/*
 * GPL HEADER START
 *
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 only,
 * as published by the Free Software Foundation.
 *
 * 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 version 2 for more details (a copy is included
 * in the LICENSE file that accompanied this code).
 *
 * You should have received a copy of the GNU General Public License
 * version 2 along with this program; If not, see
 * http://www.sun.com/software/products/lustre/docs/GPLv2.pdf
 *
 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
 * CA 95054 USA or visit www.sun.com if you need additional information or
 * have any questions.
 *
 * GPL HEADER END
 */
/*
 * Copyright (c) 2002, 2010, Oracle and/or its affiliates. All rights reserved.
 * Use is subject to license terms.
 *
 * Copyright (c) 2011, 2012, Intel Corporation.
 */
/*
 * This file is part of Lustre, http://www.lustre.org/
 * Lustre is a trademark of Sun Microsystems, Inc.
 *
 * lustre/lvfs/fsfilt_ext3.c
 *
 * Author: Andreas Dilger <adilger@clusterfs.com>
 */

#define DEBUG_SUBSYSTEM S_FILTER

#include <linux/init.h>
#include <linux/module.h>
#include <linux/fs.h>
#include <linux/slab.h>
#include <linux/pagemap.h>
#include <ldiskfs/ldiskfs_config.h>
#include <ext4/ext4.h>
#include <ext4/ext4_jbd2.h>
#include <linux/version.h>
#include <linux/bitops.h>
#include <linux/quota.h>

#include <linux/libcfs/libcfs.h>
#include <lustre_fsfilt.h>
#include <obd.h>
#include <linux/lustre_compat25.h>
#include <linux/lprocfs_status.h>

#include <ext4/ext4_extents.h>

#ifdef HAVE_EXT_PBLOCK /* Name changed to ext4_ext_pblock for kernel 2.6.35 */
#define ext3_ext_pblock(ex) ext_pblock((ex))
#endif

/* for kernels 2.6.18 and later */
#define FSFILT_SINGLEDATA_TRANS_BLOCKS(sb) EXT3_SINGLEDATA_TRANS_BLOCKS(sb)

#define fsfilt_ext3_ext_insert_extent(handle, inode, path, newext, flag) \
               ext3_ext_insert_extent(handle, inode, path, newext, flag)

#define ext3_mb_discard_inode_preallocations(inode) \
                 ext3_discard_preallocations(inode)

#define fsfilt_log_start_commit(journal, tid) jbd2_log_start_commit(journal, tid)
#define fsfilt_log_wait_commit(journal, tid) jbd2_log_wait_commit(journal, tid)

static struct kmem_cache *fcb_cache;

struct fsfilt_cb_data {
        struct ext4_journal_cb_entry cb_jcb; /* private data - MUST BE FIRST */
        fsfilt_cb_t cb_func;        /* MDS/OBD completion function */
        struct obd_device *cb_obd;      /* MDS/OBD completion device */
        __u64 cb_last_rcvd;          /* MDS/OST last committed operation */
        void *cb_data;            /* MDS/OST completion function data */
};

static char *fsfilt_ext3_get_label(struct super_block *sb)
{
        return EXT3_SB(sb)->s_es->s_volume_name;
}

/* kernel has ext4_blocks_for_truncate since linux-3.1.1 */
# include <ext4/truncate.h>

/*
 * We don't currently need any additional blocks for rmdir and
 * unlink transactions because we are storing the OST oa_id inside
 * the inode (which we will be changing anyways as part of this
 * transaction).
 */
static void *fsfilt_ext3_start(struct inode *inode, int op, void *desc_private,
                               int logs)
{
        /* For updates to the last received file */
        int nblocks = FSFILT_SINGLEDATA_TRANS_BLOCKS(inode->i_sb);
        journal_t *journal;
        void *handle;

        if (current->journal_info) {
                CDEBUG(D_INODE, "increasing refcount on %p\n",
                       current->journal_info);
                goto journal_start;
        }

        switch(op) {
        case FSFILT_OP_UNLINK:
                /* delete one file + create/update logs for each stripe */
                nblocks += EXT3_DELETE_TRANS_BLOCKS(inode->i_sb);
                nblocks += (EXT3_INDEX_EXTRA_TRANS_BLOCKS +
                            FSFILT_SINGLEDATA_TRANS_BLOCKS(inode->i_sb)) * logs;
                break;
        case FSFILT_OP_CANCEL_UNLINK:
                LASSERT(logs == 1);

                /* blocks for log header bitmap update OR
                 * blocks for catalog header bitmap update + unlink of logs +
                 * blocks for delete the inode (include blocks truncating). */
                nblocks = (LLOG_CHUNK_SIZE >> inode->i_blkbits) +
                          EXT3_DELETE_TRANS_BLOCKS(inode->i_sb) +
                          ext4_blocks_for_truncate(inode) + 3;
                break;
        default: CERROR("unknown transaction start op %d\n", op);
                LBUG();
        }

        LASSERT(current->journal_info == desc_private);
        journal = EXT3_SB(inode->i_sb)->s_journal;
        if (nblocks > journal->j_max_transaction_buffers) {
                CWARN("too many credits %d for op %ux%u using %d instead\n",
                       nblocks, op, logs, journal->j_max_transaction_buffers);
                nblocks = journal->j_max_transaction_buffers;
        }

 journal_start:
        LASSERTF(nblocks > 0, "can't start %d credit transaction\n", nblocks);
        handle = ext3_journal_start(inode, nblocks);

        if (!IS_ERR(handle))
                LASSERT(current->journal_info == handle);
        else
                CERROR("error starting handle for op %u (%u credits): rc %ld\n",
                       op, nblocks, PTR_ERR(handle));
        return handle;
}

static int fsfilt_ext3_commit(struct inode *inode, void *h, int force_sync)
{
        int rc;
        handle_t *handle = h;

        LASSERT(current->journal_info == handle);
        if (force_sync)
                handle->h_sync = 1; /* recovery likes this */

        rc = ext3_journal_stop(handle);

        return rc;
}

#ifndef EXT3_EXTENTS_FL
#define EXT3_EXTENTS_FL          0x00080000 /* Inode uses extents */
#endif

#ifndef EXT_ASSERT
#define EXT_ASSERT(cond)  BUG_ON(!(cond))
#endif

#define EXT_GENERATION(inode)      (EXT4_I(inode)->i_ext_generation)
#define ext3_ext_base              inode
#define ext3_ext_base2inode(inode)      (inode)
#define EXT_DEPTH(inode)                ext_depth(inode)
#define fsfilt_ext3_ext_walk_space(inode, block, num, cb, cbdata) \
                        ext3_ext_walk_space(inode, block, num, cb, cbdata);

struct bpointers {
        unsigned long *blocks;
        unsigned long start;
        int num;
        int init_num;
        int create;
};

static long ext3_ext_find_goal(struct inode *inode, struct ext3_ext_path *path,
                               unsigned long block, int *aflags)
{
        struct ext3_inode_info *ei = EXT3_I(inode);
        unsigned long bg_start;
        unsigned long colour;
        int depth;

        if (path) {
                struct ext3_extent *ex;
                depth = path->p_depth;

                /* try to predict block placement */
                if ((ex = path[depth].p_ext))
                        return ext4_ext_pblock(ex) + (block - le32_to_cpu(ex->ee_block));

                /* it looks index is empty
                 * try to find starting from index itself */
                if (path[depth].p_bh)
                        return path[depth].p_bh->b_blocknr;
        }

        /* OK. use inode's group */
        bg_start = (ei->i_block_group * EXT3_BLOCKS_PER_GROUP(inode->i_sb)) +
                le32_to_cpu(EXT3_SB(inode->i_sb)->s_es->s_first_data_block);
        colour = (current->pid % 16) *
                (EXT3_BLOCKS_PER_GROUP(inode->i_sb) / 16);
        return bg_start + colour + block;
}

#define ll_unmap_underlying_metadata(sb, blocknr) \
        unmap_underlying_metadata((sb)->s_bdev, blocknr)

#ifndef EXT3_MB_HINT_GROUP_ALLOC
static unsigned long new_blocks(handle_t *handle, struct ext3_ext_base *base,
                                struct ext3_ext_path *path, unsigned long block,
                                unsigned long *count, int *err)
{
        unsigned long pblock, goal;
        int aflags = 0;
        struct inode *inode = ext3_ext_base2inode(base);

        goal = ext3_ext_find_goal(inode, path, block, &aflags);
        aflags |= 2; /* block have been already reserved */
        pblock = ext3_mb_new_blocks(handle, inode, goal, count, aflags, err);
        return pblock;

}
#else
static unsigned long new_blocks(handle_t *handle, struct ext3_ext_base *base,
                                struct ext3_ext_path *path, unsigned long block,
                                unsigned long *count, int *err)
{
        struct inode *inode = ext3_ext_base2inode(base);
        struct ext3_allocation_request ar;
        unsigned long pblock;
        int aflags;

        /* find neighbour allocated blocks */
        ar.lleft = block;
        *err = ext3_ext_search_left(base, path, &ar.lleft, &ar.pleft);
        if (*err)
                return 0;
        ar.lright = block;
        *err = ext3_ext_search_right(base, path, &ar.lright, &ar.pright);
        if (*err)
                return 0;

        /* allocate new block */
        ar.goal = ext3_ext_find_goal(inode, path, block, &aflags);
        ar.inode = inode;
        ar.logical = block;
        ar.len = *count;
        ar.flags = EXT3_MB_HINT_DATA;
        pblock = ext3_mb_new_blocks(handle, &ar, err);
        *count = ar.len;
        return pblock;
}
#endif

static int ext3_ext_new_extent_cb(struct ext3_ext_base *base,
                                  struct ext3_ext_path *path,
                                  struct ext3_ext_cache *cex,
#ifdef HAVE_EXT_PREPARE_CB_EXTENT
                                   struct ext3_extent *ex,
#endif
                                  void *cbdata)
{
        struct bpointers *bp = cbdata;
        struct inode *inode = ext3_ext_base2inode(base);
        struct ext3_extent nex;
        unsigned long pblock;
        unsigned long tgen;
        int err, i;
        unsigned long count;
        handle_t *handle;

#ifdef EXT3_EXT_CACHE_EXTENT
        if (cex->ec_type == EXT3_EXT_CACHE_EXTENT)
#else
        if ((cex->ec_len != 0) && (cex->ec_start != 0))
#endif
                                                   {
                err = EXT_CONTINUE;
                goto map;
        }

        if (bp->create == 0) {
                i = 0;
                if (cex->ec_block < bp->start)
                        i = bp->start - cex->ec_block;
                if (i >= cex->ec_len)
                        CERROR("nothing to do?! i = %d, e_num = %u\n",
                                        i, cex->ec_len);
                for (; i < cex->ec_len && bp->num; i++) {
                        *(bp->blocks) = 0;
                        bp->blocks++;
                        bp->num--;
                        bp->start++;
                }

                return EXT_CONTINUE;
        }

        tgen = EXT_GENERATION(base);
        count = ext3_ext_calc_credits_for_insert(base, path);

        handle = ext3_journal_start(inode, count+EXT3_ALLOC_NEEDED+1);
        if (IS_ERR(handle)) {
                return PTR_ERR(handle);
        }

        if (tgen != EXT_GENERATION(base)) {
                /* the tree has changed. so path can be invalid at moment */
                ext3_journal_stop(handle);
                return EXT_REPEAT;
        }

        /* In 2.6.32 kernel, ext4_ext_walk_space()'s callback func is not
         * protected by i_data_sem as whole. so we patch it to store
         * generation to path and now verify the tree hasn't changed */
        down_write((&EXT4_I(inode)->i_data_sem));

        /* validate extent, make sure the extent tree does not changed */
        if (EXT_GENERATION(base) != path[0].p_generation) {
                /* cex is invalid, try again */
                up_write(&EXT4_I(inode)->i_data_sem);
                ext3_journal_stop(handle);
                return EXT_REPEAT;
        }

        count = cex->ec_len;
        pblock = new_blocks(handle, base, path, cex->ec_block, &count, &err);
        if (!pblock)
                goto out;
        EXT_ASSERT(count <= cex->ec_len);

        /* insert new extent */
        nex.ee_block = cpu_to_le32(cex->ec_block);
        ext3_ext_store_pblock(&nex, pblock);
        nex.ee_len = cpu_to_le16(count);
        err = fsfilt_ext3_ext_insert_extent(handle, base, path, &nex, 0);
        if (err) {
                /* free data blocks we just allocated */
                /* not a good idea to call discard here directly,
                 * but otherwise we'd need to call it every free() */
#ifdef EXT3_MB_HINT_GROUP_ALLOC
                ext3_mb_discard_inode_preallocations(inode);
#endif
#ifdef HAVE_EXT_FREE_BLOCK_WITH_BUFFER_HEAD /* Introduced in 2.6.32-rc7 */
                ext3_free_blocks(handle, inode, NULL, ext4_ext_pblock(&nex),
                                 cpu_to_le16(nex.ee_len), 0);
#else
                ext3_free_blocks(handle, inode, ext4_ext_pblock(&nex),
                                 cpu_to_le16(nex.ee_len), 0);
#endif
                goto out;
        }

        /*
         * Putting len of the actual extent we just inserted,
         * we are asking ext3_ext_walk_space() to continue
         * scaning after that block
         */
        cex->ec_len = le16_to_cpu(nex.ee_len);
        cex->ec_start = ext4_ext_pblock(&nex);
        BUG_ON(le16_to_cpu(nex.ee_len) == 0);
        BUG_ON(le32_to_cpu(nex.ee_block) != cex->ec_block);

out:
        up_write((&EXT4_I(inode)->i_data_sem));
        ext3_journal_stop(handle);
map:
        if (err >= 0) {
                /* map blocks */
                if (bp->num == 0) {
                        CERROR("hmm. why do we find this extent?\n");
                        CERROR("initial space: %lu:%u\n",
                                bp->start, bp->init_num);
#ifdef EXT3_EXT_CACHE_EXTENT
                        CERROR("current extent: %u/%u/%llu %d\n",
                                cex->ec_block, cex->ec_len,
                                (unsigned long long)cex->ec_start,
                                cex->ec_type);
#else
                        CERROR("current extent: %u/%u/%llu\n",
                                cex->ec_block, cex->ec_len,
                                (unsigned long long)cex->ec_start);
#endif
                }
                i = 0;
                if (cex->ec_block < bp->start)
                        i = bp->start - cex->ec_block;
                if (i >= cex->ec_len)
                        CERROR("nothing to do?! i = %d, e_num = %u\n",
                                        i, cex->ec_len);
                for (; i < cex->ec_len && bp->num; i++) {
                        *(bp->blocks) = cex->ec_start + i;
#ifdef EXT3_EXT_CACHE_EXTENT
                        if (cex->ec_type != EXT3_EXT_CACHE_EXTENT)
#else
                        if ((cex->ec_len == 0) || (cex->ec_start == 0))
#endif
                                                                        {
                                /* unmap any possible underlying metadata from
                                 * the block device mapping.  bug 6998. */
                                ll_unmap_underlying_metadata(inode->i_sb,
                                                             *(bp->blocks));
                        }
                        bp->blocks++;
                        bp->num--;
                        bp->start++;
                }
        }
        return err;
}

int fsfilt_map_nblocks(struct inode *inode, unsigned long block,
                       unsigned long num, unsigned long *blocks,
                       int create)
{
        struct ext3_ext_base *base = inode;
        struct bpointers bp;
        int err;

        CDEBUG(D_OTHER, "blocks %lu-%lu requested for inode %u\n",
               block, block + num - 1, (unsigned) inode->i_ino);

        bp.blocks = blocks;
        bp.start = block;
        bp.init_num = bp.num = num;
        bp.create = create;

        err = fsfilt_ext3_ext_walk_space(base, block, num,
                                         ext3_ext_new_extent_cb, &bp);
        ext3_ext_invalidate_cache(base);

        return err;
}

int fsfilt_ext3_map_ext_inode_pages(struct inode *inode, struct page **page,
                                    int pages, unsigned long *blocks,
                                    int create)
{
        int blocks_per_page = PAGE_CACHE_SIZE >> inode->i_blkbits;
        int rc = 0, i = 0;
        struct page *fp = NULL;
        int clen = 0;

        CDEBUG(D_OTHER, "inode %lu: map %d pages from %lu\n",
                inode->i_ino, pages, (*page)->index);

        /* pages are sorted already. so, we just have to find
         * contig. space and process them properly */
        while (i < pages) {
                if (fp == NULL) {
                        /* start new extent */
                        fp = *page++;
                        clen = 1;
                        i++;
                        continue;
                } else if (fp->index + clen == (*page)->index) {
                        /* continue the extent */
                        page++;
                        clen++;
                        i++;
                        continue;
                }

                /* process found extent */
                rc = fsfilt_map_nblocks(inode, fp->index * blocks_per_page,
                                        clen * blocks_per_page, blocks,
                                        create);
                if (rc)
                        GOTO(cleanup, rc);

                /* look for next extent */
                fp = NULL;
                blocks += blocks_per_page * clen;
        }

        if (fp)
                rc = fsfilt_map_nblocks(inode, fp->index * blocks_per_page,
                                        clen * blocks_per_page, blocks,
                                        create);
cleanup:
        return rc;
}

int fsfilt_ext3_map_bm_inode_pages(struct inode *inode, struct page **page,
                                   int pages, unsigned long *blocks,
                                   int create)
{
        int blocks_per_page = PAGE_CACHE_SIZE >> inode->i_blkbits;
        unsigned long *b;
        int rc = 0, i;

        for (i = 0, b = blocks; i < pages; i++, page++) {
                rc = ext3_map_inode_page(inode, *page, b, create);
                if (rc) {
                        CERROR("ino %lu, blk %lu create %d: rc %d\n",
                               inode->i_ino, *b, create, rc);
                        break;
                }

                b += blocks_per_page;
        }
        return rc;
}

int fsfilt_ext3_map_inode_pages(struct inode *inode, struct page **page,
                                int pages, unsigned long *blocks,
                                int create, struct mutex *optional_mutex)
{
        int rc;

        if (EXT3_I(inode)->i_flags & EXT3_EXTENTS_FL) {
                rc = fsfilt_ext3_map_ext_inode_pages(inode, page, pages,
                                                     blocks, create);
                return rc;
        }
        if (optional_mutex != NULL)
                mutex_lock(optional_mutex);
        rc = fsfilt_ext3_map_bm_inode_pages(inode, page, pages, blocks, create);
        if (optional_mutex != NULL)
                mutex_unlock(optional_mutex);

        return rc;
}

int fsfilt_ext3_read(struct inode *inode, void *buf, int size, loff_t *offs)
{
        unsigned long block;
        struct buffer_head *bh;
        int err, blocksize, csize, boffs, osize = size;

        /* prevent reading after eof */
        spin_lock(&inode->i_lock);
        if (i_size_read(inode) < *offs + size) {
                size = i_size_read(inode) - *offs;
                spin_unlock(&inode->i_lock);
                if (size < 0) {
                        CDEBUG(D_EXT2, "size %llu is too short for read @%llu\n",
                               i_size_read(inode), *offs);
                        return -EBADR;
                } else if (size == 0) {
                        return 0;
                }
        } else {
                spin_unlock(&inode->i_lock);
        }

        blocksize = 1 << inode->i_blkbits;

        while (size > 0) {
                block = *offs >> inode->i_blkbits;
                boffs = *offs & (blocksize - 1);
                csize = min(blocksize - boffs, size);
                bh = ext3_bread(NULL, inode, block, 0, &err);
                if (!bh) {
                        CERROR("can't read block: %d\n", err);
                        return err;
                }

                memcpy(buf, bh->b_data + boffs, csize);
                brelse(bh);

                *offs += csize;
                buf += csize;
                size -= csize;
        }
        return osize;
}
EXPORT_SYMBOL(fsfilt_ext3_read);

static int fsfilt_ext3_read_record(struct file * file, void *buf,
                                   int size, loff_t *offs)
{
        int rc;
        rc = fsfilt_ext3_read(file->f_dentry->d_inode, buf, size, offs);
        if (rc > 0)
                rc = 0;
        return rc;
}

int fsfilt_ext3_write_handle(struct inode *inode, void *buf, int bufsize,
                                loff_t *offs, handle_t *handle)
{
        struct buffer_head *bh = NULL;
        loff_t old_size = i_size_read(inode), offset = *offs;
        loff_t new_size = i_size_read(inode);
        unsigned long block;
        int err = 0, blocksize = 1 << inode->i_blkbits, size, boffs;

        while (bufsize > 0) {
                if (bh != NULL)
                        brelse(bh);

                block = offset >> inode->i_blkbits;
                boffs = offset & (blocksize - 1);
                size = min(blocksize - boffs, bufsize);
                bh = ext3_bread(handle, inode, block, 1, &err);
                if (!bh) {
                        CERROR("can't read/create block: %d\n", err);
                        break;
                }

                err = ext3_journal_get_write_access(handle, bh);
                if (err) {
                        CERROR("journal_get_write_access() returned error %d\n",
                               err);
                        break;
                }
                LASSERT(bh->b_data + boffs + size <= bh->b_data + bh->b_size);
                memcpy(bh->b_data + boffs, buf, size);
                err = ext3_journal_dirty_metadata(handle, bh);
                if (err) {
                        CERROR("journal_dirty_metadata() returned error %d\n",
                               err);
                        break;
                }
                if (offset + size > new_size)
                        new_size = offset + size;
                offset += size;
                bufsize -= size;
                buf += size;
        }
        if (bh)
                brelse(bh);

        /* correct in-core and on-disk sizes */
        if (new_size > i_size_read(inode)) {
                spin_lock(&inode->i_lock);
                if (new_size > i_size_read(inode))
                        i_size_write(inode, new_size);
                if (i_size_read(inode) > EXT3_I(inode)->i_disksize)
                        EXT3_I(inode)->i_disksize = i_size_read(inode);
                if (i_size_read(inode) > old_size) {
                        spin_unlock(&inode->i_lock);
                        mark_inode_dirty(inode);
                } else {
                        spin_unlock(&inode->i_lock);
                }
        }

        if (err == 0)
                *offs = offset;
        return err;
}
EXPORT_SYMBOL(fsfilt_ext3_write_handle);

static int fsfilt_ext3_write_record(struct file *file, void *buf, int bufsize,
                                    loff_t *offs, int force_sync)
{
        struct inode *inode = file->f_dentry->d_inode;
        handle_t *handle;
        int err, block_count = 0, blocksize;

        /* Determine how many transaction credits are needed */
        blocksize = 1 << inode->i_blkbits;
        block_count = (*offs & (blocksize - 1)) + bufsize;
        block_count = (block_count + blocksize - 1) >> inode->i_blkbits;

        handle = ext3_journal_start(inode,
                        block_count * EXT3_DATA_TRANS_BLOCKS(inode->i_sb) + 2);
        if (IS_ERR(handle)) {
                CERROR("can't start transaction for %d blocks (%d bytes)\n",
                       block_count * EXT3_DATA_TRANS_BLOCKS(inode->i_sb) + 2,
                       bufsize);
                return PTR_ERR(handle);
        }

        err = fsfilt_ext3_write_handle(inode, buf, bufsize, offs, handle);

        if (!err && force_sync)
                handle->h_sync = 1; /* recovery likes this */

        ext3_journal_stop(handle);

        return err;
}

static int fsfilt_ext3_setup(struct super_block *sb)
{
        if (!EXT3_HAS_COMPAT_FEATURE(sb,
                                EXT3_FEATURE_COMPAT_HAS_JOURNAL)) {
                CERROR("ext3 mounted without journal\n");
                return -EINVAL;
        }

#ifdef S_PDIROPS
        CWARN("Enabling PDIROPS\n");
        set_opt(EXT3_SB(sb)->s_mount_opt, PDIROPS);
        sb->s_flags |= S_PDIROPS;
#endif
        if (!EXT3_HAS_COMPAT_FEATURE(sb, EXT3_FEATURE_COMPAT_DIR_INDEX))
                CWARN("filesystem doesn't have dir_index feature enabled\n");
        return 0;
}
static struct fsfilt_operations fsfilt_ext3_ops = {
        .fs_type                = "ext3",
        .fs_owner              = THIS_MODULE,
        .fs_getlabel        = fsfilt_ext3_get_label,
        .fs_start              = fsfilt_ext3_start,
        .fs_commit            = fsfilt_ext3_commit,
        .fs_map_inode_pages     = fsfilt_ext3_map_inode_pages,
        .fs_write_record        = fsfilt_ext3_write_record,
        .fs_read_record  = fsfilt_ext3_read_record,
        .fs_setup              = fsfilt_ext3_setup,
};

static int __init fsfilt_ext3_init(void)
{
        int rc;

        fcb_cache = kmem_cache_create("fsfilt_ext3_fcb",
                                         sizeof(struct fsfilt_cb_data), 0, 0);
        if (!fcb_cache) {
                CERROR("error allocating fsfilt journal callback cache\n");
                GOTO(out, rc = -ENOMEM);
        }

        rc = fsfilt_register_ops(&fsfilt_ext3_ops);

        if (rc) {
                int err = kmem_cache_destroy(fcb_cache);
                LASSERTF(err == 0, "error destroying new cache: rc %d\n", err);
        }
out:
        return rc;
}

static void __exit fsfilt_ext3_exit(void)
{
        int rc;

        fsfilt_unregister_ops(&fsfilt_ext3_ops);
        rc = kmem_cache_destroy(fcb_cache);
        LASSERTF(rc == 0, "couldn't destroy fcb_cache slab\n");
}

module_init(fsfilt_ext3_init);
module_exit(fsfilt_ext3_exit);

MODULE_AUTHOR("Sun Microsystems, Inc. <http://www.lustre.org/>");
MODULE_DESCRIPTION("Lustre ext3 Filesystem Helper v0.1");
MODULE_LICENSE("GPL");