/******************************************************************************
  *******************************************************************************
  **

  **  Copyright (C) 2005-2007 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 v.2.
  **
  *******************************************************************************
  ******************************************************************************/
  
  #include "dlm_internal.h"
  #include "member.h"
  #include "lock.h"
  #include "dir.h"
  #include "config.h"
  #include "requestqueue.h"
  
  struct rq_entry {
  	struct list_head list;
  	int nodeid;

  	struct dlm_message request;

  };
  
  /*
   * Requests received while the lockspace is in recovery get added to the
   * request queue and processed when recovery is complete.  This happens when
   * the lockspace is suspended on some nodes before it is on others, or the
   * lockspace is enabled on some while still suspended on others.
   */

  void dlm_add_requestqueue(struct dlm_ls *ls, int nodeid, struct dlm_message *ms)

  {
  	struct rq_entry *e;

  	int length = ms->m_header.h_length - sizeof(struct dlm_message);

  	e = kmalloc(sizeof(struct rq_entry) + length, GFP_NOFS);

  	if (!e) {

  		log_print("dlm_add_requestqueue: out of memory len %d", length);
  		return;

  	}
  
  	e->nodeid = nodeid;

  	memcpy(&e->request, ms, ms->m_header.h_length);

  	mutex_lock(&ls->ls_requestqueue_mutex);

  	list_add_tail(&e->list, &ls->ls_requestqueue);

  	mutex_unlock(&ls->ls_requestqueue_mutex);

  }

  /*
   * Called by dlm_recoverd to process normal messages saved while recovery was
   * happening.  Normal locking has been enabled before this is called.  dlm_recv
   * upon receiving a message, will wait for all saved messages to be drained
   * here before processing the message it got.  If a new dlm_ls_stop() arrives
   * while we're processing these saved messages, it may block trying to suspend
   * dlm_recv if dlm_recv is waiting for us in dlm_wait_requestqueue.  In that
   * case, we don't abort since locking_stopped is still 0.  If dlm_recv is not
   * waiting for us, then this processing may be aborted due to locking_stopped.
   */

  int dlm_process_requestqueue(struct dlm_ls *ls)
  {
  	struct rq_entry *e;

  	int error = 0;

  	mutex_lock(&ls->ls_requestqueue_mutex);

  
  	for (;;) {
  		if (list_empty(&ls->ls_requestqueue)) {

  			mutex_unlock(&ls->ls_requestqueue_mutex);

  			error = 0;
  			break;
  		}
  		e = list_entry(ls->ls_requestqueue.next, struct rq_entry, list);

  		mutex_unlock(&ls->ls_requestqueue_mutex);

  		dlm_receive_message_saved(ls, &e->request);

  		mutex_lock(&ls->ls_requestqueue_mutex);

  		list_del(&e->list);
  		kfree(e);
  
  		if (dlm_locking_stopped(ls)) {
  			log_debug(ls, "process_requestqueue abort running");

  			mutex_unlock(&ls->ls_requestqueue_mutex);

  			error = -EINTR;
  			break;
  		}
  		schedule();
  	}
  
  	return error;
  }
  
  /*
   * After recovery is done, locking is resumed and dlm_recoverd takes all the

   * saved requests and processes them as they would have been by dlm_recv.  At
   * the same time, dlm_recv will start receiving new requests from remote nodes.
   * We want to delay dlm_recv processing new requests until dlm_recoverd has
   * finished processing the old saved requests.  We don't check for locking
   * stopped here because dlm_ls_stop won't stop locking until it's suspended us
   * (dlm_recv).

   */
  
  void dlm_wait_requestqueue(struct dlm_ls *ls)
  {
  	for (;;) {

  		mutex_lock(&ls->ls_requestqueue_mutex);

  		if (list_empty(&ls->ls_requestqueue))
  			break;

  		mutex_unlock(&ls->ls_requestqueue_mutex);

  		schedule();
  	}

  	mutex_unlock(&ls->ls_requestqueue_mutex);

  }
  
  static int purge_request(struct dlm_ls *ls, struct dlm_message *ms, int nodeid)
  {
  	uint32_t type = ms->m_type;

  	/* the ls is being cleaned up and freed by release_lockspace */
  	if (!ls->ls_count)
  		return 1;

  	if (dlm_is_removed(ls, nodeid))
  		return 1;
  
  	/* directory operations are always purged because the directory is
  	   always rebuilt during recovery and the lookups resent */
  
  	if (type == DLM_MSG_REMOVE ||
  	    type == DLM_MSG_LOOKUP ||
  	    type == DLM_MSG_LOOKUP_REPLY)
  		return 1;
  
  	if (!dlm_no_directory(ls))
  		return 0;
  
  	/* with no directory, the master is likely to change as a part of
  	   recovery; requests to/from the defunct master need to be purged */
  
  	switch (type) {
  	case DLM_MSG_REQUEST:
  	case DLM_MSG_CONVERT:
  	case DLM_MSG_UNLOCK:
  	case DLM_MSG_CANCEL:
  		/* we're no longer the master of this resource, the sender
  		   will resend to the new master (see waiter_needs_recovery) */
  
  		if (dlm_hash2nodeid(ls, ms->m_hash) != dlm_our_nodeid())
  			return 1;
  		break;
  
  	case DLM_MSG_REQUEST_REPLY:
  	case DLM_MSG_CONVERT_REPLY:
  	case DLM_MSG_UNLOCK_REPLY:
  	case DLM_MSG_CANCEL_REPLY:
  	case DLM_MSG_GRANT:
  		/* this reply is from the former master of the resource,
  		   we'll resend to the new master if needed */
  
  		if (dlm_hash2nodeid(ls, ms->m_hash) != nodeid)
  			return 1;
  		break;
  	}
  
  	return 0;
  }
  
  void dlm_purge_requestqueue(struct dlm_ls *ls)
  {
  	struct dlm_message *ms;
  	struct rq_entry *e, *safe;

  	mutex_lock(&ls->ls_requestqueue_mutex);

  	list_for_each_entry_safe(e, safe, &ls->ls_requestqueue, list) {

  		ms =  &e->request;

  
  		if (purge_request(ls, ms, e->nodeid)) {
  			list_del(&e->list);
  			kfree(e);
  		}
  	}

  	mutex_unlock(&ls->ls_requestqueue_mutex);

  }