delayed-inode.c

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/*
 * Copyright (C) 2011 Fujitsu.  All rights reserved.
 * Written by Miao Xie <[email protected]>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public
 * License v2 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.
 *
 * You should have received a copy of the GNU General Public
 * License along with this program; if not, write to the
 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 * Boston, MA 021110-1307, USA.
 */

#include <linux/slab.h>
#include "delayed-inode.h"
#include "disk-io.h"
#include "transaction.h"

#define BTRFS_DELAYED_WRITEBACK     400
#define BTRFS_DELAYED_BACKGROUND    100

static struct kmem_cache *delayed_node_cache;

int __init btrfs_delayed_inode_init(void)
{
    delayed_node_cache = kmem_cache_create("btrfs_delayed_node",
                    sizeof(struct btrfs_delayed_node),
                    0,
                    SLAB_RECLAIM_ACCOUNT | SLAB_MEM_SPREAD,
                    NULL);
    if (!delayed_node_cache)
        return -ENOMEM;
    return 0;
}

void btrfs_delayed_inode_exit(void)
{
    if (delayed_node_cache)
        kmem_cache_destroy(delayed_node_cache);
}

static inline void btrfs_init_delayed_node(
                struct btrfs_delayed_node *delayed_node,
                struct btrfs_root *root, u64 inode_id)
{
    delayed_node->root = root;
    delayed_node->inode_id = inode_id;
    atomic_set(&delayed_node->refs, 0);
    delayed_node->count = 0;
    delayed_node->in_list = 0;
    delayed_node->inode_dirty = 0;
    delayed_node->ins_root = RB_ROOT;
    delayed_node->del_root = RB_ROOT;
    mutex_init(&delayed_node->mutex);
    delayed_node->index_cnt = 0;
    INIT_LIST_HEAD(&delayed_node->n_list);
    INIT_LIST_HEAD(&delayed_node->p_list);
    delayed_node->bytes_reserved = 0;
    memset(&delayed_node->inode_item, 0, sizeof(delayed_node->inode_item));
}

static inline int btrfs_is_continuous_delayed_item(
                    struct btrfs_delayed_item *item1,
                    struct btrfs_delayed_item *item2)
{
    if (item1->key.type == BTRFS_DIR_INDEX_KEY &&
        item1->key.objectid == item2->key.objectid &&
        item1->key.type == item2->key.type &&
        item1->key.offset + 1 == item2->key.offset)
        return 1;
    return 0;
}

static inline struct btrfs_delayed_root *btrfs_get_delayed_root(
                            struct btrfs_root *root)
{
    return root->fs_info->delayed_root;
}

static struct btrfs_delayed_node *btrfs_get_delayed_node(struct inode *inode)
{
    struct btrfs_inode *btrfs_inode = BTRFS_I(inode);
    struct btrfs_root *root = btrfs_inode->root;
    u64 ino = btrfs_ino(inode);
    struct btrfs_delayed_node *node;

    node = ACCESS_ONCE(btrfs_inode->delayed_node);
    if (node) {
        atomic_inc(&node->refs);
        return node;
    }

    spin_lock(&root->inode_lock);
    node = radix_tree_lookup(&root->delayed_nodes_tree, ino);
    if (node) {
        if (btrfs_inode->delayed_node) {
            atomic_inc(&node->refs);    /* can be accessed */
            BUG_ON(btrfs_inode->delayed_node != node);
            spin_unlock(&root->inode_lock);
            return node;
        }
        btrfs_inode->delayed_node = node;
        atomic_inc(&node->refs);    /* can be accessed */
        atomic_inc(&node->refs);    /* cached in the inode */
        spin_unlock(&root->inode_lock);
        return node;
    }
    spin_unlock(&root->inode_lock);

    return NULL;
}

/* Will return either the node or PTR_ERR(-ENOMEM) */
static struct btrfs_delayed_node *btrfs_get_or_create_delayed_node(
                            struct inode *inode)
{
    struct btrfs_delayed_node *node;
    struct btrfs_inode *btrfs_inode = BTRFS_I(inode);
    struct btrfs_root *root = btrfs_inode->root;
    u64 ino = btrfs_ino(inode);
    int ret;

again:
    node = btrfs_get_delayed_node(inode);
    if (node)
        return node;

    node = kmem_cache_alloc(delayed_node_cache, GFP_NOFS);
    if (!node)
        return ERR_PTR(-ENOMEM);
    btrfs_init_delayed_node(node, root, ino);

    atomic_inc(&node->refs);    /* cached in the btrfs inode */
    atomic_inc(&node->refs);    /* can be accessed */

    ret = radix_tree_preload(GFP_NOFS & ~__GFP_HIGHMEM);
    if (ret) {
        kmem_cache_free(delayed_node_cache, node);
        return ERR_PTR(ret);
    }

    spin_lock(&root->inode_lock);
    ret = radix_tree_insert(&root->delayed_nodes_tree, ino, node);
    if (ret == -EEXIST) {
        kmem_cache_free(delayed_node_cache, node);
        spin_unlock(&root->inode_lock);
        radix_tree_preload_end();
        goto again;
    }
    btrfs_inode->delayed_node = node;
    spin_unlock(&root->inode_lock);
    radix_tree_preload_end();

    return node;
}

/*
 * Call it when holding delayed_node->mutex
 *
 * If mod = 1, add this node into the prepared list.
 */
static void btrfs_queue_delayed_node(struct btrfs_delayed_root *root,
                     struct btrfs_delayed_node *node,
                     int mod)
{
    spin_lock(&root->lock);
    if (node->in_list) {
        if (!list_empty(&node->p_list))
            list_move_tail(&node->p_list, &root->prepare_list);
        else if (mod)
            list_add_tail(&node->p_list, &root->prepare_list);
    } else {
        list_add_tail(&node->n_list, &root->node_list);
        list_add_tail(&node->p_list, &root->prepare_list);
        atomic_inc(&node->refs);    /* inserted into list */
        root->nodes++;
        node->in_list = 1;
    }
    spin_unlock(&root->lock);
}

/* Call it when holding delayed_node->mutex */
static void btrfs_dequeue_delayed_node(struct btrfs_delayed_root *root,
                       struct btrfs_delayed_node *node)
{
    spin_lock(&root->lock);
    if (node->in_list) {
        root->nodes--;
        atomic_dec(&node->refs);    /* not in the list */
        list_del_init(&node->n_list);
        if (!list_empty(&node->p_list))
            list_del_init(&node->p_list);
        node->in_list = 0;
    }
    spin_unlock(&root->lock);
}

struct btrfs_delayed_node *btrfs_first_delayed_node(
            struct btrfs_delayed_root *delayed_root)
{
    struct list_head *p;
    struct btrfs_delayed_node *node = NULL;

    spin_lock(&delayed_root->lock);
    if (list_empty(&delayed_root->node_list))
        goto out;

    p = delayed_root->node_list.next;
    node = list_entry(p, struct btrfs_delayed_node, n_list);
    atomic_inc(&node->refs);
out:
    spin_unlock(&delayed_root->lock);

    return node;
}

struct btrfs_delayed_node *btrfs_next_delayed_node(
                        struct btrfs_delayed_node *node)
{
    struct btrfs_delayed_root *delayed_root;
    struct list_head *p;
    struct btrfs_delayed_node *next = NULL;

    delayed_root = node->root->fs_info->delayed_root;
    spin_lock(&delayed_root->lock);
    if (!node->in_list) {   /* not in the list */
        if (list_empty(&delayed_root->node_list))
            goto out;
        p = delayed_root->node_list.next;
    } else if (list_is_last(&node->n_list, &delayed_root->node_list))
        goto out;
    else
        p = node->n_list.next;

    next = list_entry(p, struct btrfs_delayed_node, n_list);
    atomic_inc(&next->refs);
out:
    spin_unlock(&delayed_root->lock);

    return next;
}

static void __btrfs_release_delayed_node(
                struct btrfs_delayed_node *delayed_node,
                int mod)
{
    struct btrfs_delayed_root *delayed_root;

    if (!delayed_node)
        return;

    delayed_root = delayed_node->root->fs_info->delayed_root;

    mutex_lock(&delayed_node->mutex);
    if (delayed_node->count)
        btrfs_queue_delayed_node(delayed_root, delayed_node, mod);
    else
        btrfs_dequeue_delayed_node(delayed_root, delayed_node);
    mutex_unlock(&delayed_node->mutex);

    if (atomic_dec_and_test(&delayed_node->refs)) {
        struct btrfs_root *root = delayed_node->root;
        spin_lock(&root->inode_lock);
        if (atomic_read(&delayed_node->refs) == 0) {
            radix_tree_delete(&root->delayed_nodes_tree,
                      delayed_node->inode_id);
            kmem_cache_free(delayed_node_cache, delayed_node);
        }
        spin_unlock(&root->inode_lock);
    }
}

static inline void btrfs_release_delayed_node(struct btrfs_delayed_node *node)
{
    __btrfs_release_delayed_node(node, 0);
}

struct btrfs_delayed_node *btrfs_first_prepared_delayed_node(
                    struct btrfs_delayed_root *delayed_root)
{
    struct list_head *p;
    struct btrfs_delayed_node *node = NULL;

    spin_lock(&delayed_root->lock);
    if (list_empty(&delayed_root->prepare_list))
        goto out;

    p = delayed_root->prepare_list.next;
    list_del_init(p);
    node = list_entry(p, struct btrfs_delayed_node, p_list);
    atomic_inc(&node->refs);
out:
    spin_unlock(&delayed_root->lock);

    return node;
}

static inline void btrfs_release_prepared_delayed_node(
                    struct btrfs_delayed_node *node)
{
    __btrfs_release_delayed_node(node, 1);
}

struct btrfs_delayed_item *btrfs_alloc_delayed_item(u32 data_len)
{
    struct btrfs_delayed_item *item;
    item = kmalloc(sizeof(*item) + data_len, GFP_NOFS);
    if (item) {
        item->data_len = data_len;
        item->ins_or_del = 0;
        item->bytes_reserved = 0;
        item->delayed_node = NULL;
        atomic_set(&item->refs, 1);
    }
    return item;
}

/*
 * __btrfs_lookup_delayed_item - look up the delayed item by key
 * @delayed_node: pointer to the delayed node
 * @key:      the key to look up
 * @prev:     used to store the prev item if the right item isn't found
 * @next:     used to store the next item if the right item isn't found
 *
 * Note: if we don't find the right item, we will return the prev item and
 * the next item.
 */
static struct btrfs_delayed_item *__btrfs_lookup_delayed_item(
                struct rb_root *root,
                struct btrfs_key *key,
                struct btrfs_delayed_item **prev,
                struct btrfs_delayed_item **next)
{
    struct rb_node *node, *prev_node = NULL;
    struct btrfs_delayed_item *delayed_item = NULL;
    int ret = 0;

    node = root->rb_node;

    while (node) {
        delayed_item = rb_entry(node, struct btrfs_delayed_item,
                    rb_node);
        prev_node = node;
        ret = btrfs_comp_cpu_keys(&delayed_item->key, key);
        if (ret < 0)
            node = node->rb_right;
        else if (ret > 0)
            node = node->rb_left;
        else
            return delayed_item;
    }

    if (prev) {
        if (!prev_node)
            *prev = NULL;
        else if (ret < 0)
            *prev = delayed_item;
        else if ((node = rb_prev(prev_node)) != NULL) {
            *prev = rb_entry(node, struct btrfs_delayed_item,
                     rb_node);
        } else
            *prev = NULL;
    }

    if (next) {
        if (!prev_node)
            *next = NULL;
        else if (ret > 0)
            *next = delayed_item;
        else if ((node = rb_next(prev_node)) != NULL) {
            *next = rb_entry(node, struct btrfs_delayed_item,
                     rb_node);
        } else
            *next = NULL;
    }
    return NULL;
}

struct btrfs_delayed_item *__btrfs_lookup_delayed_insertion_item(
                    struct btrfs_delayed_node *delayed_node,
                    struct btrfs_key *key)
{
    struct btrfs_delayed_item *item;

    item = __btrfs_lookup_delayed_item(&delayed_node->ins_root, key,
                       NULL, NULL);
    return item;
}

struct btrfs_delayed_item *__btrfs_lookup_delayed_deletion_item(
                    struct btrfs_delayed_node *delayed_node,
                    struct btrfs_key *key)
{
    struct btrfs_delayed_item *item;

    item = __btrfs_lookup_delayed_item(&delayed_node->del_root, key,
                       NULL, NULL);
    return item;
}

struct btrfs_delayed_item *__btrfs_search_delayed_insertion_item(
                    struct btrfs_delayed_node *delayed_node,
                    struct btrfs_key *key)
{
    struct btrfs_delayed_item *item, *next;

    item = __btrfs_lookup_delayed_item(&delayed_node->ins_root, key,
                       NULL, &next);
    if (!item)
        item = next;

    return item;
}

struct btrfs_delayed_item *__btrfs_search_delayed_deletion_item(
                    struct btrfs_delayed_node *delayed_node,
                    struct btrfs_key *key)
{
    struct btrfs_delayed_item *item, *next;

    item = __btrfs_lookup_delayed_item(&delayed_node->del_root, key,
                       NULL, &next);
    if (!item)
        item = next;

    return item;
}

static int __btrfs_add_delayed_item(struct btrfs_delayed_node *delayed_node,
                    struct btrfs_delayed_item *ins,
                    int action)
{
    struct rb_node **p, *node;
    struct rb_node *parent_node = NULL;
    struct rb_root *root;
    struct btrfs_delayed_item *item;
    int cmp;

    if (action == BTRFS_DELAYED_INSERTION_ITEM)
        root = &delayed_node->ins_root;
    else if (action == BTRFS_DELAYED_DELETION_ITEM)
        root = &delayed_node->del_root;
    else
        BUG();
    p = &root->rb_node;
    node = &ins->rb_node;

    while (*p) {
        parent_node = *p;
        item = rb_entry(parent_node, struct btrfs_delayed_item,
                 rb_node);

        cmp = btrfs_comp_cpu_keys(&item->key, &ins->key);
        if (cmp < 0)
            p = &(*p)->rb_right;
        else if (cmp > 0)
            p = &(*p)->rb_left;
        else
            return -EEXIST;
    }

    rb_link_node(node, parent_node, p);
    rb_insert_color(node, root);
    ins->delayed_node = delayed_node;
    ins->ins_or_del = action;

    if (ins->key.type == BTRFS_DIR_INDEX_KEY &&
        action == BTRFS_DELAYED_INSERTION_ITEM &&
        ins->key.offset >= delayed_node->index_cnt)
            delayed_node->index_cnt = ins->key.offset + 1;

    delayed_node->count++;
    atomic_inc(&delayed_node->root->fs_info->delayed_root->items);
    return 0;
}

static int __btrfs_add_delayed_insertion_item(struct btrfs_delayed_node *node,
                          struct btrfs_delayed_item *item)
{
    return __btrfs_add_delayed_item(node, item,
                    BTRFS_DELAYED_INSERTION_ITEM);
}

static int __btrfs_add_delayed_deletion_item(struct btrfs_delayed_node *node,
                         struct btrfs_delayed_item *item)
{
    return __btrfs_add_delayed_item(node, item,
                    BTRFS_DELAYED_DELETION_ITEM);
}

static void __btrfs_remove_delayed_item(struct btrfs_delayed_item *delayed_item)
{
    struct rb_root *root;
    struct btrfs_delayed_root *delayed_root;

    delayed_root = delayed_item->delayed_node->root->fs_info->delayed_root;

    BUG_ON(!delayed_root);
    BUG_ON(delayed_item->ins_or_del != BTRFS_DELAYED_DELETION_ITEM &&
           delayed_item->ins_or_del != BTRFS_DELAYED_INSERTION_ITEM);

    if (delayed_item->ins_or_del == BTRFS_DELAYED_INSERTION_ITEM)
        root = &delayed_item->delayed_node->ins_root;
    else
        root = &delayed_item->delayed_node->del_root;

    rb_erase(&delayed_item->rb_node, root);
    delayed_item->delayed_node->count--;
    if (atomic_dec_return(&delayed_root->items) <
        BTRFS_DELAYED_BACKGROUND &&
        waitqueue_active(&delayed_root->wait))
        wake_up(&delayed_root->wait);
}

static void btrfs_release_delayed_item(struct btrfs_delayed_item *item)
{
    if (item) {
        __btrfs_remove_delayed_item(item);
        if (atomic_dec_and_test(&item->refs))
            kfree(item);
    }
}

struct btrfs_delayed_item *__btrfs_first_delayed_insertion_item(
                    struct btrfs_delayed_node *delayed_node)
{
    struct rb_node *p;
    struct btrfs_delayed_item *item = NULL;

    p = rb_first(&delayed_node->ins_root);
    if (p)
        item = rb_entry(p, struct btrfs_delayed_item, rb_node);

    return item;
}

struct btrfs_delayed_item *__btrfs_first_delayed_deletion_item(
                    struct btrfs_delayed_node *delayed_node)
{
    struct rb_node *p;
    struct btrfs_delayed_item *item = NULL;

    p = rb_first(&delayed_node->del_root);
    if (p)
        item = rb_entry(p, struct btrfs_delayed_item, rb_node);

    return item;
}

struct btrfs_delayed_item *__btrfs_next_delayed_item(
                        struct btrfs_delayed_item *item)
{
    struct rb_node *p;
    struct btrfs_delayed_item *next = NULL;

    p = rb_next(&item->rb_node);
    if (p)
        next = rb_entry(p, struct btrfs_delayed_item, rb_node);

    return next;
}

static inline struct btrfs_root *btrfs_get_fs_root(struct btrfs_root *root,
                           u64 root_id)
{
    struct btrfs_key root_key;

    if (root->objectid == root_id)
        return root;

    root_key.objectid = root_id;
    root_key.type = BTRFS_ROOT_ITEM_KEY;
    root_key.offset = (u64)-1;
    return btrfs_read_fs_root_no_name(root->fs_info, &root_key);
}

static int btrfs_delayed_item_reserve_metadata(struct btrfs_trans_handle *trans,
                           struct btrfs_root *root,
                           struct btrfs_delayed_item *item)
{
    struct btrfs_block_rsv *src_rsv;
    struct btrfs_block_rsv *dst_rsv;
    u64 num_bytes;
    int ret;

    if (!trans->bytes_reserved)
        return 0;

    src_rsv = trans->block_rsv;
    dst_rsv = &root->fs_info->delayed_block_rsv;

    num_bytes = btrfs_calc_trans_metadata_size(root, 1);
    ret = btrfs_block_rsv_migrate(src_rsv, dst_rsv, num_bytes);
    if (!ret) {
        trace_btrfs_space_reservation(root->fs_info, "delayed_item",
                          item->key.objectid,
                          num_bytes, 1);
        item->bytes_reserved = num_bytes;
    }

    return ret;
}

static void btrfs_delayed_item_release_metadata(struct btrfs_root *root,
                        struct btrfs_delayed_item *item)
{
    struct btrfs_block_rsv *rsv;

    if (!item->bytes_reserved)
        return;

    rsv = &root->fs_info->delayed_block_rsv;
    trace_btrfs_space_reservation(root->fs_info, "delayed_item",
                      item->key.objectid, item->bytes_reserved,
                      0);
    btrfs_block_rsv_release(root, rsv,
                item->bytes_reserved);
}

static int btrfs_delayed_inode_reserve_metadata(
                    struct btrfs_trans_handle *trans,
                    struct btrfs_root *root,
                    struct inode *inode,
                    struct btrfs_delayed_node *node)
{
    struct btrfs_block_rsv *src_rsv;
    struct btrfs_block_rsv *dst_rsv;
    u64 num_bytes;
    int ret;
    bool release = false;

    src_rsv = trans->block_rsv;
    dst_rsv = &root->fs_info->delayed_block_rsv;

    num_bytes = btrfs_calc_trans_metadata_size(root, 1);

    /*
     * btrfs_dirty_inode will update the inode under btrfs_join_transaction
     * which doesn't reserve space for speed.  This is a problem since we
     * still need to reserve space for this update, so try to reserve the
     * space.
     *
     * Now if src_rsv == delalloc_block_rsv we'll let it just steal since
     * we're accounted for.
     */
    if (!src_rsv || (!trans->bytes_reserved &&
             src_rsv->type != BTRFS_BLOCK_RSV_DELALLOC)) {
        ret = btrfs_block_rsv_add_noflush(root, dst_rsv, num_bytes);
        /*
         * Since we're under a transaction reserve_metadata_bytes could
         * try to commit the transaction which will make it return
         * EAGAIN to make us stop the transaction we have, so return
         * ENOSPC instead so that btrfs_dirty_inode knows what to do.
         */
        if (ret == -EAGAIN)
            ret = -ENOSPC;
        if (!ret) {
            node->bytes_reserved = num_bytes;
            trace_btrfs_space_reservation(root->fs_info,
                              "delayed_inode",
                              btrfs_ino(inode),
                              num_bytes, 1);
        }
        return ret;
    } else if (src_rsv->type == BTRFS_BLOCK_RSV_DELALLOC) {
        spin_lock(&BTRFS_I(inode)->lock);
        if (test_and_clear_bit(BTRFS_INODE_DELALLOC_META_RESERVED,
                       &BTRFS_I(inode)->runtime_flags)) {
            spin_unlock(&BTRFS_I(inode)->lock);
            release = true;
            goto migrate;
        }
        spin_unlock(&BTRFS_I(inode)->lock);

        /* Ok we didn't have space pre-reserved.  This shouldn't happen
         * too often but it can happen if we do delalloc to an existing
         * inode which gets dirtied because of the time update, and then
         * isn't touched again until after the transaction commits and
         * then we try to write out the data.  First try to be nice and
         * reserve something strictly for us.  If not be a pain and try
         * to steal from the delalloc block rsv.
         */
        ret = btrfs_block_rsv_add_noflush(root, dst_rsv, num_bytes);
        if (!ret)
            goto out;

        ret = btrfs_block_rsv_migrate(src_rsv, dst_rsv, num_bytes);
        if (!ret)
            goto out;

        /*
         * Ok this is a problem, let's just steal from the global rsv
         * since this really shouldn't happen that often.
         */
        WARN_ON(1);
        ret = btrfs_block_rsv_migrate(&root->fs_info->global_block_rsv,
                          dst_rsv, num_bytes);
        goto out;
    }

migrate:
    ret = btrfs_block_rsv_migrate(src_rsv, dst_rsv, num_bytes);

out:
    /*
     * Migrate only takes a reservation, it doesn't touch the size of the
     * block_rsv.  This is to simplify people who don't normally have things
     * migrated from their block rsv.  If they go to release their
     * reservation, that will decrease the size as well, so if migrate
     * reduced size we'd end up with a negative size.  But for the
     * delalloc_meta_reserved stuff we will only know to drop 1 reservation,
     * but we could in fact do this reserve/migrate dance several times
     * between the time we did the original reservation and we'd clean it
     * up.  So to take care of this, release the space for the meta
     * reservation here.  I think it may be time for a documentation page on
     * how block rsvs. work.
     */
    if (!ret) {
        trace_btrfs_space_reservation(root->fs_info, "delayed_inode",
                          btrfs_ino(inode), num_bytes, 1);
        node->bytes_reserved = num_bytes;
    }

    if (release) {
        trace_btrfs_space_reservation(root->fs_info, "delalloc",
                          btrfs_ino(inode), num_bytes, 0);
        btrfs_block_rsv_release(root, src_rsv, num_bytes);
    }

    return ret;
}

static void btrfs_delayed_inode_release_metadata(struct btrfs_root *root,
                        struct btrfs_delayed_node *node)
{
    struct btrfs_block_rsv *rsv;

    if (!node->bytes_reserved)
        return;

    rsv = &root->fs_info->delayed_block_rsv;
    trace_btrfs_space_reservation(root->fs_info, "delayed_inode",
                      node->inode_id, node->bytes_reserved, 0);
    btrfs_block_rsv_release(root, rsv,
                node->bytes_reserved);
    node->bytes_reserved = 0;
}

/*
 * This helper will insert some continuous items into the same leaf according
 * to the free space of the leaf.
 */
static int btrfs_batch_insert_items(struct btrfs_trans_handle *trans,
                struct btrfs_root *root,
                struct btrfs_path *path,
                struct btrfs_delayed_item *item)
{
    struct btrfs_delayed_item *curr, *next;
    int free_space;
    int total_data_size = 0, total_size = 0;
    struct extent_buffer *leaf;
    char *data_ptr;
    struct btrfs_key *keys;
    u32 *data_size;
    struct list_head head;
    int slot;
    int nitems;
    int i;
    int ret = 0;

    BUG_ON(!path->nodes[0]);

    leaf = path->nodes[0];
    free_space = btrfs_leaf_free_space(root, leaf);
    INIT_LIST_HEAD(&head);

    next = item;
    nitems = 0;

    /*
     * count the number of the continuous items that we can insert in batch
     */
    while (total_size + next->data_len + sizeof(struct btrfs_item) <=
           free_space) {
        total_data_size += next->data_len;
        total_size += next->data_len + sizeof(struct btrfs_item);
        list_add_tail(&next->tree_list, &head);
        nitems++;

        curr = next;
        next = __btrfs_next_delayed_item(curr);
        if (!next)
            break;

        if (!btrfs_is_continuous_delayed_item(curr, next))
            break;
    }

    if (!nitems) {
        ret = 0;
        goto out;
    }

    /*
     * we need allocate some memory space, but it might cause the task
     * to sleep, so we set all locked nodes in the path to blocking locks
     * first.
     */
    btrfs_set_path_blocking(path);

    keys = kmalloc(sizeof(struct btrfs_key) * nitems, GFP_NOFS);
    if (!keys) {
        ret = -ENOMEM;
        goto out;
    }

    data_size = kmalloc(sizeof(u32) * nitems, GFP_NOFS);
    if (!data_size) {
        ret = -ENOMEM;
        goto error;
    }

    /* get keys of all the delayed items */
    i = 0;
    list_for_each_entry(next, &head, tree_list) {
        keys[i] = next->key;
        data_size[i] = next->data_len;
        i++;
    }

    /* reset all the locked nodes in the patch to spinning locks. */
    btrfs_clear_path_blocking(path, NULL, 0);

    /* insert the keys of the items */
    setup_items_for_insert(trans, root, path, keys, data_size,
                   total_data_size, total_size, nitems);

    /* insert the dir index items */
    slot = path->slots[0];
    list_for_each_entry_safe(curr, next, &head, tree_list) {
        data_ptr = btrfs_item_ptr(leaf, slot, char);
        write_extent_buffer(leaf, &curr->data,
                    (unsigned long)data_ptr,
                    curr->data_len);
        slot++;

        btrfs_delayed_item_release_metadata(root, curr);

        list_del(&curr->tree_list);
        btrfs_release_delayed_item(curr);
    }

error:
    kfree(data_size);
    kfree(keys);
out:
    return ret;
}

/*
 * This helper can just do simple insertion that needn't extend item for new
 * data, such as directory name index insertion, inode insertion.
 */
static int btrfs_insert_delayed_item(struct btrfs_trans_handle *trans,
                     struct btrfs_root *root,
                     struct btrfs_path *path,
                     struct btrfs_delayed_item *delayed_item)
{
    struct extent_buffer *leaf;
    struct btrfs_item *item;
    char *ptr;
    int ret;

    ret = btrfs_insert_empty_item(trans, root, path, &delayed_item->key,
                      delayed_item->data_len);
    if (ret < 0 && ret != -EEXIST)
        return ret;

    leaf = path->nodes[0];

    item = btrfs_item_nr(leaf, path->slots[0]);
    ptr = btrfs_item_ptr(leaf, path->slots[0], char);

    write_extent_buffer(leaf, delayed_item->data, (unsigned long)ptr,
                delayed_item->data_len);
    btrfs_mark_buffer_dirty(leaf);

    btrfs_delayed_item_release_metadata(root, delayed_item);
    return 0;
}

/*
 * we insert an item first, then if there are some continuous items, we try
 * to insert those items into the same leaf.
 */
static int btrfs_insert_delayed_items(struct btrfs_trans_handle *trans,
                      struct btrfs_path *path,
                      struct btrfs_root *root,
                      struct btrfs_delayed_node *node)
{
    struct btrfs_delayed_item *curr, *prev;
    int ret = 0;

do_again:
    mutex_lock(&node->mutex);
    curr = __btrfs_first_delayed_insertion_item(node);
    if (!curr)
        goto insert_end;

    ret = btrfs_insert_delayed_item(trans, root, path, curr);
    if (ret < 0) {
        btrfs_release_path(path);
        goto insert_end;
    }

    prev = curr;
    curr = __btrfs_next_delayed_item(prev);
    if (curr && btrfs_is_continuous_delayed_item(prev, curr)) {
        /* insert the continuous items into the same leaf */
        path->slots[0]++;
        btrfs_batch_insert_items(trans, root, path, curr);
    }
    btrfs_release_delayed_item(prev);
    btrfs_mark_buffer_dirty(path->nodes[0]);

    btrfs_release_path(path);
    mutex_unlock(&node->mutex);
    goto do_again;

insert_end:
    mutex_unlock(&node->mutex);
    return ret;
}

static int btrfs_batch_delete_items(struct btrfs_trans_handle *trans,
                    struct btrfs_root *root,
                    struct btrfs_path *path,
                    struct btrfs_delayed_item *item)
{
    struct btrfs_delayed_item *curr, *next;
    struct extent_buffer *leaf;
    struct btrfs_key key;
    struct list_head head;
    int nitems, i, last_item;
    int ret = 0;

    BUG_ON(!path->nodes[0]);

    leaf = path->nodes[0];

    i = path->slots[0];
    last_item = btrfs_header_nritems(leaf) - 1;
    if (i > last_item)
        return -ENOENT; /* FIXME: Is errno suitable? */

    next = item;
    INIT_LIST_HEAD(&head);
    btrfs_item_key_to_cpu(leaf, &key, i);
    nitems = 0;
    /*
     * count the number of the dir index items that we can delete in batch
     */
    while (btrfs_comp_cpu_keys(&next->key, &key) == 0) {
        list_add_tail(&next->tree_list, &head);
        nitems++;

        curr = next;
        next = __btrfs_next_delayed_item(curr);
        if (!next)
            break;

        if (!btrfs_is_continuous_delayed_item(curr, next))
            break;

        i++;
        if (i > last_item)
            break;
        btrfs_item_key_to_cpu(leaf, &key, i);
    }

    if (!nitems)
        return 0;

    ret = btrfs_del_items(trans, root, path, path->slots[0], nitems);
    if (ret)
        goto out;

    list_for_each_entry_safe(curr, next, &head, tree_list) {
        btrfs_delayed_item_release_metadata(root, curr);
        list_del(&curr->tree_list);
        btrfs_release_delayed_item(curr);
    }

out:
    return ret;
}

static int btrfs_delete_delayed_items(struct btrfs_trans_handle *trans,
                      struct btrfs_path *path,
                      struct btrfs_root *root,
                      struct btrfs_delayed_node *node)
{
    struct btrfs_delayed_item *curr, *prev;
    int ret = 0;

do_again:
    mutex_lock(&node->mutex);
    curr = __btrfs_first_delayed_deletion_item(node);
    if (!curr)
        goto delete_fail;

    ret = btrfs_search_slot(trans, root, &curr->key, path, -1, 1);
    if (ret < 0)
        goto delete_fail;
    else if (ret > 0) {
        /*
         * can't find the item which the node points to, so this node
         * is invalid, just drop it.
         */
        prev = curr;
        curr = __btrfs_next_delayed_item(prev);
        btrfs_release_delayed_item(prev);
        ret = 0;
        btrfs_release_path(path);
        if (curr) {
            mutex_unlock(&node->mutex);
            goto do_again;
        } else
            goto delete_fail;
    }

    btrfs_batch_delete_items(trans, root, path, curr);
    btrfs_release_path(path);
    mutex_unlock(&node->mutex);
    goto do_again;

delete_fail:
    btrfs_release_path(path);
    mutex_unlock(&node->mutex);
    return ret;
}

static void btrfs_release_delayed_inode(struct btrfs_delayed_node *delayed_node)
{
    struct btrfs_delayed_root *delayed_root;

    if (delayed_node && delayed_node->inode_dirty) {
        BUG_ON(!delayed_node->root);
        delayed_node->inode_dirty = 0;
        delayed_node->count--;

        delayed_root = delayed_node->root->fs_info->delayed_root;
        if (atomic_dec_return(&delayed_root->items) <
            BTRFS_DELAYED_BACKGROUND &&
            waitqueue_active(&delayed_root->wait))
            wake_up(&delayed_root->wait);
    }
}

static int btrfs_update_delayed_inode(struct btrfs_trans_handle *trans,
                      struct btrfs_root *root,
                      struct btrfs_path *path,
                      struct btrfs_delayed_node *node)
{
    struct btrfs_key key;
    struct btrfs_inode_item *inode_item;
    struct extent_buffer *leaf;
    int ret;

    mutex_lock(&node->mutex);
    if (!node->inode_dirty) {
        mutex_unlock(&node->mutex);
        return 0;
    }

    key.objectid = node->inode_id;
    btrfs_set_key_type(&key, BTRFS_INODE_ITEM_KEY);
    key.offset = 0;
    ret = btrfs_lookup_inode(trans, root, path, &key, 1);
    if (ret > 0) {
        btrfs_release_path(path);
        mutex_unlock(&node->mutex);
        return -ENOENT;
    } else if (ret < 0) {
        mutex_unlock(&node->mutex);
        return ret;
    }

    btrfs_unlock_up_safe(path, 1);
    leaf = path->nodes[0];
    inode_item = btrfs_item_ptr(leaf, path->slots[0],
                    struct btrfs_inode_item);
    write_extent_buffer(leaf, &node->inode_item, (unsigned long)inode_item,
                sizeof(struct btrfs_inode_item));
    btrfs_mark_buffer_dirty(leaf);
    btrfs_release_path(path);

    btrfs_delayed_inode_release_metadata(root, node);
    btrfs_release_delayed_inode(node);
    mutex_unlock(&node->mutex);

    return 0;
}

/*
 * Called when committing the transaction.
 * Returns 0 on success.
 * Returns < 0 on error and returns with an aborted transaction with any
 * outstanding delayed items cleaned up.
 */
static int __btrfs_run_delayed_items(struct btrfs_trans_handle *trans,
                     struct btrfs_root *root, int nr)
{
    struct btrfs_root *curr_root = root;
    struct btrfs_delayed_root *delayed_root;
    struct btrfs_delayed_node *curr_node, *prev_node;
    struct btrfs_path *path;
    struct btrfs_block_rsv *block_rsv;
    int ret = 0;
    bool count = (nr > 0);

    if (trans->aborted)
        return -EIO;

    path = btrfs_alloc_path();
    if (!path)
        return -ENOMEM;
    path->leave_spinning = 1;

    block_rsv = trans->block_rsv;
    trans->block_rsv = &root->fs_info->delayed_block_rsv;

    delayed_root = btrfs_get_delayed_root(root);

    curr_node = btrfs_first_delayed_node(delayed_root);
    while (curr_node && (!count || (count && nr--))) {
        curr_root = curr_node->root;
        ret = btrfs_insert_delayed_items(trans, path, curr_root,
                         curr_node);
        if (!ret)
            ret = btrfs_delete_delayed_items(trans, path,
                        curr_root, curr_node);
        if (!ret)
            ret = btrfs_update_delayed_inode(trans, curr_root,
                        path, curr_node);
        if (ret) {
            btrfs_release_delayed_node(curr_node);
            curr_node = NULL;
            btrfs_abort_transaction(trans, root, ret);
            break;
        }

        prev_node = curr_node;
        curr_node = btrfs_next_delayed_node(curr_node);
        btrfs_release_delayed_node(prev_node);
    }

    if (curr_node)
        btrfs_release_delayed_node(curr_node);
    btrfs_free_path(path);
    trans->block_rsv = block_rsv;

    return ret;
}

int btrfs_run_delayed_items(struct btrfs_trans_handle *trans,
                struct btrfs_root *root)
{
    return __btrfs_run_delayed_items(trans, root, -1);
}

int btrfs_run_delayed_items_nr(struct btrfs_trans_handle *trans,
                   struct btrfs_root *root, int nr)
{
    return __btrfs_run_delayed_items(trans, root, nr);
}

static int __btrfs_commit_inode_delayed_items(struct btrfs_trans_handle *trans,
                          struct btrfs_delayed_node *node)
{
    struct btrfs_path *path;
    struct btrfs_block_rsv *block_rsv;
    int ret;

    path = btrfs_alloc_path();
    if (!path)
        return -ENOMEM;
    path->leave_spinning = 1;

    block_rsv = trans->block_rsv;
    trans->block_rsv = &node->root->fs_info->delayed_block_rsv;

    ret = btrfs_insert_delayed_items(trans, path, node->root, node);
    if (!ret)
        ret = btrfs_delete_delayed_items(trans, path, node->root, node);
    if (!ret)
        ret = btrfs_update_delayed_inode(trans, node->root, path, node);
    btrfs_free_path(path);

    trans->block_rsv = block_rsv;
    return ret;
}

int btrfs_commit_inode_delayed_items(struct btrfs_trans_handle *trans,
                     struct inode *inode)
{
    struct btrfs_delayed_node *delayed_node = btrfs_get_delayed_node(inode);
    int ret;

    if (!delayed_node)
        return 0;

    mutex_lock(&delayed_node->mutex);
    if (!delayed_node->count) {
        mutex_unlock(&delayed_node->mutex);
        btrfs_release_delayed_node(delayed_node);
        return 0;
    }
    mutex_unlock(&delayed_node->mutex);

    ret = __btrfs_commit_inode_delayed_items(trans, delayed_node);
    btrfs_release_delayed_node(delayed_node);
    return ret;
}

void btrfs_remove_delayed_node(struct inode *inode)
{
    struct btrfs_delayed_node *delayed_node;

    delayed_node = ACCESS_ONCE(BTRFS_I(inode)->delayed_node);
    if (!delayed_node)
        return;

    BTRFS_I(inode)->delayed_node = NULL;
    btrfs_release_delayed_node(delayed_node);
}

struct btrfs_async_delayed_node {
    struct btrfs_root *root;
    struct btrfs_delayed_node *delayed_node;
    struct btrfs_work work;
};

static void btrfs_async_run_delayed_node_done(struct btrfs_work *work)
{
    struct btrfs_async_delayed_node *async_node;
    struct btrfs_trans_handle *trans;
    struct btrfs_path *path;
    struct btrfs_delayed_node *delayed_node = NULL;
    struct btrfs_root *root;
    struct btrfs_block_rsv *block_rsv;
    unsigned long nr = 0;
    int need_requeue = 0;
    int ret;

    async_node = container_of(work, struct btrfs_async_delayed_node, work);

    path = btrfs_alloc_path();
    if (!path)
        goto out;
    path->leave_spinning = 1;

    delayed_node = async_node->delayed_node;
    root = delayed_node->root;

    trans = btrfs_join_transaction(root);
    if (IS_ERR(trans))
        goto free_path;

    block_rsv = trans->block_rsv;
    trans->block_rsv = &root->fs_info->delayed_block_rsv;

    ret = btrfs_insert_delayed_items(trans, path, root, delayed_node);
    if (!ret)
        ret = btrfs_delete_delayed_items(trans, path, root,
                         delayed_node);

    if (!ret)
        btrfs_update_delayed_inode(trans, root, path, delayed_node);

    /*
     * Maybe new delayed items have been inserted, so we need requeue
     * the work. Besides that, we must dequeue the empty delayed nodes
     * to avoid the race between delayed items balance and the worker.
     * The race like this:
     *  Task1               Worker thread
     *                  count == 0, needn't requeue
     *                    also needn't insert the
     *                    delayed node into prepare
     *                    list again.
     *  add lots of delayed items
     *  queue the delayed node
     *    already in the list,
     *    and not in the prepare
     *    list, it means the delayed
     *    node is being dealt with
     *    by the worker.
     *  do delayed items balance
     *    the delayed node is being
     *    dealt with by the worker
     *    now, just wait.
     *                  the worker goto idle.
     * Task1 will sleep until the transaction is commited.
     */
    mutex_lock(&delayed_node->mutex);
    if (delayed_node->count)
        need_requeue = 1;
    else
        btrfs_dequeue_delayed_node(root->fs_info->delayed_root,
                       delayed_node);
    mutex_unlock(&delayed_node->mutex);

    nr = trans->blocks_used;

    trans->block_rsv = block_rsv;
    btrfs_end_transaction_dmeta(trans, root);
    __btrfs_btree_balance_dirty(root, nr);
free_path:
    btrfs_free_path(path);
out:
    if (need_requeue)
        btrfs_requeue_work(&async_node->work);
    else {
        btrfs_release_prepared_delayed_node(delayed_node);
        kfree(async_node);
    }
}

static int btrfs_wq_run_delayed_node(struct btrfs_delayed_root *delayed_root,
                     struct btrfs_root *root, int all)
{
    struct btrfs_async_delayed_node *async_node;
    struct btrfs_delayed_node *curr;
    int count = 0;

again:
    curr = btrfs_first_prepared_delayed_node(delayed_root);
    if (!curr)
        return 0;

    async_node = kmalloc(sizeof(*async_node), GFP_NOFS);
    if (!async_node) {
        btrfs_release_prepared_delayed_node(curr);
        return -ENOMEM;
    }

    async_node->root = root;
    async_node->delayed_node = curr;

    async_node->work.func = btrfs_async_run_delayed_node_done;
    async_node->work.flags = 0;

    btrfs_queue_worker(&root->fs_info->delayed_workers, &async_node->work);
    count++;

    if (all || count < 4)
        goto again;

    return 0;
}

void btrfs_assert_delayed_root_empty(struct btrfs_root *root)
{
    struct btrfs_delayed_root *delayed_root;
    delayed_root = btrfs_get_delayed_root(root);
    WARN_ON(btrfs_first_delayed_node(delayed_root));
}

void btrfs_balance_delayed_items(struct btrfs_root *root)
{
    struct btrfs_delayed_root *delayed_root;

    delayed_root = btrfs_get_delayed_root(root);

    if (atomic_read(&delayed_root->items) < BTRFS_DELAYED_BACKGROUND)
        return;

    if (atomic_read(&delayed_root->items) >= BTRFS_DELAYED_WRITEBACK) {
        int ret;
        ret = btrfs_wq_run_delayed_node(delayed_root, root, 1);
        if (ret)
            return;

        wait_event_interruptible_timeout(
                delayed_root->wait,
                (atomic_read(&delayed_root->items) <
                 BTRFS_DELAYED_BACKGROUND),
                HZ);
        return;
    }

    btrfs_wq_run_delayed_node(delayed_root, root, 0);
}

/* Will return 0 or -ENOMEM */
int btrfs_insert_delayed_dir_index(struct btrfs_trans_handle *trans,
                   struct btrfs_root *root, const char *name,
                   int name_len, struct inode *dir,
                   struct btrfs_disk_key *disk_key, u8 type,
                   u64 index)
{
    struct btrfs_delayed_node *delayed_node;
    struct btrfs_delayed_item *delayed_item;
    struct btrfs_dir_item *dir_item;
    int ret;

    delayed_node = btrfs_get_or_create_delayed_node(dir);
    if (IS_ERR(delayed_node))
        return PTR_ERR(delayed_node);

    delayed_item = btrfs_alloc_delayed_item(sizeof(*dir_item) + name_len);
    if (!delayed_item) {
        ret = -ENOMEM;
        goto release_node;
    }

    delayed_item->key.objectid = btrfs_ino(dir);
    btrfs_set_key_type(&delayed_item->key, BTRFS_DIR_INDEX_KEY);
    delayed_item->key.offset = index;

    dir_item = (struct btrfs_dir_item *)delayed_item->data;
    dir_item->location = *disk_key;
    dir_item->transid = cpu_to_le64(trans->transid);
    dir_item->data_len = 0;
    dir_item->name_len = cpu_to_le16(name_len);
    dir_item->type = type;
    memcpy((char *)(dir_item + 1), name, name_len);

    ret = btrfs_delayed_item_reserve_metadata(trans, root, delayed_item);
    /*
     * we have reserved enough space when we start a new transaction,
     * so reserving metadata failure is impossible
     */
    BUG_ON(ret);


    mutex_lock(&delayed_node->mutex);
    ret = __btrfs_add_delayed_insertion_item(delayed_node, delayed_item);
    if (unlikely(ret)) {
        printk(KERN_ERR "err add delayed dir index item(name: %s) into "
                "the insertion tree of the delayed node"
                "(root id: %llu, inode id: %llu, errno: %d)\n",
                name,
                (unsigned long long)delayed_node->root->objectid,
                (unsigned long long)delayed_node->inode_id,
                ret);
        BUG();
    }
    mutex_unlock(&delayed_node->mutex);

release_node:
    btrfs_release_delayed_node(delayed_node);
    return ret;
}

static int btrfs_delete_delayed_insertion_item(struct btrfs_root *root,
                           struct btrfs_delayed_node *node,
                           struct btrfs_key *key)
{
    struct btrfs_delayed_item *item;

    mutex_lock(&node->mutex);
    item = __btrfs_lookup_delayed_insertion_item(node, key);
    if (!item) {
        mutex_unlock(&node->mutex);
        return 1;
    }

    btrfs_delayed_item_release_metadata(root, item);
    btrfs_release_delayed_item(item);
    mutex_unlock(&node->mutex);
    return 0;
}

int btrfs_delete_delayed_dir_index(struct btrfs_trans_handle *trans,
                   struct btrfs_root *root, struct inode *dir,
                   u64 index)
{
    struct btrfs_delayed_node *node;
    struct btrfs_delayed_item *item;
    struct btrfs_key item_key;
    int ret;

    node = btrfs_get_or_create_delayed_node(dir);
    if (IS_ERR(node))
        return PTR_ERR(node);

    item_key.objectid = btrfs_ino(dir);
    btrfs_set_key_type(&item_key, BTRFS_DIR_INDEX_KEY);
    item_key.offset = index;

    ret = btrfs_delete_delayed_insertion_item(root, node, &item_key);
    if (!ret)
        goto end;

    item = btrfs_alloc_delayed_item(0);
    if (!item) {
        ret = -ENOMEM;
        goto end;
    }

    item->key = item_key;

    ret = btrfs_delayed_item_reserve_metadata(trans, root, item);
    /*
     * we have reserved enough space when we start a new transaction,
     * so reserving metadata failure is impossible.
     */
    BUG_ON(ret);

    mutex_lock(&node->mutex);
    ret = __btrfs_add_delayed_deletion_item(node, item);
    if (unlikely(ret)) {
        printk(KERN_ERR "err add delayed dir index item(index: %llu) "
                "into the deletion tree of the delayed node"
                "(root id: %llu, inode id: %llu, errno: %d)\n",
                (unsigned long long)index,
                (unsigned long long)node->root->objectid,
                (unsigned long long)node->inode_id,
                ret);
        BUG();
    }
    mutex_unlock(&node->mutex);
end:
    btrfs_release_delayed_node(node);
    return ret;
}

int btrfs_inode_delayed_dir_index_count(struct inode *inode)
{
    struct btrfs_delayed_node *delayed_node = btrfs_get_delayed_node(inode);

    if (!delayed_node)
        return -ENOENT;

    /*
     * Since we have held i_mutex of this directory, it is impossible that
     * a new directory index is added into the delayed node and index_cnt
     * is updated now. So we needn't lock the delayed node.
     */
    if (!delayed_node->index_cnt) {
        btrfs_release_delayed_node(delayed_node);
        return -EINVAL;
    }

    BTRFS_I(inode)->index_cnt = delayed_node->index_cnt;
    btrfs_release_delayed_node(delayed_node);
    return 0;
}

void btrfs_get_delayed_items(struct inode *inode, struct list_head *ins_list,
                 struct list_head *del_list)
{
    struct btrfs_delayed_node *delayed_node;
    struct btrfs_delayed_item *item;

    delayed_node = btrfs_get_delayed_node(inode);
    if (!delayed_node)
        return;

    mutex_lock(&delayed_node->mutex);
    item = __btrfs_first_delayed_insertion_item(delayed_node);
    while (item) {
        atomic_inc(&item->refs);
        list_add_tail(&item->readdir_list, ins_list);
        item = __btrfs_next_delayed_item(item);
    }

    item = __btrfs_first_delayed_deletion_item(delayed_node);
    while (item) {
        atomic_inc(&item->refs);
        list_add_tail(&item->readdir_list, del_list);
        item = __btrfs_next_delayed_item(item);
    }
    mutex_unlock(&delayed_node->mutex);
    /*
     * This delayed node is still cached in the btrfs inode, so refs
     * must be > 1 now, and we needn't check it is going to be freed
     * or not.
     *
     * Besides that, this function is used to read dir, we do not
     * insert/delete delayed items in this period. So we also needn't
     * requeue or dequeue this delayed node.
     */
    atomic_dec(&delayed_node->refs);
}

void btrfs_put_delayed_items(struct list_head *ins_list,
                 struct list_head *del_list)
{
    struct btrfs_delayed_item *curr, *next;

    list_for_each_entry_safe(curr, next, ins_list, readdir_list) {
        list_del(&curr->readdir_list);
        if (atomic_dec_and_test(&curr->refs))
            kfree(curr);
    }

    list_for_each_entry_safe(curr, next, del_list, readdir_list) {
        list_del(&curr->readdir_list);
        if (atomic_dec_and_test(&curr->refs))
            kfree(curr);
    }
}

int btrfs_should_delete_dir_index(struct list_head *del_list,
                  u64 index)
{
    struct btrfs_delayed_item *curr, *next;
    int ret;

    if (list_empty(del_list))
        return 0;

    list_for_each_entry_safe(curr, next, del_list, readdir_list) {
        if (curr->key.offset > index)
            break;

        list_del(&curr->readdir_list);
        ret = (curr->key.offset == index);

        if (atomic_dec_and_test(&curr->refs))
            kfree(curr);

        if (ret)
            return 1;
        else
            continue;
    }
    return 0;
}

/*
 * btrfs_readdir_delayed_dir_index - read dir info stored in the delayed tree
 *
 */
int btrfs_readdir_delayed_dir_index(struct file *filp, void *dirent,
                    filldir_t filldir,
                    struct list_head *ins_list)
{
    struct btrfs_dir_item *di;
    struct btrfs_delayed_item *curr, *next;
    struct btrfs_key location;
    char *name;
    int name_len;
    int over = 0;
    unsigned char d_type;

    if (list_empty(ins_list))
        return 0;

    /*
     * Changing the data of the delayed item is impossible. So
     * we needn't lock them. And we have held i_mutex of the
     * directory, nobody can delete any directory indexes now.
     */
    list_for_each_entry_safe(curr, next, ins_list, readdir_list) {
        list_del(&curr->readdir_list);

        if (curr->key.offset < filp->f_pos) {
            if (atomic_dec_and_test(&curr->refs))
                kfree(curr);
            continue;
        }

        filp->f_pos = curr->key.offset;

        di = (struct btrfs_dir_item *)curr->data;
        name = (char *)(di + 1);
        name_len = le16_to_cpu(di->name_len);

        d_type = btrfs_filetype_table[di->type];
        btrfs_disk_key_to_cpu(&location, &di->location);

        over = filldir(dirent, name, name_len, curr->key.offset,
                   location.objectid, d_type);

        if (atomic_dec_and_test(&curr->refs))
            kfree(curr);

        if (over)
            return 1;
    }
    return 0;
}

BTRFS_SETGET_STACK_FUNCS(stack_inode_generation, struct btrfs_inode_item,
             generation, 64);
BTRFS_SETGET_STACK_FUNCS(stack_inode_sequence, struct btrfs_inode_item,
             sequence, 64);
BTRFS_SETGET_STACK_FUNCS(stack_inode_transid, struct btrfs_inode_item,
             transid, 64);
BTRFS_SETGET_STACK_FUNCS(stack_inode_size, struct btrfs_inode_item, size, 64);
BTRFS_SETGET_STACK_FUNCS(stack_inode_nbytes, struct btrfs_inode_item,
             nbytes, 64);
BTRFS_SETGET_STACK_FUNCS(stack_inode_block_group, struct btrfs_inode_item,
             block_group, 64);
BTRFS_SETGET_STACK_FUNCS(stack_inode_nlink, struct btrfs_inode_item, nlink, 32);
BTRFS_SETGET_STACK_FUNCS(stack_inode_uid, struct btrfs_inode_item, uid, 32);
BTRFS_SETGET_STACK_FUNCS(stack_inode_gid, struct btrfs_inode_item, gid, 32);
BTRFS_SETGET_STACK_FUNCS(stack_inode_mode, struct btrfs_inode_item, mode, 32);
BTRFS_SETGET_STACK_FUNCS(stack_inode_rdev, struct btrfs_inode_item, rdev, 64);
BTRFS_SETGET_STACK_FUNCS(stack_inode_flags, struct btrfs_inode_item, flags, 64);

BTRFS_SETGET_STACK_FUNCS(stack_timespec_sec, struct btrfs_timespec, sec, 64);
BTRFS_SETGET_STACK_FUNCS(stack_timespec_nsec, struct btrfs_timespec, nsec, 32);

static void fill_stack_inode_item(struct btrfs_trans_handle *trans,
                  struct btrfs_inode_item *inode_item,
                  struct inode *inode)
{
    btrfs_set_stack_inode_uid(inode_item, i_uid_read(inode));
    btrfs_set_stack_inode_gid(inode_item, i_gid_read(inode));
    btrfs_set_stack_inode_size(inode_item, BTRFS_I(inode)->disk_i_size);
    btrfs_set_stack_inode_mode(inode_item, inode->i_mode);
    btrfs_set_stack_inode_nlink(inode_item, inode->i_nlink);
    btrfs_set_stack_inode_nbytes(inode_item, inode_get_bytes(inode));
    btrfs_set_stack_inode_generation(inode_item,
                     BTRFS_I(inode)->generation);
    btrfs_set_stack_inode_sequence(inode_item, inode->i_version);
    btrfs_set_stack_inode_transid(inode_item, trans->transid);
    btrfs_set_stack_inode_rdev(inode_item, inode->i_rdev);
    btrfs_set_stack_inode_flags(inode_item, BTRFS_I(inode)->flags);
    btrfs_set_stack_inode_block_group(inode_item, 0);

    btrfs_set_stack_timespec_sec(btrfs_inode_atime(inode_item),
                     inode->i_atime.tv_sec);
    btrfs_set_stack_timespec_nsec(btrfs_inode_atime(inode_item),
                      inode->i_atime.tv_nsec);

    btrfs_set_stack_timespec_sec(btrfs_inode_mtime(inode_item),
                     inode->i_mtime.tv_sec);
    btrfs_set_stack_timespec_nsec(btrfs_inode_mtime(inode_item),
                      inode->i_mtime.tv_nsec);

    btrfs_set_stack_timespec_sec(btrfs_inode_ctime(inode_item),
                     inode->i_ctime.tv_sec);
    btrfs_set_stack_timespec_nsec(btrfs_inode_ctime(inode_item),
                      inode->i_ctime.tv_nsec);
}

int btrfs_fill_inode(struct inode *inode, u32 *rdev)
{
    struct btrfs_delayed_node *delayed_node;
    struct btrfs_inode_item *inode_item;
    struct btrfs_timespec *tspec;

    delayed_node = btrfs_get_delayed_node(inode);
    if (!delayed_node)
        return -ENOENT;

    mutex_lock(&delayed_node->mutex);
    if (!delayed_node->inode_dirty) {
        mutex_unlock(&delayed_node->mutex);
        btrfs_release_delayed_node(delayed_node);
        return -ENOENT;
    }

    inode_item = &delayed_node->inode_item;

    i_uid_write(inode, btrfs_stack_inode_uid(inode_item));
    i_gid_write(inode, btrfs_stack_inode_gid(inode_item));
    btrfs_i_size_write(inode, btrfs_stack_inode_size(inode_item));
    inode->i_mode = btrfs_stack_inode_mode(inode_item);
    set_nlink(inode, btrfs_stack_inode_nlink(inode_item));
    inode_set_bytes(inode, btrfs_stack_inode_nbytes(inode_item));
    BTRFS_I(inode)->generation = btrfs_stack_inode_generation(inode_item);
    inode->i_version = btrfs_stack_inode_sequence(inode_item);
    inode->i_rdev = 0;
    *rdev = btrfs_stack_inode_rdev(inode_item);
    BTRFS_I(inode)->flags = btrfs_stack_inode_flags(inode_item);

    tspec = btrfs_inode_atime(inode_item);
    inode->i_atime.tv_sec = btrfs_stack_timespec_sec(tspec);
    inode->i_atime.tv_nsec = btrfs_stack_timespec_nsec(tspec);

    tspec = btrfs_inode_mtime(inode_item);
    inode->i_mtime.tv_sec = btrfs_stack_timespec_sec(tspec);
    inode->i_mtime.tv_nsec = btrfs_stack_timespec_nsec(tspec);

    tspec = btrfs_inode_ctime(inode_item);
    inode->i_ctime.tv_sec = btrfs_stack_timespec_sec(tspec);
    inode->i_ctime.tv_nsec = btrfs_stack_timespec_nsec(tspec);

    inode->i_generation = BTRFS_I(inode)->generation;
    BTRFS_I(inode)->index_cnt = (u64)-1;

    mutex_unlock(&delayed_node->mutex);
    btrfs_release_delayed_node(delayed_node);
    return 0;
}

int btrfs_delayed_update_inode(struct btrfs_trans_handle *trans,
                   struct btrfs_root *root, struct inode *inode)
{
    struct btrfs_delayed_node *delayed_node;
    int ret = 0;

    delayed_node = btrfs_get_or_create_delayed_node(inode);
    if (IS_ERR(delayed_node))
        return PTR_ERR(delayed_node);

    mutex_lock(&delayed_node->mutex);
    if (delayed_node->inode_dirty) {
        fill_stack_inode_item(trans, &delayed_node->inode_item, inode);
        goto release_node;
    }

    ret = btrfs_delayed_inode_reserve_metadata(trans, root, inode,
                           delayed_node);
    if (ret)
        goto release_node;

    fill_stack_inode_item(trans, &delayed_node->inode_item, inode);
    delayed_node->inode_dirty = 1;
    delayed_node->count++;
    atomic_inc(&root->fs_info->delayed_root->items);
release_node:
    mutex_unlock(&delayed_node->mutex);
    btrfs_release_delayed_node(delayed_node);
    return ret;
}

static void __btrfs_kill_delayed_node(struct btrfs_delayed_node *delayed_node)
{
    struct btrfs_root *root = delayed_node->root;
    struct btrfs_delayed_item *curr_item, *prev_item;

    mutex_lock(&delayed_node->mutex);
    curr_item = __btrfs_first_delayed_insertion_item(delayed_node);
    while (curr_item) {
        btrfs_delayed_item_release_metadata(root, curr_item);
        prev_item = curr_item;
        curr_item = __btrfs_next_delayed_item(prev_item);
        btrfs_release_delayed_item(prev_item);
    }

    curr_item = __btrfs_first_delayed_deletion_item(delayed_node);
    while (curr_item) {
        btrfs_delayed_item_release_metadata(root, curr_item);
        prev_item = curr_item;
        curr_item = __btrfs_next_delayed_item(prev_item);
        btrfs_release_delayed_item(prev_item);
    }

    if (delayed_node->inode_dirty) {
        btrfs_delayed_inode_release_metadata(root, delayed_node);
        btrfs_release_delayed_inode(delayed_node);
    }
    mutex_unlock(&delayed_node->mutex);
}

void btrfs_kill_delayed_inode_items(struct inode *inode)
{
    struct btrfs_delayed_node *delayed_node;

    delayed_node = btrfs_get_delayed_node(inode);
    if (!delayed_node)
        return;

    __btrfs_kill_delayed_node(delayed_node);
    btrfs_release_delayed_node(delayed_node);
}

void btrfs_kill_all_delayed_nodes(struct btrfs_root *root)
{
    u64 inode_id = 0;
    struct btrfs_delayed_node *delayed_nodes[8];
    int i, n;

    while (1) {
        spin_lock(&root->inode_lock);
        n = radix_tree_gang_lookup(&root->delayed_nodes_tree,
                       (void **)delayed_nodes, inode_id,
                       ARRAY_SIZE(delayed_nodes));
        if (!n) {
            spin_unlock(&root->inode_lock);
            break;
        }

        inode_id = delayed_nodes[n - 1]->inode_id + 1;

        for (i = 0; i < n; i++)
            atomic_inc(&delayed_nodes[i]->refs);
        spin_unlock(&root->inode_lock);

        for (i = 0; i < n; i++) {
            __btrfs_kill_delayed_node(delayed_nodes[i]);
            btrfs_release_delayed_node(delayed_nodes[i]);
        }
    }
}

void btrfs_destroy_delayed_inodes(struct btrfs_root *root)
{
    struct btrfs_delayed_root *delayed_root;
    struct btrfs_delayed_node *curr_node, *prev_node;

    delayed_root = btrfs_get_delayed_root(root);

    curr_node = btrfs_first_delayed_node(delayed_root);
    while (curr_node) {
        __btrfs_kill_delayed_node(curr_node);

        prev_node = curr_node;
        curr_node = btrfs_next_delayed_node(curr_node);
        btrfs_release_delayed_node(prev_node);
    }
}