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
 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, &register_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(&register_lock);
 49	t = __get_policy_once(name);
 50	spin_unlock(&register_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(&register_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, &register_list);
 96		r = 0;
 97	}
 98	spin_unlock(&register_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(&register_lock);
107	list_del_init(&type->list);
108	spin_unlock(&register_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/*----------------------------------------------------------------*/