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/*
* Copyright (C) 2012 Red Hat. All rights reserved.
*
* This file is released under the GPL.
*/
#include "dm-cache-policy-internal.h"
#include "dm.h"
#include <linux/module.h>
#include <linux/slab.h>
/*----------------------------------------------------------------*/
#define DM_MSG_PREFIX "cache-policy"
static DEFINE_SPINLOCK(register_lock);
static LIST_HEAD(register_list);
static struct dm_cache_policy_type *__find_policy(const char *name)
{
struct dm_cache_policy_type *t;
list_for_each_entry(t, ®ister_list, list)
if (!strcmp(t->name, name))
return t;
return NULL;
}
static struct dm_cache_policy_type *__get_policy_once(const char *name)
{
struct dm_cache_policy_type *t = __find_policy(name);
if (t && !try_module_get(t->owner)) {
DMWARN("couldn't get module %s", name);
t = ERR_PTR(-EINVAL);
}
return t;
}
static struct dm_cache_policy_type *get_policy_once(const char *name)
{
struct dm_cache_policy_type *t;
spin_lock(®ister_lock);
t = __get_policy_once(name);
spin_unlock(®ister_lock);
return t;
}
static struct dm_cache_policy_type *get_policy(const char *name)
{
struct dm_cache_policy_type *t;
t = get_policy_once(name);
if (IS_ERR(t))
return NULL;
if (t)
return t;
request_module("dm-cache-%s", name);
t = get_policy_once(name);
if (IS_ERR(t))
return NULL;
return t;
}
static void put_policy(struct dm_cache_policy_type *t)
{
module_put(t->owner);
}
int dm_cache_policy_register(struct dm_cache_policy_type *type)
{
int r;
/* One size fits all for now */
if (type->hint_size != 0 && type->hint_size != 4) {
DMWARN("hint size must be 0 or 4 but %llu supplied.", (unsigned long long) type->hint_size);
return -EINVAL;
}
spin_lock(®ister_lock);
if (__find_policy(type->name)) {
DMWARN("attempt to register policy under duplicate name %s", type->name);
r = -EINVAL;
} else {
list_add(&type->list, ®ister_list);
r = 0;
}
spin_unlock(®ister_lock);
return r;
}
EXPORT_SYMBOL_GPL(dm_cache_policy_register);
void dm_cache_policy_unregister(struct dm_cache_policy_type *type)
{
spin_lock(®ister_lock);
list_del_init(&type->list);
spin_unlock(®ister_lock);
}
EXPORT_SYMBOL_GPL(dm_cache_policy_unregister);
struct dm_cache_policy *dm_cache_policy_create(const char *name,
dm_cblock_t cache_size,
sector_t origin_size,
sector_t cache_block_size)
{
struct dm_cache_policy *p = NULL;
struct dm_cache_policy_type *type;
type = get_policy(name);
if (!type) {
DMWARN("unknown policy type");
return NULL;
}
p = type->create(cache_size, origin_size, cache_block_size);
if (!p) {
put_policy(type);
return NULL;
}
p->private = type;
return p;
}
EXPORT_SYMBOL_GPL(dm_cache_policy_create);
void dm_cache_policy_destroy(struct dm_cache_policy *p)
{
struct dm_cache_policy_type *t = p->private;
p->destroy(p);
put_policy(t);
}
EXPORT_SYMBOL_GPL(dm_cache_policy_destroy);
const char *dm_cache_policy_get_name(struct dm_cache_policy *p)
{
struct dm_cache_policy_type *t = p->private;
return t->name;
}
EXPORT_SYMBOL_GPL(dm_cache_policy_get_name);
size_t dm_cache_policy_get_hint_size(struct dm_cache_policy *p)
{
struct dm_cache_policy_type *t = p->private;
return t->hint_size;
}
EXPORT_SYMBOL_GPL(dm_cache_policy_get_hint_size);
/*----------------------------------------------------------------*/
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