ocfs2: Add support for incrementing refcount in the tree.

[safe/jmp/linux-2.6] / fs / ocfs2 / refcounttree.c

/* -*- mode: c; c-basic-offset: 8; -*-
 * vim: noexpandtab sw=8 ts=8 sts=0:
 *
 * refcounttree.c
 *
 * Copyright (C) 2009 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 version 2 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 for more details.
 */

#include <linux/sort.h>
#define MLOG_MASK_PREFIX ML_REFCOUNT
#include <cluster/masklog.h>
#include "ocfs2.h"
#include "inode.h"
#include "alloc.h"
#include "suballoc.h"
#include "journal.h"
#include "uptodate.h"
#include "super.h"
#include "buffer_head_io.h"
#include "blockcheck.h"
#include "refcounttree.h"
#include "sysfile.h"
#include "dlmglue.h"
#include "extent_map.h"

static inline struct ocfs2_refcount_tree *
cache_info_to_refcount(struct ocfs2_caching_info *ci)
{
        return container_of(ci, struct ocfs2_refcount_tree, rf_ci);
}

static int ocfs2_validate_refcount_block(struct super_block *sb,
                                         struct buffer_head *bh)
{
        int rc;
        struct ocfs2_refcount_block *rb =
                (struct ocfs2_refcount_block *)bh->b_data;

        mlog(0, "Validating refcount block %llu\n",
             (unsigned long long)bh->b_blocknr);

        BUG_ON(!buffer_uptodate(bh));

        /*
         * If the ecc fails, we return the error but otherwise
         * leave the filesystem running.  We know any error is
         * local to this block.
         */
        rc = ocfs2_validate_meta_ecc(sb, bh->b_data, &rb->rf_check);
        if (rc) {
                mlog(ML_ERROR, "Checksum failed for refcount block %llu\n",
                     (unsigned long long)bh->b_blocknr);
                return rc;
        }


        if (!OCFS2_IS_VALID_REFCOUNT_BLOCK(rb)) {
                ocfs2_error(sb,
                            "Refcount block #%llu has bad signature %.*s",
                            (unsigned long long)bh->b_blocknr, 7,
                            rb->rf_signature);
                return -EINVAL;
        }

        if (le64_to_cpu(rb->rf_blkno) != bh->b_blocknr) {
                ocfs2_error(sb,
                            "Refcount block #%llu has an invalid rf_blkno "
                            "of %llu",
                            (unsigned long long)bh->b_blocknr,
                            (unsigned long long)le64_to_cpu(rb->rf_blkno));
                return -EINVAL;
        }

        if (le32_to_cpu(rb->rf_fs_generation) != OCFS2_SB(sb)->fs_generation) {
                ocfs2_error(sb,
                            "Refcount block #%llu has an invalid "
                            "rf_fs_generation of #%u",
                            (unsigned long long)bh->b_blocknr,
                            le32_to_cpu(rb->rf_fs_generation));
                return -EINVAL;
        }

        return 0;
}

static int ocfs2_read_refcount_block(struct ocfs2_caching_info *ci,
                                     u64 rb_blkno,
                                     struct buffer_head **bh)
{
        int rc;
        struct buffer_head *tmp = *bh;

        rc = ocfs2_read_block(ci, rb_blkno, &tmp,
                              ocfs2_validate_refcount_block);

        /* If ocfs2_read_block() got us a new bh, pass it up. */
        if (!rc && !*bh)
                *bh = tmp;

        return rc;
}

static u64 ocfs2_refcount_cache_owner(struct ocfs2_caching_info *ci)
{
        struct ocfs2_refcount_tree *rf = cache_info_to_refcount(ci);

        return rf->rf_blkno;
}

static struct super_block *
ocfs2_refcount_cache_get_super(struct ocfs2_caching_info *ci)
{
        struct ocfs2_refcount_tree *rf = cache_info_to_refcount(ci);

        return rf->rf_sb;
}

static void ocfs2_refcount_cache_lock(struct ocfs2_caching_info *ci)
{
        struct ocfs2_refcount_tree *rf = cache_info_to_refcount(ci);

        spin_lock(&rf->rf_lock);
}

static void ocfs2_refcount_cache_unlock(struct ocfs2_caching_info *ci)
{
        struct ocfs2_refcount_tree *rf = cache_info_to_refcount(ci);

        spin_unlock(&rf->rf_lock);
}

static void ocfs2_refcount_cache_io_lock(struct ocfs2_caching_info *ci)
{
        struct ocfs2_refcount_tree *rf = cache_info_to_refcount(ci);

        mutex_lock(&rf->rf_io_mutex);
}

static void ocfs2_refcount_cache_io_unlock(struct ocfs2_caching_info *ci)
{
        struct ocfs2_refcount_tree *rf = cache_info_to_refcount(ci);

        mutex_unlock(&rf->rf_io_mutex);
}

static const struct ocfs2_caching_operations ocfs2_refcount_caching_ops = {
        .co_owner               = ocfs2_refcount_cache_owner,
        .co_get_super           = ocfs2_refcount_cache_get_super,
        .co_cache_lock          = ocfs2_refcount_cache_lock,
        .co_cache_unlock        = ocfs2_refcount_cache_unlock,
        .co_io_lock             = ocfs2_refcount_cache_io_lock,
        .co_io_unlock           = ocfs2_refcount_cache_io_unlock,
};

static struct ocfs2_refcount_tree *
ocfs2_find_refcount_tree(struct ocfs2_super *osb, u64 blkno)
{
        struct rb_node *n = osb->osb_rf_lock_tree.rb_node;
        struct ocfs2_refcount_tree *tree = NULL;

        while (n) {
                tree = rb_entry(n, struct ocfs2_refcount_tree, rf_node);

                if (blkno < tree->rf_blkno)
                        n = n->rb_left;
                else if (blkno > tree->rf_blkno)
                        n = n->rb_right;
                else
                        return tree;
        }

        return NULL;
}

/* osb_lock is already locked. */
static void ocfs2_insert_refcount_tree(struct ocfs2_super *osb,
                                       struct ocfs2_refcount_tree *new)
{
        u64 rf_blkno = new->rf_blkno;
        struct rb_node *parent = NULL;
        struct rb_node **p = &osb->osb_rf_lock_tree.rb_node;
        struct ocfs2_refcount_tree *tmp;

        while (*p) {
                parent = *p;

                tmp = rb_entry(parent, struct ocfs2_refcount_tree,
                               rf_node);

                if (rf_blkno < tmp->rf_blkno)
                        p = &(*p)->rb_left;
                else if (rf_blkno > tmp->rf_blkno)
                        p = &(*p)->rb_right;
                else {
                        /* This should never happen! */
                        mlog(ML_ERROR, "Duplicate refcount block %llu found!\n",
                             (unsigned long long)rf_blkno);
                        BUG();
                }
        }

        rb_link_node(&new->rf_node, parent, p);
        rb_insert_color(&new->rf_node, &osb->osb_rf_lock_tree);
}

static void ocfs2_free_refcount_tree(struct ocfs2_refcount_tree *tree)
{
        ocfs2_metadata_cache_exit(&tree->rf_ci);
        ocfs2_simple_drop_lockres(OCFS2_SB(tree->rf_sb), &tree->rf_lockres);
        ocfs2_lock_res_free(&tree->rf_lockres);
        kfree(tree);
}

static inline void
ocfs2_erase_refcount_tree_from_list_no_lock(struct ocfs2_super *osb,
                                        struct ocfs2_refcount_tree *tree)
{
        rb_erase(&tree->rf_node, &osb->osb_rf_lock_tree);
        if (osb->osb_ref_tree_lru && osb->osb_ref_tree_lru == tree)
                osb->osb_ref_tree_lru = NULL;
}

static void ocfs2_erase_refcount_tree_from_list(struct ocfs2_super *osb,
                                        struct ocfs2_refcount_tree *tree)
{
        spin_lock(&osb->osb_lock);
        ocfs2_erase_refcount_tree_from_list_no_lock(osb, tree);
        spin_unlock(&osb->osb_lock);
}

void ocfs2_kref_remove_refcount_tree(struct kref *kref)
{
        struct ocfs2_refcount_tree *tree =
                container_of(kref, struct ocfs2_refcount_tree, rf_getcnt);

        ocfs2_free_refcount_tree(tree);
}

static inline void
ocfs2_refcount_tree_get(struct ocfs2_refcount_tree *tree)
{
        kref_get(&tree->rf_getcnt);
}

static inline void
ocfs2_refcount_tree_put(struct ocfs2_refcount_tree *tree)
{
        kref_put(&tree->rf_getcnt, ocfs2_kref_remove_refcount_tree);
}

static inline void ocfs2_init_refcount_tree_ci(struct ocfs2_refcount_tree *new,
                                               struct super_block *sb)
{
        ocfs2_metadata_cache_init(&new->rf_ci, &ocfs2_refcount_caching_ops);
        mutex_init(&new->rf_io_mutex);
        new->rf_sb = sb;
        spin_lock_init(&new->rf_lock);
}

static inline void ocfs2_init_refcount_tree_lock(struct ocfs2_super *osb,
                                        struct ocfs2_refcount_tree *new,
                                        u64 rf_blkno, u32 generation)
{
        init_rwsem(&new->rf_sem);
        ocfs2_refcount_lock_res_init(&new->rf_lockres, osb,
                                     rf_blkno, generation);
}

static struct ocfs2_refcount_tree*
ocfs2_allocate_refcount_tree(struct ocfs2_super *osb, u64 rf_blkno)
{
        struct ocfs2_refcount_tree *new;

        new = kzalloc(sizeof(struct ocfs2_refcount_tree), GFP_NOFS);
        if (!new)
                return NULL;

        new->rf_blkno = rf_blkno;
        kref_init(&new->rf_getcnt);
        ocfs2_init_refcount_tree_ci(new, osb->sb);

        return new;
}

static int ocfs2_get_refcount_tree(struct ocfs2_super *osb, u64 rf_blkno,
                                   struct ocfs2_refcount_tree **ret_tree)
{
        int ret = 0;
        struct ocfs2_refcount_tree *tree, *new = NULL;
        struct buffer_head *ref_root_bh = NULL;
        struct ocfs2_refcount_block *ref_rb;

        spin_lock(&osb->osb_lock);
        if (osb->osb_ref_tree_lru &&
            osb->osb_ref_tree_lru->rf_blkno == rf_blkno)
                tree = osb->osb_ref_tree_lru;
        else
                tree = ocfs2_find_refcount_tree(osb, rf_blkno);
        if (tree)
                goto out;

        spin_unlock(&osb->osb_lock);

        new = ocfs2_allocate_refcount_tree(osb, rf_blkno);
        if (!new) {
                ret = -ENOMEM;
                mlog_errno(ret);
                return ret;
        }
        /*
         * We need the generation to create the refcount tree lock and since
         * it isn't changed during the tree modification, we are safe here to
         * read without protection.
         * We also have to purge the cache after we create the lock since the
         * refcount block may have the stale data. It can only be trusted when
         * we hold the refcount lock.
         */
        ret = ocfs2_read_refcount_block(&new->rf_ci, rf_blkno, &ref_root_bh);
        if (ret) {
                mlog_errno(ret);
                ocfs2_metadata_cache_exit(&new->rf_ci);
                kfree(new);
                return ret;
        }

        ref_rb = (struct ocfs2_refcount_block *)ref_root_bh->b_data;
        new->rf_generation = le32_to_cpu(ref_rb->rf_generation);
        ocfs2_init_refcount_tree_lock(osb, new, rf_blkno,
                                      new->rf_generation);
        ocfs2_metadata_cache_purge(&new->rf_ci);

        spin_lock(&osb->osb_lock);
        tree = ocfs2_find_refcount_tree(osb, rf_blkno);
        if (tree)
                goto out;

        ocfs2_insert_refcount_tree(osb, new);

        tree = new;
        new = NULL;

out:
        *ret_tree = tree;

        osb->osb_ref_tree_lru = tree;

        spin_unlock(&osb->osb_lock);

        if (new)
                ocfs2_free_refcount_tree(new);

        brelse(ref_root_bh);
        return ret;
}

static int ocfs2_get_refcount_block(struct inode *inode, u64 *ref_blkno)
{
        int ret;
        struct buffer_head *di_bh = NULL;
        struct ocfs2_dinode *di;

        ret = ocfs2_read_inode_block(inode, &di_bh);
        if (ret) {
                mlog_errno(ret);
                goto out;
        }

        BUG_ON(!(OCFS2_I(inode)->ip_dyn_features & OCFS2_HAS_REFCOUNT_FL));

        di = (struct ocfs2_dinode *)di_bh->b_data;
        *ref_blkno = le64_to_cpu(di->i_refcount_loc);
        brelse(di_bh);
out:
        return ret;
}

static int __ocfs2_lock_refcount_tree(struct ocfs2_super *osb,
                                      struct ocfs2_refcount_tree *tree, int rw)
{
        int ret;

        ret = ocfs2_refcount_lock(tree, rw);
        if (ret) {
                mlog_errno(ret);
                goto out;
        }

        if (rw)
                down_write(&tree->rf_sem);
        else
                down_read(&tree->rf_sem);

out:
        return ret;
}

/*
 * Lock the refcount tree pointed by ref_blkno and return the tree.
 * In most case, we lock the tree and read the refcount block.
 * So read it here if the caller really needs it.
 *
 * If the tree has been re-created by other node, it will free the
 * old one and re-create it.
 */
int ocfs2_lock_refcount_tree(struct ocfs2_super *osb,
                             u64 ref_blkno, int rw,
                             struct ocfs2_refcount_tree **ret_tree,
                             struct buffer_head **ref_bh)
{
        int ret, delete_tree = 0;
        struct ocfs2_refcount_tree *tree = NULL;
        struct buffer_head *ref_root_bh = NULL;
        struct ocfs2_refcount_block *rb;

again:
        ret = ocfs2_get_refcount_tree(osb, ref_blkno, &tree);
        if (ret) {
                mlog_errno(ret);
                return ret;
        }

        ocfs2_refcount_tree_get(tree);

        ret = __ocfs2_lock_refcount_tree(osb, tree, rw);
        if (ret) {
                mlog_errno(ret);
                ocfs2_refcount_tree_put(tree);
                goto out;
        }

        ret = ocfs2_read_refcount_block(&tree->rf_ci, tree->rf_blkno,
                                        &ref_root_bh);
        if (ret) {
                mlog_errno(ret);
                ocfs2_unlock_refcount_tree(osb, tree, rw);
                ocfs2_refcount_tree_put(tree);
                goto out;
        }

        rb = (struct ocfs2_refcount_block *)ref_root_bh->b_data;
        /*
         * If the refcount block has been freed and re-created, we may need
         * to recreate the refcount tree also.
         *
         * Here we just remove the tree from the rb-tree, and the last
         * kref holder will unlock and delete this refcount_tree.
         * Then we goto "again" and ocfs2_get_refcount_tree will create
         * the new refcount tree for us.
         */
        if (tree->rf_generation != le32_to_cpu(rb->rf_generation)) {
                if (!tree->rf_removed) {
                        ocfs2_erase_refcount_tree_from_list(osb, tree);
                        tree->rf_removed = 1;
                        delete_tree = 1;
                }

                ocfs2_unlock_refcount_tree(osb, tree, rw);
                /*
                 * We get an extra reference when we create the refcount
                 * tree, so another put will destroy it.
                 */
                if (delete_tree)
                        ocfs2_refcount_tree_put(tree);
                brelse(ref_root_bh);
                ref_root_bh = NULL;
                goto again;
        }

        *ret_tree = tree;
        if (ref_bh) {
                *ref_bh = ref_root_bh;
                ref_root_bh = NULL;
        }
out:
        brelse(ref_root_bh);
        return ret;
}

int ocfs2_lock_refcount_tree_by_inode(struct inode *inode, int rw,
                                      struct ocfs2_refcount_tree **ret_tree,
                                      struct buffer_head **ref_bh)
{
        int ret;
        u64 ref_blkno;

        ret = ocfs2_get_refcount_block(inode, &ref_blkno);
        if (ret) {
                mlog_errno(ret);
                return ret;
        }

        return ocfs2_lock_refcount_tree(OCFS2_SB(inode->i_sb), ref_blkno,
                                        rw, ret_tree, ref_bh);
}

void ocfs2_unlock_refcount_tree(struct ocfs2_super *osb,
                                struct ocfs2_refcount_tree *tree, int rw)
{
        if (rw)
                up_write(&tree->rf_sem);
        else
                up_read(&tree->rf_sem);

        ocfs2_refcount_unlock(tree, rw);
        ocfs2_refcount_tree_put(tree);
}

void ocfs2_purge_refcount_trees(struct ocfs2_super *osb)
{
        struct rb_node *node;
        struct ocfs2_refcount_tree *tree;
        struct rb_root *root = &osb->osb_rf_lock_tree;

        while ((node = rb_last(root)) != NULL) {
                tree = rb_entry(node, struct ocfs2_refcount_tree, rf_node);

                mlog(0, "Purge tree %llu\n",
                     (unsigned long long) tree->rf_blkno);

                rb_erase(&tree->rf_node, root);
                ocfs2_free_refcount_tree(tree);
        }
}

/*
 * Create a refcount tree for an inode.
 * We take for granted that the inode is already locked.
 */
static int ocfs2_create_refcount_tree(struct inode *inode,
                                      struct buffer_head *di_bh)
{
        int ret;
        handle_t *handle = NULL;
        struct ocfs2_alloc_context *meta_ac = NULL;
        struct ocfs2_dinode *di = (struct ocfs2_dinode *)di_bh->b_data;
        struct ocfs2_inode_info *oi = OCFS2_I(inode);
        struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
        struct buffer_head *new_bh = NULL;
        struct ocfs2_refcount_block *rb;
        struct ocfs2_refcount_tree *new_tree = NULL, *tree = NULL;
        u16 suballoc_bit_start;
        u32 num_got;
        u64 first_blkno;

        BUG_ON(oi->ip_dyn_features & OCFS2_HAS_REFCOUNT_FL);

        mlog(0, "create tree for inode %lu\n", inode->i_ino);

        ret = ocfs2_reserve_new_metadata_blocks(osb, 1, &meta_ac);
        if (ret) {
                mlog_errno(ret);
                goto out;
        }

        handle = ocfs2_start_trans(osb, OCFS2_REFCOUNT_TREE_CREATE_CREDITS);
        if (IS_ERR(handle)) {
                ret = PTR_ERR(handle);
                mlog_errno(ret);
                goto out;
        }

        ret = ocfs2_journal_access_di(handle, INODE_CACHE(inode), di_bh,
                                      OCFS2_JOURNAL_ACCESS_WRITE);
        if (ret) {
                mlog_errno(ret);
                goto out_commit;
        }

        ret = ocfs2_claim_metadata(osb, handle, meta_ac, 1,
                                   &suballoc_bit_start, &num_got,
                                   &first_blkno);
        if (ret) {
                mlog_errno(ret);
                goto out_commit;
        }

        new_tree = ocfs2_allocate_refcount_tree(osb, first_blkno);
        if (!new_tree) {
                ret = -ENOMEM;
                mlog_errno(ret);
                goto out_commit;
        }

        new_bh = sb_getblk(inode->i_sb, first_blkno);
        ocfs2_set_new_buffer_uptodate(&new_tree->rf_ci, new_bh);

        ret = ocfs2_journal_access_rb(handle, &new_tree->rf_ci, new_bh,
                                      OCFS2_JOURNAL_ACCESS_CREATE);
        if (ret) {
                mlog_errno(ret);
                goto out_commit;
        }

        /* Initialize ocfs2_refcount_block. */
        rb = (struct ocfs2_refcount_block *)new_bh->b_data;
        memset(rb, 0, inode->i_sb->s_blocksize);
        strcpy((void *)rb, OCFS2_REFCOUNT_BLOCK_SIGNATURE);
        rb->rf_suballoc_slot = cpu_to_le16(osb->slot_num);
        rb->rf_suballoc_bit = cpu_to_le16(suballoc_bit_start);
        rb->rf_fs_generation = cpu_to_le32(osb->fs_generation);
        rb->rf_blkno = cpu_to_le64(first_blkno);
        rb->rf_count = cpu_to_le32(1);
        rb->rf_records.rl_count =
                        cpu_to_le16(ocfs2_refcount_recs_per_rb(osb->sb));
        spin_lock(&osb->osb_lock);
        rb->rf_generation = osb->s_next_generation++;
        spin_unlock(&osb->osb_lock);

        ocfs2_journal_dirty(handle, new_bh);

        spin_lock(&oi->ip_lock);
        oi->ip_dyn_features |= OCFS2_HAS_REFCOUNT_FL;
        di->i_dyn_features = cpu_to_le16(oi->ip_dyn_features);
        di->i_refcount_loc = cpu_to_le64(first_blkno);
        spin_unlock(&oi->ip_lock);

        mlog(0, "created tree for inode %lu, refblock %llu\n",
             inode->i_ino, (unsigned long long)first_blkno);

        ocfs2_journal_dirty(handle, di_bh);

        /*
         * We have to init the tree lock here since it will use
         * the generation number to create it.
         */
        new_tree->rf_generation = le32_to_cpu(rb->rf_generation);
        ocfs2_init_refcount_tree_lock(osb, new_tree, first_blkno,
                                      new_tree->rf_generation);

        spin_lock(&osb->osb_lock);
        tree = ocfs2_find_refcount_tree(osb, first_blkno);

        /*
         * We've just created a new refcount tree in this block.  If
         * we found a refcount tree on the ocfs2_super, it must be
         * one we just deleted.  We free the old tree before
         * inserting the new tree.
         */
        BUG_ON(tree && tree->rf_generation == new_tree->rf_generation);
        if (tree)
                ocfs2_erase_refcount_tree_from_list_no_lock(osb, tree);
        ocfs2_insert_refcount_tree(osb, new_tree);
        spin_unlock(&osb->osb_lock);
        new_tree = NULL;
        if (tree)
                ocfs2_refcount_tree_put(tree);

out_commit:
        ocfs2_commit_trans(osb, handle);

out:
        if (new_tree) {
                ocfs2_metadata_cache_exit(&new_tree->rf_ci);
                kfree(new_tree);
        }

        brelse(new_bh);
        if (meta_ac)
                ocfs2_free_alloc_context(meta_ac);

        return ret;
}

static int ocfs2_set_refcount_tree(struct inode *inode,
                                   struct buffer_head *di_bh,
                                   u64 refcount_loc)
{
        int ret;
        handle_t *handle = NULL;
        struct ocfs2_dinode *di = (struct ocfs2_dinode *)di_bh->b_data;
        struct ocfs2_inode_info *oi = OCFS2_I(inode);
        struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
        struct buffer_head *ref_root_bh = NULL;
        struct ocfs2_refcount_block *rb;
        struct ocfs2_refcount_tree *ref_tree;

        BUG_ON(oi->ip_dyn_features & OCFS2_HAS_REFCOUNT_FL);

        ret = ocfs2_lock_refcount_tree(osb, refcount_loc, 1,
                                       &ref_tree, &ref_root_bh);
        if (ret) {
                mlog_errno(ret);
                return ret;
        }

        handle = ocfs2_start_trans(osb, OCFS2_REFCOUNT_TREE_SET_CREDITS);
        if (IS_ERR(handle)) {
                ret = PTR_ERR(handle);
                mlog_errno(ret);
                goto out;
        }

        ret = ocfs2_journal_access_di(handle, INODE_CACHE(inode), di_bh,
                                      OCFS2_JOURNAL_ACCESS_WRITE);
        if (ret) {
                mlog_errno(ret);
                goto out_commit;
        }

        ret = ocfs2_journal_access_rb(handle, &ref_tree->rf_ci, ref_root_bh,
                                      OCFS2_JOURNAL_ACCESS_WRITE);
        if (ret) {
                mlog_errno(ret);
                goto out_commit;
        }

        rb = (struct ocfs2_refcount_block *)ref_root_bh->b_data;
        le32_add_cpu(&rb->rf_count, 1);

        ocfs2_journal_dirty(handle, ref_root_bh);

        spin_lock(&oi->ip_lock);
        oi->ip_dyn_features |= OCFS2_HAS_REFCOUNT_FL;
        di->i_dyn_features = cpu_to_le16(oi->ip_dyn_features);
        di->i_refcount_loc = cpu_to_le64(refcount_loc);
        spin_unlock(&oi->ip_lock);
        ocfs2_journal_dirty(handle, di_bh);

out_commit:
        ocfs2_commit_trans(osb, handle);
out:
        ocfs2_unlock_refcount_tree(osb, ref_tree, 1);
        brelse(ref_root_bh);

        return ret;
}

int ocfs2_remove_refcount_tree(struct inode *inode, struct buffer_head *di_bh)
{
        int ret, delete_tree = 0;
        handle_t *handle = NULL;
        struct ocfs2_dinode *di = (struct ocfs2_dinode *)di_bh->b_data;
        struct ocfs2_inode_info *oi = OCFS2_I(inode);
        struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
        struct ocfs2_refcount_block *rb;
        struct inode *alloc_inode = NULL;
        struct buffer_head *alloc_bh = NULL;
        struct buffer_head *blk_bh = NULL;
        struct ocfs2_refcount_tree *ref_tree;
        int credits = OCFS2_REFCOUNT_TREE_REMOVE_CREDITS;
        u64 blk = 0, bg_blkno = 0, ref_blkno = le64_to_cpu(di->i_refcount_loc);
        u16 bit = 0;

        if (!(oi->ip_dyn_features & OCFS2_HAS_REFCOUNT_FL))
                return 0;

        BUG_ON(!ref_blkno);
        ret = ocfs2_lock_refcount_tree(osb, ref_blkno, 1, &ref_tree, &blk_bh);
        if (ret) {
                mlog_errno(ret);
                return ret;
        }

        rb = (struct ocfs2_refcount_block *)blk_bh->b_data;

        /*
         * If we are the last user, we need to free the block.
         * So lock the allocator ahead.
         */
        if (le32_to_cpu(rb->rf_count) == 1) {
                blk = le64_to_cpu(rb->rf_blkno);
                bit = le16_to_cpu(rb->rf_suballoc_bit);
                bg_blkno = ocfs2_which_suballoc_group(blk, bit);

                alloc_inode = ocfs2_get_system_file_inode(osb,
                                        EXTENT_ALLOC_SYSTEM_INODE,
                                        le16_to_cpu(rb->rf_suballoc_slot));
                if (!alloc_inode) {
                        ret = -ENOMEM;
                        mlog_errno(ret);
                        goto out;
                }
                mutex_lock(&alloc_inode->i_mutex);

                ret = ocfs2_inode_lock(alloc_inode, &alloc_bh, 1);
                if (ret) {
                        mlog_errno(ret);
                        goto out_mutex;
                }

                credits += OCFS2_SUBALLOC_FREE;
        }

        handle = ocfs2_start_trans(osb, credits);
        if (IS_ERR(handle)) {
                ret = PTR_ERR(handle);
                mlog_errno(ret);
                goto out_unlock;
        }

        ret = ocfs2_journal_access_di(handle, INODE_CACHE(inode), di_bh,
                                      OCFS2_JOURNAL_ACCESS_WRITE);
        if (ret) {
                mlog_errno(ret);
                goto out_commit;
        }

        ret = ocfs2_journal_access_rb(handle, &ref_tree->rf_ci, blk_bh,
                                      OCFS2_JOURNAL_ACCESS_WRITE);
        if (ret) {
                mlog_errno(ret);
                goto out_commit;
        }

        spin_lock(&oi->ip_lock);
        oi->ip_dyn_features &= ~OCFS2_HAS_REFCOUNT_FL;
        di->i_dyn_features = cpu_to_le16(oi->ip_dyn_features);
        di->i_refcount_loc = 0;
        spin_unlock(&oi->ip_lock);
        ocfs2_journal_dirty(handle, di_bh);

        le32_add_cpu(&rb->rf_count , -1);
        ocfs2_journal_dirty(handle, blk_bh);

        if (!rb->rf_count) {
                delete_tree = 1;
                ocfs2_erase_refcount_tree_from_list(osb, ref_tree);
                ret = ocfs2_free_suballoc_bits(handle, alloc_inode,
                                               alloc_bh, bit, bg_blkno, 1);
                if (ret)
                        mlog_errno(ret);
        }

out_commit:
        ocfs2_commit_trans(osb, handle);
out_unlock:
        if (alloc_inode) {
                ocfs2_inode_unlock(alloc_inode, 1);
                brelse(alloc_bh);
        }
out_mutex:
        if (alloc_inode) {
                mutex_unlock(&alloc_inode->i_mutex);
                iput(alloc_inode);
        }
out:
        ocfs2_unlock_refcount_tree(osb, ref_tree, 1);
        if (delete_tree)
                ocfs2_refcount_tree_put(ref_tree);
        brelse(blk_bh);

        return ret;
}

static void ocfs2_find_refcount_rec_in_rl(struct ocfs2_caching_info *ci,
                                          struct buffer_head *ref_leaf_bh,
                                          u64 cpos, unsigned int len,
                                          struct ocfs2_refcount_rec *ret_rec,
                                          int *index)
{
        int i = 0;
        struct ocfs2_refcount_block *rb =
                (struct ocfs2_refcount_block *)ref_leaf_bh->b_data;
        struct ocfs2_refcount_rec *rec = NULL;

        for (; i < le16_to_cpu(rb->rf_records.rl_used); i++) {
                rec = &rb->rf_records.rl_recs[i];

                if (le64_to_cpu(rec->r_cpos) +
                    le32_to_cpu(rec->r_clusters) <= cpos)
                        continue;
                else if (le64_to_cpu(rec->r_cpos) > cpos)
                        break;

                /* ok, cpos fail in this rec. Just return. */
                if (ret_rec)
                        *ret_rec = *rec;
                goto out;
        }

        if (ret_rec) {
                /* We meet with a hole here, so fake the rec. */
                ret_rec->r_cpos = cpu_to_le64(cpos);
                ret_rec->r_refcount = 0;
                if (i < le16_to_cpu(rb->rf_records.rl_used) &&
                    le64_to_cpu(rec->r_cpos) < cpos + len)
                        ret_rec->r_clusters =
                                cpu_to_le32(le64_to_cpu(rec->r_cpos) - cpos);
                else
                        ret_rec->r_clusters = cpu_to_le32(len);
        }

out:
        *index = i;
}

/*
 * Given a cpos and len, try to find the refcount record which contains cpos.
 * 1. If cpos can be found in one refcount record, return the record.
 * 2. If cpos can't be found, return a fake record which start from cpos
 *    and end at a small value between cpos+len and start of the next record.
 *    This fake record has r_refcount = 0.
 */
static int ocfs2_get_refcount_rec(struct ocfs2_caching_info *ci,
                                  struct buffer_head *ref_root_bh,
                                  u64 cpos, unsigned int len,
                                  struct ocfs2_refcount_rec *ret_rec,
                                  int *index,
                                  struct buffer_head **ret_bh)
{
        int ret = 0, i, found;
        u32 low_cpos;
        struct ocfs2_extent_list *el;
        struct ocfs2_extent_rec *tmp, *rec = NULL;
        struct ocfs2_extent_block *eb;
        struct buffer_head *eb_bh = NULL, *ref_leaf_bh = NULL;
        struct super_block *sb = ocfs2_metadata_cache_get_super(ci);
        struct ocfs2_refcount_block *rb =
                        (struct ocfs2_refcount_block *)ref_root_bh->b_data;

        if (!(le32_to_cpu(rb->rf_flags) & OCFS2_REFCOUNT_TREE_FL)) {
                ocfs2_find_refcount_rec_in_rl(ci, ref_root_bh, cpos, len,
                                              ret_rec, index);
                *ret_bh = ref_root_bh;
                get_bh(ref_root_bh);
                return 0;
        }

        el = &rb->rf_list;
        low_cpos = cpos & OCFS2_32BIT_POS_MASK;

        if (el->l_tree_depth) {
                ret = ocfs2_find_leaf(ci, el, low_cpos, &eb_bh);
                if (ret) {
                        mlog_errno(ret);
                        goto out;
                }

                eb = (struct ocfs2_extent_block *) eb_bh->b_data;
                el = &eb->h_list;

                if (el->l_tree_depth) {
                        ocfs2_error(sb,
                        "refcount tree %llu has non zero tree "
                        "depth in leaf btree tree block %llu\n",
                        (unsigned long long)ocfs2_metadata_cache_owner(ci),
                        (unsigned long long)eb_bh->b_blocknr);
                        ret = -EROFS;
                        goto out;
                }
        }

        found = 0;
        for (i = le16_to_cpu(el->l_next_free_rec) - 1; i >= 0; i--) {
                rec = &el->l_recs[i];

                if (le32_to_cpu(rec->e_cpos) <= low_cpos) {
                        found = 1;
                        break;
                }
        }

        /* adjust len when we have ocfs2_extent_rec after it. */
        if (found && i < le16_to_cpu(el->l_next_free_rec) - 1) {
                tmp = &el->l_recs[i+1];

                if (le32_to_cpu(tmp->e_cpos) < cpos + len)
                        len = le32_to_cpu(tmp->e_cpos) - cpos;
        }

        ret = ocfs2_read_refcount_block(ci, le64_to_cpu(rec->e_blkno),
                                        &ref_leaf_bh);
        if (ret) {
                mlog_errno(ret);
                goto out;
        }

        ocfs2_find_refcount_rec_in_rl(ci, ref_leaf_bh, cpos, len,
                                      ret_rec, index);
        *ret_bh = ref_leaf_bh;
out:
        brelse(eb_bh);
        return ret;
}

enum ocfs2_ref_rec_contig {
        REF_CONTIG_NONE = 0,
        REF_CONTIG_LEFT,
        REF_CONTIG_RIGHT,
        REF_CONTIG_LEFTRIGHT,
};

static enum ocfs2_ref_rec_contig
        ocfs2_refcount_rec_adjacent(struct ocfs2_refcount_block *rb,
                                    int index)
{
        if ((rb->rf_records.rl_recs[index].r_refcount ==
            rb->rf_records.rl_recs[index + 1].r_refcount) &&
            (le64_to_cpu(rb->rf_records.rl_recs[index].r_cpos) +
            le32_to_cpu(rb->rf_records.rl_recs[index].r_clusters) ==
            le64_to_cpu(rb->rf_records.rl_recs[index + 1].r_cpos)))
                return REF_CONTIG_RIGHT;

        return REF_CONTIG_NONE;
}

static enum ocfs2_ref_rec_contig
        ocfs2_refcount_rec_contig(struct ocfs2_refcount_block *rb,
                                  int index)
{
        enum ocfs2_ref_rec_contig ret = REF_CONTIG_NONE;

        if (index < le16_to_cpu(rb->rf_records.rl_used) - 1)
                ret = ocfs2_refcount_rec_adjacent(rb, index);

        if (index > 0) {
                enum ocfs2_ref_rec_contig tmp;

                tmp = ocfs2_refcount_rec_adjacent(rb, index - 1);

                if (tmp == REF_CONTIG_RIGHT) {
                        if (ret == REF_CONTIG_RIGHT)
                                ret = REF_CONTIG_LEFTRIGHT;
                        else
                                ret = REF_CONTIG_LEFT;
                }
        }

        return ret;
}

static void ocfs2_rotate_refcount_rec_left(struct ocfs2_refcount_block *rb,
                                           int index)
{
        BUG_ON(rb->rf_records.rl_recs[index].r_refcount !=
               rb->rf_records.rl_recs[index+1].r_refcount);

        le32_add_cpu(&rb->rf_records.rl_recs[index].r_clusters,
                     le32_to_cpu(rb->rf_records.rl_recs[index+1].r_clusters));

        if (index < le16_to_cpu(rb->rf_records.rl_used) - 2)
                memmove(&rb->rf_records.rl_recs[index + 1],
                        &rb->rf_records.rl_recs[index + 2],
                        sizeof(struct ocfs2_refcount_rec) *
                        (le16_to_cpu(rb->rf_records.rl_used) - index - 2));

        memset(&rb->rf_records.rl_recs[le16_to_cpu(rb->rf_records.rl_used) - 1],
               0, sizeof(struct ocfs2_refcount_rec));
        le16_add_cpu(&rb->rf_records.rl_used, -1);
}

/*
 * Merge the refcount rec if we are contiguous with the adjacent recs.
 */
static void ocfs2_refcount_rec_merge(struct ocfs2_refcount_block *rb,
                                     int index)
{
        enum ocfs2_ref_rec_contig contig =
                                ocfs2_refcount_rec_contig(rb, index);

        if (contig == REF_CONTIG_NONE)
                return;

        if (contig == REF_CONTIG_LEFT || contig == REF_CONTIG_LEFTRIGHT) {
                BUG_ON(index == 0);
                index--;
        }

        ocfs2_rotate_refcount_rec_left(rb, index);

        if (contig == REF_CONTIG_LEFTRIGHT)
                ocfs2_rotate_refcount_rec_left(rb, index);
}

static int ocfs2_change_refcount_rec(handle_t *handle,
                                     struct ocfs2_caching_info *ci,
                                     struct buffer_head *ref_leaf_bh,
                                     int index, int change)
{
        int ret;
        struct ocfs2_refcount_block *rb =
                        (struct ocfs2_refcount_block *)ref_leaf_bh->b_data;
        struct ocfs2_refcount_rec *rec = &rb->rf_records.rl_recs[index];

        ret = ocfs2_journal_access_rb(handle, ci, ref_leaf_bh,
                                      OCFS2_JOURNAL_ACCESS_WRITE);
        if (ret) {
                mlog_errno(ret);
                goto out;
        }

        mlog(0, "change index %d, old count %u, change %d\n", index,
             le32_to_cpu(rec->r_refcount), change);
        le32_add_cpu(&rec->r_refcount, change);

        ocfs2_refcount_rec_merge(rb, index);

        ret = ocfs2_journal_dirty(handle, ref_leaf_bh);
        if (ret)
                mlog_errno(ret);
out:
        return ret;
}

static int ocfs2_expand_inline_ref_root(handle_t *handle,
                                        struct ocfs2_caching_info *ci,
                                        struct buffer_head *ref_root_bh,
                                        struct buffer_head **ref_leaf_bh,
                                        struct ocfs2_alloc_context *meta_ac)
{
        int ret;
        u16 suballoc_bit_start;
        u32 num_got;
        u64 blkno;
        struct super_block *sb = ocfs2_metadata_cache_get_super(ci);
        struct buffer_head *new_bh = NULL;
        struct ocfs2_refcount_block *new_rb;
        struct ocfs2_refcount_block *root_rb =
                        (struct ocfs2_refcount_block *)ref_root_bh->b_data;

        ret = ocfs2_journal_access_rb(handle, ci, ref_root_bh,
                                      OCFS2_JOURNAL_ACCESS_WRITE);
        if (ret) {
                mlog_errno(ret);
                goto out;
        }

        ret = ocfs2_claim_metadata(OCFS2_SB(sb), handle, meta_ac, 1,
                                   &suballoc_bit_start, &num_got,
                                   &blkno);
        if (ret) {
                mlog_errno(ret);
                goto out;
        }

        new_bh = sb_getblk(sb, blkno);
        if (new_bh == NULL) {
                ret = -EIO;
                mlog_errno(ret);
                goto out;
        }
        ocfs2_set_new_buffer_uptodate(ci, new_bh);

        ret = ocfs2_journal_access_rb(handle, ci, new_bh,
                                      OCFS2_JOURNAL_ACCESS_CREATE);
        if (ret) {
                mlog_errno(ret);
                goto out;
        }

        /*
         * Initialize ocfs2_refcount_block.
         * It should contain the same information as the old root.
         * so just memcpy it and change the corresponding field.
         */
        memcpy(new_bh->b_data, ref_root_bh->b_data, sb->s_blocksize);

        new_rb = (struct ocfs2_refcount_block *)new_bh->b_data;
        new_rb->rf_suballoc_slot = cpu_to_le16(OCFS2_SB(sb)->slot_num);
        new_rb->rf_suballoc_bit = cpu_to_le16(suballoc_bit_start);
        new_rb->rf_blkno = cpu_to_le64(blkno);
        new_rb->rf_cpos = cpu_to_le32(0);
        new_rb->rf_parent = cpu_to_le64(ref_root_bh->b_blocknr);
        new_rb->rf_flags = cpu_to_le32(OCFS2_REFCOUNT_LEAF_FL);
        ocfs2_journal_dirty(handle, new_bh);

        /* Now change the root. */
        memset(&root_rb->rf_list, 0, sb->s_blocksize -
               offsetof(struct ocfs2_refcount_block, rf_list));
        root_rb->rf_list.l_count = cpu_to_le16(ocfs2_extent_recs_per_rb(sb));
        root_rb->rf_clusters = cpu_to_le32(1);
        root_rb->rf_list.l_next_free_rec = cpu_to_le16(1);
        root_rb->rf_list.l_recs[0].e_blkno = cpu_to_le64(blkno);
        root_rb->rf_list.l_recs[0].e_leaf_clusters = cpu_to_le16(1);
        root_rb->rf_flags = cpu_to_le32(OCFS2_REFCOUNT_TREE_FL);

        ocfs2_journal_dirty(handle, ref_root_bh);

        mlog(0, "new leaf block %llu, used %u\n", (unsigned long long)blkno,
             le16_to_cpu(new_rb->rf_records.rl_used));

        *ref_leaf_bh = new_bh;
        new_bh = NULL;
out:
        brelse(new_bh);
        return ret;
}

static int ocfs2_refcount_rec_no_intersect(struct ocfs2_refcount_rec *prev,
                                           struct ocfs2_refcount_rec *next)
{
        if (ocfs2_get_ref_rec_low_cpos(prev) + le32_to_cpu(prev->r_clusters) <=
                ocfs2_get_ref_rec_low_cpos(next))
                return 1;

        return 0;
}

static int cmp_refcount_rec_by_low_cpos(const void *a, const void *b)
{
        const struct ocfs2_refcount_rec *l = a, *r = b;
        u32 l_cpos = ocfs2_get_ref_rec_low_cpos(l);
        u32 r_cpos = ocfs2_get_ref_rec_low_cpos(r);

        if (l_cpos > r_cpos)
                return 1;
        if (l_cpos < r_cpos)
                return -1;
        return 0;
}

static int cmp_refcount_rec_by_cpos(const void *a, const void *b)
{
        const struct ocfs2_refcount_rec *l = a, *r = b;
        u64 l_cpos = le64_to_cpu(l->r_cpos);
        u64 r_cpos = le64_to_cpu(r->r_cpos);

        if (l_cpos > r_cpos)
                return 1;
        if (l_cpos < r_cpos)
                return -1;
        return 0;
}

static void swap_refcount_rec(void *a, void *b, int size)
{
        struct ocfs2_refcount_rec *l = a, *r = b, tmp;

        tmp = *(struct ocfs2_refcount_rec *)l;
        *(struct ocfs2_refcount_rec *)l =
                        *(struct ocfs2_refcount_rec *)r;
        *(struct ocfs2_refcount_rec *)r = tmp;
}

/*
 * The refcount cpos are ordered by their 64bit cpos,
 * But we will use the low 32 bit to be the e_cpos in the b-tree.
 * So we need to make sure that this pos isn't intersected with others.
 *
 * Note: The refcount block is already sorted by their low 32 bit cpos,
 *       So just try the middle pos first, and we will exit when we find
 *       the good position.
 */
static int ocfs2_find_refcount_split_pos(struct ocfs2_refcount_list *rl,
                                         u32 *split_pos, int *split_index)
{
        int num_used = le16_to_cpu(rl->rl_used);
        int delta, middle = num_used / 2;

        for (delta = 0; delta < middle; delta++) {
                /* Let's check delta earlier than middle */
                if (ocfs2_refcount_rec_no_intersect(
                                        &rl->rl_recs[middle - delta - 1],
                                        &rl->rl_recs[middle - delta])) {
                        *split_index = middle - delta;
                        break;
                }

                /* For even counts, don't walk off the end */
                if ((middle + delta + 1) == num_used)
                        continue;

                /* Now try delta past middle */
                if (ocfs2_refcount_rec_no_intersect(
                                        &rl->rl_recs[middle + delta],
                                        &rl->rl_recs[middle + delta + 1])) {
                        *split_index = middle + delta + 1;
                        break;
                }
        }

        if (delta >= middle)
                return -ENOSPC;

        *split_pos = ocfs2_get_ref_rec_low_cpos(&rl->rl_recs[*split_index]);
        return 0;
}

static int ocfs2_divide_leaf_refcount_block(struct buffer_head *ref_leaf_bh,
                                            struct buffer_head *new_bh,
                                            u32 *split_cpos)
{
        int split_index = 0, num_moved, ret;
        u32 cpos = 0;
        struct ocfs2_refcount_block *rb =
                        (struct ocfs2_refcount_block *)ref_leaf_bh->b_data;
        struct ocfs2_refcount_list *rl = &rb->rf_records;
        struct ocfs2_refcount_block *new_rb =
                        (struct ocfs2_refcount_block *)new_bh->b_data;
        struct ocfs2_refcount_list *new_rl = &new_rb->rf_records;

        mlog(0, "split old leaf refcount block %llu, count = %u, used = %u\n",
             (unsigned long long)ref_leaf_bh->b_blocknr,
             le32_to_cpu(rl->rl_count), le32_to_cpu(rl->rl_used));

        /*
         * XXX: Improvement later.
         * If we know all the high 32 bit cpos is the same, no need to sort.
         *
         * In order to make the whole process safe, we do:
         * 1. sort the entries by their low 32 bit cpos first so that we can
         *    find the split cpos easily.
         * 2. call ocfs2_insert_extent to insert the new refcount block.
         * 3. move the refcount rec to the new block.
         * 4. sort the entries by their 64 bit cpos.
         * 5. dirty the new_rb and rb.
         */
        sort(&rl->rl_recs, le16_to_cpu(rl->rl_used),
             sizeof(struct ocfs2_refcount_rec),
             cmp_refcount_rec_by_low_cpos, swap_refcount_rec);

        ret = ocfs2_find_refcount_split_pos(rl, &cpos, &split_index);
        if (ret) {
                mlog_errno(ret);
                return ret;
        }

        new_rb->rf_cpos = cpu_to_le32(cpos);

        /* move refcount records starting from split_index to the new block. */
        num_moved = le16_to_cpu(rl->rl_used) - split_index;
        memcpy(new_rl->rl_recs, &rl->rl_recs[split_index],
               num_moved * sizeof(struct ocfs2_refcount_rec));

        /*ok, remove the entries we just moved over to the other block. */
        memset(&rl->rl_recs[split_index], 0,
               num_moved * sizeof(struct ocfs2_refcount_rec));

        /* change old and new rl_used accordingly. */
        le16_add_cpu(&rl->rl_used, -num_moved);
        new_rl->rl_used = cpu_to_le32(num_moved);

        sort(&rl->rl_recs, le16_to_cpu(rl->rl_used),
             sizeof(struct ocfs2_refcount_rec),
             cmp_refcount_rec_by_cpos, swap_refcount_rec);

        sort(&new_rl->rl_recs, le16_to_cpu(new_rl->rl_used),
             sizeof(struct ocfs2_refcount_rec),
             cmp_refcount_rec_by_cpos, swap_refcount_rec);

        *split_cpos = cpos;
        return 0;
}

static int ocfs2_new_leaf_refcount_block(handle_t *handle,
                                         struct ocfs2_caching_info *ci,
                                         struct buffer_head *ref_root_bh,
                                         struct buffer_head *ref_leaf_bh,
                                         struct ocfs2_alloc_context *meta_ac)
{
        int ret;
        u16 suballoc_bit_start;
        u32 num_got, new_cpos;
        u64 blkno;
        struct super_block *sb = ocfs2_metadata_cache_get_super(ci);
        struct ocfs2_refcount_block *root_rb =
                        (struct ocfs2_refcount_block *)ref_root_bh->b_data;
        struct buffer_head *new_bh = NULL;
        struct ocfs2_refcount_block *new_rb;
        struct ocfs2_extent_tree ref_et;

        BUG_ON(!(le32_to_cpu(root_rb->rf_flags) & OCFS2_REFCOUNT_TREE_FL));

        ret = ocfs2_journal_access_rb(handle, ci, ref_root_bh,
                                      OCFS2_JOURNAL_ACCESS_WRITE);
        if (ret) {
                mlog_errno(ret);
                goto out;
        }

        ret = ocfs2_journal_access_rb(handle, ci, ref_leaf_bh,
                                      OCFS2_JOURNAL_ACCESS_WRITE);
        if (ret) {
                mlog_errno(ret);
                goto out;
        }

        ret = ocfs2_claim_metadata(OCFS2_SB(sb), handle, meta_ac, 1,
                                   &suballoc_bit_start, &num_got,
                                   &blkno);
        if (ret) {
                mlog_errno(ret);
                goto out;
        }

        new_bh = sb_getblk(sb, blkno);
        if (new_bh == NULL) {
                ret = -EIO;
                mlog_errno(ret);
                goto out;
        }
        ocfs2_set_new_buffer_uptodate(ci, new_bh);

        ret = ocfs2_journal_access_rb(handle, ci, new_bh,
                                      OCFS2_JOURNAL_ACCESS_CREATE);
        if (ret) {
                mlog_errno(ret);
                goto out;
        }

        /* Initialize ocfs2_refcount_block. */
        new_rb = (struct ocfs2_refcount_block *)new_bh->b_data;
        memset(new_rb, 0, sb->s_blocksize);
        strcpy((void *)new_rb, OCFS2_REFCOUNT_BLOCK_SIGNATURE);
        new_rb->rf_suballoc_slot = cpu_to_le16(OCFS2_SB(sb)->slot_num);
        new_rb->rf_suballoc_bit = cpu_to_le16(suballoc_bit_start);
        new_rb->rf_fs_generation = cpu_to_le32(OCFS2_SB(sb)->fs_generation);
        new_rb->rf_blkno = cpu_to_le64(blkno);
        new_rb->rf_parent = cpu_to_le64(ref_root_bh->b_blocknr);
        new_rb->rf_flags = cpu_to_le32(OCFS2_REFCOUNT_LEAF_FL);
        new_rb->rf_records.rl_count =
                                cpu_to_le16(ocfs2_refcount_recs_per_rb(sb));
        new_rb->rf_generation = root_rb->rf_generation;

        ret = ocfs2_divide_leaf_refcount_block(ref_leaf_bh, new_bh, &new_cpos);
        if (ret) {
                mlog_errno(ret);
                goto out;
        }

        ocfs2_journal_dirty(handle, ref_leaf_bh);
        ocfs2_journal_dirty(handle, new_bh);

        ocfs2_init_refcount_extent_tree(&ref_et, ci, ref_root_bh);

        mlog(0, "insert new leaf block %llu at %u\n",
             (unsigned long long)new_bh->b_blocknr, new_cpos);

        /* Insert the new leaf block with the specific offset cpos. */
        ret = ocfs2_insert_extent(handle, &ref_et, new_cpos, new_bh->b_blocknr,
                                  1, 0, meta_ac);
        if (ret)
                mlog_errno(ret);

out:
        brelse(new_bh);
        return ret;
}

static int ocfs2_expand_refcount_tree(handle_t *handle,
                                      struct ocfs2_caching_info *ci,
                                      struct buffer_head *ref_root_bh,
                                      struct buffer_head *ref_leaf_bh,
                                      struct ocfs2_alloc_context *meta_ac)
{
        int ret;
        struct buffer_head *expand_bh = NULL;

        if (ref_root_bh == ref_leaf_bh) {
                /*
                 * the old root bh hasn't been expanded to a b-tree,
                 * so expand it first.
                 */
                ret = ocfs2_expand_inline_ref_root(handle, ci, ref_root_bh,
                                                   &expand_bh, meta_ac);
                if (ret) {
                        mlog_errno(ret);
                        goto out;
                }
        } else {
                expand_bh = ref_leaf_bh;
                get_bh(expand_bh);
        }


        /* Now add a new refcount block into the tree.*/
        ret = ocfs2_new_leaf_refcount_block(handle, ci, ref_root_bh,
                                            expand_bh, meta_ac);
        if (ret)
                mlog_errno(ret);
out:
        brelse(expand_bh);
        return ret;
}

/*
 * Adjust the extent rec in b-tree representing ref_leaf_bh.
 *
 * Only called when we have inserted a new refcount rec at index 0
 * which means ocfs2_extent_rec.e_cpos may need some change.
 */
static int ocfs2_adjust_refcount_rec(handle_t *handle,
                                     struct ocfs2_caching_info *ci,
                                     struct buffer_head *ref_root_bh,
                                     struct buffer_head *ref_leaf_bh,
                                     struct ocfs2_refcount_rec *rec)
{
        int ret = 0, i;
        u32 new_cpos, old_cpos;
        struct ocfs2_path *path = NULL;
        struct ocfs2_extent_tree et;
        struct ocfs2_refcount_block *rb =
                (struct ocfs2_refcount_block *)ref_root_bh->b_data;
        struct ocfs2_extent_list *el;

        if (!(le32_to_cpu(rb->rf_flags) & OCFS2_REFCOUNT_TREE_FL))
                goto out;

        rb = (struct ocfs2_refcount_block *)ref_leaf_bh->b_data;
        old_cpos = le32_to_cpu(rb->rf_cpos);
        new_cpos = le64_to_cpu(rec->r_cpos) & OCFS2_32BIT_POS_MASK;
        if (old_cpos <= new_cpos)
                goto out;

        ocfs2_init_refcount_extent_tree(&et, ci, ref_root_bh);

        path = ocfs2_new_path_from_et(&et);
        if (!path) {
                ret = -ENOMEM;
                mlog_errno(ret);
                goto out;
        }

        ret = ocfs2_find_path(ci, path, old_cpos);
        if (ret) {
                mlog_errno(ret);
                goto out;
        }

        /*
         * 2 more credits, one for the leaf refcount block, one for
         * the extent block contains the extent rec.
         */
        ret = ocfs2_extend_trans(handle, handle->h_buffer_credits + 2);
        if (ret < 0) {
                mlog_errno(ret);
                goto out;
        }

        ret = ocfs2_journal_access_rb(handle, ci, ref_leaf_bh,
                                      OCFS2_JOURNAL_ACCESS_WRITE);
        if (ret < 0) {
                mlog_errno(ret);
                goto out;
        }

        ret = ocfs2_journal_access_eb(handle, ci, path_leaf_bh(path),
                                      OCFS2_JOURNAL_ACCESS_WRITE);
        if (ret < 0) {
                mlog_errno(ret);
                goto out;
        }

        /* change the leaf extent block first. */
        el = path_leaf_el(path);

        for (i = 0; i < le16_to_cpu(el->l_next_free_rec); i++)
                if (le32_to_cpu(el->l_recs[i].e_cpos) == old_cpos)
                        break;

        BUG_ON(i == le16_to_cpu(el->l_next_free_rec));

        el->l_recs[i].e_cpos = cpu_to_le32(new_cpos);

        /* change the r_cpos in the leaf block. */
        rb->rf_cpos = cpu_to_le32(new_cpos);

        ocfs2_journal_dirty(handle, path_leaf_bh(path));
        ocfs2_journal_dirty(handle, ref_leaf_bh);

out:
        ocfs2_free_path(path);
        return ret;
}

static int ocfs2_insert_refcount_rec(handle_t *handle,
                                     struct ocfs2_caching_info *ci,
                                     struct buffer_head *ref_root_bh,
                                     struct buffer_head *ref_leaf_bh,
                                     struct ocfs2_refcount_rec *rec,
                                     int index,
                                     struct ocfs2_alloc_context *meta_ac)
{
        int ret;
        struct ocfs2_refcount_block *rb =
                        (struct ocfs2_refcount_block *)ref_leaf_bh->b_data;
        struct ocfs2_refcount_list *rf_list = &rb->rf_records;
        struct buffer_head *new_bh = NULL;

        BUG_ON(le32_to_cpu(rb->rf_flags) & OCFS2_REFCOUNT_TREE_FL);

        if (rf_list->rl_used == rf_list->rl_count) {
                u64 cpos = le64_to_cpu(rec->r_cpos);
                u32 len = le32_to_cpu(rec->r_clusters);

                ret = ocfs2_expand_refcount_tree(handle, ci, ref_root_bh,
                                                 ref_leaf_bh, meta_ac);
                if (ret) {
                        mlog_errno(ret);
                        goto out;
                }

                ret = ocfs2_get_refcount_rec(ci, ref_root_bh,
                                             cpos, len, NULL, &index,
                                             &new_bh);
                if (ret) {
                        mlog_errno(ret);
                        goto out;
                }

                ref_leaf_bh = new_bh;
                rb = (struct ocfs2_refcount_block *)ref_leaf_bh->b_data;
                rf_list = &rb->rf_records;
        }

        ret = ocfs2_journal_access_rb(handle, ci, ref_leaf_bh,
                                      OCFS2_JOURNAL_ACCESS_WRITE);
        if (ret) {
                mlog_errno(ret);
                goto out;
        }

        if (index < le16_to_cpu(rf_list->rl_used))
                memmove(&rf_list->rl_recs[index + 1],
                        &rf_list->rl_recs[index],
                        (le16_to_cpu(rf_list->rl_used) - index) *
                         sizeof(struct ocfs2_refcount_rec));

        mlog(0, "insert refcount record start %llu, len %u, count %u "
             "to leaf block %llu at index %d\n",
             (unsigned long long)le64_to_cpu(rec->r_cpos),
             le32_to_cpu(rec->r_clusters), le32_to_cpu(rec->r_refcount),
             (unsigned long long)ref_leaf_bh->b_blocknr, index);

        rf_list->rl_recs[index] = *rec;

        le16_add_cpu(&rf_list->rl_used, 1);

        ocfs2_refcount_rec_merge(rb, index);

        ret = ocfs2_journal_dirty(handle, ref_leaf_bh);
        if (ret) {
                mlog_errno(ret);
                goto out;
        }

        if (index == 0) {
                ret = ocfs2_adjust_refcount_rec(handle, ci,
                                                ref_root_bh,
                                                ref_leaf_bh, rec);
                if (ret)
                        mlog_errno(ret);
        }
out:
        brelse(new_bh);
        return ret;
}

/*
 * Split the refcount_rec indexed by "index" in ref_leaf_bh.
 * This is much simple than our b-tree code.
 * split_rec is the new refcount rec we want to insert.
 * If split_rec->r_refcount > 0, we are changing the refcount(in case we
 * increase refcount or decrease a refcount to non-zero).
 * If split_rec->r_refcount == 0, we are punching a hole in current refcount
 * rec( in case we decrease a refcount to zero).
 */
static int ocfs2_split_refcount_rec(handle_t *handle,
                                    struct ocfs2_caching_info *ci,
                                    struct buffer_head *ref_root_bh,
                                    struct buffer_head *ref_leaf_bh,
                                    struct ocfs2_refcount_rec *split_rec,
                                    int index,
                                    struct ocfs2_alloc_context *meta_ac,
                                    struct ocfs2_cached_dealloc_ctxt *dealloc)
{
        int ret, recs_need;
        u32 len;
        struct ocfs2_refcount_block *rb =
                        (struct ocfs2_refcount_block *)ref_leaf_bh->b_data;
        struct ocfs2_refcount_list *rf_list = &rb->rf_records;
        struct ocfs2_refcount_rec *orig_rec = &rf_list->rl_recs[index];
        struct ocfs2_refcount_rec *tail_rec = NULL;
        struct buffer_head *new_bh = NULL;

        BUG_ON(le32_to_cpu(rb->rf_flags) & OCFS2_REFCOUNT_TREE_FL);

        mlog(0, "original r_pos %llu, cluster %u, split %llu, cluster %u\n",
             le64_to_cpu(orig_rec->r_cpos), le32_to_cpu(orig_rec->r_clusters),
             le64_to_cpu(split_rec->r_cpos),
             le32_to_cpu(split_rec->r_clusters));

        /*
         * If we just need to split the header or tail clusters,
         * no more recs are needed, just split is OK.
         * Otherwise we at least need one new recs.
         */
        if (!split_rec->r_refcount &&
            (split_rec->r_cpos == orig_rec->r_cpos ||
             le64_to_cpu(split_rec->r_cpos) +
             le32_to_cpu(split_rec->r_clusters) ==
             le64_to_cpu(orig_rec->r_cpos) + le32_to_cpu(orig_rec->r_clusters)))
                recs_need = 0;
        else
                recs_need = 1;

        /*
         * We need one more rec if we split in the middle and the new rec have
         * some refcount in it.
         */
        if (split_rec->r_refcount &&
            (split_rec->r_cpos != orig_rec->r_cpos &&
             le64_to_cpu(split_rec->r_cpos) +
             le32_to_cpu(split_rec->r_clusters) !=
             le64_to_cpu(orig_rec->r_cpos) + le32_to_cpu(orig_rec->r_clusters)))
                recs_need++;

        /* If the leaf block don't have enough record, expand it. */
        if (le16_to_cpu(rf_list->rl_used) + recs_need > rf_list->rl_count) {
                struct ocfs2_refcount_rec tmp_rec;
                u64 cpos = le64_to_cpu(orig_rec->r_cpos);
                len = le32_to_cpu(orig_rec->r_clusters);
                ret = ocfs2_expand_refcount_tree(handle, ci, ref_root_bh,
                                                 ref_leaf_bh, meta_ac);
                if (ret) {
                        mlog_errno(ret);
                        goto out;
                }

                /*
                 * We have to re-get it since now cpos may be moved to
                 * another leaf block.
                 */
                ret = ocfs2_get_refcount_rec(ci, ref_root_bh,
                                             cpos, len, &tmp_rec, &index,
                                             &new_bh);
                if (ret) {
                        mlog_errno(ret);
                        goto out;
                }

                ref_leaf_bh = new_bh;
                rb = (struct ocfs2_refcount_block *)ref_leaf_bh->b_data;
                rf_list = &rb->rf_records;
                orig_rec = &rf_list->rl_recs[index];
        }

        ret = ocfs2_journal_access_rb(handle, ci, ref_leaf_bh,
                                      OCFS2_JOURNAL_ACCESS_WRITE);
        if (ret) {
                mlog_errno(ret);
                goto out;
        }

        /*
         * We have calculated out how many new records we need and store
         * in recs_need, so spare enough space first by moving the records
         * after "index" to the end.
         */
        if (index != le16_to_cpu(rf_list->rl_used) - 1)
                memmove(&rf_list->rl_recs[index + 1 + recs_need],
                        &rf_list->rl_recs[index + 1],
                        (le16_to_cpu(rf_list->rl_used) - index - 1) *
                         sizeof(struct ocfs2_refcount_rec));

        len = (le64_to_cpu(orig_rec->r_cpos) +
              le32_to_cpu(orig_rec->r_clusters)) -
              (le64_to_cpu(split_rec->r_cpos) +
              le32_to_cpu(split_rec->r_clusters));

        /*
         * If we have "len", the we will split in the tail and move it
         * to the end of the space we have just spared.
         */
        if (len) {
                tail_rec = &rf_list->rl_recs[index + recs_need];

                memcpy(tail_rec, orig_rec, sizeof(struct ocfs2_refcount_rec));
                le64_add_cpu(&tail_rec->r_cpos,
                             le32_to_cpu(tail_rec->r_clusters) - len);
                tail_rec->r_clusters = le32_to_cpu(len);
        }

        /*
         * If the split pos isn't the same as the original one, we need to
         * split in the head.
         *
         * Note: We have the chance that split_rec.r_refcount = 0,
         * recs_need = 0 and len > 0, which means we just cut the head from
         * the orig_rec and in that case we have done some modification in
         * orig_rec above, so the check for r_cpos is faked.
         */
        if (split_rec->r_cpos != orig_rec->r_cpos && tail_rec != orig_rec) {
                len = le64_to_cpu(split_rec->r_cpos) -
                      le64_to_cpu(orig_rec->r_cpos);
                orig_rec->r_clusters = cpu_to_le32(len);
                index++;
        }

        le16_add_cpu(&rf_list->rl_used, recs_need);

        if (split_rec->r_refcount) {
                rf_list->rl_recs[index] = *split_rec;
                mlog(0, "insert refcount record start %llu, len %u, count %u "
                     "to leaf block %llu at index %d\n",
                     (unsigned long long)le64_to_cpu(split_rec->r_cpos),
                     le32_to_cpu(split_rec->r_clusters),
                     le32_to_cpu(split_rec->r_refcount),
                     (unsigned long long)ref_leaf_bh->b_blocknr, index);

                ocfs2_refcount_rec_merge(rb, index);
        }

        ret = ocfs2_journal_dirty(handle, ref_leaf_bh);
        if (ret)
                mlog_errno(ret);

out:
        brelse(new_bh);
        return ret;
}

static int __ocfs2_increase_refcount(handle_t *handle,
                                     struct ocfs2_caching_info *ci,
                                     struct buffer_head *ref_root_bh,
                                     u64 cpos, u32 len,
                                     struct ocfs2_alloc_context *meta_ac,
                                     struct ocfs2_cached_dealloc_ctxt *dealloc)
{
        int ret = 0, index;
        struct buffer_head *ref_leaf_bh = NULL;
        struct ocfs2_refcount_rec rec;
        unsigned int set_len = 0;

        mlog(0, "Tree owner %llu, add refcount start %llu, len %u\n",
             (unsigned long long)ocfs2_metadata_cache_owner(ci),
             (unsigned long long)cpos, len);

        while (len) {
                ret = ocfs2_get_refcount_rec(ci, ref_root_bh,
                                             cpos, len, &rec, &index,
                                             &ref_leaf_bh);
                if (ret) {
                        mlog_errno(ret);
                        goto out;
                }

                set_len = le32_to_cpu(rec.r_clusters);

                /*
                 * Here we may meet with 3 situations:
                 *
                 * 1. If we find an already existing record, and the length
                 *    is the same, cool, we just need to increase the r_refcount
                 *    and it is OK.
                 * 2. If we find a hole, just insert it with r_refcount = 1.
                 * 3. If we are in the middle of one extent record, split
                 *    it.
                 */
                if (rec.r_refcount && le64_to_cpu(rec.r_cpos) == cpos &&
                    set_len <= len) {
                        mlog(0, "increase refcount rec, start %llu, len %u, "
                             "count %u\n", (unsigned long long)cpos, set_len,
                             le32_to_cpu(rec.r_refcount));
                        ret = ocfs2_change_refcount_rec(handle, ci,
                                                        ref_leaf_bh, index, 1);
                        if (ret) {
                                mlog_errno(ret);
                                goto out;
                        }
                } else if (!rec.r_refcount) {
                        rec.r_refcount = cpu_to_le32(1);

                        mlog(0, "insert refcount rec, start %llu, len %u\n",
                             (unsigned long long)le64_to_cpu(rec.r_cpos),
                             set_len);
                        ret = ocfs2_insert_refcount_rec(handle, ci, ref_root_bh,
                                                        ref_leaf_bh,
                                                        &rec, index, meta_ac);
                        if (ret) {
                                mlog_errno(ret);
                                goto out;
                        }
                } else  {
                        set_len = min((u64)(cpos + len),
                                      le64_to_cpu(rec.r_cpos) + set_len) - cpos;
                        rec.r_cpos = cpu_to_le64(cpos);
                        rec.r_clusters = cpu_to_le32(set_len);
                        le32_add_cpu(&rec.r_refcount, 1);

                        mlog(0, "split refcount rec, start %llu, "
                             "len %u, count %u\n",
                             (unsigned long long)le64_to_cpu(rec.r_cpos),
                             set_len, le32_to_cpu(rec.r_refcount));
                        ret = ocfs2_split_refcount_rec(handle, ci,
                                                       ref_root_bh, ref_leaf_bh,
                                                       &rec, index,
                                                       meta_ac, dealloc);
                        if (ret) {
                                mlog_errno(ret);
                                goto out;
                        }
                }

                cpos += set_len;
                len -= set_len;
                brelse(ref_leaf_bh);
                ref_leaf_bh = NULL;
        }

out:
        brelse(ref_leaf_bh);
        return ret;
}