From 493df71c6420b211a68ae82b889c1e8a5fe701be Mon Sep 17 00:00:00 2001 From: Jonathan Brassow Date: Thu, 2 Apr 2009 19:55:31 +0100 Subject: dm exception store: introduce registry Move exception stores into a registry. Signed-off-by: Jonathan Brassow Signed-off-by: Alasdair G Kergon --- drivers/md/dm-exception-store.c | 162 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 162 insertions(+) (limited to 'drivers/md/dm-exception-store.c') diff --git a/drivers/md/dm-exception-store.c b/drivers/md/dm-exception-store.c index dccbfb0e010f..8912a3637cae 100644 --- a/drivers/md/dm-exception-store.c +++ b/drivers/md/dm-exception-store.c @@ -14,6 +14,168 @@ #define DM_MSG_PREFIX "snapshot exception stores" +static LIST_HEAD(_exception_store_types); +static DEFINE_SPINLOCK(_lock); + +static struct dm_exception_store_type *__find_exception_store_type(const char *name) +{ + struct dm_exception_store_type *type; + + list_for_each_entry(type, &_exception_store_types, list) + if (!strcmp(name, type->name)) + return type; + + return NULL; +} + +static struct dm_exception_store_type *_get_exception_store_type(const char *name) +{ + struct dm_exception_store_type *type; + + spin_lock(&_lock); + + type = __find_exception_store_type(name); + + if (type && !try_module_get(type->module)) + type = NULL; + + spin_unlock(&_lock); + + return type; +} + +/* + * get_type + * @type_name + * + * Attempt to retrieve the dm_exception_store_type by name. If not already + * available, attempt to load the appropriate module. + * + * Exstore modules are named "dm-exstore-" followed by the 'type_name'. + * Modules may contain multiple types. + * This function will first try the module "dm-exstore-", + * then truncate 'type_name' on the last '-' and try again. + * + * For example, if type_name was "clustered-shared", it would search + * 'dm-exstore-clustered-shared' then 'dm-exstore-clustered'. + * + * 'dm-exception-store-' is too long of a name in my + * opinion, which is why I've chosen to have the files + * containing exception store implementations be 'dm-exstore-'. + * If you want your module to be autoloaded, you will follow this + * naming convention. + * + * Returns: dm_exception_store_type* on success, NULL on failure + */ +static struct dm_exception_store_type *get_type(const char *type_name) +{ + char *p, *type_name_dup; + struct dm_exception_store_type *type; + + type = _get_exception_store_type(type_name); + if (type) + return type; + + type_name_dup = kstrdup(type_name, GFP_KERNEL); + if (!type_name_dup) { + DMERR("No memory left to attempt load for \"%s\"", type_name); + return NULL; + } + + while (request_module("dm-exstore-%s", type_name_dup) || + !(type = _get_exception_store_type(type_name))) { + p = strrchr(type_name_dup, '-'); + if (!p) + break; + p[0] = '\0'; + } + + if (!type) + DMWARN("Module for exstore type \"%s\" not found.", type_name); + + kfree(type_name_dup); + + return type; +} + +static void put_type(struct dm_exception_store_type *type) +{ + spin_lock(&_lock); + module_put(type->module); + spin_unlock(&_lock); +} + +int dm_exception_store_type_register(struct dm_exception_store_type *type) +{ + int r = 0; + + spin_lock(&_lock); + if (!__find_exception_store_type(type->name)) + list_add(&type->list, &_exception_store_types); + else + r = -EEXIST; + spin_unlock(&_lock); + + return r; +} +EXPORT_SYMBOL(dm_exception_store_type_register); + +int dm_exception_store_type_unregister(struct dm_exception_store_type *type) +{ + spin_lock(&_lock); + + if (!__find_exception_store_type(type->name)) { + spin_unlock(&_lock); + return -EINVAL; + } + + list_del(&type->list); + + spin_unlock(&_lock); + + return 0; +} +EXPORT_SYMBOL(dm_exception_store_type_unregister); + +int dm_exception_store_create(const char *type_name, + struct dm_exception_store **store) +{ + int r = 0; + struct dm_exception_store_type *type; + struct dm_exception_store *tmp_store; + + tmp_store = kmalloc(sizeof(*tmp_store), GFP_KERNEL); + if (!tmp_store) + return -ENOMEM; + + type = get_type(type_name); + if (!type) { + kfree(tmp_store); + return -EINVAL; + } + + tmp_store->type = type; + + r = type->ctr(tmp_store, 0, NULL); + if (r) { + put_type(type); + kfree(tmp_store); + return r; + } + + *store = tmp_store; + return 0; +} +EXPORT_SYMBOL(dm_exception_store_create); + +void dm_exception_store_destroy(struct dm_exception_store *store) +{ + store->type->dtr(store); + put_type(store->type); + kfree(store); +} +EXPORT_SYMBOL(dm_exception_store_destroy); + int dm_exception_store_init(void) { int r; -- cgit v1.2.3