linux-imx

/*

 * Copyright (C) 2003 Sistina Software.

 * Copyright (C) 2004 Red Hat, Inc. All rights reserved.

 *

 * Module Author: Heinz Mauelshagen

 *

 * This file is released under the GPL.

 *

 * Path-Selector registration.

 */

​

#ifndef DM_PATH_SELECTOR_H

#define DM_PATH_SELECTOR_H

​

#include <linux/device-mapper.h>

​

#include "dm-mpath.h"

​

/*

 * We provide an abstraction for the code that chooses which path

 * to send some io down.

 */

struct path_selector_type;

struct path_selector {

    struct path_selector_type *type;

    void *context;

};

​

/* Information about a path selector type */

struct path_selector_type {

    char *name;

    struct module *module;

​

    unsigned int table_args;

    unsigned int info_args;

​

    /*

     * Constructs a path selector object, takes custom arguments

     */

    int (*create) (struct path_selector *ps, unsigned argc, char **argv);

    void (*destroy) (struct path_selector *ps);

​

    /*

     * Add an opaque path object, along with some selector specific

     * path args (eg, path priority).

     */

    int (*add_path) (struct path_selector *ps, struct dm_path *path,

             int argc, char **argv, char **error);

​

    /*

     * Chooses a path for this io, if no paths are available then

     * NULL will be returned.

     */

    struct dm_path *(*select_path) (struct path_selector *ps,

                    size_t nr_bytes);

​

    /*

     * Notify the selector that a path has failed.

     */

    void (*fail_path) (struct path_selector *ps, struct dm_path *p);

​

    /*

     * Ask selector to reinstate a path.