/* -*- 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);

/* 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!\n");
                        status = -EINVAL;
                        goto bail;
                }
        } else
                mlog(ML_NOTICE, "slot %d is already allocated to this node!\n",
                     slot);

        __ocfs2_fill_slot(si, slot, osb->node_num);
        osb->slot_num = slot;
        spin_unlock(&si->si_lock);

        mlog(0, "taking node slot %d\n", 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);
}