/* * Copyright (C) 2012 Red Hat. All rights reserved. * * This file is released under the GPL. */ #include "dm-cache-policy-internal.h" #include "dm.h" #include <linux/module.h> #include <linux/slab.h> /*----------------------------------------------------------------*/ #define DM_MSG_PREFIX "cache-policy" static DEFINE_SPINLOCK(register_lock); static LIST_HEAD(register_list); static struct dm_cache_policy_type *__find_policy(const char *name) { struct dm_cache_policy_type *t; list_for_each_entry(t, ®ister_list, list) if (!strcmp(t->name, name)) return t; return NULL; } static struct dm_cache_policy_type *__get_policy_once(const char *name) { struct dm_cache_policy_type *t = __find_policy(name); if (t && !try_module_get(t->owner)) { DMWARN("couldn't get module %s", name); t = ERR_PTR(-EINVAL); } return t; } static struct dm_cache_policy_type *get_policy_once(const char *name) { struct dm_cache_policy_type *t; spin_lock(®ister_lock); t = __get_policy_once(name); spin_unlock(®ister_lock); return t; } static struct dm_cache_policy_type *get_policy(const char *name) { struct dm_cache_policy_type *t; t = get_policy_once(name); if (IS_ERR(t)) return NULL; if (t) return t; request_module("dm-cache-%s", name); t = get_policy_once(name); if (IS_ERR(t)) return NULL; return t; } static void put_policy(struct dm_cache_policy_type *t) { module_put(t->owner); } int dm_cache_policy_register(struct dm_cache_policy_type *type) { int r; /* One size fits all for now */ if (type->hint_size != 0 && type->hint_size != 4) { DMWARN("hint size must be 0 or 4 but %llu supplied.", (unsigned long long) type->hint_size); return -EINVAL; } spin_lock(®ister_lock); if (__find_policy(type->name)) { DMWARN("attempt to register policy under duplicate name %s", type->name); r = -EINVAL; } else { list_add(&type->list, ®ister_list); r = 0; } spin_unlock(®ister_lock); return r; } EXPORT_SYMBOL_GPL(dm_cache_policy_register); void dm_cache_policy_unregister(struct dm_cache_policy_type *type) { spin_lock(®ister_lock); list_del_init(&type->list); spin_unlock(®ister_lock); } EXPORT_SYMBOL_GPL(dm_cache_policy_unregister); struct dm_cache_policy *dm_cache_policy_create(const char *name, dm_cblock_t cache_size, sector_t origin_size, sector_t cache_block_size) { struct dm_cache_policy *p = NULL; struct dm_cache_policy_type *type; type = get_policy(name); if (!type) { DMWARN("unknown policy type"); return NULL; } p = type->create(cache_size, origin_size, cache_block_size); if (!p) { put_policy(type); return NULL; } p->private = type; return p; } EXPORT_SYMBOL_GPL(dm_cache_policy_create); void dm_cache_policy_destroy(struct dm_cache_policy *p) { struct dm_cache_policy_type *t = p->private; p->destroy(p); put_policy(t); } EXPORT_SYMBOL_GPL(dm_cache_policy_destroy); const char *dm_cache_policy_get_name(struct dm_cache_policy *p) { struct dm_cache_policy_type *t = p->private; return t->name; } EXPORT_SYMBOL_GPL(dm_cache_policy_get_name); const unsigned *dm_cache_policy_get_version(struct dm_cache_policy *p) { struct dm_cache_policy_type *t = p->private; return t->version; } EXPORT_SYMBOL_GPL(dm_cache_policy_get_version); size_t dm_cache_policy_get_hint_size(struct dm_cache_policy *p) { struct dm_cache_policy_type *t = p->private; return t->hint_size; } EXPORT_SYMBOL_GPL(dm_cache_policy_get_hint_size); /*----------------------------------------------------------------*/