projects / linux.git / blame
| Commit | Line | Data |
|---|---|---|
| 1da177e4 LT |
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 | */ | |
| 23 | struct path_selector_type; | |
| 24 | struct path_selector { | |
| 25 | struct path_selector_type *type; | |
| 26 | void *context; | |
| 27 | }; | |
| 28 | ||
| 29 | /* Information about a path selector type */ | |
| 30 | struct 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 */ | |
| 82 | int dm_register_path_selector(struct path_selector_type *type); | |
| 83 | ||
| 84 | /* Unregister a path selector */ | |
| 85 | int dm_unregister_path_selector(struct path_selector_type *type); | |
| 86 | ||
| 87 | /* Returns a registered path selector type */ | |
| 88 | struct path_selector_type *dm_get_path_selector(const char *name); | |
| 89 | ||
| 90 | /* Releases a path selector */ | |
| 91 | void dm_put_path_selector(struct path_selector_type *pst); | |
| 92 | ||
| 93 | #endif |