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Edit File: cache.h

/* 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; }; #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_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; 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); 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. * 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 time64_t get_expiry(char **bpp) { time64_t rv; struct timespec64 boot; if (get_time(bpp, &rv)) return 0; if (rv < 0) return 0; getboottime64(&boot); return rv - boot.tv_sec; } #endif /* _LINUX_SUNRPC_CACHE_H_ */