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FS-Cache: Provide a slab for cookie allocation

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Provide a slab from which can be allocated the FS-Cache cookies that will be
presented to the netfs.

Also provide a slab constructor and a function to recursively discard a cookie
and its ancestor chain.

Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Steve Dickson <steved@redhat.com>
Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Acked-by: Al Viro <viro@zeniv.linux.org.uk>
Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
This commit is contained in:
David Howells 2009-04-03 16:42:38 +01:00
parent 4c515dd47a
commit 955d00917f
4 changed files with 80 additions and 0 deletions
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1
fs/fscache/Makefile
View file

@ -4,6 +4,7 @@
fscache-y := \
cache.o \
cookie.o \
fsdef.o \
main.o

56
fs/fscache/cookie.c Normal file
View file

@ -0,0 +1,56 @@
/* netfs cookie management
*
* Copyright (C) 2004-2007 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#define FSCACHE_DEBUG_LEVEL COOKIE
#include <linux/module.h>
#include <linux/slab.h>
#include "internal.h"
struct kmem_cache *fscache_cookie_jar;
/*
* initialise an cookie jar slab element prior to any use
*/
void fscache_cookie_init_once(void *_cookie)
{
struct fscache_cookie *cookie = _cookie;
memset(cookie, 0, sizeof(*cookie));
spin_lock_init(&cookie->lock);
INIT_HLIST_HEAD(&cookie->backing_objects);
}
/*
* destroy a cookie
*/
void __fscache_cookie_put(struct fscache_cookie *cookie)
{
struct fscache_cookie *parent;
_enter("%p", cookie);
for (;;) {
_debug("FREE COOKIE %p", cookie);
parent = cookie->parent;
BUG_ON(!hlist_empty(&cookie->backing_objects));
kmem_cache_free(fscache_cookie_jar, cookie);
if (!parent)
break;
cookie = parent;
BUG_ON(atomic_read(&cookie->usage) <= 0);
if (!atomic_dec_and_test(&cookie->usage))
break;
}
_leave("");
}

8
fs/fscache/internal.h
View file

@ -36,6 +36,14 @@ extern struct rw_semaphore fscache_addremove_sem;
extern struct fscache_cache *fscache_select_cache_for_object(
struct fscache_cookie *);
/*
* fsc-cookie.c
*/
extern struct kmem_cache *fscache_cookie_jar;
extern void fscache_cookie_init_once(void *);
extern void __fscache_cookie_put(struct fscache_cookie *);
/*
* fsc-fsdef.c
*/

15
fs/fscache/main.c
View file

@ -56,6 +56,18 @@ static int __init fscache_init(void)
if (ret < 0)
goto error_proc;
fscache_cookie_jar = kmem_cache_create("fscache_cookie_jar",
sizeof(struct fscache_cookie),
0,
0,
fscache_cookie_init_once);
if (!fscache_cookie_jar) {
printk(KERN_NOTICE
"FS-Cache: Failed to allocate a cookie jar\n");
ret = -ENOMEM;
goto error_cookie_jar;
}
fscache_root = kobject_create_and_add("fscache", kernel_kobj);
if (!fscache_root)
goto error_kobj;
@ -64,6 +76,8 @@ static int __init fscache_init(void)
return 0;
error_kobj:
kmem_cache_destroy(fscache_cookie_jar);
error_cookie_jar:
fscache_proc_cleanup();
error_proc:
slow_work_unregister_user();
@ -81,6 +95,7 @@ static void __exit fscache_exit(void)
_enter("");
kobject_put(fscache_root);
kmem_cache_destroy(fscache_cookie_jar);
fscache_proc_cleanup();
slow_work_unregister_user();
printk(KERN_NOTICE "FS-Cache: Unloaded\n");