1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Copyright (C) 2012 Red Hat. All rights reserved. 4 * 5 * This file is released under the GPL. 6 */ 7 8 #include "dm-cache-policy-internal.h" 9 #include "dm.h" 10 11 #include <linux/module.h> 12 #include <linux/slab.h> 13 14 /*----------------------------------------------------------------*/ 15 16 #define DM_MSG_PREFIX "cache-policy" 17 18 static DEFINE_SPINLOCK(register_lock); 19 static LIST_HEAD(register_list); 20 21 static struct dm_cache_policy_type *__find_policy(const char *name) 22 { 23 struct dm_cache_policy_type *t; 24 25 list_for_each_entry(t, ®ister_list, list) 26 if (!strcmp(t->name, name)) 27 return t; 28 29 return NULL; 30 } 31 32 static struct dm_cache_policy_type *__get_policy_once(const char *name) 33 { 34 struct dm_cache_policy_type *t = __find_policy(name); 35 36 if (t && !try_module_get(t->owner)) { 37 DMWARN("couldn't get module %s", name); 38 t = ERR_PTR(-EINVAL); 39 } 40 41 return t; 42 } 43 44 static struct dm_cache_policy_type *get_policy_once(const char *name) 45 { 46 struct dm_cache_policy_type *t; 47 48 spin_lock(®ister_lock); 49 t = __get_policy_once(name); 50 spin_unlock(®ister_lock); 51 52 return t; 53 } 54 55 static struct dm_cache_policy_type *get_policy(const char *name) 56 { 57 struct dm_cache_policy_type *t; 58 59 t = get_policy_once(name); 60 if (IS_ERR(t)) 61 return NULL; 62 63 if (t) 64 return t; 65 66 request_module("dm-cache-%s", name); 67 68 t = get_policy_once(name); 69 if (IS_ERR(t)) 70 return NULL; 71 72 return t; 73 } 74 75 static void put_policy(struct dm_cache_policy_type *t) 76 { 77 module_put(t->owner); 78 } 79 80 int dm_cache_policy_register(struct dm_cache_policy_type *type) 81 { 82 int r; 83 84 /* One size fits all for now */ 85 if (type->hint_size != 0 && type->hint_size != 4) { 86 DMWARN("hint size must be 0 or 4 but %llu supplied.", (unsigned long long) type->hint_size); 87 return -EINVAL; 88 } 89 90 spin_lock(®ister_lock); 91 if (__find_policy(type->name)) { 92 DMWARN("attempt to register policy under duplicate name %s", type->name); 93 r = -EINVAL; 94 } else { 95 list_add(&type->list, ®ister_list); 96 r = 0; 97 } 98 spin_unlock(®ister_lock); 99 100 return r; 101 } 102 EXPORT_SYMBOL_GPL(dm_cache_policy_register); 103 104 void dm_cache_policy_unregister(struct dm_cache_policy_type *type) 105 { 106 spin_lock(®ister_lock); 107 list_del_init(&type->list); 108 spin_unlock(®ister_lock); 109 } 110 EXPORT_SYMBOL_GPL(dm_cache_policy_unregister); 111 112 struct dm_cache_policy *dm_cache_policy_create(const char *name, 113 dm_cblock_t cache_size, 114 sector_t origin_size, 115 sector_t cache_block_size) 116 { 117 struct dm_cache_policy *p = NULL; 118 struct dm_cache_policy_type *type; 119 120 type = get_policy(name); 121 if (!type) { 122 DMWARN("unknown policy type"); 123 return ERR_PTR(-EINVAL); 124 } 125 126 p = type->create(cache_size, origin_size, cache_block_size); 127 if (!p) { 128 put_policy(type); 129 return ERR_PTR(-ENOMEM); 130 } 131 p->private = type; 132 133 return p; 134 } 135 EXPORT_SYMBOL_GPL(dm_cache_policy_create); 136 137 void dm_cache_policy_destroy(struct dm_cache_policy *p) 138 { 139 struct dm_cache_policy_type *t = p->private; 140 141 p->destroy(p); 142 put_policy(t); 143 } 144 EXPORT_SYMBOL_GPL(dm_cache_policy_destroy); 145 146 const char *dm_cache_policy_get_name(struct dm_cache_policy *p) 147 { 148 struct dm_cache_policy_type *t = p->private; 149 150 /* if t->real is set then an alias was used (e.g. "default") */ 151 if (t->real) 152 return t->real->name; 153 154 return t->name; 155 } 156 EXPORT_SYMBOL_GPL(dm_cache_policy_get_name); 157 158 const unsigned int *dm_cache_policy_get_version(struct dm_cache_policy *p) 159 { 160 struct dm_cache_policy_type *t = p->private; 161 162 return t->version; 163 } 164 EXPORT_SYMBOL_GPL(dm_cache_policy_get_version); 165 166 size_t dm_cache_policy_get_hint_size(struct dm_cache_policy *p) 167 { 168 struct dm_cache_policy_type *t = p->private; 169 170 return t->hint_size; 171 } 172 EXPORT_SYMBOL_GPL(dm_cache_policy_get_hint_size); 173 174 /*----------------------------------------------------------------*/ 175