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/* 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 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)
{
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_ */