linux-imx

/*

 * 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, &register_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(&register_lock);

    t = __get_policy_once(name);

    spin_unlock(&register_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;