/*
 * Copyright (c) 2004, 2005 Topspin Communications.  All rights reserved.
 * Copyright (c) 2005 Cisco Systems.  All rights reserved.
 * Copyright (c) 2005 Mellanox Technologies. All rights reserved.
 *
 * This software is available to you under a choice of one of two
 * licenses.  You may choose to be licensed under the terms of the GNU
 * General Public License (GPL) Version 2, available from the file
 * COPYING in the main directory of this source tree, or the
 * OpenIB.org BSD license below:
 *
 *     Redistribution and use in source and binary forms, with or
 *     without modification, are permitted provided that the following
 *     conditions are met:
 *
 *      - Redistributions of source code must retain the above
 *        copyright notice, this list of conditions and the following
 *        disclaimer.
 *
 *      - Redistributions in binary form must reproduce the above
 *        copyright notice, this list of conditions and the following
 *        disclaimer in the documentation and/or other materials
 *        provided with the distribution.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

#include <linux/mm.h>
#include <linux/scatterlist.h>
#include <linux/sched.h>
#include <linux/slab.h>

#include <asm/page.h>

#include "mthca_memfree.h"
#include "mthca_dev.h"
#include "mthca_cmd.h"

/*
 * We allocate in as big chunks as we can, up to a maximum of 256 KB
 * per chunk.
 */
enum {
        MTHCA_ICM_ALLOC_SIZE   = 1 << 18,
        MTHCA_TABLE_CHUNK_SIZE = 1 << 18
};

struct mthca_user_db_table {
        struct mutex mutex;
        struct {
                u64                uvirt;
                struct scatterlist mem;
                int                refcount;
        }                page[0];
};

static void mthca_free_icm_pages(struct mthca_dev *dev, struct mthca_icm_chunk *chunk)
{
        int i;

        if (chunk->nsg > 0)
                pci_unmap_sg(dev->pdev, chunk->mem, chunk->npages,
                             PCI_DMA_BIDIRECTIONAL);

        for (i = 0; i < chunk->npages; ++i)
                __free_pages(sg_page(&chunk->mem[i]),
                             get_order(chunk->mem[i].length));
}

static void mthca_free_icm_coherent(struct mthca_dev *dev, struct mthca_icm_chunk *chunk)
{
        int i;

        for (i = 0; i < chunk->npages; ++i) {
                dma_free_coherent(&dev->pdev->dev, chunk->mem[i].length,
                                  lowmem_page_address(sg_page(&chunk->mem[i])),
                                  sg_dma_address(&chunk->mem[i]));
        }
}

void mthca_free_icm(struct mthca_dev *dev, struct mthca_icm *icm, int coherent)
{
        struct mthca_icm_chunk *chunk, *tmp;

        if (!icm)
                return;

        list_for_each_entry_safe(chunk, tmp, &icm->chunk_list, list) {
                if (coherent)
                        mthca_free_icm_coherent(dev, chunk);
                else
                        mthca_free_icm_pages(dev, chunk);

                kfree(chunk);
        }

        kfree(icm);
}

static int mthca_alloc_icm_pages(struct scatterlist *mem, int order, gfp_t gfp_mask)
{
        struct page *page;

        /*
         * Use __GFP_ZERO because buggy firmware assumes ICM pages are
         * cleared, and subtle failures are seen if they aren't.
         */
        page = alloc_pages(gfp_mask | __GFP_ZERO, order);
        if (!page)
                return -ENOMEM;

        sg_set_page(mem, page, PAGE_SIZE << order, 0);
        return 0;
}

static int mthca_alloc_icm_coherent(struct device *dev, struct scatterlist *mem,
                                    int order, gfp_t gfp_mask)
{
        void *buf = dma_alloc_coherent(dev, PAGE_SIZE << order, &sg_dma_address(mem),
                                       gfp_mask);
        if (!buf)
                return -ENOMEM;

        sg_set_buf(mem, buf, PAGE_SIZE << order);
        BUG_ON(mem->offset);
        sg_dma_len(mem) = PAGE_SIZE << order;
        return 0;
}

struct mthca_icm *mthca_alloc_icm(struct mthca_dev *dev, int npages,
                                  gfp_t gfp_mask, int coherent)
{
        struct mthca_icm *icm;
        struct mthca_icm_chunk *chunk = NULL;
        int cur_order;
        int ret;

        /* We use sg_set_buf for coherent allocs, which assumes low memory */
        BUG_ON(coherent && (gfp_mask & __GFP_HIGHMEM));

        icm = kmalloc(sizeof *icm, gfp_mask & ~(__GFP_HIGHMEM | __GFP_NOWARN));
        if (!icm)
                return icm;

        icm->refcount = 0;
        INIT_LIST_HEAD(&icm->chunk_list);

        cur_order = get_order(MTHCA_ICM_ALLOC_SIZE);

        while (npages > 0) {
                if (!chunk) {
                        chunk = kmalloc(sizeof *chunk,
                                        gfp_mask & ~(__GFP_HIGHMEM | __GFP_NOWARN));
                        if (!chunk)
                                goto fail;

                        sg_init_table(chunk->mem, MTHCA_ICM_CHUNK_LEN);
                        chunk->npages = 0;
                        chunk->nsg    = 0;
                        list_add_tail(&chunk->list, &icm->chunk_list);
                }

                while (1 << cur_order > npages)
                        --cur_order;

                if (coherent)
                        ret = mthca_alloc_icm_coherent(&dev->pdev->dev,
                                                       &chunk->mem[chunk->npages],
                                                       cur_order, gfp_mask);
                else
                        ret = mthca_alloc_icm_pages(&chunk->mem[chunk->npages],
                                                    cur_order, gfp_mask);

                if (!ret) {
                        ++chunk->npages;

                        if (coherent)
                                ++chunk->nsg;
                        else if (chunk->npages == MTHCA_ICM_CHUNK_LEN) {
                                chunk->nsg = pci_map_sg(dev->pdev, chunk->mem,
                                                        chunk->npages,
                                                        PCI_DMA_BIDIRECTIONAL);

                                if (chunk->nsg <= 0)
                                        goto fail;
                        }

                        if (chunk->npages == MTHCA_ICM_CHUNK_LEN)
                                chunk = NULL;

                        npages -= 1 << cur_order;
                } else {
                        --cur_order;
                        if (cur_order < 0)
                                goto fail;
                }
        }

        if (!coherent && chunk) {
                chunk->nsg = pci_map_sg(dev->pdev, chunk->mem,
                                        chunk->npages,
                                        PCI_DMA_BIDIRECTIONAL);

                if (chunk->nsg <= 0)
                        goto fail;
        }

        return icm;

fail:
        mthca_free_icm(dev, icm, coherent);
        return NULL;
}

int mthca_table_get(struct mthca_dev *dev, struct mthca_icm_table *table, int obj)
{
        int i = (obj & (table->num_obj - 1)) * table->obj_size / MTHCA_TABLE_CHUNK_SIZE;
        int ret = 0;

        mutex_lock(&table->mutex);

        if (table->icm[i]) {
                ++table->icm[i]->refcount;
                goto out;
        }

        table->icm[i] = mthca_alloc_icm(dev, MTHCA_TABLE_CHUNK_SIZE >> PAGE_SHIFT,
                                        (table->lowmem ? GFP_KERNEL : GFP_HIGHUSER) |
                                        __GFP_NOWARN, table->coherent);
        if (!table->icm[i]) {
                ret = -ENOMEM;
                goto out;
        }

        if (mthca_MAP_ICM(dev, table->icm[i],
                          table->virt + i * MTHCA_TABLE_CHUNK_SIZE)) {
                mthca_free_icm(dev, table->icm[i], table->coherent);
                table->icm[i] = NULL;
                ret = -ENOMEM;
                goto out;
        }

        ++table->icm[i]->refcount;

out:
        mutex_unlock(&table->mutex);
        return ret;
}

void mthca_table_put(struct mthca_dev *dev, struct mthca_icm_table *table, int obj)
{
        int i;

        if (!mthca_is_memfree(dev))
                return;

        i = (obj & (table->num_obj - 1)) * table->obj_size / MTHCA_TABLE_CHUNK_SIZE;

        mutex_lock(&table->mutex);

        if (--table->icm[i]->refcount == 0) {
                mthca_UNMAP_ICM(dev, table->virt + i * MTHCA_TABLE_CHUNK_SIZE,
                                MTHCA_TABLE_CHUNK_SIZE / MTHCA_ICM_PAGE_SIZE);
                mthca_free_icm(dev, table->icm[i], table->coherent);
                table->icm[i] = NULL;
        }

        mutex_unlock(&table->mutex);
}

void *mthca_table_find(struct mthca_icm_table *table, int obj, dma_addr_t *dma_handle)
{
        int idx, offset, dma_offset, i;
        struct mthca_icm_chunk *chunk;
        struct mthca_icm *icm;
        struct page *page = NULL;

        if (!table->lowmem)
                return NULL;

        mutex_lock(&table->mutex);

        idx = (obj & (table->num_obj - 1)) * table->obj_size;
        icm = table->icm[idx / MTHCA_TABLE_CHUNK_SIZE];
        dma_offset = offset = idx % MTHCA_TABLE_CHUNK_SIZE;

        if (!icm)
                goto out;

        list_for_each_entry(chunk, &icm->chunk_list, list) {
                for (i = 0; i < chunk->npages; ++i) {
                        if (dma_handle && dma_offset >= 0) {
                                if (sg_dma_len(&chunk->mem[i]) > dma_offset)
                                        *dma_handle = sg_dma_address(&chunk->mem[i]) +
                                                dma_offset;
                                dma_offset -= sg_dma_len(&chunk->mem[i]);
                        }
                        /* DMA mapping can merge pages but not split them,
                         * so if we found the page, dma_handle has already
                         * been assigned to. */
                        if (chunk->mem[i].length > offset) {
                                page = sg_page(&chunk->mem[i]);
                                goto out;
                        }
                        offset -= chunk->mem[i].length;
                }
        }

out:
        mutex_unlock(&table->mutex);
        return page ? lowmem_page_address(page) + offset : NULL;
}

int mthca_table_get_range(struct mthca_dev *dev, struct mthca_icm_table *table,
                          int start, int end)
{
        int inc = MTHCA_TABLE_CHUNK_SIZE / table->obj_size;
        int i, err;

        for (i = start; i <= end; i += inc) {
                err = mthca_table_get(dev, table, i);
                if (err)
                        goto fail;
        }

        return 0;

fail:
        while (i > start) {
                i -= inc;
                mthca_table_put(dev, table, i);
        }

        return err;
}

void mthca_table_put_range(struct mthca_dev *dev, struct mthca_icm_table *table,
                           int start, int end)
{
        int i;

        if (!mthca_is_memfree(dev))
                return;

        for (i = start; i <= end; i += MTHCA_TABLE_CHUNK_SIZE / table->obj_size)
                mthca_table_put(dev, table, i);
}

struct mthca_icm_table *mthca_alloc_icm_table(struct mthca_dev *dev,
                                              u64 virt, int obj_size,
                                              int nobj, int reserved,
                                              int use_lowmem, int use_coherent)
{
        struct mthca_icm_table *table;
        int obj_per_chunk;
        int num_icm;
        unsigned chunk_size;
        int i;

        obj_per_chunk = MTHCA_TABLE_CHUNK_SIZE / obj_size;
        num_icm = DIV_ROUND_UP(nobj, obj_per_chunk);

        table = kmalloc(struct_size(table, icm, num_icm), GFP_KERNEL);
        if (!table)
                return NULL;

        table->virt     = virt;
        table->num_icm  = num_icm;
        table->num_obj  = nobj;
        table->obj_size = obj_size;
        table->lowmem   = use_lowmem;
        table->coherent = use_coherent;
        mutex_init(&table->mutex);

        for (i = 0; i < num_icm; ++i)
                table->icm[i] = NULL;

        for (i = 0; i * MTHCA_TABLE_CHUNK_SIZE < reserved * obj_size; ++i) {
                chunk_size = MTHCA_TABLE_CHUNK_SIZE;
                if ((i + 1) * MTHCA_TABLE_CHUNK_SIZE > nobj * obj_size)
                        chunk_size = nobj * obj_size - i * MTHCA_TABLE_CHUNK_SIZE;

                table->icm[i] = mthca_alloc_icm(dev, chunk_size >> PAGE_SHIFT,
                                                (use_lowmem ? GFP_KERNEL : GFP_HIGHUSER) |
                                                __GFP_NOWARN, use_coherent);
                if (!table->icm[i])
                        goto err;
                if (mthca_MAP_ICM(dev, table->icm[i],
                                  virt + i * MTHCA_TABLE_CHUNK_SIZE)) {
                        mthca_free_icm(dev, table->icm[i], table->coherent);
                        table->icm[i] = NULL;
                        goto err;
                }

                /*
                 * Add a reference to this ICM chunk so that it never
                 * gets freed (since it contains reserved firmware objects).
                 */
                ++table->icm[i]->refcount;
        }

        return table;

err:
        for (i = 0; i < num_icm; ++i)
                if (table->icm[i]) {
                        mthca_UNMAP_ICM(dev, virt + i * MTHCA_TABLE_CHUNK_SIZE,
                                        MTHCA_TABLE_CHUNK_SIZE / MTHCA_ICM_PAGE_SIZE);
                        mthca_free_icm(dev, table->icm[i], table->coherent);
                }

        kfree(table);

        return NULL;
}

void mthca_free_icm_table(struct mthca_dev *dev, struct mthca_icm_table *table)
{
        int i;

        for (i = 0; i < table->num_icm; ++i)
                if (table->icm[i]) {
                        mthca_UNMAP_ICM(dev,
                                        table->virt + i * MTHCA_TABLE_CHUNK_SIZE,
                                        MTHCA_TABLE_CHUNK_SIZE / MTHCA_ICM_PAGE_SIZE);
                        mthca_free_icm(dev, table->icm[i], table->coherent);
                }

        kfree(table);
}

static u64 mthca_uarc_virt(struct mthca_dev *dev, struct mthca_uar *uar, int page)
{
        return dev->uar_table.uarc_base +
                uar->index * dev->uar_table.uarc_size +
                page * MTHCA_ICM_PAGE_SIZE;
}

int mthca_map_user_db(struct mthca_dev *dev, struct mthca_uar *uar,
                      struct mthca_user_db_table *db_tab, int index, u64 uaddr)
{
        struct page *pages[1];
        int ret = 0;
        int i;

        if (!mthca_is_memfree(dev))
                return 0;

        if (index < 0 || index > dev->uar_table.uarc_size / 8)
                return -EINVAL;

        mutex_lock(&db_tab->mutex);

        i = index / MTHCA_DB_REC_PER_PAGE;

        if ((db_tab->page[i].refcount >= MTHCA_DB_REC_PER_PAGE)       ||
            (db_tab->page[i].uvirt && db_tab->page[i].uvirt != uaddr) ||
            (uaddr & 4095)) {
                ret = -EINVAL;
                goto out;
        }

        if (db_tab->page[i].refcount) {
                ++db_tab->page[i].refcount;
                goto out;
        }

        ret = get_user_pages_fast(uaddr & PAGE_MASK, 1, FOLL_WRITE, pages);
        if (ret < 0)
                goto out;

        sg_set_page(&db_tab->page[i].mem, pages[0], MTHCA_ICM_PAGE_SIZE,
                        uaddr & ~PAGE_MASK);

        ret = pci_map_sg(dev->pdev, &db_tab->page[i].mem, 1, PCI_DMA_TODEVICE);
        if (ret < 0) {
                put_page(pages[0]);
                goto out;
        }

        ret = mthca_MAP_ICM_page(dev, sg_dma_address(&db_tab->page[i].mem),
                                 mthca_uarc_virt(dev, uar, i));
        if (ret) {
                pci_unmap_sg(dev->pdev, &db_tab->page[i].mem, 1, PCI_DMA_TODEVICE);
                put_page(sg_page(&db_tab->page[i].mem));
                goto out;
        }

        db_tab->page[i].uvirt    = uaddr;
        db_tab->page[i].refcount = 1;

out:
        mutex_unlock(&db_tab->mutex);
        return ret;
}

void mthca_unmap_user_db(struct mthca_dev *dev, struct mthca_uar *uar,
                         struct mthca_user_db_table *db_tab, int index)
{
        if (!mthca_is_memfree(dev))
                return;

        /*
         * To make our bookkeeping simpler, we don't unmap DB
         * pages until we clean up the whole db table.
         */

        mutex_lock(&db_tab->mutex);

        --db_tab->page[index / MTHCA_DB_REC_PER_PAGE].refcount;

        mutex_unlock(&db_tab->mutex);
}

struct mthca_user_db_table *mthca_init_user_db_tab(struct mthca_dev *dev)
{
        struct mthca_user_db_table *db_tab;
        int npages;
        int i;

        if (!mthca_is_memfree(dev))
                return NULL;

        npages = dev->uar_table.uarc_size / MTHCA_ICM_PAGE_SIZE;
        db_tab = kmalloc(struct_size(db_tab, page, npages), GFP_KERNEL);
        if (!db_tab)
                return ERR_PTR(-ENOMEM);

        mutex_init(&db_tab->mutex);
        for (i = 0; i < npages; ++i) {
                db_tab->page[i].refcount = 0;
                db_tab->page[i].uvirt    = 0;
                sg_init_table(&db_tab->page[i].mem, 1);
        }

        return db_tab;
}

void mthca_cleanup_user_db_tab(struct mthca_dev *dev, struct mthca_uar *uar,
                               struct mthca_user_db_table *db_tab)
{
        int i;

        if (!mthca_is_memfree(dev))
                return;

        for (i = 0; i < dev->uar_table.uarc_size / MTHCA_ICM_PAGE_SIZE; ++i) {
                if (db_tab->page[i].uvirt) {
                        mthca_UNMAP_ICM(dev, mthca_uarc_virt(dev, uar, i), 1);
                        pci_unmap_sg(dev->pdev, &db_tab->page[i].mem, 1, PCI_DMA_TODEVICE);
                        put_page(sg_page(&db_tab->page[i].mem));
                }
        }

        kfree(db_tab);
}

int mthca_alloc_db(struct mthca_dev *dev, enum mthca_db_type type,
                   u32 qn, __be32 **db)
{
        int group;
        int start, end, dir;
        int i, j;
        struct mthca_db_page *page;
        int ret = 0;

        mutex_lock(&dev->db_tab->mutex);

        switch (type) {
        case MTHCA_DB_TYPE_CQ_ARM:
        case MTHCA_DB_TYPE_SQ:
                group = 0;
                start = 0;
                end   = dev->db_tab->max_group1;
                dir   = 1;
                break;

        case MTHCA_DB_TYPE_CQ_SET_CI:
        case MTHCA_DB_TYPE_RQ:
        case MTHCA_DB_TYPE_SRQ:
                group = 1;
                start = dev->db_tab->npages - 1;
                end   = dev->db_tab->min_group2;
                dir   = -1;
                break;

        default:
                ret = -EINVAL;
                goto out;
        }

        for (i = start; i != end; i += dir)
                if (dev->db_tab->page[i].db_rec &&
                    !bitmap_full(dev->db_tab->page[i].used,
                                 MTHCA_DB_REC_PER_PAGE)) {
                        page = dev->db_tab->page + i;
                        goto found;
                }

        for (i = start; i != end; i += dir)
                if (!dev->db_tab->page[i].db_rec) {
                        page = dev->db_tab->page + i;
                        goto alloc;
                }

        if (dev->db_tab->max_group1 >= dev->db_tab->min_group2 - 1) {
                ret = -ENOMEM;
                goto out;
        }

        if (group == 0)
                ++dev->db_tab->max_group1;
        else
                --dev->db_tab->min_group2;

        page = dev->db_tab->page + end;

alloc:
        page->db_rec = dma_zalloc_coherent(&dev->pdev->dev, MTHCA_ICM_PAGE_SIZE,
                                           &page->mapping, GFP_KERNEL);
        if (!page->db_rec) {
                ret = -ENOMEM;
                goto out;
        }

        ret = mthca_MAP_ICM_page(dev, page->mapping,
                                 mthca_uarc_virt(dev, &dev->driver_uar, i));
        if (ret) {
                dma_free_coherent(&dev->pdev->dev, MTHCA_ICM_PAGE_SIZE,
                                  page->db_rec, page->mapping);
                goto out;
        }

        bitmap_zero(page->used, MTHCA_DB_REC_PER_PAGE);

found:
        j = find_first_zero_bit(page->used, MTHCA_DB_REC_PER_PAGE);
        set_bit(j, page->used);

        if (group == 1)
                j = MTHCA_DB_REC_PER_PAGE - 1 - j;

        ret = i * MTHCA_DB_REC_PER_PAGE + j;

        page->db_rec[j] = cpu_to_be64((qn << 8) | (type << 5));

        *db = (__be32 *) &page->db_rec[j];

out:
        mutex_unlock(&dev->db_tab->mutex);

        return ret;
}

void mthca_free_db(struct mthca_dev *dev, int type, int db_index)
{
        int i, j;
        struct mthca_db_page *page;

        i = db_index / MTHCA_DB_REC_PER_PAGE;
        j = db_index % MTHCA_DB_REC_PER_PAGE;

        page = dev->db_tab->page + i;

        mutex_lock(&dev->db_tab->mutex);

        page->db_rec[j] = 0;
        if (i >= dev->db_tab->min_group2)
                j = MTHCA_DB_REC_PER_PAGE - 1 - j;
        clear_bit(j, page->used);

        if (bitmap_empty(page->used, MTHCA_DB_REC_PER_PAGE) &&
            i >= dev->db_tab->max_group1 - 1) {
                mthca_UNMAP_ICM(dev, mthca_uarc_virt(dev, &dev->driver_uar, i), 1);

                dma_free_coherent(&dev->pdev->dev, MTHCA_ICM_PAGE_SIZE,
                                  page->db_rec, page->mapping);
                page->db_rec = NULL;

                if (i == dev->db_tab->max_group1) {
                        --dev->db_tab->max_group1;
                        /* XXX may be able to unmap more pages now */
                }
                if (i == dev->db_tab->min_group2)
                        ++dev->db_tab->min_group2;
        }

        mutex_unlock(&dev->db_tab->mutex);
}

int mthca_init_db_tab(struct mthca_dev *dev)
{
        int i;

        if (!mthca_is_memfree(dev))
                return 0;

        dev->db_tab = kmalloc(sizeof *dev->db_tab, GFP_KERNEL);
        if (!dev->db_tab)
                return -ENOMEM;

        mutex_init(&dev->db_tab->mutex);

        dev->db_tab->npages     = dev->uar_table.uarc_size / MTHCA_ICM_PAGE_SIZE;
        dev->db_tab->max_group1 = 0;
        dev->db_tab->min_group2 = dev->db_tab->npages - 1;

        dev->db_tab->page = kmalloc_array(dev->db_tab->npages,
                                          sizeof(*dev->db_tab->page),
                                          GFP_KERNEL);
        if (!dev->db_tab->page) {
                kfree(dev->db_tab);
                return -ENOMEM;
        }

        for (i = 0; i < dev->db_tab->npages; ++i)
                dev->db_tab->page[i].db_rec = NULL;

        return 0;
}

void mthca_cleanup_db_tab(struct mthca_dev *dev)
{
        int i;

        if (!mthca_is_memfree(dev))
                return;

        /*
         * Because we don't always free our UARC pages when they
         * become empty to make mthca_free_db() simpler we need to
         * make a sweep through the doorbell pages and free any
         * leftover pages now.
         */
        for (i = 0; i < dev->db_tab->npages; ++i) {
                if (!dev->db_tab->page[i].db_rec)
                        continue;

                if (!bitmap_empty(dev->db_tab->page[i].used, MTHCA_DB_REC_PER_PAGE))
                        mthca_warn(dev, "Kernel UARC page %d not empty\n", i);

                mthca_UNMAP_ICM(dev, mthca_uarc_virt(dev, &dev->driver_uar, i), 1);

                dma_free_coherent(&dev->pdev->dev, MTHCA_ICM_PAGE_SIZE,
                                  dev->db_tab->page[i].db_rec,
                                  dev->db_tab->page[i].mapping);
        }

        kfree(dev->db_tab->page);
        kfree(dev->db_tab);
}