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/*
* Copyright (C) Sistina Software, Inc. 1997-2003 All rights reserved.
* Copyright (C) 2004-2006 Red Hat, Inc. All rights reserved.
*
* This copyrighted material is made available to anyone wishing to use,
* modify, copy, or redistribute it subject to the terms and conditions
* of the GNU General Public License version 2.
*/
#include <linux/module.h>
#include <linux/init.h>
#include <linux/string.h>
#include <linux/slab.h>
#include <linux/wait.h>
#include <linux/sched.h>
#include <linux/kmod.h>
#include <linux/fs.h>
#include <linux/delay.h>
#include "lm_interface.h"
struct lmh_wrapper {
struct list_head lw_list;
const struct lm_lockops *lw_ops;
};
/* List of registered low-level locking protocols. A file system selects one
of them by name at mount time, e.g. lock_nolock, lock_dlm. */
static LIST_HEAD(lmh_list);
static DEFINE_MUTEX(lmh_lock);
/**
* gfs2_register_lockproto - Register a low-level locking protocol
* @proto: the protocol definition
*
* Returns: 0 on success, -EXXX on failure
*/
int gfs2_register_lockproto(const struct lm_lockops *proto)
{
struct lmh_wrapper *lw;
mutex_lock(&lmh_lock);
list_for_each_entry(lw, &lmh_list, lw_list) {
if (!strcmp(lw->lw_ops->lm_proto_name, proto->lm_proto_name)) {
mutex_unlock(&lmh_lock);
printk(KERN_INFO "GFS2: protocol %s already exists\n",
proto->lm_proto_name);
return -EEXIST;
}
}
lw = kzalloc(sizeof(struct lmh_wrapper), GFP_KERNEL);
if (!lw) {
mutex_unlock(&lmh_lock);
return -ENOMEM;
}
lw->lw_ops = proto;
list_add(&lw->lw_list, &lmh_list);
mutex_unlock(&lmh_lock);
return 0;
}
/**
* gfs2_unregister_lockproto - Unregister a low-level locking protocol
* @proto: the protocol definition
*
*/
void gfs2_unregister_lockproto(const struct lm_lockops *proto)
{
struct lmh_wrapper *lw;
mutex_lock(&lmh_lock);
list_for_each_entry(lw, &lmh_list, lw_list) {
if (!strcmp(lw->lw_ops->lm_proto_name, proto->lm_proto_name)) {
list_del(&lw->lw_list);
mutex_unlock(&lmh_lock);
kfree(lw);
return;
}
}
mutex_unlock(&lmh_lock);
printk(KERN_WARNING "GFS2: can't unregister lock protocol %s\n",
proto->lm_proto_name);
}
/**
* gfs2_mount_lockproto - Mount a lock protocol
* @proto_name - the name of the protocol
* @table_name - the name of the lock space
* @host_data - data specific to this host
* @cb - the callback to the code using the lock module
* @sdp - The GFS2 superblock
* @min_lvb_size - the mininum LVB size that the caller can deal with
* @flags - LM_MFLAG_*
* @lockstruct - a structure returned describing the mount
*
* Returns: 0 on success, -EXXX on failure
*/
int gfs2_mount_lockproto(char *proto_name, char *table_name, char *host_data,
lm_callback_t cb, void *cb_data,
unsigned int min_lvb_size, int flags,
struct lm_lockstruct *lockstruct,
struct kobject *fskobj)
{
struct lmh_wrapper *lw = NULL;
int try = 0;
int error, found;
retry:
mutex_lock(&lmh_lock);
found = 0;
list_for_each_entry(lw, &lmh_list, lw_list) {
if (!strcmp(lw->lw_ops->lm_proto_name, proto_name)) {
found = 1;
break;
}
}
if (!found) {
if (!try && capable(CAP_SYS_MODULE)) {
try = 1;
mutex_unlock(&lmh_lock);
request_module(proto_name);
goto retry;
}
printk(KERN_INFO "GFS2: can't find protocol %s\n", proto_name);
error = -ENOENT;
goto out;
}
if (!try_module_get(lw->lw_ops->lm_owner)) {
try = 0;
mutex_unlock(&lmh_lock);
msleep(1000);
goto retry;
}
error = lw->lw_ops->lm_mount(table_name, host_data, cb, cb_data,
min_lvb_size, flags, lockstruct, fskobj);
if (error)
module_put(lw->lw_ops->lm_owner);
out:
mutex_unlock(&lmh_lock);
return error;
}
void gfs2_unmount_lockproto(struct lm_lockstruct *lockstruct)
{
mutex_lock(&lmh_lock);
lockstruct->ls_ops->lm_unmount(lockstruct->ls_lockspace);
if (lockstruct->ls_ops->lm_owner)
module_put(lockstruct->ls_ops->lm_owner);
mutex_unlock(&lmh_lock);
}
/**
* gfs2_withdraw_lockproto - abnormally unmount a lock module
* @lockstruct: the lockstruct passed into mount
*
*/
void gfs2_withdraw_lockproto(struct lm_lockstruct *lockstruct)
{
mutex_lock(&lmh_lock);
lockstruct->ls_ops->lm_withdraw(lockstruct->ls_lockspace);
if (lockstruct->ls_ops->lm_owner)
module_put(lockstruct->ls_ops->lm_owner);
mutex_unlock(&lmh_lock);
}
EXPORT_SYMBOL_GPL(gfs2_register_lockproto);
EXPORT_SYMBOL_GPL(gfs2_unregister_lockproto);
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