/*
* Copyright (C) 2003 Sistina Software
* Copyright (C) 2004-2008 Red Hat, Inc. All rights reserved.
*
* This file is released under the LGPL.
*/
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/vmalloc.h>
#include <linux/dm-io.h>
#include <linux/dm-dirty-log.h>
#include <linux/device-mapper.h>
#define DM_MSG_PREFIX "dirty region log"
struct dm_dirty_log_internal {
struct dm_dirty_log_type *type;
struct list_head list;
long use;
};
static LIST_HEAD(_log_types);
static DEFINE_SPINLOCK(_lock);
static struct dm_dirty_log_internal *__find_dirty_log_type(const char *name)
{
struct dm_dirty_log_internal *log_type;
list_for_each_entry(log_type, &_log_types, list)
if (!strcmp(name, log_type->type->name))
return log_type;
return NULL;
}
static struct dm_dirty_log_internal *_get_dirty_log_type(const char *name)
{
struct dm_dirty_log_internal *log_type;
spin_lock(&_lock);
log_type = __find_dirty_log_type(name);
if (log_type) {
if (!log_type->use && !try_module_get(log_type->type->module))
log_type = NULL;
else
log_type->use++;
}
spin_unlock(&_lock);
return log_type;
}
/*
* get_type
* @type_name
*
* Attempt to retrieve the dm_dirty_log_type by name. If not already
* available, attempt to load the appropriate module.
*
* Log modules are named "dm-log-" followed by the 'type_name'.
* Modules may contain multiple types.
* This function will first try the module "dm-log-<type_name>",
* then truncate 'type_name' on the last '-' and try again.
*
* For example, if type_name was "clustered-disk", it would search
* 'dm-log-clustered-disk' then 'dm-log-clustered'.
*
* Returns: dirty_log_type* on success, NULL on failure
*/
static struct dm_dirty_log_type *get_type(const char *type_name)
{
char *p, *type_name_dup;
struct dm_dirty_log_internal *log_type;
if (!type_name)
return NULL;
log_type = _get_dirty_log_type(type_name);
if (log_type)
return log_type->type;
type_name_dup = kstrdup(type_name, GFP_KERNEL);
if (!type_name_dup) {
DMWARN("No memory left to attempt log module load for \"%s\"",
type_name);
return NULL;
}
while (request_module("dm-log-%s", type_name_dup) ||
!(log_type = _get_dirty_log_type(type_name))) {
p = strrchr(type_name_dup, '-');
if (!p)
break;
p[0] = '\0';
}
if (!log_type)
DMWARN("Module for logging type \"%s\" not found.", type_name);
kfree(type_name_dup);
return log_type ? log_type->type : NULL;
}
static void put_type(struct dm_dirty_log_type *type)
{
struct dm_dirty_log_internal *log_type;
if (!type)
return;
spin_lock(&_lock);
log_type = __find_dirty_log_type(type->name);
if (!log_type)
goto out;
if (!--log_type->use)
module_put(type->module);
BUG_ON(log_type->use < 0);
out:
spin_unlock(&_lock);
}
static struct dm_dirty_log_internal *_alloc_dirty_log_type(struct dm_dirty_log_type *type)
{
struct dm_dirty_log_internal *log_type = kzalloc(sizeof(*log_type),
GFP_KERNEL);
if (log_type)
log_type->type = type;
return log_type;
}
int dm_dirty_log_type_register(struct dm_dirty_log_type *type)
{
struct dm_dirty_log_internal *log_type = _alloc_dirty_log_type(type);
int r = 0;
if (!log_type)
return -ENOMEM;
spin_lock(&_lock);
if (!__find_dirty_log_type(type->name))
list_add(&log_type->list, &_log_types);
else {
kfree(log_type);
r = -EEXIST;
}
spin_unlock(&_lock);
return r;
}
EXPORT_SYMBOL(dm_dirty_log_type_register);
int dm_dirty_log_type_unregister(struct dm_dirty_log_type *type)
{
struct dm_dirty_log_internal *log_type;
spin_lock(&_lock);
log_type = __find_dirty_log_type(type->name);
if (!log_type) {
spin_unlock(&_lock);
return -EINVAL;
}
if (log_type->use) {
spin_unlock(&_lock);
return -ETXTBSY;
}
list_del(&log_type->list);
spin_unlock(&_lock);
kfree(log_type);
return 0;
}
EXPORT_SYMBOL(dm_dirty_log_type_unregister);
struct dm_dirty_log *dm_dirty_log_create(const char *type_name,
struct dm_target *ti,
unsigned int argc, char **argv)
{
struct dm_dirty_log_type *type;
struct dm_dirty_log *log;
log = kmalloc(sizeof(*log), GFP_KERNEL);
if (!log)
return NULL;
type = get_type(type_name);
if (!type) {
kfree(log);
return NULL;
}
log->type = type;
if (type->ctr(log, ti, argc, argv))