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Subject[PATCH 14/43] FS-Cache: Provide a slab for cookie allocation [ver #46]
Date
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>
---

fs/fscache/Makefile | 1 +
fs/fscache/cookie.c | 56 +++++++++++++++++++++++++++++++++++++++++++++++++
fs/fscache/internal.h | 8 +++++++
fs/fscache/main.c | 15 +++++++++++++
4 files changed, 80 insertions(+), 0 deletions(-)
create mode 100644 fs/fscache/cookie.c


diff --git a/fs/fscache/Makefile b/fs/fscache/Makefile
index 556708b..f88ac17 100644
--- a/fs/fscache/Makefile
+++ b/fs/fscache/Makefile
@@ -4,6 +4,7 @@

fscache-y := \
cache.o \
+ cookie.o \
fsdef.o \
main.o

diff --git a/fs/fscache/cookie.c b/fs/fscache/cookie.c
new file mode 100644
index 0000000..47fd75b
--- /dev/null
+++ b/fs/fscache/cookie.c
@@ -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("");
+}
diff --git a/fs/fscache/internal.h b/fs/fscache/internal.h
index 0a2069a..4c6ba56 100644
--- a/fs/fscache/internal.h
+++ b/fs/fscache/internal.h
@@ -37,6 +37,14 @@ 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
*/
extern struct fscache_cookie fscache_fsdef_index;
diff --git a/fs/fscache/main.c b/fs/fscache/main.c
index c2f3e63..48b79d2 100644
--- a/fs/fscache/main.c
+++ b/fs/fscache/main.c
@@ -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");


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