source: mainline/uspace/lib/ext4/src/directory_index.c@ fcb0d76

/*
 * 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 <mem.h>
#include <sort.h>
#include <stdlib.h>
#include <str.h>
#include "ext4/directory.h"
#include "ext4/directory_index.h"
#include "ext4/filesystem.h"
#include "ext4/hash.h"
#include "ext4/inode.h"
#include "ext4/superblock.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)
{
        /* Load block 0, where will be index root located */
        uint32_t fblock;
        int 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;
        
        return block_put(block);
}

/** 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)
                return EXT4_ERR_BAD_DX_DIR;
        
        /* Check indirect levels */
        if (root->info.indirect_levels > 1)
                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)
{
        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;
        ext4_directory_dx_entry_t *q;
        ext4_directory_dx_entry_t *m;
        ext4_directory_dx_entry_t *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;
                int 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 Array 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)
{
        uint32_t num_handles = 0;
        ext4_directory_dx_block_t *p = dx_block;
        
        /* Try to find data block with next bunch of entries */
        while (true) {
                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 EOK;
                
                num_handles++;
                p--;
        }
        
        /* Check hash collision (if not occured - no next block cannot be used) */
        uint32_t current_hash = ext4_directory_dx_entry_get_hash(p->position);
        if ((hash & 1) == 0) {
                if ((current_hash & ~1) != hash)
                        return 0;
        }
        
        /* Fill new path */
        while (num_handles--) {
                uint32_t block_idx =
                    ext4_directory_dx_entry_get_block(p->position);
                uint32_t block_addr;
                
                int 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++;
                
                /* Don't forget to put old block (prevent memory leak) */
                rc = block_put(p->block);
                if (rc != EOK)
                        return rc;
                
                p->block = block;
                p->entries = ((ext4_directory_dx_node_t *) block->data)->entries;
                p->position = p->entries;
        }
        
        return ENOENT;
}

/** 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)
{
        /* Load direct block 0 (index root) */
        uint32_t root_block_addr;
        int rc2;
        int 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 the Linux driver.
         */
        ext4_directory_dx_block_t dx_blocks[2];
        ext4_directory_dx_block_t *dx_block;
        ext4_directory_dx_block_t *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 */
                rc2 = block_put(leaf_block);
                if (rc2 != EOK)
                        goto cleanup;
                
                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 != EOK)
                        goto cleanup;

        } while (rc == ENOENT);
        
        /* Entry not found */
        rc = ENOENT;
        
cleanup:
        /* The whole path must be released (preventing memory leak) */
        tmp = dx_blocks;
        
        while (tmp <= dx_block) {
                rc2 = block_put(tmp->block);
                if (rc == EOK && rc2 != EOK)
                        rc = rc2;
                ++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;
}

/** Split index node and maybe some parent nodes in the tree hierarchy.
 *
 * @param inode_ref Directory i-node
 * @param dx_blocks Array with path from root to leaf node
 * @param dx_block  Leaf block to be split if needed
 *
 * @return Error code
 *
 */
static int ext4_directory_dx_split_index(ext4_inode_ref_t *inode_ref,
                ext4_directory_dx_block_t *dx_blocks, ext4_directory_dx_block_t *dx_block)
{
        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) {
                size_t 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);
                
                /* Linux limitation */
                if ((levels > 0) && (root_limit == root_count))
                        return ENOSPC;
                
                /* Add new block to directory */
                uint32_t new_fblock;
                uint32_t new_iblock;
                int rc = ext4_filesystem_append_inode_block(inode_ref,
                    &new_fblock, &new_iblock);
                if (rc != EOK)
                        return rc;
                
                /* load new block */
                block_t *new_block;
                rc = block_get(&new_block, inode_ref->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(inode_ref->fs->superblock);
                
                /* Split leaf node */
                if (levels > 0) {
                        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);
                        
                        /* Copy data to new node */
                        memcpy((void *) new_entries, (void *) (entries + count_left),
                            count_right * sizeof(ext4_directory_dx_entry_t));
                        
                        /* Initialize new node */
                        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;
                        }
                        
                        /* Finally insert new entry */
                        ext4_directory_dx_insert_entry(dx_blocks, hash_right, new_iblock);
                        
                        return block_put(new_block);
                } else {
                        /* Create second level index */
                        
                        /* Copy data from root to child block */
                        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 entry to the path */
                        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;
}

/** Add new entry to indexed directory
 *
 * @param parent Directory i-node
 * @param child  I-node to be referenced from directory entry
 * @param name   Name of new directory entry
 *
 * @return Error code
 *
 */
int ext4_directory_dx_add_entry(ext4_inode_ref_t *parent,
    ext4_inode_ref_t *child, const char *name)
{
        int rc2 = EOK;
        
        /* Get direct block 0 (index root) */
        uint32_t root_block_addr;
        int 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;
        
        /* Initialize hinfo structure (mainly compute hash) */
        uint32_t name_len = str_size(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);
                return EXT4_ERR_BAD_DX_DIR;
        }
        
        /*
         * Hardcoded number 2 means maximum height of index
         * tree defined in Linux.
         */
        ext4_directory_dx_block_t dx_blocks[2];
        ext4_directory_dx_block_t *dx_block;
        ext4_directory_dx_block_t *dx_it;
        
        rc = ext4_directory_dx_get_leaf(&hinfo, parent, root_block,
            &dx_block, dx_blocks);
        if (rc != EOK) {
                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;
        
        /* Check if insert operation passed */
        rc = ext4_directory_try_insert_entry(fs->superblock, target_block, child,
            name, name_len);
        if (rc == EOK)
                goto release_target_index;
        
        /*
         * Check if there is needed to split index node
         * (and recursively also parent nodes)
         */
        rc = ext4_directory_dx_split_index(parent, dx_blocks, dx_block);
        if (rc != EOK)
                goto release_target_index;
        
        /* Split entries to two blocks (includes sorting by hash value) */
        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);
        
        /* Cleanup */
        rc = block_put(new_block);
        if (rc != EOK)
                return rc;
        
        /* Cleanup operations */
        
release_target_index:
        rc2 = rc;
        
        rc = block_put(target_block);
        if (rc != EOK)
                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)
                        return rc;
                
                dx_it++;
        }
        
        return rc2;
}

/**
 * @}
 */