blob: 27357b85d73d7495cbcb2d61e8522ac942317901 [file] [log] [blame]
* 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.
#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.
* repeat_count is the number of times to use the path before
* calling the function again. 0 means don't call it again unless
* the path fails.
struct dm_path *(*select_path) (struct path_selector *ps,
unsigned *repeat_count);
* 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.
int (*reinstate_path) (struct path_selector *ps, struct dm_path *p);
* Table content based on parameters added in ps_add_path_fn
* or path selector status
int (*status) (struct path_selector *ps, struct dm_path *path,
status_type_t type, char *result, unsigned int maxlen);
int (*end_io) (struct path_selector *ps, struct dm_path *path);
/* Register a path selector */
int dm_register_path_selector(struct path_selector_type *type);
/* Unregister a path selector */
int dm_unregister_path_selector(struct path_selector_type *type);
/* Returns a registered path selector type */
struct path_selector_type *dm_get_path_selector(const char *name);
/* Releases a path selector */
void dm_put_path_selector(struct path_selector_type *pst);