/*
 * YAFFS: Yet Another Flash File System. A NAND-flash specific file system.
 *
 * Copyright (C) 2002-2011 Aleph One Ltd.
 *   for Toby Churchill Ltd and Brightstar Engineering
 *
 * Created by Charles Manning <charles@aleph1.co.uk>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include "yaffs_allocator.h"
#include "yaffs_guts.h"
#include "yaffs_trace.h"
#include "yportenv.h"

/*
 * Each entry in yaffs_tnode_list and yaffs_obj_list hold blocks
 * of approx 100 objects that are themn allocated singly.
 * This is basically a simplified slab allocator.
 *
 * We don't use the Linux slab allocator because slab does not allow
 * us to dump all the objects in one hit when we do a umount and tear
 * down  all the tnodes and objects. slab requires that we first free
 * the individual objects.
 *
 * Once yaffs has been mainlined I shall try to motivate for a change
 * to slab to provide the extra features we need here.
 */

struct yaffs_tnode_list {
        struct yaffs_tnode_list *next;
        struct yaffs_tnode *tnodes;
};

struct yaffs_obj_list {
        struct yaffs_obj_list *next;
        struct yaffs_obj *objects;
};

struct yaffs_allocator {
        int n_tnodes_created;
        struct yaffs_tnode *free_tnodes;
        int n_free_tnodes;
        struct yaffs_tnode_list *alloc_tnode_list;

        int n_obj_created;
        struct list_head free_objs;
        int n_free_objects;

        struct yaffs_obj_list *allocated_obj_list;
};

static void yaffs_deinit_raw_tnodes(struct yaffs_dev *dev)
{
        struct yaffs_allocator *allocator =
            (struct yaffs_allocator *)dev->allocator;
        struct yaffs_tnode_list *tmp;

        if (!allocator) {
                BUG();
                return;
        }

        while (allocator->alloc_tnode_list) {
                tmp = allocator->alloc_tnode_list->next;

                kfree(allocator->alloc_tnode_list->tnodes);
                kfree(allocator->alloc_tnode_list);
                allocator->alloc_tnode_list = tmp;
        }

        allocator->free_tnodes = NULL;
        allocator->n_free_tnodes = 0;
        allocator->n_tnodes_created = 0;
}

static void yaffs_init_raw_tnodes(struct yaffs_dev *dev)
{
        struct yaffs_allocator *allocator = dev->allocator;

        if (!allocator) {
                BUG();
                return;
        }

        allocator->alloc_tnode_list = NULL;
        allocator->free_tnodes = NULL;
        allocator->n_free_tnodes = 0;
        allocator->n_tnodes_created = 0;
}

static int yaffs_create_tnodes(struct yaffs_dev *dev, int n_tnodes)
{
        struct yaffs_allocator *allocator =
            (struct yaffs_allocator *)dev->allocator;
        int i;
        struct yaffs_tnode *new_tnodes;
        u8 *mem;
        struct yaffs_tnode *curr;
        struct yaffs_tnode *next;
        struct yaffs_tnode_list *tnl;

        if (!allocator) {
                BUG();
                return YAFFS_FAIL;
        }

        if (n_tnodes < 1)
                return YAFFS_OK;

        /* make these things */
        new_tnodes = kmalloc(n_tnodes * dev->tnode_size, GFP_NOFS);
        mem = (u8 *) new_tnodes;

        if (!new_tnodes) {
                yaffs_trace(YAFFS_TRACE_ERROR,
                        "yaffs: Could not allocate Tnodes");
                return YAFFS_FAIL;
        }

        /* New hookup for wide tnodes */
        for (i = 0; i < n_tnodes - 1; i++) {
                curr = (struct yaffs_tnode *)&mem[i * dev->tnode_size];
                next = (struct yaffs_tnode *)&mem[(i + 1) * dev->tnode_size];
                curr->internal[0] = next;
        }

        curr = (struct yaffs_tnode *)&mem[(n_tnodes - 1) * dev->tnode_size];
        curr->internal[0] = allocator->free_tnodes;
        allocator->free_tnodes = (struct yaffs_tnode *)mem;

        allocator->n_free_tnodes += n_tnodes;
        allocator->n_tnodes_created += n_tnodes;

        /* Now add this bunch of tnodes to a list for freeing up.
         * NB If we can't add this to the management list it isn't fatal
         * but it just means we can't free this bunch of tnodes later.
         */
        tnl = kmalloc(sizeof(struct yaffs_tnode_list), GFP_NOFS);
        if (!tnl) {
                yaffs_trace(YAFFS_TRACE_ERROR,
                        "Could not add tnodes to management list");
                return YAFFS_FAIL;
        } else {
                tnl->tnodes = new_tnodes;
                tnl->next = allocator->alloc_tnode_list;
                allocator->alloc_tnode_list = tnl;
        }

        yaffs_trace(YAFFS_TRACE_ALLOCATE, "Tnodes added");

        return YAFFS_OK;
}

struct yaffs_tnode *yaffs_alloc_raw_tnode(struct yaffs_dev *dev)
{
        struct yaffs_allocator *allocator =
            (struct yaffs_allocator *)dev->allocator;
        struct yaffs_tnode *tn = NULL;

        if (!allocator) {
                BUG();
                return NULL;
        }

        /* If there are none left make more */
        if (!allocator->free_tnodes)
                yaffs_create_tnodes(dev, YAFFS_ALLOCATION_NTNODES);

        if (allocator->free_tnodes) {
                tn = allocator->free_tnodes;
                allocator->free_tnodes = allocator->free_tnodes->internal[0];
                allocator->n_free_tnodes--;
        }

        return tn;
}

/* FreeTnode frees up a tnode and puts it back on the free list */
void yaffs_free_raw_tnode(struct yaffs_dev *dev, struct yaffs_tnode *tn)
{
        struct yaffs_allocator *allocator = dev->allocator;

        if (!allocator) {
                BUG();
                return;
        }

        if (tn) {
                tn->internal[0] = allocator->free_tnodes;
                allocator->free_tnodes = tn;
                allocator->n_free_tnodes++;
        }
        dev->checkpoint_blocks_required = 0;    /* force recalculation */
}

/*--------------- yaffs_obj alloaction ------------------------
 *
 * Free yaffs_objs are stored in a list using obj->siblings.
 * The blocks of allocated objects are stored in a linked list.
 */

static void yaffs_init_raw_objs(struct yaffs_dev *dev)
{
        struct yaffs_allocator *allocator = dev->allocator;

        if (!allocator) {
                BUG();
                return;
        }

        allocator->allocated_obj_list = NULL;
        INIT_LIST_HEAD(&allocator->free_objs);
        allocator->n_free_objects = 0;
}

static void yaffs_deinit_raw_objs(struct yaffs_dev *dev)
{
        struct yaffs_allocator *allocator = dev->allocator;
        struct yaffs_obj_list *tmp;

        if (!allocator) {
                BUG();
                return;
        }

        while (allocator->allocated_obj_list) {
                tmp = allocator->allocated_obj_list->next;
                kfree(allocator->allocated_obj_list->objects);
                kfree(allocator->allocated_obj_list);
                allocator->allocated_obj_list = tmp;
        }

        INIT_LIST_HEAD(&allocator->free_objs);
        allocator->n_free_objects = 0;
        allocator->n_obj_created = 0;
}

static int yaffs_create_free_objs(struct yaffs_dev *dev, int n_obj)
{
        struct yaffs_allocator *allocator = dev->allocator;
        int i;
        struct yaffs_obj *new_objs;
        struct yaffs_obj_list *list;

        if (!allocator) {
                BUG();
                return YAFFS_FAIL;
        }

        if (n_obj < 1)
                return YAFFS_OK;

        /* make these things */
        new_objs = kmalloc(n_obj * sizeof(struct yaffs_obj), GFP_NOFS);
        list = kmalloc(sizeof(struct yaffs_obj_list), GFP_NOFS);

        if (!new_objs || !list) {
                kfree(new_objs);
                new_objs = NULL;
                kfree(list);
                list = NULL;
                yaffs_trace(YAFFS_TRACE_ALLOCATE,
                        "Could not allocate more objects");
                return YAFFS_FAIL;
        }

        /* Hook them into the free list */
        for (i = 0; i < n_obj; i++)
                list_add(&new_objs[i].siblings, &allocator->free_objs);

        allocator->n_free_objects += n_obj;
        allocator->n_obj_created += n_obj;

        /* Now add this bunch of Objects to a list for freeing up. */

        list->objects = new_objs;
        list->next = allocator->allocated_obj_list;
        allocator->allocated_obj_list = list;

        return YAFFS_OK;
}

struct yaffs_obj *yaffs_alloc_raw_obj(struct yaffs_dev *dev)
{
        struct yaffs_obj *obj = NULL;
        struct list_head *lh;
        struct yaffs_allocator *allocator = dev->allocator;

        if (!allocator) {
                BUG();
                return obj;
        }

        /* If there are none left make more */
        if (list_empty(&allocator->free_objs))
                yaffs_create_free_objs(dev, YAFFS_ALLOCATION_NOBJECTS);

        if (!list_empty(&allocator->free_objs)) {
                lh = allocator->free_objs.next;
                obj = list_entry(lh, struct yaffs_obj, siblings);
                list_del_init(lh);
                allocator->n_free_objects--;
        }

        return obj;
}

void yaffs_free_raw_obj(struct yaffs_dev *dev, struct yaffs_obj *obj)
{

        struct yaffs_allocator *allocator = dev->allocator;

        if (!allocator) {
                BUG();
                return;
        }

        /* Link into the free list. */
        list_add(&obj->siblings, &allocator->free_objs);
        allocator->n_free_objects++;
}

void yaffs_deinit_raw_tnodes_and_objs(struct yaffs_dev *dev)
{

        if (!dev->allocator) {
                BUG();
                return;
        }

        yaffs_deinit_raw_tnodes(dev);
        yaffs_deinit_raw_objs(dev);
        kfree(dev->allocator);
        dev->allocator = NULL;
}

void yaffs_init_raw_tnodes_and_objs(struct yaffs_dev *dev)
{
        struct yaffs_allocator *allocator;

        if (dev->allocator) {
                BUG();
                return;
        }

        allocator = kmalloc(sizeof(struct yaffs_allocator), GFP_NOFS);
        if (allocator) {
                dev->allocator = allocator;
                yaffs_init_raw_tnodes(dev);
                yaffs_init_raw_objs(dev);
        }
}