linux-imx

/*

 * Copyright (C) 2001-2002 Sistina Software (UK) Limited.

 * Copyright (C) 2006-2008 Red Hat GmbH

 *

 * This file is released under the GPL.

 */

​

#include "dm-exception-store.h"

​

#include <linux/ctype.h>

#include <linux/mm.h>

#include <linux/pagemap.h>

#include <linux/vmalloc.h>

#include <linux/module.h>

#include <linux/slab.h>

​

#define DM_MSG_PREFIX "snapshot exception stores"

​

static LIST_HEAD(_exception_store_types);

static DEFINE_SPINLOCK(_lock);

​

static struct dm_exception_store_type *__find_exception_store_type(const char *name)

{

    struct dm_exception_store_type *type;

​

    list_for_each_entry(type, &_exception_store_types, list)

        if (!strcmp(name, type->name))

            return type;

​

    return NULL;

}

​

static struct dm_exception_store_type *_get_exception_store_type(const char *name)

{

    struct dm_exception_store_type *type;

​

    spin_lock(&_lock);

​

    type = __find_exception_store_type(name);

​

    if (type && !try_module_get(type->module))

        type = NULL;

​

    spin_unlock(&_lock);

​

    return type;

}

​

/*

 * get_type

 * @type_name

 *

 * Attempt to retrieve the dm_exception_store_type by name.  If not already

 * available, attempt to load the appropriate module.

 *

 * Exstore modules are named "dm-exstore-" followed by the 'type_name'.

 * Modules may contain multiple types.

 * This function will first try the module "dm-exstore-<type_name>",

 * then truncate 'type_name' on the last '-' and try again.

 *

 * For example, if type_name was "clustered-shared", it would search

 * 'dm-exstore-clustered-shared' then 'dm-exstore-clustered'.

 *

 * 'dm-exception-store-<type_name>' is too long of a name in my

 * opinion, which is why I've chosen to have the files

 * containing exception store implementations be 'dm-exstore-<type_name>'.

 * If you want your module to be autoloaded, you will follow this

 * naming convention.

 *

 * Returns: dm_exception_store_type* on success, NULL on failure

 */

static struct dm_exception_store_type *get_type(const char *type_name)

{

    char *p, *type_name_dup;

    struct dm_exception_store_type *type;

​

    type = _get_exception_store_type(type_name);

    if (type)

        return type;

​

    type_name_dup = kstrdup(type_name, GFP_KERNEL);

    if (!type_name_dup) {

        DMERR("No memory left to attempt load for \"%s\"", type_name);

        return NULL;

    }

​

    while (request_module("dm-exstore-%s", type_name_dup) ||

           !(type = _get_exception_store_type(type_name))) {

        p = strrchr(type_name_dup, '-');

        if (!p)

            break;

        p[0] = '\0';