source: mainline/uspace/lib/ext4/libext4_directory_index.c@ e6f6260

/*
 * Copyright (c) 2012 Frantisek Princ
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * - Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 * - The name of the author may not be used to endorse or promote products
 *   derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/** @addtogroup libext4
 * @{
 */ 

/**
 * @file        libext4_directory_index.c
 * @brief       Ext4 directory index operations.
 */

#include <byteorder.h>
#include <errno.h>
#include <malloc.h>
#include <sort.h>
#include <string.h>
#include "libext4.h"

/** Type entry to pass to sorting algorithm.
 *
 */
typedef struct ext4_dx_sort_entry {
        uint32_t hash;
        uint32_t rec_len;
        void *dentry;
} ext4_dx_sort_entry_t;


/** Get hash version used in directory index.
 *
 * @param root_info     pointer to root info structure of index
 * @return                      hash algorithm version
 */
uint8_t ext4_directory_dx_root_info_get_hash_version(
                ext4_directory_dx_root_info_t *root_info)
{
        return root_info->hash_version;
}

/** Set hash version, that will be used in directory index.
 *
 * @param root_info             pointer to root info structure of index
 * @param version               hash algorithm version
 */
void ext4_directory_dx_root_info_set_hash_version(
                ext4_directory_dx_root_info_t *root_info, uint8_t version)
{
        root_info->hash_version = version;
}

/** Get length of root_info structure in bytes.
 *
 * @param root_info     pointer to root info structure of index
 * @return                      length of the structure
 */
uint8_t ext4_directory_dx_root_info_get_info_length(
                ext4_directory_dx_root_info_t *root_info)
{
        return root_info->info_length;
}

/** Set length of root_info structure in bytes.
 *
 * @param root_info             pointer to root info structure of index
 * @param info_length   length of the structure
 */
void ext4_directory_dx_root_info_set_info_length(
                ext4_directory_dx_root_info_t *root_info, uint8_t info_length)
{
        root_info->info_length = info_length;
}

/** Get number of indirect levels of HTree.
 *
 * @param root_info     pointer to root info structure of index
 * @return                      height of HTree (actually only 0 or 1)
 */
uint8_t ext4_directory_dx_root_info_get_indirect_levels(
                ext4_directory_dx_root_info_t *root_info)
{
        return root_info->indirect_levels;
}

/** Set number of indirect levels of HTree.
 *
 * @param root_info     pointer to root info structure of index
 * @param levels        height of HTree (actually only 0 or 1)
 */
void ext4_directory_dx_root_info_set_indirect_levels(
                ext4_directory_dx_root_info_t *root_info, uint8_t levels)
{
        root_info->indirect_levels = levels;
}

/** Get maximum number of index node entries.
 *
 * @param countlimit    pointer to counlimit structure
 * @return                              maximum of entries in node
 */
uint16_t ext4_directory_dx_countlimit_get_limit(
                ext4_directory_dx_countlimit_t *countlimit)
{
        return uint16_t_le2host(countlimit->limit);
}

/** Set maximum number of index node entries.
 *
 * @param countlimit    pointer to counlimit structure
 * @param limit                 maximum of entries in node
 */
void ext4_directory_dx_countlimit_set_limit(
                ext4_directory_dx_countlimit_t *countlimit, uint16_t limit)
{
        countlimit->limit = host2uint16_t_le(limit);
}

/** Get current number of index node entries.
 *
 * @param countlimit    pointer to counlimit structure
 * @return                              number of entries in node
 */
uint16_t ext4_directory_dx_countlimit_get_count(
                ext4_directory_dx_countlimit_t *countlimit)
{
        return uint16_t_le2host(countlimit->count);
}

/** Set current number of index node entries.
 *
 * @param countlimit    pointer to counlimit structure
 * @param count                 number of entries in node
 */
void ext4_directory_dx_countlimit_set_count(
                ext4_directory_dx_countlimit_t *countlimit, uint16_t count)
{
        countlimit->count = host2uint16_t_le(count);
}

/** Get hash value of index entry.
 *
 * @param entry         pointer to index entry
 * @return          hash value
 */
uint32_t ext4_directory_dx_entry_get_hash(ext4_directory_dx_entry_t *entry)
{
        return uint32_t_le2host(entry->hash);
}


/** Set hash value of index entry.
 *
 * @param entry         pointer to index entry
 * @param hash          hash value
 */
void ext4_directory_dx_entry_set_hash(ext4_directory_dx_entry_t *entry,
                uint32_t hash)
{
        entry->hash = host2uint32_t_le(hash);
}

/** Get block address where child node is located.
 *
 * @param entry         pointer to index entry
 * @return          block address of child node
 */
uint32_t ext4_directory_dx_entry_get_block(ext4_directory_dx_entry_t *entry)
{
        return uint32_t_le2host(entry->block);
}

/** Set block address where child node is located.
 *
 * @param entry         pointer to index entry
 * @param block         block address of child node
 */
void ext4_directory_dx_entry_set_block(ext4_directory_dx_entry_t *entry,
                uint32_t block)
{
        entry->block = host2uint32_t_le(block);
}


/**************************************************************************/

/** Initialize index structure of new directory.
 *
 * @param dir   pointer to directory i-node
 * @return              error code
 */
int ext4_directory_dx_init(ext4_inode_ref_t *dir)
{
        int rc;

        // Load block 0, where will be index root located
        uint32_t fblock;
        rc = ext4_filesystem_get_inode_data_block_index(dir, 0, &fblock);
        if (rc != EOK) {
                return rc;
        }

        block_t *block;
        rc = block_get(&block, dir->fs->device, fblock, BLOCK_FLAGS_NONE);
        if (rc != EOK) {
                return rc;
        }

        // Initialize pointers to data structures
        ext4_directory_dx_root_t *root = block->data;
        ext4_directory_dx_root_info_t *info = &(root->info);

        // Initialize root info structure
        uint8_t hash_version =
                        ext4_superblock_get_default_hash_version(dir->fs->superblock);

        ext4_directory_dx_root_info_set_hash_version(info, hash_version);
        ext4_directory_dx_root_info_set_indirect_levels(info, 0);
        ext4_directory_dx_root_info_set_info_length(info, 8);

        // Set limit and current number of entries
        ext4_directory_dx_countlimit_t *countlimit =
                        (ext4_directory_dx_countlimit_t *)&root->entries;
        ext4_directory_dx_countlimit_set_count(countlimit, 1);

        uint32_t block_size = ext4_superblock_get_block_size(dir->fs->superblock);
        uint32_t entry_space = block_size - 2 * sizeof(ext4_directory_dx_dot_entry_t)
                - sizeof(ext4_directory_dx_root_info_t);
        uint16_t root_limit = entry_space / sizeof(ext4_directory_dx_entry_t);
        ext4_directory_dx_countlimit_set_limit(countlimit, root_limit);

        // Append new block, where will be new entries inserted in the future
        uint32_t iblock;
        rc = ext4_filesystem_append_inode_block(dir, &fblock, &iblock);
        if (rc != EOK) {
                block_put(block);
                return rc;
        }

        block_t *new_block;
        rc = block_get(&new_block, dir->fs->device, fblock, BLOCK_FLAGS_NOREAD);
        if (rc != EOK) {
                block_put(block);
                return rc;
        }

        // Fill the whole block with empty entry
        ext4_directory_entry_ll_t *block_entry = new_block->data;
        ext4_directory_entry_ll_set_entry_length(block_entry, block_size);
        ext4_directory_entry_ll_set_inode(block_entry, 0);

        new_block->dirty = true;
        rc = block_put(new_block);
        if (rc != EOK) {
                block_put(block);
                return rc;
        }

        // Connect new block to the only entry in index
        ext4_directory_dx_entry_t *entry = root->entries;
        ext4_directory_dx_entry_set_block(entry, iblock);

        block->dirty = true;

        rc = block_put(block);
        if (rc != EOK) {
                return rc;
        }

        return EOK;
}

/** Initialize hash info structure necessary for index operations.
 *
 * @param hinfo                 pointer to hinfo to be initialized
 * @param root_block    root block (number 0) of index
 * @param sb                    pointer to superblock
 * @param name_len              length of name to be computed hash value from
 * @param name                  name to be computed hash value from
 * @return                              error code
 */
static int ext4_directory_hinfo_init(ext4_hash_info_t *hinfo, block_t *root_block,
                ext4_superblock_t *sb, size_t name_len, const char *name)
{

        ext4_directory_dx_root_t *root = (ext4_directory_dx_root_t *)root_block->data;

        if (root->info.hash_version != EXT4_HASH_VERSION_TEA &&
                        root->info.hash_version != EXT4_HASH_VERSION_HALF_MD4 &&
                        root->info.hash_version != EXT4_HASH_VERSION_LEGACY) {
                return EXT4_ERR_BAD_DX_DIR;
        }

        // Check unused flags
        if (root->info.unused_flags != 0) {
                EXT4FS_DBG("ERR: unused_flags = \%u", root->info.unused_flags);
                return EXT4_ERR_BAD_DX_DIR;
        }

        // Check indirect levels
        if (root->info.indirect_levels > 1) {
                EXT4FS_DBG("ERR: indirect_levels = \%u", root->info.indirect_levels);
                return EXT4_ERR_BAD_DX_DIR;
        }

        // Check if node limit is correct
        uint32_t block_size = ext4_superblock_get_block_size(sb);
        uint32_t entry_space = block_size;
        entry_space -= 2 * sizeof(ext4_directory_dx_dot_entry_t);
        entry_space -= sizeof(ext4_directory_dx_root_info_t);
    entry_space = entry_space / sizeof(ext4_directory_dx_entry_t);

    uint16_t limit = ext4_directory_dx_countlimit_get_limit((ext4_directory_dx_countlimit_t *)&root->entries);
    if (limit != entry_space) {
        return EXT4_ERR_BAD_DX_DIR;
        }

    // Check hash version and modify if necessary
        hinfo->hash_version = ext4_directory_dx_root_info_get_hash_version(&root->info);
        if ((hinfo->hash_version <= EXT4_HASH_VERSION_TEA)
                        && (ext4_superblock_has_flag(sb, EXT4_SUPERBLOCK_FLAGS_UNSIGNED_HASH))) {
                // 3 is magic from ext4 linux implementation
                hinfo->hash_version += 3;
        }

        // Load hash seed from superblock
        hinfo->seed = ext4_superblock_get_hash_seed(sb);

        // Compute hash value of name
        if (name) {
                ext4_hash_string(hinfo, name_len, name);
        }

        return EOK;
}

/** Walk through index tree and load leaf with corresponding hash value.
 *
 * @param hinfo                 initialized hash info structure
 * @param inode_ref     current i-node
 * @param root_block    root block (iblock 0), where is root node located
 * @param dx_block              pointer to leaf node in dx_blocks array
 * @param dx_blocks             array with the whole path from root to leaf
 * @return                              error code
 */
static int ext4_directory_dx_get_leaf(ext4_hash_info_t *hinfo,
                ext4_inode_ref_t *inode_ref, block_t *root_block,
                ext4_directory_dx_block_t **dx_block, ext4_directory_dx_block_t *dx_blocks)
{
        int rc;

        ext4_directory_dx_block_t *tmp_dx_block = dx_blocks;

        ext4_directory_dx_root_t *root = (ext4_directory_dx_root_t *)root_block->data;
        ext4_directory_dx_entry_t *entries = (ext4_directory_dx_entry_t *)&root->entries;

        uint16_t limit = ext4_directory_dx_countlimit_get_limit((ext4_directory_dx_countlimit_t *)entries);
        uint8_t indirect_level = ext4_directory_dx_root_info_get_indirect_levels(&root->info);

        block_t *tmp_block = root_block;
        ext4_directory_dx_entry_t *p, *q, *m, *at;

        // Walk through the index tree
        while (true) {

                uint16_t count = ext4_directory_dx_countlimit_get_count((ext4_directory_dx_countlimit_t *)entries);
                if ((count == 0) || (count > limit)) {
                        return EXT4_ERR_BAD_DX_DIR;
                }


                // Do binary search in every node
                p = entries + 1;
                q = entries + count - 1;

                while (p <= q) {
                        m = p + (q - p) / 2;
                        if (ext4_directory_dx_entry_get_hash(m) > hinfo->hash) {
                                q = m - 1;
                        } else {
                                p = m + 1;
                        }
                }

                at = p - 1;

                // Write results
                tmp_dx_block->block = tmp_block;
                tmp_dx_block->entries = entries;
                tmp_dx_block->position = at;

                // Is algorithm in the leaf?
        if (indirect_level == 0) {
                *dx_block = tmp_dx_block;
                return EOK;
        }

        // Goto child node
                uint32_t next_block = ext4_directory_dx_entry_get_block(at);

        indirect_level--;

        uint32_t fblock;
        rc = ext4_filesystem_get_inode_data_block_index(
                        inode_ref, next_block, &fblock);
        if (rc != EOK) {
                return rc;
        }

        rc = block_get(&tmp_block, inode_ref->fs->device, fblock, BLOCK_FLAGS_NONE);
        if (rc != EOK) {
                return rc;
        }

                entries = ((ext4_directory_dx_node_t *) tmp_block->data)->entries;
                limit = ext4_directory_dx_countlimit_get_limit(
                                (ext4_directory_dx_countlimit_t *)entries);

        uint16_t entry_space = ext4_superblock_get_block_size(inode_ref->fs->superblock)
                        - sizeof(ext4_directory_dx_dot_entry_t);
        entry_space = entry_space / sizeof(ext4_directory_dx_entry_t);


                if (limit != entry_space) {
                        block_put(tmp_block);
                return EXT4_ERR_BAD_DX_DIR;
                }

                ++tmp_dx_block;
        }

        // Unreachable
        return EOK;
}


/** Check if the the next block would be checked during entry search.
 *
 * @param inode_ref                     directory i-node
 * @param hash                          hash value to check
 * @param dx_block                      current block
 * @param dx_blocks                     aray with path from root to leaf node
 * @return                                      error code
 */
static int ext4_directory_dx_next_block(ext4_inode_ref_t *inode_ref, uint32_t hash,
                ext4_directory_dx_block_t *dx_block, ext4_directory_dx_block_t *dx_blocks)
{
        int rc;

    uint32_t num_handles = 0;
    ext4_directory_dx_block_t *p = dx_block;

    // TODO comment
    while (1) {

        p->position++;
        uint16_t count = ext4_directory_dx_countlimit_get_count((ext4_directory_dx_countlimit_t *)p->entries);

        if (p->position < p->entries + count) {
                break;
        }

        if (p == dx_blocks) {
                return 0;
        }

        num_handles++;
        p--;
    }

    // TODO comment
    uint32_t current_hash = ext4_directory_dx_entry_get_hash(p->position);
    if ((hash & 1) == 0) {
        if ((current_hash & ~1) != hash) {
                return 0;
        }
    }

    // TODO comment
    while (num_handles--) {

        uint32_t block_idx = ext4_directory_dx_entry_get_block(p->position);
        uint32_t block_addr;
        rc = ext4_filesystem_get_inode_data_block_index(inode_ref, block_idx, &block_addr);
        if (rc != EOK) {
                return rc;
        }

        block_t *block;
        rc = block_get(&block, inode_ref->fs->device, block_addr, BLOCK_FLAGS_NONE);
        if (rc != EOK) {
                return rc;
        }

        p++;

        block_put(p->block);
        p->block = block;
        p->entries = ((ext4_directory_dx_node_t *) block->data)->entries;
        p->position = p->entries;
    }

    return 1;

}

/** Try to find directory entry using directory index.
 *
 * @param result                output value - if entry will be found,
 *                      than will be passed through this parameter
 * @param inode_ref             directory i-node
 * @param name_len              length of name to be found
 * @param name                  name to be found
 * @return                              error code
 */
int ext4_directory_dx_find_entry(ext4_directory_search_result_t *result,
                ext4_inode_ref_t *inode_ref, size_t name_len, const char *name)
{
        int rc;

        // Load direct block 0 (index root)
        uint32_t root_block_addr;
        rc = ext4_filesystem_get_inode_data_block_index(inode_ref, 0, &root_block_addr);
        if (rc != EOK) {
                return rc;
        }

        ext4_filesystem_t *fs = inode_ref->fs;

        block_t *root_block;
        rc = block_get(&root_block, fs->device, root_block_addr, BLOCK_FLAGS_NONE);
        if (rc != EOK) {
                return rc;
        }

        // Initialize hash info (compute hash value)
        ext4_hash_info_t hinfo;
        rc = ext4_directory_hinfo_init(&hinfo, root_block, fs->superblock, name_len, name);
        if (rc != EOK) {
                block_put(root_block);
                return EXT4_ERR_BAD_DX_DIR;
        }

        // Hardcoded number 2 means maximum height of index tree, specified in linux driver
        ext4_directory_dx_block_t dx_blocks[2];
        ext4_directory_dx_block_t *dx_block, *tmp;
        rc = ext4_directory_dx_get_leaf(&hinfo, inode_ref, root_block, &dx_block, dx_blocks);
        if (rc != EOK) {
                block_put(root_block);
                return EXT4_ERR_BAD_DX_DIR;
        }

        do {
                // Load leaf block
                uint32_t leaf_block_idx = ext4_directory_dx_entry_get_block(dx_block->position);
                uint32_t leaf_block_addr;
        rc = ext4_filesystem_get_inode_data_block_index(inode_ref, leaf_block_idx, &leaf_block_addr);
        if (rc != EOK) {
                goto cleanup;
        }

        block_t *leaf_block;
                rc = block_get(&leaf_block, fs->device, leaf_block_addr, BLOCK_FLAGS_NONE);
                if (rc != EOK) {
                        goto cleanup;
                }

                // Linear search inside block
                ext4_directory_entry_ll_t *res_dentry;
                rc = ext4_directory_find_in_block(leaf_block, fs->superblock, name_len, name, &res_dentry);

                // Found => return it
                if (rc == EOK) {
                        result->block = leaf_block;
                        result->dentry = res_dentry;
                        goto cleanup;
                }

                // Not found, leave untouched
                block_put(leaf_block);

                if (rc != ENOENT) {
                        goto cleanup;
                }

                // check if the next block could be checked
                rc = ext4_directory_dx_next_block(inode_ref, hinfo.hash, dx_block, &dx_blocks[0]);
                if (rc < 0) {
                        goto cleanup;
                }

        } while (rc == 1);

        // Entry not found
        rc = ENOENT;

cleanup:

        // The whole path must be released (preventing memory leak)
        tmp = dx_blocks;
        while (tmp <= dx_block) {
                block_put(tmp->block);
                ++tmp;
        }
        return rc;
}

/** Compare function used to pass in quicksort implementation.
 *
 * It can compare two entries by hash value.
 *
 * @param arg1          first entry
 * @param arg2          second entry
 * @param dummy         unused parameter, can be NULL
 * @return                      classic compare result (0: equal, -1: arg1 < arg2, 1: arg1 > arg2)
 */
static int ext4_directory_dx_entry_comparator(void *arg1, void *arg2, void *dummy)
{
        ext4_dx_sort_entry_t *entry1 = arg1;
        ext4_dx_sort_entry_t *entry2 = arg2;

        if (entry1->hash == entry2->hash) {
                return 0;
        }

        if (entry1->hash < entry2->hash) {
                return -1;
        } else {
                return 1;
        }

}

/** Insert new index entry to block.
 *
 * Note that space for new entry must be checked by caller.
 *
 * @param index_block           block where to insert new entry
 * @param hash                          hash value covered by child node
 * @param iblock                        logical number of child block
 *
 */
static void ext4_directory_dx_insert_entry(
                ext4_directory_dx_block_t *index_block, uint32_t hash, uint32_t iblock)
{
        ext4_directory_dx_entry_t *old_index_entry = index_block->position;
        ext4_directory_dx_entry_t *new_index_entry = old_index_entry + 1;

        ext4_directory_dx_countlimit_t *countlimit =
                        (ext4_directory_dx_countlimit_t *)index_block->entries;
        uint32_t count = ext4_directory_dx_countlimit_get_count(countlimit);

        ext4_directory_dx_entry_t *start_index = index_block->entries;
        size_t bytes = (void *)(start_index + count) - (void *)(new_index_entry);

        memmove(new_index_entry + 1, new_index_entry, bytes);

        ext4_directory_dx_entry_set_block(new_index_entry, iblock);
        ext4_directory_dx_entry_set_hash(new_index_entry, hash);

        ext4_directory_dx_countlimit_set_count(countlimit, count + 1);

        index_block->block->dirty = true;
}

/** Split directory entries to two parts preventing node overflow.
 *
 * @param inode_ref                     directory i-node
 * @param hinfo                         hash info
 * @param old_data_block        block with data to be split
 * @param index_block           block where index entries are located
 * @param new_data_block        output value for newly allocated data block
 */
static int ext4_directory_dx_split_data(ext4_inode_ref_t *inode_ref,
                ext4_hash_info_t *hinfo, block_t *old_data_block,
                ext4_directory_dx_block_t *index_block, block_t **new_data_block)
{
        int rc = EOK;

        // Allocate buffer for directory entries
        uint32_t block_size =
                        ext4_superblock_get_block_size(inode_ref->fs->superblock);
        void *entry_buffer = malloc(block_size);
        if (entry_buffer == NULL) {
                return ENOMEM;
        }

        // dot entry has the smallest size available
        uint32_t max_entry_count =  block_size / sizeof(ext4_directory_dx_dot_entry_t);

        // Allocate sort entry
        ext4_dx_sort_entry_t *sort_array = malloc(max_entry_count * sizeof(ext4_dx_sort_entry_t));
        if (sort_array == NULL) {
                free(entry_buffer);
                return ENOMEM;
        }

        uint32_t idx = 0;
        uint32_t real_size = 0;

        // Initialize hinfo
        ext4_hash_info_t tmp_hinfo;
        memcpy(&tmp_hinfo, hinfo, sizeof(ext4_hash_info_t));

        // Load all valid entries to the buffer
        ext4_directory_entry_ll_t *dentry = old_data_block->data;
        void *entry_buffer_ptr = entry_buffer;
        while ((void *)dentry < old_data_block->data + block_size) {

                // Read only valid entries
                if (ext4_directory_entry_ll_get_inode(dentry) != 0) {

                        uint8_t len = ext4_directory_entry_ll_get_name_length(
                                        inode_ref->fs->superblock, dentry);
                        ext4_hash_string(&tmp_hinfo, len, (char *)dentry->name);

                        uint32_t rec_len = 8 + len;

                        if ((rec_len % 4) != 0) {
                                rec_len += 4 - (rec_len % 4);
                        }

                        memcpy(entry_buffer_ptr, dentry, rec_len);

                        sort_array[idx].dentry = entry_buffer_ptr;
                        sort_array[idx].rec_len = rec_len;
                        sort_array[idx].hash = tmp_hinfo.hash;

                        entry_buffer_ptr += rec_len;
                        real_size += rec_len;
                        idx++;
                }

                dentry = (void *)dentry + ext4_directory_entry_ll_get_entry_length(dentry);
        }

        // Sort all entries
        qsort(sort_array, idx, sizeof(ext4_dx_sort_entry_t),
                        ext4_directory_dx_entry_comparator, NULL);

        // Allocate new block for store the second part of entries
        uint32_t new_fblock;
        uint32_t new_iblock;
        rc = ext4_filesystem_append_inode_block(inode_ref, &new_fblock, &new_iblock);
        if (rc != EOK) {
                free(sort_array);
                free(entry_buffer);
                return rc;
        }

        // Load new block
        block_t *new_data_block_tmp;
        rc = block_get(&new_data_block_tmp, inode_ref->fs->device,
                        new_fblock, BLOCK_FLAGS_NOREAD);
        if (rc != EOK) {
                free(sort_array);
                free(entry_buffer);
                return rc;
        }

        // Distribute entries to two blocks (by size)
        // Compute the half
        uint32_t new_hash = 0;
        uint32_t current_size = 0;
        uint32_t mid = 0;
        for (uint32_t i = 0; i < idx; ++i) {
                if ((current_size + sort_array[i].rec_len) > (real_size / 2)) {
                        new_hash = sort_array[i].hash;
                        mid = i;
                        break;
                }

                current_size += sort_array[i].rec_len;
        }

        // Check hash collision
        uint32_t continued = 0;
        if (new_hash == sort_array[mid-1].hash) {
                continued = 1;
        }

        uint32_t offset = 0;
        void *ptr;

        // First part - to the old block
        for (uint32_t i = 0; i < mid; ++i) {
                ptr = old_data_block->data + offset;
                memcpy(ptr, sort_array[i].dentry, sort_array[i].rec_len);

                ext4_directory_entry_ll_t *tmp = ptr;
                if (i < (mid - 1)) {
                        ext4_directory_entry_ll_set_entry_length(tmp, sort_array[i].rec_len);
                } else {
                        ext4_directory_entry_ll_set_entry_length(tmp, block_size - offset);
                }

                offset += sort_array[i].rec_len;
        }

        // Second part - to the new block
        offset = 0;
        for (uint32_t i = mid; i < idx; ++i) {
                ptr = new_data_block_tmp->data + offset;
                memcpy(ptr, sort_array[i].dentry, sort_array[i].rec_len);

                ext4_directory_entry_ll_t *tmp = ptr;
                if (i < (idx - 1)) {
                        ext4_directory_entry_ll_set_entry_length(tmp, sort_array[i].rec_len);
                } else {
                        ext4_directory_entry_ll_set_entry_length(tmp, block_size - offset);
                }

                offset += sort_array[i].rec_len;
        }

        // Do some steps to finish operation
        old_data_block->dirty = true;
        new_data_block_tmp->dirty = true;

        free(sort_array);
        free(entry_buffer);

        ext4_directory_dx_insert_entry(index_block, new_hash + continued, new_iblock);

        *new_data_block = new_data_block_tmp;

        return EOK;
}

/** TODO start comments from here
 *
 */
static int ext4_directory_dx_split_index(ext4_filesystem_t *fs,
                ext4_inode_ref_t *inode_ref, ext4_directory_dx_block_t *dx_blocks,
                ext4_directory_dx_block_t *dx_block)
{
        int rc;

        ext4_directory_dx_entry_t *entries;
        if (dx_block == dx_blocks) {
                entries = ((ext4_directory_dx_root_t *) dx_block->block->data)->entries;
        } else {
                entries = ((ext4_directory_dx_node_t *) dx_block->block->data)->entries;
        }

        ext4_directory_dx_countlimit_t *countlimit =
                        (ext4_directory_dx_countlimit_t *)entries;
        uint16_t leaf_limit = ext4_directory_dx_countlimit_get_limit(countlimit);
        uint16_t leaf_count = ext4_directory_dx_countlimit_get_count(countlimit);

        // Check if is necessary to split index block
        if (leaf_limit == leaf_count) {
                EXT4FS_DBG("need to split index block !!!");

                unsigned int levels = dx_block - dx_blocks;

                ext4_directory_dx_entry_t *root_entries =
                                        ((ext4_directory_dx_root_t *)dx_blocks[0].block->data)->entries;

                ext4_directory_dx_countlimit_t *root_countlimit =
                                (ext4_directory_dx_countlimit_t *)root_entries;
                uint16_t root_limit =
                                ext4_directory_dx_countlimit_get_limit(root_countlimit);
                uint16_t root_count =
                                ext4_directory_dx_countlimit_get_count(root_countlimit);

                if ((levels > 0) && (root_limit == root_count)) {
                        EXT4FS_DBG("Directory index is full");
                        return ENOSPC;
                }

                uint32_t new_fblock;
                uint32_t new_iblock;
                rc =  ext4_filesystem_append_inode_block(
                                inode_ref, &new_fblock, &new_iblock);
                if (rc != EOK) {
                        return rc;
                }

                // New block allocated
                block_t * new_block;
                rc = block_get(&new_block, fs->device, new_fblock, BLOCK_FLAGS_NOREAD);
                if (rc != EOK) {
                        return rc;
                }

                ext4_directory_dx_node_t *new_node = new_block->data;
                ext4_directory_dx_entry_t *new_entries = new_node->entries;

                uint32_t block_size = ext4_superblock_get_block_size(fs->superblock);

                if (levels > 0) {
                        EXT4FS_DBG("split index leaf node");
                        uint32_t count_left = leaf_count / 2;
                        uint32_t count_right = leaf_count - count_left;
                        uint32_t hash_right =
                                        ext4_directory_dx_entry_get_hash(entries + count_left);

                        memcpy((void *) new_entries, (void *) (entries + count_left),
                                        count_right * sizeof(ext4_directory_dx_entry_t));

                        ext4_directory_dx_countlimit_t *left_countlimit =
                                        (ext4_directory_dx_countlimit_t *)entries;
                        ext4_directory_dx_countlimit_t *right_countlimit =
                                        (ext4_directory_dx_countlimit_t *)new_entries;

                        ext4_directory_dx_countlimit_set_count(left_countlimit, count_left);
                        ext4_directory_dx_countlimit_set_count(right_countlimit, count_right);

                        uint32_t entry_space = block_size - sizeof(ext4_fake_directory_entry_t);
                        uint32_t node_limit = entry_space / sizeof(ext4_directory_dx_entry_t);
                        ext4_directory_dx_countlimit_set_limit(right_countlimit, node_limit);

                        // Which index block is target for new entry
                        uint32_t position_index = (dx_block->position - dx_block->entries);
                        if (position_index >= count_left) {

                                dx_block->block->dirty = true;

                                block_t *block_tmp = dx_block->block;
                                dx_block->block = new_block;
                                dx_block->position = new_entries + position_index - count_left;
                                dx_block->entries = new_entries;

                                new_block = block_tmp;

                        }

                        ext4_directory_dx_insert_entry(dx_blocks, hash_right, new_iblock);

                        return block_put(new_block);

                } else {
                        EXT4FS_DBG("create second level");

                        memcpy((void *) new_entries, (void *) entries,
                                        leaf_count * sizeof(ext4_directory_dx_entry_t));

                        ext4_directory_dx_countlimit_t *new_countlimit =
                                        (ext4_directory_dx_countlimit_t *)new_entries;

                        uint32_t entry_space = block_size - sizeof(ext4_fake_directory_entry_t);
                        uint32_t node_limit = entry_space / sizeof(ext4_directory_dx_entry_t);
                        ext4_directory_dx_countlimit_set_limit(new_countlimit, node_limit);

                        // Set values in root node
                        ext4_directory_dx_countlimit_t *new_root_countlimit =
                                        (ext4_directory_dx_countlimit_t *)entries;

                        ext4_directory_dx_countlimit_set_count(new_root_countlimit, 1);
                        ext4_directory_dx_entry_set_block(entries, new_iblock);

                        ((ext4_directory_dx_root_t *)dx_blocks[0].block->data)->info.indirect_levels = 1;

                        /* Add new access path frame */
                        dx_block = dx_blocks + 1;
                        dx_block->position = dx_block->position - entries + new_entries;
                        dx_block->entries = new_entries;
                        dx_block->block = new_block;
                }

        }

        return EOK;
}

int ext4_directory_dx_add_entry(ext4_inode_ref_t *parent,
                ext4_inode_ref_t *child, const char *name)
{
        int rc = EOK;
        int rc2 = EOK;

        // get direct block 0 (index root)
        uint32_t root_block_addr;
        rc = ext4_filesystem_get_inode_data_block_index(parent, 0, &root_block_addr);
        if (rc != EOK) {
                return rc;
        }

        ext4_filesystem_t *fs = parent->fs;

        block_t *root_block;
        rc = block_get(&root_block, fs->device, root_block_addr, BLOCK_FLAGS_NONE);
        if (rc != EOK) {
                return rc;
        }

        uint32_t name_len = strlen(name);
        ext4_hash_info_t hinfo;
        rc = ext4_directory_hinfo_init(&hinfo, root_block, fs->superblock, name_len, name);
        if (rc != EOK) {
                block_put(root_block);
                EXT4FS_DBG("hinfo initialization error");
                return EXT4_ERR_BAD_DX_DIR;
        }

        // Hardcoded number 2 means maximum height of index tree !!!
        ext4_directory_dx_block_t dx_blocks[2];
        ext4_directory_dx_block_t *dx_block, *dx_it;
        rc = ext4_directory_dx_get_leaf(&hinfo, parent, root_block, &dx_block, dx_blocks);
        if (rc != EOK) {
                EXT4FS_DBG("get leaf error");
                rc = EXT4_ERR_BAD_DX_DIR;
                goto release_index;
        }


        // Try to insert to existing data block
        uint32_t leaf_block_idx = ext4_directory_dx_entry_get_block(dx_block->position);
        uint32_t leaf_block_addr;
        rc = ext4_filesystem_get_inode_data_block_index(parent, leaf_block_idx, &leaf_block_addr);
        if (rc != EOK) {
                goto release_index;
        }


        block_t *target_block;
        rc = block_get(&target_block, fs->device, leaf_block_addr, BLOCK_FLAGS_NONE);
        if (rc != EOK) {
                goto release_index;
        }


        rc = ext4_directory_try_insert_entry(fs->superblock, target_block, child, name, name_len);
        if (rc == EOK) {
                goto release_target_index;
        }

    EXT4FS_DBG("no free space found");

        rc = ext4_directory_dx_split_index(fs, parent, dx_blocks, dx_block);
        if (rc != EOK) {
                goto release_target_index;
        }

        block_t *new_block = NULL;
        rc = ext4_directory_dx_split_data(parent, &hinfo, target_block, dx_block, &new_block);
        if (rc != EOK) {
                rc2 = rc;
                goto release_target_index;
        }

        // Where to save new entry
        uint32_t new_block_hash = ext4_directory_dx_entry_get_hash(dx_block->position + 1);
        if (hinfo.hash >= new_block_hash) {
                rc = ext4_directory_try_insert_entry(fs->superblock, new_block, child, name, name_len);
        } else {
                rc = ext4_directory_try_insert_entry(fs->superblock, target_block, child, name, name_len);
        }




        rc = block_put(new_block);
        if (rc != EOK) {
                EXT4FS_DBG("error writing new block");
                return rc;
        }

release_target_index:

        rc2 = rc;

        rc = block_put(target_block);
        if (rc != EOK) {
                EXT4FS_DBG("error writing target block");
                return rc;
        }

release_index:

        if (rc != EOK) {
                rc2 = rc;
        }

        dx_it = dx_blocks;

        while (dx_it <= dx_block) {
                rc = block_put(dx_it->block);
                if (rc != EOK) {
                        EXT4FS_DBG("error writing index block");
                        return rc;
                }
                dx_it++;
        }

        return rc2;
}


/**
 * @}
 */