/*
   * 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 <linux/lm_interface.h>

  
  struct lmh_wrapper {
  	struct list_head lw_list;

  	const struct lm_lockops *lw_ops;

  };

  static int nolock_mount(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);

  /* 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 const struct lm_lockops nolock_ops = {
  	.lm_proto_name = "lock_nolock",
  	.lm_mount = nolock_mount,
  };
  
  static struct lmh_wrapper nolock_proto  = {
  	.lw_list = LIST_HEAD_INIT(nolock_proto.lw_list),
  	.lw_ops = &nolock_ops,
  };

  static LIST_HEAD(lmh_list);
  static DEFINE_MUTEX(lmh_lock);

  static int nolock_mount(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)
  {
  	char *c;
  	unsigned int jid;
  
  	c = strstr(host_data, "jid=");
  	if (!c)
  		jid = 0;
  	else {
  		c += 4;
  		sscanf(c, "%u", &jid);
  	}
  
  	lockstruct->ls_jid = jid;
  	lockstruct->ls_first = 1;
  	lockstruct->ls_lvb_size = min_lvb_size;
  	lockstruct->ls_ops = &nolock_ops;
  	lockstruct->ls_flags = LM_LSFLAG_LOCAL;
  
  	return 0;
  }

  /**

   * 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
  ",

  			       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
  ",

  	       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);

  	if (list_empty(&nolock_proto.lw_list))

  		list_add(&nolock_proto.lw_list, &lmh_list);

  	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
  ", proto_name);

  		error = -ENOENT;
  		goto out;
  	}

  	if (lw->lw_ops->lm_owner &&
  	    !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);

  	if (lockstruct->ls_ops->lm_unmount)
  		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);