[linux-2.6-block.git] / include / linux / sunrpc / cache.h

/*
 * 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>
 *
 * Released under terms in GPL version 2.  See COPYING.
 *
 */

#ifndef _LINUX_SUNRPC_CACHE_H_
#define _LINUX_SUNRPC_CACHE_H_

#include <linux/kref.h>
#include <linux/slab.h>
#include <linux/atomic.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 cache_head * next;
	time_t		expiry_time;	/* After time time, don't use the data */
	time_t		last_refresh;   /* If CACHE_PENDING, this is when upcall 
					 * was sent, else this is when update was received
					 */
	struct kref	ref;
	unsigned long	flags;
};
#define	CACHE_VALID	0	/* Entry contains valid data */
#define	CACHE_NEGATIVE	1	/* Negative entry - there is no match for the key */
#define	CACHE_PENDING	2	/* An upcall has been sent but no reply received yet*/

#define	CACHE_NEW_EXPIRY 120	/* keep new things pending confirmation for 120 seconds */

struct cache_detail_procfs {
	struct proc_dir_entry	*proc_ent;
	struct proc_dir_entry   *flush_ent, *channel_ent, *content_ent;
};

struct cache_detail_pipefs {
	struct dentry *dir;
};

struct cache_detail {
	struct module *		owner;
	int			hash_size;
	struct cache_head **	hash_table;
	rwlock_t		hash_lock;

	atomic_t		inuse; /* active user-space update or lookup */

	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);
	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
	 */
	time_t			flush_time;		/* flush all cache items with last_refresh
							 * earlier than this */
	struct list_head	others;
	time_t			nextcheck;
	int			entries;

	/* fields for communication over channel */
	struct list_head	queue;

	atomic_t		readers;		/* how many time is /chennel open */
	time_t			last_close;		/* if no readers, when did last close */
	time_t			last_warn;		/* when we last warned about no readers */

	union {
		struct cache_detail_procfs procfs;
		struct cache_detail_pipefs pipefs;
	} u;
	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);
	int 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);
};


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(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,
		void (*cache_request)(struct cache_detail *,
				      struct cache_head *,
				      char **,
				      int *));


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 void cache_put(struct cache_head *h, struct cache_detail *cd)
{
	if (atomic_read(&h->ref.refcount) <= 2 &&
	    h->expiry_time < cd->nextcheck)
		cd->nextcheck = h->expiry_time;
	kref_put(&h->ref, cd->cache_put);
}

static inline int cache_valid(struct cache_head *h)
{
	/* If an item has been unhashed pending removal when
	 * the refcount drops to 0, the expiry_time will be
	 * set to 0.  We don't want to consider such items
	 * valid in this context even though CACHE_VALID is
	 * set.
	 */
	return (h->expiry_time != 0 && test_bit(CACHE_VALID, &h->flags));
}

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(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 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;
}

/*
 * timestamps kept in the cache are expressed in seconds
 * since boot.  This is the best for measuring differences in
 * real time.
 */
static inline time_t seconds_since_boot(void)
{
	struct timespec boot;
	getboottime(&boot);
	return get_seconds() - boot.tv_sec;
}

static inline time_t convert_to_wallclock(time_t sinceboot)
{
	struct timespec boot;
	getboottime(&boot);
	return boot.tv_sec + sinceboot;
}

static inline time_t get_expiry(char **bpp)
{
	int rv;
	struct timespec boot;

	if (get_int(bpp, &rv))
		return 0;
	if (rv < 0)
		return 0;
	getboottime(&boot);
	return rv - boot.tv_sec;
}

#endif /*  _LINUX_SUNRPC_CACHE_H_ */
Commit	Line	Data
1da177e4 LT	1	/*
	2	* include/linux/sunrpc/cache.h
	3	*
	4	* Generic code for various authentication-related caches
	5	* used by sunrpc clients and servers.
	6	*
	7	* Copyright (C) 2002 Neil Brown <neilb@cse.unsw.edu.au>
	8	*
	9	* Released under terms in GPL version 2. See COPYING.
	10	*
	11	*/
	12
	13	#ifndef _LINUX_SUNRPC_CACHE_H_
	14	#define _LINUX_SUNRPC_CACHE_H_
	15
57cc7215	16	#include <linux/kref.h>
1da177e4	17	#include <linux/slab.h>
60063497	18	#include <linux/atomic.h>
1da177e4 LT	19	#include <linux/proc_fs.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	*
25985edc	38	* Entries have a ref count and a 'hashed' flag which counts the existence
1da177e4 LT	39	* in the hash table.
1da177e4 LT	40	* We only expire entries when refcount is zero.
25985edc	41	* Existence in the cache is counted the refcount.
1da177e4 LT	42	*/
	43
	44	/* Every cache item has a common header that is used
	45	* for expiring and refreshing entries.
	46	*
	47	*/
	48	struct cache_head {
	49	struct cache_head * next;
	50	time_t expiry_time; /* After time time, don't use the data */
	51	time_t last_refresh; /* If CACHE_PENDING, this is when upcall
	52	* was sent, else this is when update was received
	53	*/
baab935f	54	struct kref ref;
1da177e4 LT	55	unsigned long flags;
	56	};
	57	#define CACHE_VALID 0 /* Entry contains valid data */
	58	#define CACHE_NEGATIVE 1 /* Negative entry - there is no match for the key */
	59	#define CACHE_PENDING 2 /* An upcall has been sent but no reply received yet*/
	60
	61	#define CACHE_NEW_EXPIRY 120 /* keep new things pending confirmation for 120 seconds */
	62
173912a6 TM	63	struct cache_detail_procfs {
	64	struct proc_dir_entry *proc_ent;
	65	struct proc_dir_entry flush_ent, channel_ent, *content_ent;
	66	};
	67
8854e82d TM	68	struct cache_detail_pipefs {
	69	struct dentry *dir;
	70	};
	71
1da177e4	72	struct cache_detail {
f35279d3	73	struct module * owner;
1da177e4 LT	74	int hash_size;
	75	struct cache_head ** hash_table;
	76	rwlock_t hash_lock;
	77
	78	atomic_t inuse; /* active user-space update or lookup */
	79
	80	char *name;
baab935f	81	void (cache_put)(struct kref );
1da177e4	82
bc74b4f5 TM	83	int (cache_upcall)(struct cache_detail ,
	84	struct cache_head *);
	85
73fb847a SK	86	void (cache_request)(struct cache_detail cd,
	87	struct cache_head *ch,
	88	char *bpp, int blen);
	89
1da177e4 LT	90	int (cache_parse)(struct cache_detail ,
	91	char *buf, int len);
	92
	93	int (cache_show)(struct seq_file m,
	94	struct cache_detail *cd,
	95	struct cache_head *h);
2da8ca26 TM	96	void (warn_no_listener)(struct cache_detail cd,
2da8ca26 TM	97	int has_died);
1da177e4	98
15a5f6bd N	99	struct cache_head * (*alloc)(void);
	100	int (match)(struct cache_head orig, struct cache_head *new);
	101	void (init)(struct cache_head orig, struct cache_head *new);
	102	void (update)(struct cache_head orig, struct cache_head *new);
	103
1da177e4 LT	104	/* fields below this comment are for internal use
	105	* and should not be touched by cache owners
	106	*/
	107	time_t flush_time; /* flush all cache items with last_refresh
	108	* earlier than this */
	109	struct list_head others;
	110	time_t nextcheck;
	111	int entries;
	112
	113	/* fields for communication over channel */
	114	struct list_head queue;
1da177e4 LT	115
	116	atomic_t readers; /* how many time is /chennel open */
	117	time_t last_close; /* if no readers, when did last close */
	118	time_t last_warn; /* when we last warned about no readers */
173912a6 TM	119
	120	union {
	121	struct cache_detail_procfs procfs;
8854e82d	122	struct cache_detail_pipefs pipefs;
173912a6	123	} u;
0a402d5a	124	struct net *net;
1da177e4 LT	125	};
	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	*/
	132	struct cache_req {
	133	struct cache_deferred_req (defer)(struct cache_req *req);
f16b6e8d N	134	int thread_wait; /* How long (jiffies) we can block the
	135	* current thread to wait for updates.
	136	*/
1da177e4 LT	137	};
	138	/* this must be embedded in a deferred_request that is being
	139	* delayed awaiting cache-fill
	140	*/
	141	struct cache_deferred_req {
11174492	142	struct hlist_node hash; /* on hash chain */
1da177e4 LT	143	struct list_head recent; /* on fifo */
1da177e4 LT	144	struct cache_head item; / cache item we wait on */
1da177e4 LT	145	void owner; / we might need to discard all defered requests
	146	* owned by someone */
	147	void (revisit)(struct cache_deferred_req req,
	148	int too_many);
	149	};
	150
7d317f2c	151
8854e82d TM	152	extern const struct file_operations cache_file_operations_pipefs;
	153	extern const struct file_operations content_file_operations_pipefs;
	154	extern const struct file_operations cache_flush_operations_pipefs;
	155
15a5f6bd N	156	extern struct cache_head *
	157	sunrpc_cache_lookup(struct cache_detail *detail,
	158	struct cache_head *key, int hash);
	159	extern struct cache_head *
	160	sunrpc_cache_update(struct cache_detail *detail,
	161	struct cache_head new, struct cache_head old, int hash);
	162
bc74b4f5 TM	163	extern int
	164	sunrpc_cache_pipe_upcall(struct cache_detail detail, struct cache_head h,
	165	void (cache_request)(struct cache_detail ,
	166	struct cache_head *,
	167	char **,
	168	int *));
	169
1da177e4	170
1da177e4 LT	171	extern void cache_clean_deferred(void *owner);
	172
	173	static inline struct cache_head cache_get(struct cache_head h)
	174	{
baab935f	175	kref_get(&h->ref);
1da177e4 LT	176	return h;
	177	}
	178
	179
baab935f	180	static inline void cache_put(struct cache_head h, struct cache_detail cd)
1da177e4	181	{
baab935f	182	if (atomic_read(&h->ref.refcount) <= 2 &&
1da177e4 LT	183	h->expiry_time < cd->nextcheck)
1da177e4 LT	184	cd->nextcheck = h->expiry_time;
baab935f	185	kref_put(&h->ref, cd->cache_put);
1da177e4 LT	186	}
1da177e4 LT	187
7b2b1fee GB	188	static inline int cache_valid(struct cache_head *h)
	189	{
	190	/* If an item has been unhashed pending removal when
	191	* the refcount drops to 0, the expiry_time will be
	192	* set to 0. We don't want to consider such items
	193	* valid in this context even though CACHE_VALID is
	194	* set.
	195	*/
	196	return (h->expiry_time != 0 && test_bit(CACHE_VALID, &h->flags));
	197	}
	198
1da177e4 LT	199	extern int cache_check(struct cache_detail *detail,
	200	struct cache_head h, struct cache_req rqstp);
	201	extern void cache_flush(void);
	202	extern void cache_purge(struct cache_detail *detail);
	203	#define NEVER (0x7FFFFFFF)
8eab945c	204	extern void __init cache_initialize(void);
593ce16b	205	extern int cache_register_net(struct cache_detail cd, struct net net);
593ce16b	206	extern void cache_unregister_net(struct cache_detail cd, struct net net);
1da177e4	207
0a402d5a SK	208	extern struct cache_detail cache_create_net(struct cache_detail tmpl, struct net *net);
	209	extern void cache_destroy_net(struct cache_detail cd, struct net net);
	210
820f9442 SK	211	extern void sunrpc_init_cache_detail(struct cache_detail *cd);
820f9442 SK	212	extern void sunrpc_destroy_cache_detail(struct cache_detail *cd);
8854e82d	213	extern int sunrpc_cache_register_pipefs(struct dentry parent, const char ,
64f1426f	214	umode_t, struct cache_detail *);
8854e82d TM	215	extern void sunrpc_cache_unregister_pipefs(struct cache_detail *);
8854e82d TM	216
1da177e4 LT	217	extern void qword_add(char *bpp, int lp, char *str);
	218	extern void qword_addhex(char *bpp, int lp, char *buf, int blen);
	219	extern int qword_get(char *bpp, char dest, int bufsize);
	220
	221	static inline int get_int(char *bpp, int anint)
	222	{
	223	char buf[50];
621eb19c BF	224	char *ep;
621eb19c BF	225	int rv;
d9c2ede6 EZ	226	int len = qword_get(bpp, buf, sizeof(buf));
	227
	228	if (len < 0)
	229	return -EINVAL;
	230	if (len == 0)
	231	return -ENOENT;
	232
621eb19c BF	233	rv = simple_strtol(buf, &ep, 0);
621eb19c BF	234	if (*ep)
d9c2ede6 EZ	235	return -EINVAL;
d9c2ede6 EZ	236
621eb19c	237	*anint = rv;
1da177e4 LT	238	return 0;
	239	}
	240
a007c4c3 BF	241	static inline int get_uint(char *bpp, unsigned int anint)
	242	{
	243	char buf[50];
	244	int len = qword_get(bpp, buf, sizeof(buf));
	245
	246	if (len < 0)
	247	return -EINVAL;
	248	if (len == 0)
	249	return -ENOENT;
	250
	251	if (kstrtouint(buf, 0, anint))
	252	return -EINVAL;
	253
	254	return 0;
	255	}
	256
c5b29f88 N	257	/*
	258	* timestamps kept in the cache are expressed in seconds
	259	* since boot. This is the best for measuring differences in
	260	* real time.
	261	*/
	262	static inline time_t seconds_since_boot(void)
	263	{
	264	struct timespec boot;
	265	getboottime(&boot);
	266	return get_seconds() - boot.tv_sec;
	267	}
	268
	269	static inline time_t convert_to_wallclock(time_t sinceboot)
	270	{
	271	struct timespec boot;
	272	getboottime(&boot);
	273	return boot.tv_sec + sinceboot;
	274	}
	275
1da177e4 LT	276	static inline time_t get_expiry(char **bpp)
	277	{
	278	int rv;
c5b29f88 N	279	struct timespec boot;
c5b29f88 N	280
1da177e4 LT	281	if (get_int(bpp, &rv))
	282	return 0;
	283	if (rv < 0)
	284	return 0;
c5b29f88 N	285	getboottime(&boot);
c5b29f88 N	286	return rv - boot.tv_sec;
1da177e4 LT	287	}
	288
	289	#endif /* _LINUX_SUNRPC_CACHE_H_ */