/******************************************************************************
  *******************************************************************************
  **
  **  Copyright (C) Sistina Software, Inc.  1997-2003  All rights reserved.

  **  Copyright (C) 2004-2010 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 "lock.h"

  #include "user.h"

  static uint64_t			dlm_cb_seq;
  static spinlock_t		dlm_cb_seq_spin;

  static void dlm_dump_lkb_callbacks(struct dlm_lkb *lkb)
  {
  	int i;
  
  	log_print("last_bast %x %llu flags %x mode %d sb %d %x",
  		  lkb->lkb_id,
  		  (unsigned long long)lkb->lkb_last_bast.seq,
  		  lkb->lkb_last_bast.flags,
  		  lkb->lkb_last_bast.mode,
  		  lkb->lkb_last_bast.sb_status,
  		  lkb->lkb_last_bast.sb_flags);
  
  	log_print("last_cast %x %llu flags %x mode %d sb %d %x",
  		  lkb->lkb_id,
  		  (unsigned long long)lkb->lkb_last_cast.seq,
  		  lkb->lkb_last_cast.flags,
  		  lkb->lkb_last_cast.mode,
  		  lkb->lkb_last_cast.sb_status,
  		  lkb->lkb_last_cast.sb_flags);
  
  	for (i = 0; i < DLM_CALLBACKS_SIZE; i++) {
  		log_print("cb %x %llu flags %x mode %d sb %d %x",
  			  lkb->lkb_id,
  			  (unsigned long long)lkb->lkb_callbacks[i].seq,
  			  lkb->lkb_callbacks[i].flags,
  			  lkb->lkb_callbacks[i].mode,
  			  lkb->lkb_callbacks[i].sb_status,
  			  lkb->lkb_callbacks[i].sb_flags);
  	}
  }

  int dlm_add_lkb_callback(struct dlm_lkb *lkb, uint32_t flags, int mode,
  			 int status, uint32_t sbflags, uint64_t seq)
  {
  	struct dlm_ls *ls = lkb->lkb_resource->res_ls;
  	uint64_t prev_seq;
  	int prev_mode;

  	int i, rv;

  
  	for (i = 0; i < DLM_CALLBACKS_SIZE; i++) {
  		if (lkb->lkb_callbacks[i].seq)
  			continue;
  
  		/*
  		 * Suppress some redundant basts here, do more on removal.
  		 * Don't even add a bast if the callback just before it
  		 * is a bast for the same mode or a more restrictive mode.
  		 * (the addional > PR check is needed for PR/CW inversion)
  		 */
  
  		if ((i > 0) && (flags & DLM_CB_BAST) &&
  		    (lkb->lkb_callbacks[i-1].flags & DLM_CB_BAST)) {
  
  			prev_seq = lkb->lkb_callbacks[i-1].seq;
  			prev_mode = lkb->lkb_callbacks[i-1].mode;
  
  			if ((prev_mode == mode) ||
  			    (prev_mode > mode && prev_mode > DLM_LOCK_PR)) {
  
  				log_debug(ls, "skip %x add bast %llu mode %d "
  					  "for bast %llu mode %d",
  					  lkb->lkb_id,
  					  (unsigned long long)seq,
  					  mode,
  					  (unsigned long long)prev_seq,
  					  prev_mode);

  				rv = 0;
  				goto out;

  			}
  		}
  
  		lkb->lkb_callbacks[i].seq = seq;
  		lkb->lkb_callbacks[i].flags = flags;
  		lkb->lkb_callbacks[i].mode = mode;
  		lkb->lkb_callbacks[i].sb_status = status;
  		lkb->lkb_callbacks[i].sb_flags = (sbflags & 0x000000FF);

  		rv = 0;

  		break;
  	}
  
  	if (i == DLM_CALLBACKS_SIZE) {
  		log_error(ls, "no callbacks %x %llu flags %x mode %d sb %d %x",
  			  lkb->lkb_id, (unsigned long long)seq,
  			  flags, mode, status, sbflags);
  		dlm_dump_lkb_callbacks(lkb);

  		rv = -1;
  		goto out;

  	}

   out:
  	return rv;

  }
  
  int dlm_rem_lkb_callback(struct dlm_ls *ls, struct dlm_lkb *lkb,
  			 struct dlm_callback *cb, int *resid)

  {

  	int i, rv;

  
  	*resid = 0;

  	if (!lkb->lkb_callbacks[0].seq) {
  		rv = -ENOENT;
  		goto out;
  	}

  
  	/* oldest undelivered cb is callbacks[0] */
  
  	memcpy(cb, &lkb->lkb_callbacks[0], sizeof(struct dlm_callback));
  	memset(&lkb->lkb_callbacks[0], 0, sizeof(struct dlm_callback));
  
  	/* shift others down */
  
  	for (i = 1; i < DLM_CALLBACKS_SIZE; i++) {
  		if (!lkb->lkb_callbacks[i].seq)
  			break;
  		memcpy(&lkb->lkb_callbacks[i-1], &lkb->lkb_callbacks[i],
  		       sizeof(struct dlm_callback));
  		memset(&lkb->lkb_callbacks[i], 0, sizeof(struct dlm_callback));
  		(*resid)++;
  	}
  
  	/* if cb is a bast, it should be skipped if the blocking mode is
  	   compatible with the last granted mode */
  
  	if ((cb->flags & DLM_CB_BAST) && lkb->lkb_last_cast.seq) {
  		if (dlm_modes_compat(cb->mode, lkb->lkb_last_cast.mode)) {
  			cb->flags |= DLM_CB_SKIP;
  
  			log_debug(ls, "skip %x bast %llu mode %d "
  				  "for cast %llu mode %d",
  				  lkb->lkb_id,
  				  (unsigned long long)cb->seq,
  				  cb->mode,
  				  (unsigned long long)lkb->lkb_last_cast.seq,
  				  lkb->lkb_last_cast.mode);

  			rv = 0;
  			goto out;

  		}
  	}
  
  	if (cb->flags & DLM_CB_CAST) {
  		memcpy(&lkb->lkb_last_cast, cb, sizeof(struct dlm_callback));
  		lkb->lkb_last_cast_time = ktime_get();
  	}
  
  	if (cb->flags & DLM_CB_BAST) {
  		memcpy(&lkb->lkb_last_bast, cb, sizeof(struct dlm_callback));
  		lkb->lkb_last_bast_time = ktime_get();
  	}

  	rv = 0;
   out:
  	return rv;

  }

  void dlm_add_cb(struct dlm_lkb *lkb, uint32_t flags, int mode, int status,
  		uint32_t sbflags)

  {

  	struct dlm_ls *ls = lkb->lkb_resource->res_ls;
  	uint64_t new_seq, prev_seq;

  	int rv;

  	spin_lock(&dlm_cb_seq_spin);
  	new_seq = ++dlm_cb_seq;
  	spin_unlock(&dlm_cb_seq_spin);

  	if (lkb->lkb_flags & DLM_IFL_USER) {

  		dlm_user_add_ast(lkb, flags, mode, status, sbflags, new_seq);

  		return;
  	}

  	mutex_lock(&lkb->lkb_cb_mutex);
  	prev_seq = lkb->lkb_callbacks[0].seq;

  	rv = dlm_add_lkb_callback(lkb, flags, mode, status, sbflags, new_seq);
  	if (rv < 0)
  		goto out;
  
  	if (!prev_seq) {

  		kref_get(&lkb->lkb_ref);

  		if (test_bit(LSFL_CB_DELAY, &ls->ls_flags)) {
  			mutex_lock(&ls->ls_cb_mutex);
  			list_add(&lkb->lkb_cb_list, &ls->ls_cb_delay);
  			mutex_unlock(&ls->ls_cb_mutex);
  		} else {
  			queue_work(ls->ls_callback_wq, &lkb->lkb_cb_work);
  		}
  	}
   out:
  	mutex_unlock(&lkb->lkb_cb_mutex);

  }

  void dlm_callback_work(struct work_struct *work)

  {

  	struct dlm_lkb *lkb = container_of(work, struct dlm_lkb, lkb_cb_work);
  	struct dlm_ls *ls = lkb->lkb_resource->res_ls;

  	void (*castfn) (void *astparam);
  	void (*bastfn) (void *astparam, int mode);

  	struct dlm_callback callbacks[DLM_CALLBACKS_SIZE];
  	int i, rv, resid;

  	memset(&callbacks, 0, sizeof(callbacks));

  	mutex_lock(&lkb->lkb_cb_mutex);
  	if (!lkb->lkb_callbacks[0].seq) {
  		/* no callback work exists, shouldn't happen */
  		log_error(ls, "dlm_callback_work %x no work", lkb->lkb_id);
  		dlm_print_lkb(lkb);
  		dlm_dump_lkb_callbacks(lkb);
  	}

  	for (i = 0; i < DLM_CALLBACKS_SIZE; i++) {
  		rv = dlm_rem_lkb_callback(ls, lkb, &callbacks[i], &resid);
  		if (rv < 0)
  			break;
  	}

  	if (resid) {
  		/* cbs remain, loop should have removed all, shouldn't happen */
  		log_error(ls, "dlm_callback_work %x resid %d", lkb->lkb_id,
  			  resid);
  		dlm_print_lkb(lkb);
  		dlm_dump_lkb_callbacks(lkb);
  	}
  	mutex_unlock(&lkb->lkb_cb_mutex);

  	castfn = lkb->lkb_astfn;
  	bastfn = lkb->lkb_bastfn;

  	for (i = 0; i < DLM_CALLBACKS_SIZE; i++) {
  		if (!callbacks[i].seq)
  			break;
  		if (callbacks[i].flags & DLM_CB_SKIP) {
  			continue;
  		} else if (callbacks[i].flags & DLM_CB_BAST) {
  			bastfn(lkb->lkb_astparam, callbacks[i].mode);
  		} else if (callbacks[i].flags & DLM_CB_CAST) {
  			lkb->lkb_lksb->sb_status = callbacks[i].sb_status;
  			lkb->lkb_lksb->sb_flags = callbacks[i].sb_flags;
  			castfn(lkb->lkb_astparam);

  		}

  	}

  	/* undo kref_get from dlm_add_callback, may cause lkb to be freed */
  	dlm_put_lkb(lkb);

  }

  int dlm_callback_start(struct dlm_ls *ls)

  {

  	ls->ls_callback_wq = alloc_workqueue("dlm_callback",

  					     WQ_UNBOUND |
  					     WQ_MEM_RECLAIM |
  					     WQ_NON_REENTRANT,
  					     0);

  	if (!ls->ls_callback_wq) {
  		log_print("can't start dlm_callback workqueue");
  		return -ENOMEM;

  	}
  	return 0;
  }

  void dlm_callback_stop(struct dlm_ls *ls)

  {

  	if (ls->ls_callback_wq)
  		destroy_workqueue(ls->ls_callback_wq);

  }

  void dlm_callback_suspend(struct dlm_ls *ls)

  {

  	set_bit(LSFL_CB_DELAY, &ls->ls_flags);

  	if (ls->ls_callback_wq)
  		flush_workqueue(ls->ls_callback_wq);

  }

  void dlm_callback_resume(struct dlm_ls *ls)

  {

  	struct dlm_lkb *lkb, *safe;
  	int count = 0;

  	clear_bit(LSFL_CB_DELAY, &ls->ls_flags);
  
  	if (!ls->ls_callback_wq)
  		return;
  
  	mutex_lock(&ls->ls_cb_mutex);
  	list_for_each_entry_safe(lkb, safe, &ls->ls_cb_delay, lkb_cb_list) {
  		list_del_init(&lkb->lkb_cb_list);
  		queue_work(ls->ls_callback_wq, &lkb->lkb_cb_work);
  		count++;
  	}
  	mutex_unlock(&ls->ls_cb_mutex);
  
  	log_debug(ls, "dlm_callback_resume %d", count);

  }