/* -*- mode: c; c-basic-offset: 8; -*-
   * vim: noexpandtab sw=8 ts=8 sts=0:
   *
   * slot_map.c
   *
   *
   *
   * Copyright (C) 2002, 2004 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; either
   * version 2 of the License, or (at your option) any later version.
   *
   * 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.
   *
   * You should have received a copy of the GNU General Public
   * License along with this program; if not, write to the
   * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
   * Boston, MA 021110-1307, USA.
   */
  
  #include <linux/types.h>
  #include <linux/slab.h>
  #include <linux/highmem.h>

  
  #define MLOG_MASK_PREFIX ML_SUPER
  #include <cluster/masklog.h>
  
  #include "ocfs2.h"
  
  #include "dlmglue.h"
  #include "extent_map.h"
  #include "heartbeat.h"
  #include "inode.h"
  #include "slot_map.h"
  #include "super.h"
  #include "sysfile.h"
  
  #include "buffer_head_io.h"
  
  static s16 __ocfs2_node_num_to_slot(struct ocfs2_slot_info *si,
  				    s16 global);
  static void __ocfs2_fill_slot(struct ocfs2_slot_info *si,
  			      s16 slot_num,
  			      s16 node_num);
  
  /* Use the slot information we've collected to create a map of mounted
   * nodes. Should be holding an EX on super block. assumes slot info is
   * up to date. Note that we call this *after* we find a slot, so our
   * own node should be set in the map too... */
  void ocfs2_populate_mounted_map(struct ocfs2_super *osb)
  {
  	int i;
  	struct ocfs2_slot_info *si = osb->slot_info;
  
  	spin_lock(&si->si_lock);
  
  	for (i = 0; i < si->si_size; i++)
  		if (si->si_global_node_nums[i] != OCFS2_INVALID_SLOT)
  			ocfs2_node_map_set_bit(osb, &osb->mounted_map,
  					      si->si_global_node_nums[i]);
  
  	spin_unlock(&si->si_lock);
  }
  
  /* post the slot information on disk into our slot_info struct. */
  void ocfs2_update_slot_info(struct ocfs2_slot_info *si)
  {
  	int i;
  	__le16 *disk_info;
  
  	/* we don't read the slot block here as ocfs2_super_lock
  	 * should've made sure we have the most recent copy. */
  	spin_lock(&si->si_lock);
  	disk_info = (__le16 *) si->si_bh->b_data;
  
  	for (i = 0; i < si->si_size; i++)
  		si->si_global_node_nums[i] = le16_to_cpu(disk_info[i]);
  
  	spin_unlock(&si->si_lock);
  }
  
  /* post the our slot info stuff into it's destination bh and write it
   * out. */
  int ocfs2_update_disk_slots(struct ocfs2_super *osb,
  			    struct ocfs2_slot_info *si)
  {
  	int status, i;
  	__le16 *disk_info = (__le16 *) si->si_bh->b_data;
  
  	spin_lock(&si->si_lock);
  	for (i = 0; i < si->si_size; i++)
  		disk_info[i] = cpu_to_le16(si->si_global_node_nums[i]);
  	spin_unlock(&si->si_lock);
  
  	status = ocfs2_write_block(osb, si->si_bh, si->si_inode);
  	if (status < 0)
  		mlog_errno(status);
  
  	return status;
  }
  
  /* try to find global node in the slot info. Returns
   * OCFS2_INVALID_SLOT if nothing is found. */
  static s16 __ocfs2_node_num_to_slot(struct ocfs2_slot_info *si,
  				    s16 global)
  {
  	int i;
  	s16 ret = OCFS2_INVALID_SLOT;
  
  	for(i = 0; i < si->si_num_slots; i++) {
  		if (global == si->si_global_node_nums[i]) {
  			ret = (s16) i;
  			break;
  		}
  	}
  	return ret;
  }

  static s16 __ocfs2_find_empty_slot(struct ocfs2_slot_info *si, s16 preferred)

  {
  	int i;
  	s16 ret = OCFS2_INVALID_SLOT;

  	if (preferred >= 0 && preferred < si->si_num_slots) {
  		if (OCFS2_INVALID_SLOT == si->si_global_node_nums[preferred]) {
  			ret = preferred;
  			goto out;
  		}
  	}

  	for(i = 0; i < si->si_num_slots; i++) {
  		if (OCFS2_INVALID_SLOT == si->si_global_node_nums[i]) {
  			ret = (s16) i;
  			break;
  		}
  	}

  out:

  	return ret;
  }
  
  s16 ocfs2_node_num_to_slot(struct ocfs2_slot_info *si,
  			   s16 global)
  {
  	s16 ret;
  
  	spin_lock(&si->si_lock);
  	ret = __ocfs2_node_num_to_slot(si, global);
  	spin_unlock(&si->si_lock);
  	return ret;
  }
  
  static void __ocfs2_fill_slot(struct ocfs2_slot_info *si,
  			      s16 slot_num,
  			      s16 node_num)
  {
  	BUG_ON(slot_num == OCFS2_INVALID_SLOT);
  	BUG_ON(slot_num >= si->si_num_slots);
  	BUG_ON((node_num != O2NM_INVALID_NODE_NUM) &&
  	       (node_num >= O2NM_MAX_NODES));
  
  	si->si_global_node_nums[slot_num] = node_num;
  }
  
  void ocfs2_clear_slot(struct ocfs2_slot_info *si,
  		      s16 slot_num)
  {
  	spin_lock(&si->si_lock);
  	__ocfs2_fill_slot(si, slot_num, OCFS2_INVALID_SLOT);
  	spin_unlock(&si->si_lock);
  }
  
  int ocfs2_init_slot_info(struct ocfs2_super *osb)
  {
  	int status, i;
  	u64 blkno;
  	struct inode *inode = NULL;
  	struct buffer_head *bh = NULL;
  	struct ocfs2_slot_info *si;

  	si = kzalloc(sizeof(struct ocfs2_slot_info), GFP_KERNEL);

  	if (!si) {
  		status = -ENOMEM;
  		mlog_errno(status);
  		goto bail;
  	}
  
  	spin_lock_init(&si->si_lock);
  	si->si_num_slots = osb->max_slots;
  	si->si_size = OCFS2_MAX_SLOTS;
  
  	for(i = 0; i < si->si_num_slots; i++)
  		si->si_global_node_nums[i] = OCFS2_INVALID_SLOT;
  
  	inode = ocfs2_get_system_file_inode(osb, SLOT_MAP_SYSTEM_INODE,
  					    OCFS2_INVALID_SLOT);
  	if (!inode) {
  		status = -EINVAL;
  		mlog_errno(status);
  		goto bail;
  	}

  	status = ocfs2_extent_map_get_blocks(inode, 0ULL, &blkno, NULL, NULL);

  	if (status < 0) {
  		mlog_errno(status);
  		goto bail;
  	}
  
  	status = ocfs2_read_block(osb, blkno, &bh, 0, inode);
  	if (status < 0) {
  		mlog_errno(status);
  		goto bail;
  	}
  
  	si->si_inode = inode;
  	si->si_bh = bh;
  	osb->slot_info = si;
  bail:
  	if (status < 0 && si)
  		ocfs2_free_slot_info(si);
  
  	return status;
  }
  
  void ocfs2_free_slot_info(struct ocfs2_slot_info *si)
  {
  	if (si->si_inode)
  		iput(si->si_inode);
  	if (si->si_bh)
  		brelse(si->si_bh);
  	kfree(si);
  }
  
  int ocfs2_find_slot(struct ocfs2_super *osb)
  {
  	int status;
  	s16 slot;
  	struct ocfs2_slot_info *si;
  
  	mlog_entry_void();
  
  	si = osb->slot_info;
  
  	ocfs2_update_slot_info(si);
  
  	spin_lock(&si->si_lock);
  	/* search for ourselves first and take the slot if it already
  	 * exists. Perhaps we need to mark this in a variable for our
  	 * own journal recovery? Possibly not, though we certainly
  	 * need to warn to the user */
  	slot = __ocfs2_node_num_to_slot(si, osb->node_num);
  	if (slot == OCFS2_INVALID_SLOT) {
  		/* if no slot yet, then just take 1st available
  		 * one. */

  		slot = __ocfs2_find_empty_slot(si, osb->preferred_slot);

  		if (slot == OCFS2_INVALID_SLOT) {
  			spin_unlock(&si->si_lock);
  			mlog(ML_ERROR, "no free slots available!
  ");
  			status = -EINVAL;
  			goto bail;
  		}
  	} else
  		mlog(ML_NOTICE, "slot %d is already allocated to this node!
  ",
  		     slot);
  
  	__ocfs2_fill_slot(si, slot, osb->node_num);
  	osb->slot_num = slot;
  	spin_unlock(&si->si_lock);

  	mlog(0, "taking node slot %d
  ", osb->slot_num);

  
  	status = ocfs2_update_disk_slots(osb, si);
  	if (status < 0)
  		mlog_errno(status);
  
  bail:
  	mlog_exit(status);
  	return status;
  }
  
  void ocfs2_put_slot(struct ocfs2_super *osb)
  {
  	int status;
  	struct ocfs2_slot_info *si = osb->slot_info;
  
  	if (!si)
  		return;
  
  	ocfs2_update_slot_info(si);
  
  	spin_lock(&si->si_lock);
  	__ocfs2_fill_slot(si, osb->slot_num, OCFS2_INVALID_SLOT);
  	osb->slot_num = OCFS2_INVALID_SLOT;
  	spin_unlock(&si->si_lock);
  
  	status = ocfs2_update_disk_slots(osb, si);
  	if (status < 0) {
  		mlog_errno(status);
  		goto bail;
  	}
  
  bail:
  	osb->slot_info = NULL;
  	ocfs2_free_slot_info(si);
  }