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