/* 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 <neilb@cse.unsw.edu.au> */ #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 {	struct hlist_node	cache_list;	time64_t	expiry_time;	/* After time expiry_time, don't use					 * the data */	time64_t	last_refresh;   /* If CACHE_PENDING, this is when upcall was					 * sent, else this is when update was					 * received, though it is alway set to					 * be *after* ->flush_time.					 */	struct kref	ref;	unsigned long	flags;}; /* cache_head.flags */enum {	CACHE_VALID,		/* Entry contains valid data */	CACHE_NEGATIVE,		/* Negative entry - there is no match for the key */	CACHE_PENDING,		/* An upcall has been sent but no reply received yet*/	CACHE_CLEANED,		/* Entry has been cleaned from cache */}; #define	CACHE_NEW_EXPIRY 120	/* keep new things pending confirmation for 120 seconds */ struct cache_detail {	struct module *		owner;	int			hash_size;	struct hlist_head *	hash_table;	spinlock_t		hash_lock; 	char			*name;	void			(*cache_put)(struct kref *); 	int			(*cache_upcall)(struct cache_detail *,						struct cache_head *); 	void			(*cache_request)(struct cache_detail *cd,						 struct cache_head *ch,						 char **bpp, int *blen); 	int			(*cache_parse)(struct cache_detail *,					       char *buf, int len); 	int			(*cache_show)(struct seq_file *m,					      struct cache_detail *cd,					      struct cache_head *h);	void			(*warn_no_listener)(struct cache_detail *cd,					      int has_died); 	struct cache_head *	(*alloc)(void);	void			(*flush)(void);	int			(*match)(struct cache_head *orig, struct cache_head *new);	void			(*init)(struct cache_head *orig, struct cache_head *new);	void			(*update)(struct cache_head *orig, struct cache_head *new); 	/* fields below this comment are for internal use	 * and should not be touched by cache owners	 */	time64_t		flush_time;		/* flush all cache items with							 * last_refresh at or earlier							 * than this.  last_refresh							 * is never set at or earlier							 * than this.							 */	struct list_head	others;	time64_t		nextcheck;	int			entries; 	/* fields for communication over channel */	struct list_head	queue; 	atomic_t		writers;		/* how many time is /channel open */	time64_t		last_close;		/* if no writers, when did last close */	time64_t		last_warn;		/* when we last warned about no writers */ 	union {		struct proc_dir_entry	*procfs;		struct dentry		*pipefs;	};	struct net		*net;}; /* this must be embedded in any request structure that * identifies an object that will want a callback on * a cache fill */struct cache_req {	struct cache_deferred_req *(*defer)(struct cache_req *req);	unsigned long	thread_wait;	/* How long (jiffies) we can block the					 * current thread to wait for updates.					 */}; /* this must be embedded in a deferred_request that is being * delayed awaiting cache-fill */struct cache_deferred_req {	struct hlist_node	hash;	/* on hash chain */	struct list_head	recent; /* on fifo */	struct cache_head	*item;  /* cache item we wait on */	void			*owner; /* we might need to discard all defered requests					 * owned by someone */	void			(*revisit)(struct cache_deferred_req *req,					   int too_many);}; /* * 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){	struct timespec64 boot;	getboottime64(&boot);	return ktime_get_real_seconds() - boot.tv_sec;} static inline time64_t convert_to_wallclock(time64_t sinceboot){	struct timespec64 boot;	getboottime64(&boot);	return boot.tv_sec + 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 intsunrpc_cache_pipe_upcall(struct cache_detail *detail, struct cache_head *h);extern intsunrpc_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){	kref_get(&h->ref);	return h;} static inline struct cache_head  *cache_get_rcu(struct cache_head *h){	if (kref_get_unless_zero(&h->ref))		return h;	return NULL;} static inline void cache_put(struct cache_head *h, struct cache_detail *cd){	if (kref_read(&h->ref) <= 2 &&	    h->expiry_time < cd->nextcheck)		cd->nextcheck = h->expiry_time;	kref_put(&h->ref, cd->cache_put);} static inline bool cache_is_expired(struct cache_detail *detail, struct cache_head *h){	if (h->expiry_time < seconds_since_boot())		return true;	if (!test_bit(CACHE_VALID, &h->flags))		return false;	return detail->flush_time >= h->last_refresh;} 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 (0x7FFFFFFF)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){	char buf[50];	char *ep;	int rv;	int len = qword_get(bpp, buf, sizeof(buf)); 	if (len < 0)		return -EINVAL;	if (len == 0)		return -ENOENT; 	rv = simple_strtol(buf, &ep, 0);	if (*ep)		return -EINVAL; 	*anint = rv;	return 0;} static inline int get_uint(char **bpp, unsigned int *anint){	char buf[50];	int len = qword_get(bpp, buf, sizeof(buf)); 	if (len < 0)		return -EINVAL;	if (len == 0)		return -ENOENT; 	if (kstrtouint(buf, 0, anint))		return -EINVAL; 	return 0;} static inline int get_time(char **bpp, time64_t *time){	char buf[50];	long long ll;	int len = qword_get(bpp, buf, sizeof(buf)); 	if (len < 0)		return -EINVAL;	if (len == 0)		return -ENOENT; 	if (kstrtoll(buf, 0, &ll))		return -EINVAL; 	*time = ll;	return 0;} static inline int get_expiry(char **bpp, time64_t *rvp){	int error;	struct timespec64 boot; 	error = get_time(bpp, rvp);	if (error)		return error; 	getboottime64(&boot);	(*rvp) -= boot.tv_sec;	return 0;} #endif /*  _LINUX_SUNRPC_CACHE_H_ */