ocfs2: Add the ocfs2_control misc device.

 */

 */

#include <linux/module.h>

#include <linux/module.h>

#include <linux/fs.h>

#include <linux/miscdevice.h>

#include <linux/mutex.h>

#include <linux/reboot.h>

#include "stackglue.h"

#include "stackglue.h"

static int __init user_stack_init(void)

/*

 * 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.

 */

/*

 * 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;

};

static atomic_t ocfs2_control_opened;

static LIST_HEAD(ocfs2_live_connection_list);

static DEFINE_MUTEX(ocfs2_control_lock);

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_write(struct file *file,

				   const char __user *buf,

				   size_t count,

				   loff_t *ppos)

{

{

	return 0;

	return 0;

}

}

static ssize_t ocfs2_control_read(struct file *file,

				  char __user *buf,

				  size_t count,

				  loff_t *ppos)

{

	return 0;

}

static int ocfs2_control_release(struct inode *inode, struct file *file)

{

	if (atomic_dec_and_test(&ocfs2_control_opened)) {

		mutex_lock(&ocfs2_control_lock);

		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();

		}

		mutex_unlock(&ocfs2_control_lock);

	}

	return 0;

}

static int ocfs2_control_open(struct inode *inode, struct file *file)

{

	atomic_inc(&ocfs2_control_opened);

	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)

static void __exit user_stack_exit(void)

{

{

	ocfs2_control_exit();

}

}

MODULE_AUTHOR("Oracle");

MODULE_AUTHOR("Oracle");