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 <linux/device-mapper.h> 13 #include <linux/module.h> 14 15 #include "dm-path-selector.h" 16 17 #include <linux/slab.h> 18 19 struct ps_internal { 20 struct path_selector_type pst; 21 struct list_head list; 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 29 static struct ps_internal *__find_path_selector_type(const char *name) 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 && !try_module_get(psi->pst.module)) 48 psi = NULL; 49 up_read(&_ps_lock); 50 51 return psi; 52 } 53 54 struct path_selector_type *dm_get_path_selector(const char *name) 55 { 56 struct ps_internal *psi; 57 58 if (!name) 59 return NULL; 60 61 psi = get_path_selector(name); 62 if (!psi) { 63 request_module("dm-%s", name); 64 psi = get_path_selector(name); 65 } 66 67 return psi ? &psi->pst : NULL; 68 } 69 70 void dm_put_path_selector(struct path_selector_type *pst) 71 { 72 struct ps_internal *psi; 73 74 if (!pst) 75 return; 76 77 down_read(&_ps_lock); 78 psi = __find_path_selector_type(pst->name); 79 if (!psi) 80 goto out; 81 82 module_put(psi->pst.module); 83 out: 84 up_read(&_ps_lock); 85 } 86 87 static struct ps_internal *_alloc_path_selector(struct path_selector_type *pst) 88 { 89 struct ps_internal *psi = kzalloc(sizeof(*psi), GFP_KERNEL); 90 91 if (psi) 92 psi->pst = *pst; 93 94 return psi; 95 } 96 97 int dm_register_path_selector(struct path_selector_type *pst) 98 { 99 int r = 0; 100 struct ps_internal *psi = _alloc_path_selector(pst); 101 102 if (!psi) 103 return -ENOMEM; 104 105 down_write(&_ps_lock); 106 107 if (__find_path_selector_type(pst->name)) { 108 kfree(psi); 109 r = -EEXIST; 110 } else 111 list_add(&psi->list, &_path_selectors); 112 113 up_write(&_ps_lock); 114 115 return r; 116 } 117 118 int dm_unregister_path_selector(struct path_selector_type *pst) 119 { 120 struct ps_internal *psi; 121 122 down_write(&_ps_lock); 123 124 psi = __find_path_selector_type(pst->name); 125 if (!psi) { 126 up_write(&_ps_lock); 127 return -EINVAL; 128 } 129 130 list_del(&psi->list); 131 132 up_write(&_ps_lock); 133 134 kfree(psi); 135 136 return 0; 137 } 138 139 EXPORT_SYMBOL_GPL(dm_register_path_selector); 140 EXPORT_SYMBOL_GPL(dm_unregister_path_selector); 141