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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/kstrtox.h>
18#include <linux/proc_fs.h>
19#include <linux/wait.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 hlist_node cache_list;
50 time64_t expiry_time; /* After time expiry_time, don't use
51 * the data */
52 time64_t last_refresh; /* If CACHE_PENDING, this is when upcall was
53 * sent, else this is when update was
54 * received, though it is alway set to
55 * be *after* ->flush_time.
56 */
57 struct kref ref;
58 unsigned long flags;
59};
60
61/* cache_head.flags */
62enum {
63 CACHE_VALID, /* Entry contains valid data */
64 CACHE_NEGATIVE, /* Negative entry - there is no match for the key */
65 CACHE_PENDING, /* An upcall has been sent but no reply received yet*/
66 CACHE_CLEANED, /* Entry has been cleaned from cache */
67};
68
69#define CACHE_NEW_EXPIRY 120 /* keep new things pending confirmation for 120 seconds */
70
71struct cache_detail {
72 struct module * owner;
73 int hash_size;
74 struct hlist_head * hash_table;
75 spinlock_t hash_lock;
76
77 char *name;
78 void (*cache_put)(struct kref *);
79
80 int (*cache_upcall)(struct cache_detail *,
81 struct cache_head *);
82
83 void (*cache_request)(struct cache_detail *cd,
84 struct cache_head *ch,
85 char **bpp, int *blen);
86
87 int (*cache_parse)(struct cache_detail *,
88 char *buf, int len);
89
90 int (*cache_show)(struct seq_file *m,
91 struct cache_detail *cd,
92 struct cache_head *h);
93 void (*warn_no_listener)(struct cache_detail *cd,
94 int has_died);
95
96 struct cache_head * (*alloc)(void);
97 void (*flush)(void);
98 int (*match)(struct cache_head *orig, struct cache_head *new);
99 void (*init)(struct cache_head *orig, struct cache_head *new);
100 void (*update)(struct cache_head *orig, struct cache_head *new);
101
102 /* fields below this comment are for internal use
103 * and should not be touched by cache owners
104 */
105 time64_t flush_time; /* flush all cache items with
106 * last_refresh at or earlier
107 * than this. last_refresh
108 * is never set at or earlier
109 * than this.
110 */
111 struct list_head others;
112 time64_t nextcheck;
113 int entries;
114
115 /* fields for communication over channel */
116 struct list_head requests;
117 struct list_head readers;
118 spinlock_t queue_lock;
119 wait_queue_head_t queue_wait;
120 u64 next_seqno;
121
122 atomic_t writers; /* how many time is /channel open */
123 time64_t last_close; /* if no writers, when did last close */
124 time64_t last_warn; /* when we last warned about no writers */
125
126 union {
127 struct proc_dir_entry *procfs;
128 struct dentry *pipefs;
129 };
130 struct net *net;
131};
132
133/* this must be embedded in any request structure that
134 * identifies an object that will want a callback on
135 * a cache fill
136 */
137struct cache_req {
138 struct cache_deferred_req *(*defer)(struct cache_req *req);
139 unsigned long thread_wait; /* How long (jiffies) we can block the
140 * current thread to wait for updates.
141 */
142};
143
144/* this must be embedded in a deferred_request that is being
145 * delayed awaiting cache-fill
146 */
147struct cache_deferred_req {
148 struct hlist_node hash; /* on hash chain */
149 struct list_head recent; /* on fifo */
150 struct cache_head *item; /* cache item we wait on */
151 void *owner; /* we might need to discard all defered requests
152 * owned by someone */
153 void (*revisit)(struct cache_deferred_req *req,
154 int too_many);
155};
156
157/*
158 * timestamps kept in the cache are expressed in seconds
159 * since boot. This is the best for measuring differences in
160 * real time.
161 * This reimplemnts ktime_get_boottime_seconds() in a slightly
162 * faster but less accurate way. When we end up converting
163 * back to wallclock (CLOCK_REALTIME), that error often
164 * cancels out during the reverse operation.
165 */
166static inline time64_t seconds_since_boot(void)
167{
168 struct timespec64 boot;
169 getboottime64(&boot);
170 return ktime_get_real_seconds() - boot.tv_sec;
171}
172
173static inline time64_t convert_to_wallclock(time64_t sinceboot)
174{
175 struct timespec64 boot;
176 getboottime64(&boot);
177 return boot.tv_sec + sinceboot;
178}
179
180extern const struct file_operations cache_file_operations_pipefs;
181extern const struct file_operations content_file_operations_pipefs;
182extern const struct file_operations cache_flush_operations_pipefs;
183
184extern struct cache_head *
185sunrpc_cache_lookup_rcu(struct cache_detail *detail,
186 struct cache_head *key, int hash);
187extern struct cache_head *
188sunrpc_cache_update(struct cache_detail *detail,
189 struct cache_head *new, struct cache_head *old, int hash);
190
191extern int
192sunrpc_cache_pipe_upcall(struct cache_detail *detail, struct cache_head *h);
193extern int
194sunrpc_cache_pipe_upcall_timeout(struct cache_detail *detail,
195 struct cache_head *h);
196
197
198extern void cache_clean_deferred(void *owner);
199
200static inline struct cache_head *cache_get(struct cache_head *h)
201{
202 kref_get(&h->ref);
203 return h;
204}
205
206static inline struct cache_head *cache_get_rcu(struct cache_head *h)
207{
208 if (kref_get_unless_zero(&h->ref))
209 return h;
210 return NULL;
211}
212
213static inline void cache_put(struct cache_head *h, struct cache_detail *cd)
214{
215 if (kref_read(&h->ref) <= 2 &&
216 h->expiry_time < cd->nextcheck)
217 cd->nextcheck = h->expiry_time;
218 kref_put(&h->ref, cd->cache_put);
219}
220
221static inline bool cache_is_expired(struct cache_detail *detail, struct cache_head *h)
222{
223 if (h->expiry_time < seconds_since_boot())
224 return true;
225 if (!test_bit(CACHE_VALID, &h->flags))
226 return false;
227 return detail->flush_time >= h->last_refresh;
228}
229
230extern int cache_check_rcu(struct cache_detail *detail,
231 struct cache_head *h, struct cache_req *rqstp);
232extern int cache_check(struct cache_detail *detail,
233 struct cache_head *h, struct cache_req *rqstp);
234extern void cache_flush(void);
235extern void cache_purge(struct cache_detail *detail);
236#define NEVER (0x7FFFFFFF)
237extern void __init cache_initialize(void);
238extern int cache_register_net(struct cache_detail *cd, struct net *net);
239extern void cache_unregister_net(struct cache_detail *cd, struct net *net);
240
241extern struct cache_detail *cache_create_net(const struct cache_detail *tmpl, struct net *net);
242extern void cache_destroy_net(struct cache_detail *cd, struct net *net);
243
244extern void sunrpc_init_cache_detail(struct cache_detail *cd);
245extern void sunrpc_destroy_cache_detail(struct cache_detail *cd);
246extern int sunrpc_cache_register_pipefs(struct dentry *parent, const char *,
247 umode_t, struct cache_detail *);
248extern void sunrpc_cache_unregister_pipefs(struct cache_detail *);
249extern void sunrpc_cache_unhash(struct cache_detail *, struct cache_head *);
250
251/* Must store cache_detail in seq_file->private if using next three functions */
252extern void *cache_seq_start_rcu(struct seq_file *file, loff_t *pos);
253extern void *cache_seq_next_rcu(struct seq_file *file, void *p, loff_t *pos);
254extern void cache_seq_stop_rcu(struct seq_file *file, void *p);
255
256extern void qword_add(char **bpp, int *lp, char *str);
257extern void qword_addhex(char **bpp, int *lp, char *buf, int blen);
258extern int qword_get(char **bpp, char *dest, int bufsize);
259
260static inline int get_int(char **bpp, int *anint)
261{
262 char buf[50];
263 char *ep;
264 int rv;
265 int len = qword_get(bpp, buf, sizeof(buf));
266
267 if (len < 0)
268 return -EINVAL;
269 if (len == 0)
270 return -ENOENT;
271
272 rv = simple_strtol(buf, &ep, 0);
273 if (*ep)
274 return -EINVAL;
275
276 *anint = rv;
277 return 0;
278}
279
280static inline int get_uint(char **bpp, unsigned int *anint)
281{
282 char buf[50];
283 int len = qword_get(bpp, buf, sizeof(buf));
284
285 if (len < 0)
286 return -EINVAL;
287 if (len == 0)
288 return -ENOENT;
289
290 if (kstrtouint(buf, 0, anint))
291 return -EINVAL;
292
293 return 0;
294}
295
296static inline int get_time(char **bpp, time64_t *time)
297{
298 char buf[50];
299 long long ll;
300 int len = qword_get(bpp, buf, sizeof(buf));
301
302 if (len < 0)
303 return -EINVAL;
304 if (len == 0)
305 return -ENOENT;
306
307 if (kstrtoll(buf, 0, &ll))
308 return -EINVAL;
309
310 *time = ll;
311 return 0;
312}
313
314static inline int get_expiry(char **bpp, time64_t *rvp)
315{
316 int error;
317 struct timespec64 boot;
318
319 error = get_time(bpp, rvp);
320 if (error)
321 return error;
322
323 getboottime64(&boot);
324 (*rvp) -= boot.tv_sec;
325 return 0;
326}
327
328#endif /* _LINUX_SUNRPC_CACHE_H_ */