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Viewing changes to drivers/md/dm-path-selector.c

  • Committer: Package Import Robot
  • Author(s): Alessio Igor Bogani
  • Date: 2011-10-26 11:13:05 UTC
  • Revision ID: package-import@ubuntu.com-20111026111305-tz023xykf0i6eosh
Tags: upstream-3.2.0
Import upstream version 3.2.0

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drivers/md/dm-path-selector.c
 
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/*
 
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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 <linux/module.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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};
 
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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 && !try_module_get(psi->pst.module))
 
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                psi = NULL;
 
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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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        module_put(psi->pst.module);
 
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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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        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);