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Release 4.12 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 <>
 * Released under terms in GPL version 2.  See COPYING.



#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 hlist_node	cache_list;
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, though it is alway set to
                                         * be *after* ->flush_time.
struct kref	ref;
unsigned long	flags;

#define	CACHE_VALID	0	
/* Entry contains valid data */

/* 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_CLEANED	3	
/* 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;
rwlock_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);
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 at or earlier
                                                         * than this.  last_refresh
                                                         * is never set at or 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 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);
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);

 * 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; }


Neil Brown27100.00%1100.00%

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


Neil Brown27100.00%1100.00%

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); extern void cache_clean_deferred(void *owner);
static inline struct cache_head *cache_get(struct cache_head *h) { kref_get(&h->ref); return h; }


Neil Brown25100.00%2100.00%

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); }


Neil Brown5698.25%375.00%
Peter Zijlstra11.75%125.00%

static inline bool cache_is_expired(struct cache_detail *detail, struct cache_head *h) { if (!test_bit(CACHE_VALID, &h->flags)) return false; return (h->expiry_time < seconds_since_boot()) || (detail->flush_time >= h->last_refresh); }


Greg Banks1935.85%125.00%
Neil Brown1732.08%250.00%
Kinglong Mee1732.08%125.00%

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 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(struct seq_file *file, loff_t *pos); extern void *cache_seq_next(struct seq_file *file, void *p, loff_t *pos); extern void cache_seq_stop(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; }


Neil Brown6569.89%240.00%
J. Bruce Fields2324.73%120.00%
Eldad Zack55.38%240.00%

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; }


J. Bruce Fields76100.00%1100.00%

static inline int get_time(char **bpp, time_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 = (time_t)ll; return 0; }


Harshula Jayasuriya88100.00%1100.00%

static inline time_t get_expiry(char **bpp) { time_t rv; struct timespec boot; if (get_time(bpp, &rv)) return 0; if (rv < 0) return 0; getboottime(&boot); return rv - boot.tv_sec; }


Neil Brown5296.30%266.67%
Harshula Jayasuriya23.70%133.33%

#endif /* _LINUX_SUNRPC_CACHE_H_ */

Overall Contributors

Neil Brown73758.91%1939.58%
J. Bruce Fields1038.23%510.42%
Harshula Jayasuriya907.19%12.08%
Trond Myklebust887.03%48.33%
Stanislav Kinsbursky836.63%36.25%
Kinglong Mee735.84%48.33%
Pavel Emelyanov282.24%12.08%
Greg Banks191.52%12.08%
Artem B. Bityutskiy80.64%12.08%
Bruce W Allan50.40%12.08%
Andrew Morton50.40%12.08%
Eldad Zack50.40%24.17%
Alexey Dobriyan30.24%12.08%
Peter Zijlstra10.08%12.08%
Al Viro10.08%12.08%
Lucas De Marchi10.08%12.08%
Arun Sharma10.08%12.08%
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