linux/include/linux/sunrpc/cache.h

/* SPDX-License-Identifier: GPL-2.0-only */
/*
 * include/linux/sunrpc/cache.h
 *
 * Generic code for various authentication-related caches
 * used by sunrpc clients and servers.
 *
 * Copyright (C) 2002 Neil Brown <[email protected]>
 */

#ifndef _LINUX_SUNRPC_CACHE_H_
#define _LINUX_SUNRPC_CACHE_H_

#include <linux/kref.h>
#include <linux/slab.h>
#include <linux/atomic.h>
#include <linux/kstrtox.h>
#include <linux/proc_fs.h>

/*
 * Each cache requires:
 *  - A 'struct cache_detail' which contains information specific to the cache
 *    for common code to use.
 *  - An item structure that must contain a "struct cache_head"
 *  - A lookup function defined using DefineCacheLookup
 *  - A 'put' function that can release a cache item. It will only
 *    be called after cache_put has succeed, so there are guarantee
 *    to be no references.
 *  - A function to calculate a hash of an item's key.
 *
 * as well as assorted code fragments (e.g. compare keys) and numbers
 * (e.g. hash size, goal_age, etc).
 *
 * Each cache must be registered so that it can be cleaned regularly.
 * When the cache is unregistered, it is flushed completely.
 *
 * Entries have a ref count and a 'hashed' flag which counts the existence
 * in the hash table.
 * We only expire entries when refcount is zero.
 * Existence in the cache is counted  the refcount.
 */

/* Every cache item has a common header that is used
 * for expiring and refreshing entries.
 * 
 */
struct cache_head { … };

/* cache_head.flags */
enum { … };

#define CACHE_NEW_EXPIRY …

struct cache_detail { … };

/* this must be embedded in any request structure that
 * identifies an object that will want a callback on
 * a cache fill
 */
struct cache_req { … };

/* this must be embedded in a deferred_request that is being
 * delayed awaiting cache-fill
 */
struct cache_deferred_req { … };

/*
 * timestamps kept in the cache are expressed in seconds
 * since boot.  This is the best for measuring differences in
 * real time.
 * This reimplemnts ktime_get_boottime_seconds() in a slightly
 * faster but less accurate way. When we end up converting
 * back to wallclock (CLOCK_REALTIME), that error often
 * cancels out during the reverse operation.
 */
static inline time64_t seconds_since_boot(void)
{ … }

static inline time64_t convert_to_wallclock(time64_t sinceboot)
{ … }

extern const struct file_operations cache_file_operations_pipefs;
extern const struct file_operations content_file_operations_pipefs;
extern const struct file_operations cache_flush_operations_pipefs;

extern struct cache_head *
sunrpc_cache_lookup_rcu(struct cache_detail *detail,
			struct cache_head *key, int hash);
extern struct cache_head *
sunrpc_cache_update(struct cache_detail *detail,
		    struct cache_head *new, struct cache_head *old, int hash);

extern int
sunrpc_cache_pipe_upcall(struct cache_detail *detail, struct cache_head *h);
extern int
sunrpc_cache_pipe_upcall_timeout(struct cache_detail *detail,
				 struct cache_head *h);


extern void cache_clean_deferred(void *owner);

static inline struct cache_head  *cache_get(struct cache_head *h)
{ … }

static inline struct cache_head  *cache_get_rcu(struct cache_head *h)
{ … }

static inline void cache_put(struct cache_head *h, struct cache_detail *cd)
{ … }

static inline bool cache_is_expired(struct cache_detail *detail, struct cache_head *h)
{ … }

extern int cache_check(struct cache_detail *detail,
		       struct cache_head *h, struct cache_req *rqstp);
extern void cache_flush(void);
extern void cache_purge(struct cache_detail *detail);
#define NEVER …
extern void __init cache_initialize(void);
extern int cache_register_net(struct cache_detail *cd, struct net *net);
extern void cache_unregister_net(struct cache_detail *cd, struct net *net);

extern struct cache_detail *cache_create_net(const struct cache_detail *tmpl, struct net *net);
extern void cache_destroy_net(struct cache_detail *cd, struct net *net);

extern void sunrpc_init_cache_detail(struct cache_detail *cd);
extern void sunrpc_destroy_cache_detail(struct cache_detail *cd);
extern int sunrpc_cache_register_pipefs(struct dentry *parent, const char *,
					umode_t, struct cache_detail *);
extern void sunrpc_cache_unregister_pipefs(struct cache_detail *);
extern void sunrpc_cache_unhash(struct cache_detail *, struct cache_head *);

/* Must store cache_detail in seq_file->private if using next three functions */
extern void *cache_seq_start_rcu(struct seq_file *file, loff_t *pos);
extern void *cache_seq_next_rcu(struct seq_file *file, void *p, loff_t *pos);
extern void cache_seq_stop_rcu(struct seq_file *file, void *p);

extern void qword_add(char **bpp, int *lp, char *str);
extern void qword_addhex(char **bpp, int *lp, char *buf, int blen);
extern int qword_get(char **bpp, char *dest, int bufsize);

static inline int get_int(char **bpp, int *anint)
{ … }

static inline int get_uint(char **bpp, unsigned int *anint)
{ … }

static inline int get_time(char **bpp, time64_t *time)
{ … }

static inline int get_expiry(char **bpp, time64_t *rvp)
{ … }

#endif /*  _LINUX_SUNRPC_CACHE_H_ */