Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 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 | #include "dm.h" |
| 13 | #include "dm-path-selector.h" |
| 14 | |
| 15 | #include <linux/slab.h> |
| 16 | |
| 17 | struct ps_internal { |
| 18 | struct path_selector_type pst; |
| 19 | |
| 20 | struct list_head list; |
| 21 | long use; |
| 22 | }; |
| 23 | |
| 24 | #define pst_to_psi(__pst) container_of((__pst), struct ps_internal, pst) |
| 25 | |
| 26 | static LIST_HEAD(_path_selectors); |
| 27 | static DECLARE_RWSEM(_ps_lock); |
| 28 | |
Alasdair G Kergon | 5e198d9 | 2005-05-05 16:16:09 -0700 | [diff] [blame] | 29 | static struct ps_internal *__find_path_selector_type(const char *name) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 30 | { |
| 31 | struct ps_internal *psi; |
| 32 | |
| 33 | list_for_each_entry(psi, &_path_selectors, list) { |
| 34 | if (!strcmp(name, psi->pst.name)) |
| 35 | return psi; |
| 36 | } |
| 37 | |
| 38 | return NULL; |
| 39 | } |
| 40 | |
| 41 | static struct ps_internal *get_path_selector(const char *name) |
| 42 | { |
| 43 | struct ps_internal *psi; |
| 44 | |
| 45 | down_read(&_ps_lock); |
| 46 | psi = __find_path_selector_type(name); |
| 47 | if (psi) { |
| 48 | if ((psi->use == 0) && !try_module_get(psi->pst.module)) |
| 49 | psi = NULL; |
| 50 | else |
| 51 | psi->use++; |
| 52 | } |
| 53 | up_read(&_ps_lock); |
| 54 | |
| 55 | return psi; |
| 56 | } |
| 57 | |
| 58 | struct path_selector_type *dm_get_path_selector(const char *name) |
| 59 | { |
| 60 | struct ps_internal *psi; |
| 61 | |
| 62 | if (!name) |
| 63 | return NULL; |
| 64 | |
| 65 | psi = get_path_selector(name); |
| 66 | if (!psi) { |
| 67 | request_module("dm-%s", name); |
| 68 | psi = get_path_selector(name); |
| 69 | } |
| 70 | |
| 71 | return psi ? &psi->pst : NULL; |
| 72 | } |
| 73 | |
| 74 | void dm_put_path_selector(struct path_selector_type *pst) |
| 75 | { |
| 76 | struct ps_internal *psi; |
| 77 | |
| 78 | if (!pst) |
| 79 | return; |
| 80 | |
| 81 | down_read(&_ps_lock); |
| 82 | psi = __find_path_selector_type(pst->name); |
| 83 | if (!psi) |
| 84 | goto out; |
| 85 | |
| 86 | if (--psi->use == 0) |
| 87 | module_put(psi->pst.module); |
| 88 | |
Eric Sesterhenn | c163c72 | 2006-03-26 18:21:58 +0200 | [diff] [blame] | 89 | BUG_ON(psi->use < 0); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 90 | |
| 91 | out: |
| 92 | up_read(&_ps_lock); |
| 93 | } |
| 94 | |
| 95 | static struct ps_internal *_alloc_path_selector(struct path_selector_type *pst) |
| 96 | { |
Dmitry Monakhov | 094262d | 2007-10-19 22:38:51 +0100 | [diff] [blame^] | 97 | struct ps_internal *psi = kzalloc(sizeof(*psi), GFP_KERNEL); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 98 | |
Dmitry Monakhov | 094262d | 2007-10-19 22:38:51 +0100 | [diff] [blame^] | 99 | if (psi) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 100 | psi->pst = *pst; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 101 | |
| 102 | return psi; |
| 103 | } |
| 104 | |
| 105 | int dm_register_path_selector(struct path_selector_type *pst) |
| 106 | { |
| 107 | int r = 0; |
| 108 | struct ps_internal *psi = _alloc_path_selector(pst); |
| 109 | |
| 110 | if (!psi) |
| 111 | return -ENOMEM; |
| 112 | |
| 113 | down_write(&_ps_lock); |
| 114 | |
| 115 | if (__find_path_selector_type(pst->name)) { |
| 116 | kfree(psi); |
| 117 | r = -EEXIST; |
| 118 | } else |
| 119 | list_add(&psi->list, &_path_selectors); |
| 120 | |
| 121 | up_write(&_ps_lock); |
| 122 | |
| 123 | return r; |
| 124 | } |
| 125 | |
| 126 | int dm_unregister_path_selector(struct path_selector_type *pst) |
| 127 | { |
| 128 | struct ps_internal *psi; |
| 129 | |
| 130 | down_write(&_ps_lock); |
| 131 | |
| 132 | psi = __find_path_selector_type(pst->name); |
| 133 | if (!psi) { |
| 134 | up_write(&_ps_lock); |
| 135 | return -EINVAL; |
| 136 | } |
| 137 | |
| 138 | if (psi->use) { |
| 139 | up_write(&_ps_lock); |
| 140 | return -ETXTBSY; |
| 141 | } |
| 142 | |
| 143 | list_del(&psi->list); |
| 144 | |
| 145 | up_write(&_ps_lock); |
| 146 | |
| 147 | kfree(psi); |
| 148 | |
| 149 | return 0; |
| 150 | } |
| 151 | |
| 152 | EXPORT_SYMBOL_GPL(dm_register_path_selector); |
| 153 | EXPORT_SYMBOL_GPL(dm_unregister_path_selector); |