/* -*- mode: c; c-basic-offset: 8; -*-
* vim: noexpandtab sw=8 ts=8 sts=0:
*
* stack_user.c
*
* Code which interfaces ocfs2 with fs/dlm and a userspace stack.
*
* 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/module.h>
#include <linux/fs.h>
#include <linux/miscdevice.h>
#include <linux/mutex.h>
#include <linux/reboot.h>
#include <asm/uaccess.h>
#include "stackglue.h"
/*
* The control protocol starts with a handshake. Until the handshake
* is complete, the control device will fail all write(2)s.
*
* The handshake is simple. First, the client reads until EOF. Each line
* of output is a supported protocol tag. All protocol tags are a single
* character followed by a two hex digit version number. Currently the
* only things supported is T01, for "Text-base version 0x01". Next, the
* client writes the version they would like to use. If the version tag
* written is unknown, -EINVAL is returned. Once the negotiation is
* complete, the client can start sending messages.
*/
/*
* Whether or not the client has done the handshake.
* For now, we have just one protocol version.
*/
#define OCFS2_CONTROL_PROTO "T01\n"
#define OCFS2_CONTROL_PROTO_LEN 4
#define OCFS2_CONTROL_HANDSHAKE_INVALID (0)
#define OCFS2_CONTROL_HANDSHAKE_READ (1)
#define OCFS2_CONTROL_HANDSHAKE_VALID (2)
/*
* ocfs2_live_connection is refcounted because the filesystem and
* miscdevice sides can detach in different order. Let's just be safe.
*/
struct ocfs2_live_connection {
struct list_head oc_list;
struct ocfs2_cluster_connection *oc_conn;
};
struct ocfs2_control_private {
struct list_head op_list;
int op_state;
};
static atomic_t ocfs2_control_opened;
static LIST_HEAD(ocfs2_live_connection_list);
static LIST_HEAD(ocfs2_control_private_list);
static DEFINE_MUTEX(ocfs2_control_lock);
static inline void ocfs2_control_set_handshake_state(struct file *file,
int state)
{
struct ocfs2_control_private *p = file->private_data;
p->op_state = state;
}
static inline int ocfs2_control_get_handshake_state(struct file *file)
{
struct ocfs2_control_private *p = file->private_data;
return p->op_state;
}
static struct ocfs2_live_connection *ocfs2_connection_find(const char *name)
{
size_t len = strlen(name);
struct ocfs2_live_connection *c;
BUG_ON(!mutex_is_locked(&ocfs2_control_lock));
list_for_each_entry(c, &ocfs2_live_connection_list, oc_list) {
if ((c->oc_conn->cc_namelen == len) &&
!strncmp(c->oc_conn->cc_name, name, len))
return c;
}
return c;
}
/*
* ocfs2_live_connection structures are created underneath the ocfs2
* mount path. Since the VFS prevents multiple calls to
* fill_super(), we can't get dupes here.
*/
static int ocfs2_live_connection_new(struct ocfs2_cluster_connection *conn,
struct ocfs2_live_connection **c_ret)
{
int rc = 0;
struct ocfs2_live_connection *c;
c = kzalloc(sizeof(struct ocfs2_live_connection), GFP_KERNEL);
if (!c)
return -ENOMEM;
mutex_lock(&ocfs2_control_lock);
c->oc_conn = conn;
if (atomic_read(&ocfs2_control_opened))
list_add(&c->oc_list, &ocfs2_live_connection_list);
else {
printk(KERN_ERR
"ocfs2: Userspace control daemon is not present\n");
rc = -ESRCH;
}
mutex_unlock(&ocfs2_control_lock);
if (!rc)
*c_ret = c;
else
kfree(c);
return rc;
}
/*
* This function disconnects the cluster connection from ocfs2_control.
* Afterwards, userspace can't affect the cluster connection.
*/
static void ocfs2_live_connection_drop(struct ocfs2_live_connection *c)
{
mutex_lock(&ocfs2_control_lock);
list_del_init(&c->oc_list);
c->oc_conn = NULL;
mutex_unlock(&ocfs2_control_lock);
kfree(c);
}
static ssize_t ocfs2_control_cfu(char *target, size_t target_len,
const char __user *buf, size_t count)
{
/* The T01 expects write(2) calls to have exactly one command */
if (count != target_len)
return -EINVAL;
if (copy_from_user(target, buf, target_len))
return -EFAULT;
return count;
}
static ssize_t ocfs2_control_validate_handshake(struct file *file,
const char __user *buf,
size_t count)
{
ssize_t ret;
char kbuf[OCFS2_CONTROL_PROTO_LEN];
ret = ocfs2_control_cfu(kbuf, OCFS2_CONTROL_PROTO_LEN,
buf, count);
if (ret != count)
return ret;
if (strncmp(kbuf, OCFS2_CONTROL_PROTO, OCFS2_CONTROL_PROTO_LEN))
return -EINVAL;
atomic_inc(&ocfs2_control_opened);
ocfs2_control_set_handshake_state(file,
OCFS2_CONTROL_HANDSHAKE_VALID);
return count;
}
static ssize_t ocfs2_control_write(struct file *file,
const char __user *buf,
size_t count,
loff_t *ppos)
{
ssize_t ret;
switch (ocfs2_control_get_handshake_state(file)) {
case OCFS2_CONTROL_HANDSHAKE_INVALID:
ret = -EINVAL;
break;
case OCFS2_CONTROL_HANDSHAKE_READ:
ret = ocfs2_control_validate_handshake(file, buf,
count);
break;
case OCFS2_CONTROL_HANDSHAKE_VALID:
ret = count; /* XXX */
break;
default:
BUG();
ret = -EIO;
break;
}
return ret;
}
/*
* This is a naive version. If we ever have a new protocol, we'll expand
* it. Probably using seq_file.
*/
static ssize_t ocfs2_control_read(struct file *file,
char __user *buf,
size_t count,
loff_t *ppos)
{
char *proto_string = OCFS2_CONTROL_PROTO;
size_t to_write = 0;
if (*ppos >= OCFS2_CONTROL_PROTO_LEN)
return 0;
to_write = OCFS2_CONTROL_PROTO_LEN - *ppos;
if (to_write > count)
to_write = count;
if (copy_to_user(buf, proto_string + *ppos, to_write))
return -EFAULT;
*ppos += to_write;
/* Have we read the whole protocol list? */
if (*ppos >= OCFS2_CONTROL_PROTO_LEN)
ocfs2_control_set_handshake_state(file,
OCFS2_CONTROL_HANDSHAKE_READ);
return to_write;
}
static int ocfs2_control_release(struct inode *inode, struct file *file)
{
struct ocfs2_control_private *p = file->private_data;
mutex_lock(&ocfs2_control_lock);
if (ocfs2_control_get_handshake_state(file) !=
OCFS2_CONTROL_HANDSHAKE_VALID)
goto out;
if (atomic_dec_and_test(&ocfs2_control_opened)) {
if (!list_empty(&ocfs2_live_connection_list)) {
/* XXX: Do bad things! */
printk(KERN_ERR
"ocfs2: Unexpected release of ocfs2_control!\n"
" Loss of cluster connection requires "
"an emergency restart!\n");
emergency_restart();
}
}
out:
list_del_init(&p->op_list);
file->private_data = NULL;
mutex_unlock(&ocfs2_control_lock);
kfree(p);
return 0;
}
static int ocfs2_control_open(struct inode *inode, struct file *file)
{
struct ocfs2_control_private *p;
p = kzalloc(sizeof(struct ocfs2_control_private), GFP_KERNEL);
if (!p)
return -ENOMEM;
mutex_lock(&ocfs2_control_lock);
file->private_data = p;
list_add(&p->op_list, &ocfs2_control_private_list);
mutex_unlock(&ocfs2_control_lock);
return 0;
}
static const struct file_operations ocfs2_control_fops = {
.open = ocfs2_control_open,
.release = ocfs2_control_release,
.read = ocfs2_control_read,
.write = ocfs2_control_write,
.owner = THIS_MODULE,
};
struct miscdevice ocfs2_control_device = {
.minor = MISC_DYNAMIC_MINOR,
.name = "ocfs2_control",
.fops = &ocfs2_control_fops,
};
static int ocfs2_control_init(void)
{
int rc;
atomic_set(&ocfs2_control_opened, 0);
rc = misc_register(&ocfs2_control_device);
if (rc)
printk(KERN_ERR
"ocfs2: Unable to register ocfs2_control device "
"(errno %d)\n",
-rc);
return rc;
}
static void ocfs2_control_exit(void)
{
int rc;
rc = misc_deregister(&ocfs2_control_device);
if (rc)
printk(KERN_ERR
"ocfs2: Unable to deregister ocfs2_control device "
"(errno %d)\n",
-rc);
}
static int __init user_stack_init(void)
{
return ocfs2_control_init();
}
static void __exit user_stack_exit(void)
{
ocfs2_control_exit();
}
MODULE_AUTHOR("Oracle");
MODULE_DESCRIPTION("ocfs2 driver for userspace cluster stacks");
MODULE_LICENSE("GPL");
module_init(user_stack_init);
module_exit(user_stack_exit);
