1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
|
/*
* 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.
*
* 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);
#endif
|
