156 lines
2.6 KiB
C
156 lines
2.6 KiB
C
/*
|
|
* Copyright (C) 2003 Sistina Software.
|
|
* Copyright (C) 2004 Red Hat, Inc. All rights reserved.
|
|
*
|
|
* Module Author: Heinz Mauelshagen
|
|
*
|
|
* This file is released under the GPL.
|
|
*
|
|
* Path selector registration.
|
|
*/
|
|
|
|
#include "dm.h"
|
|
#include "dm-path-selector.h"
|
|
|
|
#include <linux/slab.h>
|
|
|
|
struct ps_internal {
|
|
struct path_selector_type pst;
|
|
|
|
struct list_head list;
|
|
long use;
|
|
};
|
|
|
|
#define pst_to_psi(__pst) container_of((__pst), struct ps_internal, pst)
|
|
|
|
static LIST_HEAD(_path_selectors);
|
|
static DECLARE_RWSEM(_ps_lock);
|
|
|
|
static struct ps_internal *__find_path_selector_type(const char *name)
|
|
{
|
|
struct ps_internal *psi;
|
|
|
|
list_for_each_entry(psi, &_path_selectors, list) {
|
|
if (!strcmp(name, psi->pst.name))
|
|
return psi;
|
|
}
|
|
|
|
return NULL;
|
|
}
|
|
|
|
static struct ps_internal *get_path_selector(const char *name)
|
|
{
|
|
struct ps_internal *psi;
|
|
|
|
down_read(&_ps_lock);
|
|
psi = __find_path_selector_type(name);
|
|
if (psi) {
|
|
if ((psi->use == 0) && !try_module_get(psi->pst.module))
|
|
psi = NULL;
|
|
else
|
|
psi->use++;
|
|
}
|
|
up_read(&_ps_lock);
|
|
|
|
return psi;
|
|
}
|
|
|
|
struct path_selector_type *dm_get_path_selector(const char *name)
|
|
{
|
|
struct ps_internal *psi;
|
|
|
|
if (!name)
|
|
return NULL;
|
|
|
|
psi = get_path_selector(name);
|
|
if (!psi) {
|
|
request_module("dm-%s", name);
|
|
psi = get_path_selector(name);
|
|
}
|
|
|
|
return psi ? &psi->pst : NULL;
|
|
}
|
|
|
|
void dm_put_path_selector(struct path_selector_type *pst)
|
|
{
|
|
struct ps_internal *psi;
|
|
|
|
if (!pst)
|
|
return;
|
|
|
|
down_read(&_ps_lock);
|
|
psi = __find_path_selector_type(pst->name);
|
|
if (!psi)
|
|
goto out;
|
|
|
|
if (--psi->use == 0)
|
|
module_put(psi->pst.module);
|
|
|
|
BUG_ON(psi->use < 0);
|
|
|
|
out:
|
|
up_read(&_ps_lock);
|
|
}
|
|
|
|
static struct ps_internal *_alloc_path_selector(struct path_selector_type *pst)
|
|
{
|
|
struct ps_internal *psi = kmalloc(sizeof(*psi), GFP_KERNEL);
|
|
|
|
if (psi) {
|
|
memset(psi, 0, sizeof(*psi));
|
|
psi->pst = *pst;
|
|
}
|
|
|
|
return psi;
|
|
}
|
|
|
|
int dm_register_path_selector(struct path_selector_type *pst)
|
|
{
|
|
int r = 0;
|
|
struct ps_internal *psi = _alloc_path_selector(pst);
|
|
|
|
if (!psi)
|
|
return -ENOMEM;
|
|
|
|
down_write(&_ps_lock);
|
|
|
|
if (__find_path_selector_type(pst->name)) {
|
|
kfree(psi);
|
|
r = -EEXIST;
|
|
} else
|
|
list_add(&psi->list, &_path_selectors);
|
|
|
|
up_write(&_ps_lock);
|
|
|
|
return r;
|
|
}
|
|
|
|
int dm_unregister_path_selector(struct path_selector_type *pst)
|
|
{
|
|
struct ps_internal *psi;
|
|
|
|
down_write(&_ps_lock);
|
|
|
|
psi = __find_path_selector_type(pst->name);
|
|
if (!psi) {
|
|
up_write(&_ps_lock);
|
|
return -EINVAL;
|
|
}
|
|
|
|
if (psi->use) {
|
|
up_write(&_ps_lock);
|
|
return -ETXTBSY;
|
|
}
|
|
|
|
list_del(&psi->list);
|
|
|
|
up_write(&_ps_lock);
|
|
|
|
kfree(psi);
|
|
|
|
return 0;
|
|
}
|
|
|
|
EXPORT_SYMBOL_GPL(dm_register_path_selector);
|
|
EXPORT_SYMBOL_GPL(dm_unregister_path_selector);
|