linux/fs/ocfs2/stackglue.c

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/* -*- mode: c; c-basic-offset: 8; -*-
* vim: noexpandtab sw=8 ts=8 sts=0:
*
* stackglue.c
*
* Code which implements an OCFS2 specific interface to underlying
* cluster stacks.
*
* Copyright (C) 2007 Oracle. All rights reserved.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public
* License as published by the Free Software Foundation, version 2.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*/
#include <linux/list.h>
#include <linux/spinlock.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/kmod.h>
#include "stackglue.h"
static struct ocfs2_locking_protocol *lproto;
static DEFINE_SPINLOCK(ocfs2_stack_lock);
static LIST_HEAD(ocfs2_stack_list);
/*
* The stack currently in use. If not null, active_stack->sp_count > 0,
* the module is pinned, and the locking protocol cannot be changed.
*/
static struct ocfs2_stack_plugin *active_stack;
static struct ocfs2_stack_plugin *ocfs2_stack_lookup(const char *name)
{
struct ocfs2_stack_plugin *p;
assert_spin_locked(&ocfs2_stack_lock);
list_for_each_entry(p, &ocfs2_stack_list, sp_list) {
if (!strcmp(p->sp_name, name))
return p;
}
return NULL;
}
static int ocfs2_stack_driver_request(const char *name)
{
int rc;
struct ocfs2_stack_plugin *p;
spin_lock(&ocfs2_stack_lock);
if (active_stack) {
/*
* If the active stack isn't the one we want, it cannot
* be selected right now.
*/
if (!strcmp(active_stack->sp_name, name))
rc = 0;
else
rc = -EBUSY;
goto out;
}
p = ocfs2_stack_lookup(name);
if (!p || !try_module_get(p->sp_owner)) {
rc = -ENOENT;
goto out;
}
/* Ok, the stack is pinned */
p->sp_count++;
active_stack = p;
rc = 0;
out:
spin_unlock(&ocfs2_stack_lock);
return rc;
}
/*
* This function looks up the appropriate stack and makes it active. If
* there is no stack, it tries to load it. It will fail if the stack still
* cannot be found. It will also fail if a different stack is in use.
*/
static int ocfs2_stack_driver_get(const char *name)
{
int rc;
rc = ocfs2_stack_driver_request(name);
if (rc == -ENOENT) {
request_module("ocfs2_stack_%s", name);
rc = ocfs2_stack_driver_request(name);
}
if (rc == -ENOENT) {
printk(KERN_ERR
"ocfs2: Cluster stack driver \"%s\" cannot be found\n",
name);
} else if (rc == -EBUSY) {
printk(KERN_ERR
"ocfs2: A different cluster stack driver is in use\n");
}
return rc;
}
static void ocfs2_stack_driver_put(void)
{
spin_lock(&ocfs2_stack_lock);
BUG_ON(active_stack == NULL);
BUG_ON(active_stack->sp_count == 0);
active_stack->sp_count--;
if (!active_stack->sp_count) {
module_put(active_stack->sp_owner);
active_stack = NULL;
}
spin_unlock(&ocfs2_stack_lock);
}
int ocfs2_stack_glue_register(struct ocfs2_stack_plugin *plugin)
{
int rc;
spin_lock(&ocfs2_stack_lock);
if (!ocfs2_stack_lookup(plugin->sp_name)) {
plugin->sp_count = 0;
plugin->sp_proto = lproto;
list_add(&plugin->sp_list, &ocfs2_stack_list);
printk(KERN_INFO "ocfs2: Registered cluster interface %s\n",
plugin->sp_name);
rc = 0;
} else {
printk(KERN_ERR "ocfs2: Stack \"%s\" already registered\n",
plugin->sp_name);
rc = -EEXIST;
}
spin_unlock(&ocfs2_stack_lock);
return rc;
}
EXPORT_SYMBOL_GPL(ocfs2_stack_glue_register);
void ocfs2_stack_glue_unregister(struct ocfs2_stack_plugin *plugin)
{
struct ocfs2_stack_plugin *p;
spin_lock(&ocfs2_stack_lock);
p = ocfs2_stack_lookup(plugin->sp_name);
if (p) {
BUG_ON(p != plugin);
BUG_ON(plugin == active_stack);
BUG_ON(plugin->sp_count != 0);
list_del_init(&plugin->sp_list);
printk(KERN_INFO "ocfs2: Unregistered cluster interface %s\n",
plugin->sp_name);
} else {
printk(KERN_ERR "Stack \"%s\" is not registered\n",
plugin->sp_name);
}
spin_unlock(&ocfs2_stack_lock);
}
EXPORT_SYMBOL_GPL(ocfs2_stack_glue_unregister);
void ocfs2_stack_glue_set_locking_protocol(struct ocfs2_locking_protocol *proto)
{
struct ocfs2_stack_plugin *p;
BUG_ON(proto == NULL);
spin_lock(&ocfs2_stack_lock);
BUG_ON(active_stack != NULL);
lproto = proto;
list_for_each_entry(p, &ocfs2_stack_list, sp_list) {
p->sp_proto = lproto;
}
spin_unlock(&ocfs2_stack_lock);
}
EXPORT_SYMBOL_GPL(ocfs2_stack_glue_set_locking_protocol);
int ocfs2_dlm_lock(struct ocfs2_cluster_connection *conn,
int mode,
union ocfs2_dlm_lksb *lksb,
u32 flags,
void *name,
unsigned int namelen,
void *astarg)
{
BUG_ON(lproto == NULL);
return active_stack->sp_ops->dlm_lock(conn, mode, lksb, flags,
name, namelen, astarg);
}
EXPORT_SYMBOL_GPL(ocfs2_dlm_lock);
int ocfs2_dlm_unlock(struct ocfs2_cluster_connection *conn,
union ocfs2_dlm_lksb *lksb,
u32 flags,
void *astarg)
{
BUG_ON(lproto == NULL);
return active_stack->sp_ops->dlm_unlock(conn, lksb, flags, astarg);
}
EXPORT_SYMBOL_GPL(ocfs2_dlm_unlock);
int ocfs2_dlm_lock_status(union ocfs2_dlm_lksb *lksb)
{
return active_stack->sp_ops->lock_status(lksb);
}
EXPORT_SYMBOL_GPL(ocfs2_dlm_lock_status);
/*
* Why don't we cast to ocfs2_meta_lvb? The "clean" answer is that we
* don't cast at the glue level. The real answer is that the header
* ordering is nigh impossible.
*/
void *ocfs2_dlm_lvb(union ocfs2_dlm_lksb *lksb)
{
return active_stack->sp_ops->lock_lvb(lksb);
}
EXPORT_SYMBOL_GPL(ocfs2_dlm_lvb);
void ocfs2_dlm_dump_lksb(union ocfs2_dlm_lksb *lksb)
{
active_stack->sp_ops->dump_lksb(lksb);
}
EXPORT_SYMBOL_GPL(ocfs2_dlm_dump_lksb);
int ocfs2_cluster_connect(const char *group,
int grouplen,
void (*recovery_handler)(int node_num,
void *recovery_data),
void *recovery_data,
struct ocfs2_cluster_connection **conn)
{
int rc = 0;
struct ocfs2_cluster_connection *new_conn;
BUG_ON(group == NULL);
BUG_ON(conn == NULL);
BUG_ON(recovery_handler == NULL);
if (grouplen > GROUP_NAME_MAX) {
rc = -EINVAL;
goto out;
}
new_conn = kzalloc(sizeof(struct ocfs2_cluster_connection),
GFP_KERNEL);
if (!new_conn) {
rc = -ENOMEM;
goto out;
}
memcpy(new_conn->cc_name, group, grouplen);
new_conn->cc_namelen = grouplen;
new_conn->cc_recovery_handler = recovery_handler;
new_conn->cc_recovery_data = recovery_data;
/* Start the new connection at our maximum compatibility level */
new_conn->cc_version = lproto->lp_max_version;
/* This will pin the stack driver if successful */
rc = ocfs2_stack_driver_get("o2cb");
if (rc)
goto out_free;
rc = active_stack->sp_ops->connect(new_conn);
if (rc) {
ocfs2_stack_driver_put();
goto out_free;
}
*conn = new_conn;
out_free:
if (rc)
kfree(new_conn);
out:
return rc;
}
EXPORT_SYMBOL_GPL(ocfs2_cluster_connect);
/* If hangup_pending is 0, the stack driver will be dropped */
int ocfs2_cluster_disconnect(struct ocfs2_cluster_connection *conn,
int hangup_pending)
{
int ret;
BUG_ON(conn == NULL);
ret = active_stack->sp_ops->disconnect(conn, hangup_pending);
/* XXX Should we free it anyway? */
if (!ret) {
kfree(conn);
if (!hangup_pending)
ocfs2_stack_driver_put();
}
return ret;
}
EXPORT_SYMBOL_GPL(ocfs2_cluster_disconnect);
void ocfs2_cluster_hangup(const char *group, int grouplen)
{
BUG_ON(group == NULL);
BUG_ON(group[grouplen] != '\0');
active_stack->sp_ops->hangup(group, grouplen);
/* cluster_disconnect() was called with hangup_pending==1 */
ocfs2_stack_driver_put();
}
EXPORT_SYMBOL_GPL(ocfs2_cluster_hangup);
int ocfs2_cluster_this_node(unsigned int *node)
{
return active_stack->sp_ops->this_node(node);
}
EXPORT_SYMBOL_GPL(ocfs2_cluster_this_node);
static int __init ocfs2_stack_glue_init(void)
{
return 0;
}
static void __exit ocfs2_stack_glue_exit(void)
{
lproto = NULL;
}
MODULE_AUTHOR("Oracle");
MODULE_DESCRIPTION("ocfs2 cluter stack glue layer");
MODULE_LICENSE("GPL");
module_init(ocfs2_stack_glue_init);
module_exit(ocfs2_stack_glue_exit);