct net *net;
121};
122
123
124/* this must be embedded in any request structure that
125 * identifies an object that will want a callback on
126 * a cache fill
127 */
128struct cache_req {
129 struct cache_deferred_req *(*defer)(struct cache_req *req);
130 int thread_wait; /* How long (jiffies) we can block the
131 * current thread to wait for updates.
132 */
133};
134/* this must be embedded in a deferred_request that is being
135 * delayed awaiting cache-fill
136 */
137struct cache_deferred_req {
138 struct hlist_node hash; /* on hash chain */
139 struct list_head recent; /* on fifo */
140 struct cache_head *item; /* cache item we wait on */
141 void *owner; /* we might need to discard all defered requests
142 * owned by someone */
143 void (*revisit)(struct cache_deferred_req *req,
144 int too_many);
145};
146
147/*
148 * timestamps kept in the cache are expressed in seconds
149 * since boot. This is the best for measuring differences in
150 * real time.
151 * This reimplemnts ktime_get_boottime_seconds() in a slightly
152 * faster but less accurate way. When we end up converting
153 * back to wallclock (CLOCK_REALTIME), that error often
154 * cancels out during the reverse operation.
155 */
156static inline time64_t seconds_since_boot(void)
157{
158 struct timespec64 boot;
159 getboottime64(&boot);
160 return ktime_get_real_seconds() - boot.tv_sec;
161}
162
163static inline time64_t convert_to_wallclock(time64_t sinceboot)
164{
165 struct timespec64 boot;
166 getboottime64(&boot);
167 return boot.tv_sec + sinceboot;
168}
169
170extern const struct file_operations cache_file_operations_pipefs;
171extern const struct file_operations content_file_operations_pipefs;
172extern const struct file_operations cache_flush_operations_pipefs;
173
174extern struct cache_head *
175sunrpc_cache_lookup_rcu(struct cache_detail *detail,
176 struct cache_head *key, int hash);
177extern struct cache_head *
178sunrpc_cache_update(struct cache_detail *detail,
179 struct cache_head *new, struct cache_head *old, int hash);
180
181extern int
182sunrpc_cache_pipe_upcall(struct cache_detail *detail, struct cache_head *h);
183extern int
184sunrpc_cache_pipe_upcall_timeout(struct cache_detail *detail,
185 struct cache_head *h);
186
187
188extern void cache_clean_deferred(void *owner);
189
190static inline struct cache_head *cache_get(struct cache_head *h)
191{
192 kref_get(&h->ref);
193 return h;
194}
195
196static inline struct cache_head *cache_get_rcu(struct cache_head *h)
197{
198 if (kref_get_unless_zero(&h->ref))
199 return h;
200 return NULL;
201}
202
203static inline void cache_put(struct cache_head *h, struct cache_detail *cd)
204{
205 if (kref_read(&h->ref) <= 2 &&
206 h->expiry_time < cd->nextcheck)
207 cd->nextcheck = h->expiry_time;
208 kref_put(&h->ref, cd->cache_put);
209}
210
211static inline bool cache_is_expired(struct cache_detail *detail, struct cache_head *h)
212{
213 if (h->expiry_time < seconds_since_boot())
214 return true;
215 if (!test_bit(CACHE_VALID, &h->flags))
216 return false;
217 return detail->flush_time >= h->last_refresh;
218}
219
220extern int cache_check(struct cache_detail *detail,
221 struct cache_head *h, struct cache_req *rqstp);
222extern void cache_flush(void);
223extern void cache_purge(struct cache_detail *detail);
224#define NEVER (0x7FFFFFFF)
225extern void __init cache_initialize(void);
226extern int cache_register_net(struct cache_detail *cd, struct net *net);
227extern void cache_unregister_net(struct cache_detail *cd, struct net *net);
228
229extern struct cache_detail *cache_create_net(const struct cache_detail *tmpl, struct net *net);
230extern void cache_destroy_net(struct cache_detail *cd, struct net *net);
231
232extern void sunrpc_init_cache_detail(struct cache_detail *cd);
233extern void sunrpc_destroy_cache_detail(struct cache_detail *cd);
234extern int sunrpc_cache_register_pipefs(struct dentry *parent, const char *,
235 umode_t, struct cache_detail *);
236extern void sunrpc_cache_unregister_pipefs(struct cache_detail *);
237extern void sunrpc_cache_unhash(struct cache_detail *, struct cache_head *);
238
239/* Must store cache_detail in seq_file->private if using next three functions */
240extern void *cache_seq_start_rcu(struct seq_file *file, loff_t *pos);
241extern void *cache_seq_next_rcu(struct seq_file *file, void *p, loff_t *pos);
242extern void cache_seq_stop_rcu(struct seq_file *file, void *p);
243
244extern void qword_add(char **bpp, int *lp, char *str);
245extern void qword_addhex(char **bpp, int *lp, char *buf, int blen);
246extern int qword_get(char **bpp, char *dest, int bufsize);
247
248static inline int get_int(char **bpp, int *anint)
249{
250 char buf[50];
251 char *ep;
252 int rv;
253 int len = qword_get(bpp, buf, sizeof(buf));
254
255 if (len < 0)
256 return -EINVAL;
257 if (len == 0)
258 return -ENOENT;
259
260 rv = simple_strtol(buf, &ep, 0);
261 if (*ep)
262 return -EINVAL;
263
264 *anint = rv;
265 return 0;
266}
267
268static inline int get_uint(char **bpp, unsigned int *anint)
269{
270 char buf[50];
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 (kstrtouint(buf, 0, anint))
279 return -EINVAL;
280
281 return 0;
282}
283
284static inline int get_time(char **bpp, time64_t *time)
285{
286 char buf[50];
287 long long ll;
288 int len = qword_get(bpp, buf, sizeof(buf));
289
290 if (len < 0)
291 return -EINVAL;
292 if (len == 0)
293 return -ENOENT;
294
295 if (kstrtoll(buf, 0, &ll))
296 return -EINVAL;
297
298 *time = ll;
299 return 0;
300}
301
302static inline time64_t get_expiry(char **bpp)
303{
304 time64_t rv;
305 struct timespec64 boot;
306
307 if (get_time(bpp, &rv))
308 return 0;
309 if (rv < 0)
310 return 0;
311 getboottime64(&boot);
312 return rv - boot.tv_sec;
313}
314
315#endif /* _LINUX_SUNRPC_CACHE_H_ */