313 lines
10 KiB
C
313 lines
10 KiB
C
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/*
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* include/linux/sunrpc/cache.h
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*
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* Generic code for various authentication-related caches
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* used by sunrpc clients and servers.
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*
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* Copyright (C) 2002 Neil Brown <neilb@cse.unsw.edu.au>
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*
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* Released under terms in GPL version 2. See COPYING.
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*
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*/
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#ifndef _LINUX_SUNRPC_CACHE_H_
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#define _LINUX_SUNRPC_CACHE_H_
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#include <linux/slab.h>
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#include <asm/atomic.h>
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#include <linux/proc_fs.h>
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/*
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* Each cache requires:
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* - A 'struct cache_detail' which contains information specific to the cache
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* for common code to use.
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* - An item structure that must contain a "struct cache_head"
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* - A lookup function defined using DefineCacheLookup
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* - A 'put' function that can release a cache item. It will only
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* be called after cache_put has succeed, so there are guarantee
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* to be no references.
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* - A function to calculate a hash of an item's key.
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*
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* as well as assorted code fragments (e.g. compare keys) and numbers
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* (e.g. hash size, goal_age, etc).
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*
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* Each cache must be registered so that it can be cleaned regularly.
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* When the cache is unregistered, it is flushed completely.
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*
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* Entries have a ref count and a 'hashed' flag which counts the existance
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* in the hash table.
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* We only expire entries when refcount is zero.
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* Existance in the cache is counted the refcount.
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*/
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/* Every cache item has a common header that is used
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* for expiring and refreshing entries.
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*
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*/
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struct cache_head {
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struct cache_head * next;
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time_t expiry_time; /* After time time, don't use the data */
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time_t last_refresh; /* If CACHE_PENDING, this is when upcall
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* was sent, else this is when update was received
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*/
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atomic_t refcnt;
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unsigned long flags;
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};
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#define CACHE_VALID 0 /* Entry contains valid data */
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#define CACHE_NEGATIVE 1 /* Negative entry - there is no match for the key */
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#define CACHE_PENDING 2 /* An upcall has been sent but no reply received yet*/
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#define CACHE_NEW_EXPIRY 120 /* keep new things pending confirmation for 120 seconds */
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struct cache_detail {
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int hash_size;
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struct cache_head ** hash_table;
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rwlock_t hash_lock;
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atomic_t inuse; /* active user-space update or lookup */
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char *name;
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void (*cache_put)(struct cache_head *,
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struct cache_detail*);
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void (*cache_request)(struct cache_detail *cd,
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struct cache_head *h,
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char **bpp, int *blen);
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int (*cache_parse)(struct cache_detail *,
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char *buf, int len);
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int (*cache_show)(struct seq_file *m,
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struct cache_detail *cd,
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struct cache_head *h);
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/* fields below this comment are for internal use
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* and should not be touched by cache owners
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*/
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time_t flush_time; /* flush all cache items with last_refresh
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* earlier than this */
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struct list_head others;
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time_t nextcheck;
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int entries;
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/* fields for communication over channel */
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struct list_head queue;
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struct proc_dir_entry *proc_ent;
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struct proc_dir_entry *flush_ent, *channel_ent, *content_ent;
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atomic_t readers; /* how many time is /chennel open */
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time_t last_close; /* if no readers, when did last close */
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time_t last_warn; /* when we last warned about no readers */
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void (*warn_no_listener)(struct cache_detail *cd);
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};
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/* this must be embedded in any request structure that
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* identifies an object that will want a callback on
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* a cache fill
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*/
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struct cache_req {
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struct cache_deferred_req *(*defer)(struct cache_req *req);
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};
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/* this must be embedded in a deferred_request that is being
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* delayed awaiting cache-fill
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*/
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struct cache_deferred_req {
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struct list_head hash; /* on hash chain */
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struct list_head recent; /* on fifo */
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struct cache_head *item; /* cache item we wait on */
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time_t recv_time;
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void *owner; /* we might need to discard all defered requests
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* owned by someone */
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void (*revisit)(struct cache_deferred_req *req,
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int too_many);
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};
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/*
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* just like a template in C++, this macro does cache lookup
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* for us.
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* The function is passed some sort of HANDLE from which a cache_detail
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* structure can be determined (via SETUP, DETAIL), a template
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* cache entry (type RTN*), and a "set" flag. Using the HASHFN and the
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* TEST, the function will try to find a matching cache entry in the cache.
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* If "set" == 0 :
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* If an entry is found, it is returned
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* If no entry is found, a new non-VALID entry is created.
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* If "set" == 1 and INPLACE == 0 :
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* If no entry is found a new one is inserted with data from "template"
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* If a non-CACHE_VALID entry is found, it is updated from template using UPDATE
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* If a CACHE_VALID entry is found, a new entry is swapped in with data
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* from "template"
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* If set == 1, and INPLACE == 1 :
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* As above, except that if a CACHE_VALID entry is found, we UPDATE in place
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* instead of swapping in a new entry.
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*
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* If the passed handle has the CACHE_NEGATIVE flag set, then UPDATE is not
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* run but insteead CACHE_NEGATIVE is set in any new item.
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* In any case, the new entry is returned with a reference count.
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*
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*
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* RTN is a struct type for a cache entry
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* MEMBER is the member of the cache which is cache_head, which must be first
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* FNAME is the name for the function
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* ARGS are arguments to function and must contain RTN *item, int set. May
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* also contain something to be usedby SETUP or DETAIL to find cache_detail.
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* SETUP locates the cache detail and makes it available as...
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* DETAIL identifies the cache detail, possibly set up by SETUP
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* HASHFN returns a hash value of the cache entry "item"
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* TEST tests if "tmp" matches "item"
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* INIT copies key information from "item" to "new"
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* UPDATE copies content information from "item" to "tmp"
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* INPLACE is true if updates can happen inplace rather than allocating a new structure
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*
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* WARNING: any substantial changes to this must be reflected in
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* net/sunrpc/svcauth.c(auth_domain_lookup)
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* which is a similar routine that is open-coded.
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*/
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#define DefineCacheLookup(RTN,MEMBER,FNAME,ARGS,SETUP,DETAIL,HASHFN,TEST,INIT,UPDATE,INPLACE) \
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RTN *FNAME ARGS \
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{ \
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RTN *tmp, *new=NULL; \
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struct cache_head **hp, **head; \
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SETUP; \
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head = &(DETAIL)->hash_table[HASHFN]; \
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retry: \
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if (set||new) write_lock(&(DETAIL)->hash_lock); \
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else read_lock(&(DETAIL)->hash_lock); \
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for(hp=head; *hp != NULL; hp = &tmp->MEMBER.next) { \
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tmp = container_of(*hp, RTN, MEMBER); \
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if (TEST) { /* found a match */ \
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\
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if (set && !INPLACE && test_bit(CACHE_VALID, &tmp->MEMBER.flags) && !new) \
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break; \
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\
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if (new) \
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{INIT;} \
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if (set) { \
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if (!INPLACE && test_bit(CACHE_VALID, &tmp->MEMBER.flags))\
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{ /* need to swap in new */ \
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RTN *t2; \
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\
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new->MEMBER.next = tmp->MEMBER.next; \
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*hp = &new->MEMBER; \
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tmp->MEMBER.next = NULL; \
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t2 = tmp; tmp = new; new = t2; \
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} \
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if (test_bit(CACHE_NEGATIVE, &item->MEMBER.flags)) \
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set_bit(CACHE_NEGATIVE, &tmp->MEMBER.flags); \
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else { \
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UPDATE; \
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clear_bit(CACHE_NEGATIVE, &tmp->MEMBER.flags); \
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} \
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} \
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cache_get(&tmp->MEMBER); \
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if (set||new) write_unlock(&(DETAIL)->hash_lock); \
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else read_unlock(&(DETAIL)->hash_lock); \
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if (set) \
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cache_fresh(DETAIL, &tmp->MEMBER, item->MEMBER.expiry_time); \
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if (set && !INPLACE && new) cache_fresh(DETAIL, &new->MEMBER, 0); \
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if (new) (DETAIL)->cache_put(&new->MEMBER, DETAIL); \
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return tmp; \
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} \
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} \
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/* Didn't find anything */ \
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if (new) { \
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INIT; \
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new->MEMBER.next = *head; \
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*head = &new->MEMBER; \
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(DETAIL)->entries ++; \
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cache_get(&new->MEMBER); \
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if (set) { \
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tmp = new; \
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if (test_bit(CACHE_NEGATIVE, &item->MEMBER.flags)) \
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set_bit(CACHE_NEGATIVE, &tmp->MEMBER.flags); \
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else {UPDATE;} \
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} \
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} \
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if (set||new) write_unlock(&(DETAIL)->hash_lock); \
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else read_unlock(&(DETAIL)->hash_lock); \
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if (new && set) \
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cache_fresh(DETAIL, &new->MEMBER, item->MEMBER.expiry_time); \
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if (new) \
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return new; \
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new = kmalloc(sizeof(*new), GFP_KERNEL); \
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if (new) { \
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cache_init(&new->MEMBER); \
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goto retry; \
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} \
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return NULL; \
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}
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#define DefineSimpleCacheLookup(STRUCT,INPLACE) \
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DefineCacheLookup(struct STRUCT, h, STRUCT##_lookup, (struct STRUCT *item, int set), /*no setup */, \
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& STRUCT##_cache, STRUCT##_hash(item), STRUCT##_match(item, tmp),\
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STRUCT##_init(new, item), STRUCT##_update(tmp, item),INPLACE)
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#define cache_for_each(pos, detail, index, member) \
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for (({read_lock(&(detail)->hash_lock); index = (detail)->hash_size;}) ; \
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({if (index==0)read_unlock(&(detail)->hash_lock); index--;}); \
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) \
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for (pos = container_of((detail)->hash_table[index], typeof(*pos), member); \
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&pos->member; \
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pos = container_of(pos->member.next, typeof(*pos), member))
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extern void cache_clean_deferred(void *owner);
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static inline struct cache_head *cache_get(struct cache_head *h)
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{
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atomic_inc(&h->refcnt);
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return h;
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}
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static inline int cache_put(struct cache_head *h, struct cache_detail *cd)
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{
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if (atomic_read(&h->refcnt) <= 2 &&
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h->expiry_time < cd->nextcheck)
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cd->nextcheck = h->expiry_time;
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return atomic_dec_and_test(&h->refcnt);
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}
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extern void cache_init(struct cache_head *h);
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extern void cache_fresh(struct cache_detail *detail,
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struct cache_head *head, time_t expiry);
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extern int cache_check(struct cache_detail *detail,
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struct cache_head *h, struct cache_req *rqstp);
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extern void cache_flush(void);
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extern void cache_purge(struct cache_detail *detail);
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#define NEVER (0x7FFFFFFF)
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extern void cache_register(struct cache_detail *cd);
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extern int cache_unregister(struct cache_detail *cd);
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extern void qword_add(char **bpp, int *lp, char *str);
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extern void qword_addhex(char **bpp, int *lp, char *buf, int blen);
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extern int qword_get(char **bpp, char *dest, int bufsize);
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static inline int get_int(char **bpp, int *anint)
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{
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char buf[50];
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char *ep;
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int rv;
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int len = qword_get(bpp, buf, 50);
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if (len < 0) return -EINVAL;
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if (len ==0) return -ENOENT;
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rv = simple_strtol(buf, &ep, 0);
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if (*ep) return -EINVAL;
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*anint = rv;
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return 0;
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}
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static inline time_t get_expiry(char **bpp)
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{
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int rv;
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if (get_int(bpp, &rv))
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return 0;
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if (rv < 0)
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return 0;
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return rv;
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}
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#endif /* _LINUX_SUNRPC_CACHE_H_ */
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