linux/fs/ocfs2/stackglue.c
Joel Becker 9c6c877c04 ocfs2: Add the 'cluster_stack' sysfs file.
Userspace can now query and specify the cluster stack in use via the
/sys/fs/ocfs2/cluster_stack file.  By default, it is 'o2cb', which is
the classic stack.  Thus, old tools that do not know how to modify this
file will work just fine.  The stack cannot be modified if there is a
live filesystem.

ocfs2_cluster_connect() now takes the expected cluster stack as an
argument.  This way, the filesystem and the stack glue ensure they are
speaking to the same backend.

If the stack is 'o2cb', the o2cb stack plugin is used.  For any other
value, the fsdlm stack plugin is selected.

Signed-off-by: Joel Becker <joel.becker@oracle.com>
Signed-off-by: Mark Fasheh <mfasheh@suse.com>
2008-04-18 08:56:05 -07:00

561 lines
13 KiB
C

/* -*- 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 <linux/fs.h>
#include <linux/kobject.h>
#include <linux/sysfs.h>
#include "ocfs2_fs.h"
#include "stackglue.h"
#define OCFS2_STACK_PLUGIN_O2CB "o2cb"
#define OCFS2_STACK_PLUGIN_USER "user"
static struct ocfs2_locking_protocol *lproto;
static DEFINE_SPINLOCK(ocfs2_stack_lock);
static LIST_HEAD(ocfs2_stack_list);
static char cluster_stack_name[OCFS2_STACK_LABEL_LEN + 1];
/*
* 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 *stack_name,
const char *plugin_name)
{
int rc;
struct ocfs2_stack_plugin *p;
spin_lock(&ocfs2_stack_lock);
/*
* If the stack passed by the filesystem isn't the selected one,
* we can't continue.
*/
if (strcmp(stack_name, cluster_stack_name)) {
rc = -EBUSY;
goto out;
}
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, plugin_name))
rc = 0;
else
rc = -EBUSY;
goto out;
}
p = ocfs2_stack_lookup(plugin_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 *stack_name)
{
int rc;
char *plugin_name = OCFS2_STACK_PLUGIN_O2CB;
/*
* Classic stack does not pass in a stack name. This is
* compatible with older tools as well.
*/
if (!stack_name || !*stack_name)
stack_name = OCFS2_STACK_PLUGIN_O2CB;
if (strlen(stack_name) != OCFS2_STACK_LABEL_LEN) {
printk(KERN_ERR
"ocfs2 passed an invalid cluster stack label: \"%s\"\n",
stack_name);
return -EINVAL;
}
/* Anything that isn't the classic stack is a user stack */
if (strcmp(stack_name, OCFS2_STACK_PLUGIN_O2CB))
plugin_name = OCFS2_STACK_PLUGIN_USER;
rc = ocfs2_stack_driver_request(stack_name, plugin_name);
if (rc == -ENOENT) {
request_module("ocfs2_stack_%s", plugin_name);
rc = ocfs2_stack_driver_request(stack_name, plugin_name);
}
if (rc == -ENOENT) {
printk(KERN_ERR
"ocfs2: Cluster stack driver \"%s\" cannot be found\n",
plugin_name);
} else if (rc == -EBUSY) {
printk(KERN_ERR
"ocfs2: A different cluster stack 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 *stack_name,
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(stack_name);
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);
/*
* Sysfs bits
*/
static ssize_t ocfs2_max_locking_protocol_show(struct kobject *kobj,
struct kobj_attribute *attr,
char *buf)
{
ssize_t ret = 0;
spin_lock(&ocfs2_stack_lock);
if (lproto)
ret = snprintf(buf, PAGE_SIZE, "%u.%u\n",
lproto->lp_max_version.pv_major,
lproto->lp_max_version.pv_minor);
spin_unlock(&ocfs2_stack_lock);
return ret;
}
static struct kobj_attribute ocfs2_attr_max_locking_protocol =
__ATTR(max_locking_protocol, S_IFREG | S_IRUGO,
ocfs2_max_locking_protocol_show, NULL);
static ssize_t ocfs2_loaded_cluster_plugins_show(struct kobject *kobj,
struct kobj_attribute *attr,
char *buf)
{
ssize_t ret = 0, total = 0, remain = PAGE_SIZE;
struct ocfs2_stack_plugin *p;
spin_lock(&ocfs2_stack_lock);
list_for_each_entry(p, &ocfs2_stack_list, sp_list) {
ret = snprintf(buf, remain, "%s\n",
p->sp_name);
if (ret < 0) {
total = ret;
break;
}
if (ret == remain) {
/* snprintf() didn't fit */
total = -E2BIG;
break;
}
total += ret;
remain -= ret;
}
spin_unlock(&ocfs2_stack_lock);
return total;
}
static struct kobj_attribute ocfs2_attr_loaded_cluster_plugins =
__ATTR(loaded_cluster_plugins, S_IFREG | S_IRUGO,
ocfs2_loaded_cluster_plugins_show, NULL);
static ssize_t ocfs2_active_cluster_plugin_show(struct kobject *kobj,
struct kobj_attribute *attr,
char *buf)
{
ssize_t ret = 0;
spin_lock(&ocfs2_stack_lock);
if (active_stack) {
ret = snprintf(buf, PAGE_SIZE, "%s\n",
active_stack->sp_name);
if (ret == PAGE_SIZE)
ret = -E2BIG;
}
spin_unlock(&ocfs2_stack_lock);
return ret;
}
static struct kobj_attribute ocfs2_attr_active_cluster_plugin =
__ATTR(active_cluster_plugin, S_IFREG | S_IRUGO,
ocfs2_active_cluster_plugin_show, NULL);
static ssize_t ocfs2_cluster_stack_show(struct kobject *kobj,
struct kobj_attribute *attr,
char *buf)
{
ssize_t ret;
spin_lock(&ocfs2_stack_lock);
ret = snprintf(buf, PAGE_SIZE, "%s\n", cluster_stack_name);
spin_unlock(&ocfs2_stack_lock);
return ret;
}
static ssize_t ocfs2_cluster_stack_store(struct kobject *kobj,
struct kobj_attribute *attr,
const char *buf, size_t count)
{
size_t len = count;
ssize_t ret;
if (len == 0)
return len;
if (buf[len - 1] == '\n')
len--;
if ((len != OCFS2_STACK_LABEL_LEN) ||
(strnlen(buf, len) != len))
return -EINVAL;
spin_lock(&ocfs2_stack_lock);
if (active_stack) {
if (!strncmp(buf, cluster_stack_name, len))
ret = count;
else
ret = -EBUSY;
} else {
memcpy(cluster_stack_name, buf, len);
ret = count;
}
spin_unlock(&ocfs2_stack_lock);
return ret;
}
static struct kobj_attribute ocfs2_attr_cluster_stack =
__ATTR(cluster_stack, S_IFREG | S_IRUGO | S_IWUSR,
ocfs2_cluster_stack_show,
ocfs2_cluster_stack_store);
static struct attribute *ocfs2_attrs[] = {
&ocfs2_attr_max_locking_protocol.attr,
&ocfs2_attr_loaded_cluster_plugins.attr,
&ocfs2_attr_active_cluster_plugin.attr,
&ocfs2_attr_cluster_stack.attr,
NULL,
};
static struct attribute_group ocfs2_attr_group = {
.attrs = ocfs2_attrs,
};
static struct kset *ocfs2_kset;
static void ocfs2_sysfs_exit(void)
{
kset_unregister(ocfs2_kset);
}
static int ocfs2_sysfs_init(void)
{
int ret;
ocfs2_kset = kset_create_and_add("ocfs2", NULL, fs_kobj);
if (!ocfs2_kset)
return -ENOMEM;
ret = sysfs_create_group(&ocfs2_kset->kobj, &ocfs2_attr_group);
if (ret)
goto error;
return 0;
error:
kset_unregister(ocfs2_kset);
return ret;
}
static int __init ocfs2_stack_glue_init(void)
{
strcpy(cluster_stack_name, OCFS2_STACK_PLUGIN_O2CB);
return ocfs2_sysfs_init();
}
static void __exit ocfs2_stack_glue_exit(void)
{
lproto = NULL;
ocfs2_sysfs_exit();
}
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);