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1// SPDX-License-Identifier: GPL-2.0-only2/*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 18static DEFINE_SPINLOCK(register_lock);19static LIST_HEAD(register_list);20 21static 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 32static 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 44static 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 55static 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 75static void put_policy(struct dm_cache_policy_type *t)76{77 module_put(t->owner);78}79 80int 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}102EXPORT_SYMBOL_GPL(dm_cache_policy_register);103 104void 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}110EXPORT_SYMBOL_GPL(dm_cache_policy_unregister);111 112struct 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}135EXPORT_SYMBOL_GPL(dm_cache_policy_create);136 137void 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}144EXPORT_SYMBOL_GPL(dm_cache_policy_destroy);145 146const 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}156EXPORT_SYMBOL_GPL(dm_cache_policy_get_name);157 158const 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}164EXPORT_SYMBOL_GPL(dm_cache_policy_get_version);165 166size_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}172EXPORT_SYMBOL_GPL(dm_cache_policy_get_hint_size);173 174/*----------------------------------------------------------------*/175