2006-01-17 00:50:04 +08:00
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/*
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* Copyright (C) Sistina Software, Inc. 1997-2003 All rights reserved.
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* Copyright (C) 2004-2005 Red Hat, Inc. All rights reserved.
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*
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* This copyrighted material is made available to anyone wishing to use,
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* modify, copy, or redistribute it subject to the terms and conditions
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* of the GNU General Public License v.2.
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*/
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#include <linux/module.h>
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#include <linux/init.h>
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#include <linux/string.h>
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#include <linux/slab.h>
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#include <linux/wait.h>
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#include <linux/sched.h>
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#include <linux/kmod.h>
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#include <linux/fs.h>
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#include <linux/delay.h>
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#include "lm_interface.h"
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struct lmh_wrapper {
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struct list_head lw_list;
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struct lm_lockops *lw_ops;
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};
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/* List of registered low-level locking protocols. A file system selects one
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of them by name at mount time, e.g. lock_nolock, lock_dlm. */
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static struct list_head lmh_list;
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static struct semaphore lmh_lock;
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/**
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* gfs_register_lockproto - Register a low-level locking protocol
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* @proto: the protocol definition
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*
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* Returns: 0 on success, -EXXX on failure
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*/
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int gfs_register_lockproto(struct lm_lockops *proto)
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{
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struct lmh_wrapper *lw;
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down(&lmh_lock);
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list_for_each_entry(lw, &lmh_list, lw_list) {
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if (!strcmp(lw->lw_ops->lm_proto_name, proto->lm_proto_name)) {
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up(&lmh_lock);
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2006-02-27 23:57:14 +08:00
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printk(KERN_INFO "GFS2: protocol %s already exists\n",
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2006-01-17 00:50:04 +08:00
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proto->lm_proto_name);
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return -EEXIST;
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}
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}
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2006-02-27 23:57:14 +08:00
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lw = kzalloc(sizeof(struct lmh_wrapper), GFP_KERNEL);
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2006-01-17 00:50:04 +08:00
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if (!lw) {
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up(&lmh_lock);
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return -ENOMEM;
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}
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lw->lw_ops = proto;
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list_add(&lw->lw_list, &lmh_list);
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up(&lmh_lock);
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return 0;
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}
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/**
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* gfs_unregister_lockproto - Unregister a low-level locking protocol
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* @proto: the protocol definition
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*
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*/
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void gfs_unregister_lockproto(struct lm_lockops *proto)
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{
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struct lmh_wrapper *lw;
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down(&lmh_lock);
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list_for_each_entry(lw, &lmh_list, lw_list) {
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if (!strcmp(lw->lw_ops->lm_proto_name, proto->lm_proto_name)) {
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list_del(&lw->lw_list);
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up(&lmh_lock);
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kfree(lw);
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return;
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}
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}
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up(&lmh_lock);
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2006-02-27 23:57:14 +08:00
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printk(KERN_WARNING "GFS2: can't unregister lock protocol %s\n",
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2006-01-17 00:50:04 +08:00
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proto->lm_proto_name);
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}
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/**
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* gfs2_mount_lockproto - Mount a lock protocol
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* @proto_name - the name of the protocol
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* @table_name - the name of the lock space
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* @host_data - data specific to this host
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* @cb - the callback to the code using the lock module
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* @fsdata - data to pass back with the callback
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* @min_lvb_size - the mininum LVB size that the caller can deal with
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* @flags - LM_MFLAG_*
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* @lockstruct - a structure returned describing the mount
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*
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* Returns: 0 on success, -EXXX on failure
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*/
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int gfs2_mount_lockproto(char *proto_name, char *table_name, char *host_data,
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lm_callback_t cb, lm_fsdata_t *fsdata,
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unsigned int min_lvb_size, int flags,
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struct lm_lockstruct *lockstruct,
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struct kobject *fskobj)
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{
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struct lmh_wrapper *lw = NULL;
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int try = 0;
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int error, found;
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retry:
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down(&lmh_lock);
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found = 0;
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list_for_each_entry(lw, &lmh_list, lw_list) {
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if (!strcmp(lw->lw_ops->lm_proto_name, proto_name)) {
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found = 1;
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break;
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}
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}
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if (!found) {
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if (!try && capable(CAP_SYS_MODULE)) {
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try = 1;
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up(&lmh_lock);
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request_module(proto_name);
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goto retry;
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}
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2006-02-27 23:57:14 +08:00
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printk(KERN_INFO "GFS2: can't find protocol %s\n", proto_name);
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2006-01-17 00:50:04 +08:00
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error = -ENOENT;
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goto out;
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}
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if (!try_module_get(lw->lw_ops->lm_owner)) {
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try = 0;
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up(&lmh_lock);
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msleep(1000);
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goto retry;
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}
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error = lw->lw_ops->lm_mount(table_name, host_data, cb, fsdata,
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min_lvb_size, flags, lockstruct, fskobj);
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if (error)
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module_put(lw->lw_ops->lm_owner);
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out:
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up(&lmh_lock);
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return error;
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}
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void gfs2_unmount_lockproto(struct lm_lockstruct *lockstruct)
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{
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down(&lmh_lock);
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lockstruct->ls_ops->lm_unmount(lockstruct->ls_lockspace);
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if (lockstruct->ls_ops->lm_owner)
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module_put(lockstruct->ls_ops->lm_owner);
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up(&lmh_lock);
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}
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/**
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* gfs2_withdraw_lockproto - abnormally unmount a lock module
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* @lockstruct: the lockstruct passed into mount
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*
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*/
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void gfs2_withdraw_lockproto(struct lm_lockstruct *lockstruct)
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{
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down(&lmh_lock);
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lockstruct->ls_ops->lm_withdraw(lockstruct->ls_lockspace);
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if (lockstruct->ls_ops->lm_owner)
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module_put(lockstruct->ls_ops->lm_owner);
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up(&lmh_lock);
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}
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void __init gfs2_init_lmh(void)
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{
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init_MUTEX(&lmh_lock);
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INIT_LIST_HEAD(&lmh_list);
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}
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EXPORT_SYMBOL_GPL(gfs_register_lockproto);
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EXPORT_SYMBOL_GPL(gfs_unregister_lockproto);
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