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authorLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 18:20:36 -0400
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 18:20:36 -0400
commit1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch)
tree0bba044c4ce775e45a88a51686b5d9f90697ea9d /drivers/md/dm-path-selector.h
Linux-2.6.12-rc2v2.6.12-rc2
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
Diffstat (limited to 'drivers/md/dm-path-selector.h')
-rw-r--r--drivers/md/dm-path-selector.h93
1 files changed, 93 insertions, 0 deletions
diff --git a/drivers/md/dm-path-selector.h b/drivers/md/dm-path-selector.h
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1/*
2 * Copyright (C) 2003 Sistina Software.
3 * Copyright (C) 2004 Red Hat, Inc. All rights reserved.
4 *
5 * Module Author: Heinz Mauelshagen
6 *
7 * This file is released under the GPL.
8 *
9 * Path-Selector registration.
10 */
11
12#ifndef DM_PATH_SELECTOR_H
13#define DM_PATH_SELECTOR_H
14
15#include <linux/device-mapper.h>
16
17#include "dm-mpath.h"
18
19/*
20 * We provide an abstraction for the code that chooses which path
21 * to send some io down.
22 */
23struct path_selector_type;
24struct path_selector {
25 struct path_selector_type *type;
26 void *context;
27};
28
29/* Information about a path selector type */
30struct path_selector_type {
31 char *name;
32 struct module *module;
33
34 unsigned int table_args;
35 unsigned int info_args;
36
37 /*
38 * Constructs a path selector object, takes custom arguments
39 */
40 int (*create) (struct path_selector *ps, unsigned argc, char **argv);
41 void (*destroy) (struct path_selector *ps);
42
43 /*
44 * Add an opaque path object, along with some selector specific
45 * path args (eg, path priority).
46 */
47 int (*add_path) (struct path_selector *ps, struct path *path,
48 int argc, char **argv, char **error);
49
50 /*
51 * Chooses a path for this io, if no paths are available then
52 * NULL will be returned.
53 *
54 * repeat_count is the number of times to use the path before
55 * calling the function again. 0 means don't call it again unless
56 * the path fails.
57 */
58 struct path *(*select_path) (struct path_selector *ps,
59 unsigned *repeat_count);
60
61 /*
62 * Notify the selector that a path has failed.
63 */
64 void (*fail_path) (struct path_selector *ps, struct path *p);
65
66 /*
67 * Ask selector to reinstate a path.
68 */
69 int (*reinstate_path) (struct path_selector *ps, struct path *p);
70
71 /*
72 * Table content based on parameters added in ps_add_path_fn
73 * or path selector status
74 */
75 int (*status) (struct path_selector *ps, struct path *path,
76 status_type_t type, char *result, unsigned int maxlen);
77
78 int (*end_io) (struct path_selector *ps, struct path *path);
79};
80
81/* Register a path selector */
82int dm_register_path_selector(struct path_selector_type *type);
83
84/* Unregister a path selector */
85int dm_unregister_path_selector(struct path_selector_type *type);
86
87/* Returns a registered path selector type */
88struct path_selector_type *dm_get_path_selector(const char *name);
89
90/* Releases a path selector */
91void dm_put_path_selector(struct path_selector_type *pst);
92
93#endif