WebSVN - shark - Blame - Rev 1618 - /shark/branches/xen/drivers/linuxc26/include/linux/sunrpc/cache.h

Rev	Author	Line No.	Line
423	giacomo	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
		16	#include <linux/slab.h>
		17	#include <asm/atomic.h>
		18	#include <linux/proc_fs.h>
		19
		20	/*
		21	* Each cache requires:
		22	* - A 'struct cache_detail' which contains information specific to the cache
		23	* for common code to use.
		24	* - An item structure that must contain a "struct cache_head"
		25	* - A lookup function defined using DefineCacheLookup
		26	* - A 'put' function that can release a cache item. It will only
		27	* be called after cache_put has succeed, so there are guarantee
		28	* to be no references.
		29	* - A function to calculate a hash of an item's key.
		30	*
		31	* as well as assorted code fragments (e.g. compare keys) and numbers
		32	* (e.g. hash size, goal_age, etc).
		33	*
		34	* Each cache must be registered so that it can be cleaned regularly.
		35	* When the cache is unregistered, it is flushed completely.
		36	*
		37	* Entries have a ref count and a 'hashed' flag which counts the existance
		38	* in the hash table.
		39	* We only expire entries when refcount is zero.
		40	* Existance in the cache is not measured in refcount but rather in
		41	* CACHE_HASHED flag.
		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	*/
		54	atomic_t refcnt;
		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	#define CACHE_HASHED 3 /* Entry is in a hash table */
		61
		62	#define CACHE_NEW_EXPIRY 120 /* keep new things pending confirmation for 120 seconds */
		63
		64	struct cache_detail {
		65	int hash_size;
		66	struct cache_head ** hash_table;
		67	rwlock_t hash_lock;
		68
		69	atomic_t inuse; /* active user-space update or lookup */
		70
		71	char *name;
		72	void (cache_put)(struct cache_head ,
		73	struct cache_detail*);
		74
		75	void (cache_request)(struct cache_detail cd,
		76	struct cache_head *h,
		77	char *bpp, int blen);
		78	int (cache_parse)(struct cache_detail ,
		79	char *buf, int len);
		80
		81	int (cache_show)(struct seq_file m,
		82	struct cache_detail *cd,
		83	struct cache_head *h);
		84
		85	/* fields below this comment are for internal use
		86	* and should not be touched by cache owners
		87	*/
		88	time_t flush_time; /* flush all cache items with last_refresh
		89	* earlier than this */
		90	struct list_head others;
		91	time_t nextcheck;
		92	int entries;
		93
		94	/* fields for communication over channel */
		95	struct list_head queue;
		96	struct proc_dir_entry *proc_ent;
		97	atomic_t readers; /* how many time is /chennel open */
		98	time_t last_close; /* it no readers, when did last close */
		99	};
		100
		101
		102	/* this must be embedded in any request structure that
		103	* identifies an object that will want a callback on
		104	* a cache fill
		105	*/
		106	struct cache_req {
		107	struct cache_deferred_req (defer)(struct cache_req *req);
		108	};
		109	/* this must be embedded in a deferred_request that is being
		110	* delayed awaiting cache-fill
		111	*/
		112	struct cache_deferred_req {
		113	struct list_head hash; /* on hash chain */
		114	struct list_head recent; /* on fifo */
		115	struct cache_head item; / cache item we wait on */
		116	time_t recv_time;
		117	void owner; / we might need to discard all defered requests
		118	* owned by someone */
		119	void (revisit)(struct cache_deferred_req req,
		120	int too_many);
		121	};
		122
		123	/*
		124	* just like a template in C++, this macro does cache lookup
		125	* for us.
		126	* The function is passed some sort of HANDLE from which a cache_detail
		127	* structure can be determined (via SETUP, DETAIL), a template
		128	* cache entry (type RTN*), and a "set" flag. Using the HASHFN and the
		129	* TEST, the function will try to find a matching cache entry in the cache.
		130	* If "set" == 0 :
		131	* If an entry is found, it is returned
		132	* If no entry is found, a new non-VALID entry is created.
		133	* If "set" == 1 :
		134	* If no entry is found a new one is inserted with data from "template"
		135	* If a non-CACHE_VALID entry is found, it is updated from template using UPDATE
		136	* If a CACHE_VALID entry is found, a new entry is swapped in with data
		137	* from "template"
		138	* If set == 2, we UPDATE, but don't swap. i.e. update in place
		139	*
		140	* If the passed handle has the CACHE_NEGATIVE flag set, then UPDATE is not
		141	* run but insteead CACHE_NEGATIVE is set in any new item.
		142
		143	* In any case, the new entry is returned with a reference count.
		144	*
		145	*
		146	* RTN is a struct type for a cache entry
		147	* MEMBER is the member of the cache which is cache_head, which must be first
		148	* FNAME is the name for the function
		149	* ARGS are arguments to function and must contain RTN *item, int set. May
		150	* also contain something to be usedby SETUP or DETAIL to find cache_detail.
		151	* SETUP locates the cache detail and makes it available as...
		152	* DETAIL identifies the cache detail, possibly set up by SETUP
		153	* HASHFN returns a hash value of the cache entry "item"
		154	* TEST tests if "tmp" matches "item"
		155	* INIT copies key information from "item" to "new"
		156	* UPDATE copies content information from "item" to "tmp"
		157	* INPLACE is true if updates can happen inplace rather than allocating a new structure
		158	*/
		159	#define DefineCacheLookup(RTN,MEMBER,FNAME,ARGS,SETUP,DETAIL,HASHFN,TEST,INIT,UPDATE,INPLACE) \
		160	RTN *FNAME ARGS \
		161	{ \
		162	RTN tmp, new=NULL; \
		163	struct cache_head hp, head; \
		164	SETUP; \
		165	retry: \
		166	head = &(DETAIL)->hash_table[HASHFN]; \
		167	if (set\|\|new) write_lock(&(DETAIL)->hash_lock); \
		168	else read_lock(&(DETAIL)->hash_lock); \
		169	for(hp=head; *hp != NULL; hp = &tmp->MEMBER.next) { \
		170	tmp = container_of(*hp, RTN, MEMBER); \
		171	if (TEST) { /* found a match */ \
		172	\
		173	if (set && !INPLACE && test_bit(CACHE_VALID, &tmp->MEMBER.flags) && !new) \
		174	break; \
		175	\
		176	cache_get(&tmp->MEMBER); \
		177	if (set) { \
		178	if (!INPLACE && test_bit(CACHE_VALID, &tmp->MEMBER.flags))\
		179	{ /* need to swap in new */ \
		180	RTN *t2; \
		181	\
		182	new->MEMBER.next = tmp->MEMBER.next; \
		183	*hp = &new->MEMBER; \
		184	tmp->MEMBER.next = NULL; \
		185	set_bit(CACHE_HASHED, &new->MEMBER.flags); \
		186	clear_bit(CACHE_HASHED, &tmp->MEMBER.flags); \
		187	t2 = tmp; tmp = new; new = t2; \
		188	} \
		189	if (test_bit(CACHE_NEGATIVE, &item->MEMBER.flags)) \
		190	set_bit(CACHE_NEGATIVE, &tmp->MEMBER.flags); \
		191	else {UPDATE;} \
		192	} \
		193	if (set\|\|new) write_unlock(&(DETAIL)->hash_lock); \
		194	else read_unlock(&(DETAIL)->hash_lock); \
		195	if (set) \
		196	cache_fresh(DETAIL, &tmp->MEMBER, item->MEMBER.expiry_time); \
		197	if (set && !INPLACE && new) cache_fresh(DETAIL, &new->MEMBER, 0); \
		198	if (new) (DETAIL)->cache_put(&new->MEMBER, DETAIL); \
		199	return tmp; \
		200	} \
		201	} \
		202	/* Didn't find anything */ \
		203	if (new) { \
		204	new->MEMBER.next = *head; \
		205	*head = &new->MEMBER; \
		206	(DETAIL)->entries ++; \
		207	set_bit(CACHE_HASHED, &new->MEMBER.flags); \
		208	if (set) { \
		209	tmp = new; \
		210	if (test_bit(CACHE_NEGATIVE, &item->MEMBER.flags)) \
		211	set_bit(CACHE_NEGATIVE, &tmp->MEMBER.flags); \
		212	else {UPDATE;} \
		213	} \
		214	} \
		215	if (set\|\|new) write_unlock(&(DETAIL)->hash_lock); \
		216	else read_unlock(&(DETAIL)->hash_lock); \
		217	if (new && set) \
		218	cache_fresh(DETAIL, &new->MEMBER, item->MEMBER.expiry_time); \
		219	if (new) \
		220	return new; \
		221	new = kmalloc(sizeof(*new), GFP_KERNEL); \
		222	if (new) { \
		223	cache_init(&new->MEMBER); \
		224	cache_get(&new->MEMBER); \
		225	INIT; \
		226	tmp = new; \
		227	goto retry; \
		228	} \
		229	return NULL; \
		230	}
		231
		232	#define DefineSimpleCacheLookup(STRUCT,INPLACE) \
		233	DefineCacheLookup(struct STRUCT, h, STRUCT##_lookup, (struct STRUCT item, int set), /no setup */, \
		234	& STRUCT##_cache, STRUCT##_hash(item), STRUCT##_match(item, tmp),\
		235	STRUCT##_init(new, item), STRUCT##_update(tmp, item),INPLACE)
		236
		237	#define cache_for_each(pos, detail, index, member) \
		238	for (({read_lock(&(detail)->hash_lock); index = (detail)->hash_size;}) ; \
		239	({if (index==0)read_unlock(&(detail)->hash_lock); index--;}); \
		240	) \
		241	for (pos = container_of((detail)->hash_table[index], typeof(*pos), member); \
		242	&pos->member; \
		243	pos = container_of(pos->member.next, typeof(*pos), member))
		244
		245
		246
		247	extern void cache_defer_req(struct cache_req req, struct cache_head item);
		248	extern void cache_revisit_request(struct cache_head *item);
		249	extern void cache_clean_deferred(void *owner);
		250
		251	static inline struct cache_head cache_get(struct cache_head h)
		252	{
		253	atomic_inc(&h->refcnt);
		254	return h;
		255	}
		256
		257
		258	static inline int cache_put(struct cache_head h, struct cache_detail cd)
		259	{
		260	atomic_dec(&h->refcnt);
		261	if (!atomic_read(&h->refcnt) &&
		262	h->expiry_time < cd->nextcheck)
		263	cd->nextcheck = h->expiry_time;
		264	if (!test_bit(CACHE_HASHED, &h->flags) &&
		265	!atomic_read(&h->refcnt))
		266	return 1;
		267
		268	return 0;
		269	}
		270
		271	extern void cache_init(struct cache_head *h);
		272	extern void cache_fresh(struct cache_detail *detail,
		273	struct cache_head *head, time_t expiry);
		274	extern int cache_check(struct cache_detail *detail,
		275	struct cache_head h, struct cache_req rqstp);
		276	extern int cache_clean(void);
		277	extern void cache_flush(void);
		278	extern void cache_purge(struct cache_detail *detail);
		279	#define NEVER (0x7FFFFFFF)
		280	extern void cache_register(struct cache_detail *cd);
		281	extern int cache_unregister(struct cache_detail *cd);
		282	extern struct cache_detail cache_find(char name);
		283	extern void cache_drop(struct cache_detail *detail);
		284
		285	extern void qword_add(char *bpp, int lp, char *str);
		286	extern void qword_addhex(char *bpp, int lp, char *buf, int blen);
		287	extern int qword_get(char *bpp, char dest, int bufsize);
		288
		289	static inline int get_int(char *bpp, int anint)
		290	{
		291	char buf[50];
		292	char *ep;
		293	int rv;
		294	int len = qword_get(bpp, buf, 50);
		295	if (len < 0) return -EINVAL;
		296	if (len ==0) return -ENOENT;
		297	rv = simple_strtol(buf, &ep, 0);
		298	if (*ep) return -EINVAL;
		299	*anint = rv;
		300	return 0;
		301	}
		302
		303	static inline time_t get_expiry(char **bpp)
		304	{
		305	int rv;
		306	if (get_int(bpp, &rv))
		307	return 0;
		308	if (rv < 0)
		309	return 0;
		310	return rv;
		311	}
		312
		313	#endif /* _LINUX_SUNRPC_CACHE_H_ */

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