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diff --git a/src/ext4_fs.c b/src/ext4_fs.c
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+++ b/src/ext4_fs.c
@@ -0,0 +1,1713 @@
+/*
+ * Copyright (c) 2013 Grzegorz Kostka (kostka.grzegorz@gmail.com)
+ *
+ *
+ * HelenOS:
+ * Copyright (c) 2012 Martin Sucha
+ * 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 lwext4
+ * @{
+ */
+/**
+ * @file  ext4_fs.c
+ * @brief More complex filesystem functions.
+ */
+
+#include "ext4_config.h"
+#include "ext4_types.h"
+#include "ext4_fs.h"
+#include "ext4_errno.h"
+#include "ext4_blockdev.h"
+#include "ext4_super.h"
+#include "ext4_crc32.h"
+#include "ext4_debug.h"
+#include "ext4_block_group.h"
+#include "ext4_balloc.h"
+#include "ext4_bitmap.h"
+#include "ext4_inode.h"
+#include "ext4_ialloc.h"
+#include "ext4_extent.h"
+
+#include <string.h>
+
+int ext4_fs_init(struct ext4_fs *fs, struct ext4_blockdev *bdev)
+{
+	int r, i;
+	uint16_t tmp;
+	uint32_t bsize;
+	bool read_only = false;
+
+	ext4_assert(fs && bdev);
+
+	fs->bdev = bdev;
+
+	r = ext4_sb_read(fs->bdev, &fs->sb);
+	if (r != EOK)
+		return r;
+
+	if (!ext4_sb_check(&fs->sb))
+		return ENOTSUP;
+
+	bsize = ext4_sb_get_block_size(&fs->sb);
+	if (bsize > EXT4_MAX_BLOCK_SIZE)
+		return ENXIO;
+
+	r = ext4_fs_check_features(fs, &read_only);
+	if (r != EOK)
+		return r;
+
+	if (read_only)
+		return ENOTSUP;
+
+	/* Compute limits for indirect block levels */
+	uint32_t blocks_id = bsize / sizeof(uint32_t);
+
+	fs->inode_block_limits[0] = EXT4_INODE_DIRECT_BLOCK_COUNT;
+	fs->inode_blocks_per_level[0] = 1;
+
+	for (i = 1; i < 4; i++) {
+		fs->inode_blocks_per_level[i] =
+		    fs->inode_blocks_per_level[i - 1] * blocks_id;
+		fs->inode_block_limits[i] = fs->inode_block_limits[i - 1] +
+					    fs->inode_blocks_per_level[i];
+	}
+
+	/*Validate FS*/
+	tmp = ext4_get16(&fs->sb, state);
+	if (tmp & EXT4_SUPERBLOCK_STATE_ERROR_FS)
+		ext4_dbg(DEBUG_FS, DBG_WARN
+				"last umount error: superblock fs_error flag\n");
+
+
+	/* Mark system as mounted */
+	ext4_set16(&fs->sb, state, EXT4_SUPERBLOCK_STATE_ERROR_FS);
+	r = ext4_sb_write(fs->bdev, &fs->sb);
+	if (r != EOK)
+		return r;
+
+	/*Update mount count*/
+	ext4_set16(&fs->sb, mount_count, ext4_get16(&fs->sb, mount_count) + 1);
+
+	return r;
+}
+
+int ext4_fs_fini(struct ext4_fs *fs)
+{
+	ext4_assert(fs);
+
+	/*Set superblock state*/
+	ext4_set16(&fs->sb, state, EXT4_SUPERBLOCK_STATE_VALID_FS);
+
+	return ext4_sb_write(fs->bdev, &fs->sb);
+}
+
+static void ext4_fs_debug_features_inc(uint32_t features_incompatible)
+{
+	if (features_incompatible & EXT4_FINCOM_COMPRESSION)
+		ext4_dbg(DEBUG_FS, DBG_NONE "compression\n");
+	if (features_incompatible & EXT4_FINCOM_FILETYPE)
+		ext4_dbg(DEBUG_FS, DBG_NONE "filetype\n");
+	if (features_incompatible & EXT4_FINCOM_RECOVER)
+		ext4_dbg(DEBUG_FS, DBG_NONE "recover\n");
+	if (features_incompatible & EXT4_FINCOM_JOURNAL_DEV)
+		ext4_dbg(DEBUG_FS, DBG_NONE "journal_dev\n");
+	if (features_incompatible & EXT4_FINCOM_META_BG)
+		ext4_dbg(DEBUG_FS, DBG_NONE "meta_bg\n");
+	if (features_incompatible & EXT4_FINCOM_EXTENTS)
+		ext4_dbg(DEBUG_FS, DBG_NONE "extents\n");
+	if (features_incompatible & EXT4_FINCOM_64BIT)
+		ext4_dbg(DEBUG_FS, DBG_NONE "64bit\n");
+	if (features_incompatible & EXT4_FINCOM_MMP)
+		ext4_dbg(DEBUG_FS, DBG_NONE "mnp\n");
+	if (features_incompatible & EXT4_FINCOM_FLEX_BG)
+		ext4_dbg(DEBUG_FS, DBG_NONE "flex_bg\n");
+	if (features_incompatible & EXT4_FINCOM_EA_INODE)
+		ext4_dbg(DEBUG_FS, DBG_NONE "ea_inode\n");
+	if (features_incompatible & EXT4_FINCOM_DIRDATA)
+		ext4_dbg(DEBUG_FS, DBG_NONE "dirdata\n");
+	if (features_incompatible & EXT4_FINCOM_BG_USE_META_CSUM)
+		ext4_dbg(DEBUG_FS, DBG_NONE "meta_csum\n");
+	if (features_incompatible & EXT4_FINCOM_LARGEDIR)
+		ext4_dbg(DEBUG_FS, DBG_NONE "largedir\n");
+	if (features_incompatible & EXT4_FINCOM_INLINE_DATA)
+		ext4_dbg(DEBUG_FS, DBG_NONE "inline_data\n");
+}
+static void ext4_fs_debug_features_comp(uint32_t features_compatible)
+{
+	if (features_compatible & EXT4_FCOM_DIR_PREALLOC)
+		ext4_dbg(DEBUG_FS, DBG_NONE "dir_prealloc\n");
+	if (features_compatible & EXT4_FCOM_IMAGIC_INODES)
+		ext4_dbg(DEBUG_FS, DBG_NONE "imagic_inodes\n");
+	if (features_compatible & EXT4_FCOM_HAS_JOURNAL)
+		ext4_dbg(DEBUG_FS, DBG_NONE "has_journal\n");
+	if (features_compatible & EXT4_FCOM_EXT_ATTR)
+		ext4_dbg(DEBUG_FS, DBG_NONE "ext_attr\n");
+	if (features_compatible & EXT4_FCOM_RESIZE_INODE)
+		ext4_dbg(DEBUG_FS, DBG_NONE "resize_inode\n");
+	if (features_compatible & EXT4_FCOM_DIR_INDEX)
+		ext4_dbg(DEBUG_FS, DBG_NONE "dir_index\n");
+}
+
+static void ext4_fs_debug_features_ro(uint32_t features_ro)
+{
+	if (features_ro & EXT4_FRO_COM_SPARSE_SUPER)
+		ext4_dbg(DEBUG_FS, DBG_NONE "sparse_super\n");
+	if (features_ro & EXT4_FRO_COM_LARGE_FILE)
+		ext4_dbg(DEBUG_FS, DBG_NONE "large_file\n");
+	if (features_ro & EXT4_FRO_COM_BTREE_DIR)
+		ext4_dbg(DEBUG_FS, DBG_NONE "btree_dir\n");
+	if (features_ro & EXT4_FRO_COM_HUGE_FILE)
+		ext4_dbg(DEBUG_FS, DBG_NONE "huge_file\n");
+	if (features_ro & EXT4_FRO_COM_GDT_CSUM)
+		ext4_dbg(DEBUG_FS, DBG_NONE "gtd_csum\n");
+	if (features_ro & EXT4_FRO_COM_DIR_NLINK)
+		ext4_dbg(DEBUG_FS, DBG_NONE "dir_nlink\n");
+	if (features_ro & EXT4_FRO_COM_EXTRA_ISIZE)
+		ext4_dbg(DEBUG_FS, DBG_NONE "extra_isize\n");
+	if (features_ro & EXT4_FRO_COM_QUOTA)
+		ext4_dbg(DEBUG_FS, DBG_NONE "quota\n");
+	if (features_ro & EXT4_FRO_COM_BIGALLOC)
+		ext4_dbg(DEBUG_FS, DBG_NONE "bigalloc\n");
+	if (features_ro & EXT4_FRO_COM_METADATA_CSUM)
+		ext4_dbg(DEBUG_FS, DBG_NONE "metadata_csum\n");
+}
+
+int ext4_fs_check_features(struct ext4_fs *fs, bool *read_only)
+{
+	ext4_assert(fs && read_only);
+	uint32_t v;
+	if (ext4_get32(&fs->sb, rev_level) == 0) {
+		*read_only = false;
+		return EOK;
+	}
+
+	ext4_dbg(DEBUG_FS, DBG_INFO "sblock features_incompatible:\n");
+	ext4_fs_debug_features_inc(ext4_get32(&fs->sb, features_incompatible));
+
+	ext4_dbg(DEBUG_FS, DBG_INFO "sblock features_compatible:\n");
+	ext4_fs_debug_features_comp(ext4_get32(&fs->sb, features_compatible));
+
+	ext4_dbg(DEBUG_FS, DBG_INFO "sblock features_read_only:\n");
+	ext4_fs_debug_features_ro(ext4_get32(&fs->sb, features_read_only));
+
+	/*Check features_incompatible*/
+	v = (ext4_get32(&fs->sb, features_incompatible) &
+	     (~CONFIG_SUPPORTED_FINCOM));
+	if (v) {
+		ext4_dbg(DEBUG_FS, DBG_ERROR
+				"sblock has unsupported features incompatible:\n");
+		ext4_fs_debug_features_inc(v);
+		return ENOTSUP;
+	}
+
+	/*Check features_read_only*/
+	v = ext4_get32(&fs->sb, features_read_only);
+	v &= ~CONFIG_SUPPORTED_FRO_COM;
+	if (v) {
+		ext4_dbg(DEBUG_FS, DBG_WARN
+			"sblock has unsupported features read only:\n");
+		ext4_fs_debug_features_ro(v);
+		*read_only = true;
+		return EOK;
+	}
+	*read_only = false;
+
+	return EOK;
+}
+
+/**@brief Determine whether the block is inside the group.
+ * @param baddr   block address
+ * @param bgid    block group id
+ * @return Error code
+ */
+static bool ext4_block_in_group(struct ext4_sblock *s, ext4_fsblk_t baddr,
+			        uint32_t bgid)
+{
+	uint32_t actual_bgid;
+	actual_bgid = ext4_balloc_get_bgid_of_block(s, baddr);
+	if (actual_bgid == bgid)
+		return true;
+	return false;
+}
+
+/**@brief   To avoid calling the atomic setbit hundreds or thousands of times, we only
+ *          need to use it within a single byte (to ensure we get endianness right).
+ *          We can use memset for the rest of the bitmap as there are no other users.
+ */
+static void ext4_fs_mark_bitmap_end(int start_bit, int end_bit, void *bitmap)
+{
+	int i;
+
+	if (start_bit >= end_bit)
+		return;
+
+	for (i = start_bit; (unsigned)i < ((start_bit + 7) & ~7UL); i++)
+		ext4_bmap_bit_set(bitmap, i);
+
+	if (i < end_bit)
+		memset((char *)bitmap + (i >> 3), 0xff, (end_bit - i) >> 3);
+}
+
+/**@brief Initialize block bitmap in block group.
+ * @param bg_ref Reference to block group
+ * @return Error code
+ */
+static int ext4_fs_init_block_bitmap(struct ext4_block_group_ref *bg_ref)
+{
+	struct ext4_sblock *sb = &bg_ref->fs->sb;
+	struct ext4_bgroup *bg = bg_ref->block_group;
+	int rc;
+
+	uint32_t i, bit, bit_max;
+	uint32_t group_blocks;
+	uint16_t inode_size = ext4_get16(sb, inode_size);
+	uint32_t block_size = ext4_sb_get_block_size(sb);
+	uint32_t inodes_per_group = ext4_get32(sb, inodes_per_group);
+
+	ext4_fsblk_t bmp_blk = ext4_bg_get_block_bitmap(bg, sb);
+	ext4_fsblk_t bmp_inode = ext4_bg_get_inode_bitmap(bg, sb);
+	ext4_fsblk_t inode_table = ext4_bg_get_inode_table_first_block(bg, sb);
+	ext4_fsblk_t first_bg = ext4_balloc_get_block_of_bgid(sb, bg_ref->index);
+
+	uint32_t dsc_per_block =  block_size / ext4_sb_get_desc_size(sb);
+
+	bool flex_bg = ext4_sb_feature_incom(sb, EXT4_FINCOM_FLEX_BG);
+	bool meta_bg = ext4_sb_feature_incom(sb, EXT4_FINCOM_META_BG);
+
+	uint32_t inode_table_bcnt = inodes_per_group * inode_size / block_size;
+
+	struct ext4_block block_bitmap;
+	rc = ext4_trans_block_get_noread(bg_ref->fs->bdev, &block_bitmap, bmp_blk);
+	if (rc != EOK)
+		return rc;
+
+	memset(block_bitmap.data, 0, block_size);
+	bit_max = ext4_sb_is_super_in_bg(sb, bg_ref->index);
+
+	uint32_t count = ext4_sb_first_meta_bg(sb) * dsc_per_block;
+	if (!meta_bg || bg_ref->index < count) {
+		if (bit_max) {
+			bit_max += ext4_bg_num_gdb(sb, bg_ref->index);
+			bit_max += ext4_get16(sb, s_reserved_gdt_blocks);
+		}
+	} else { /* For META_BG_BLOCK_GROUPS */
+		bit_max += ext4_bg_num_gdb(sb, bg_ref->index);
+	}
+	for (bit = 0; bit < bit_max; bit++)
+		ext4_bmap_bit_set(block_bitmap.data, bit);
+
+	if (bg_ref->index == ext4_block_group_cnt(sb) - 1) {
+		/*
+		 * Even though mke2fs always initialize first and last group
+		 * if some other tool enabled the EXT4_BG_BLOCK_UNINIT we need
+		 * to make sure we calculate the right free blocks
+		 */
+
+		group_blocks = (uint32_t)(ext4_sb_get_blocks_cnt(sb) -
+					  ext4_get32(sb, first_data_block) -
+					  ext4_get32(sb, blocks_per_group) *
+					  (ext4_block_group_cnt(sb) - 1));
+	} else {
+		group_blocks = ext4_get32(sb, blocks_per_group);
+	}
+
+	bool in_bg;
+	in_bg = ext4_block_in_group(sb, bmp_blk, bg_ref->index);
+	if (!flex_bg || in_bg)
+		ext4_bmap_bit_set(block_bitmap.data,
+				  (uint32_t)(bmp_blk - first_bg));
+
+	in_bg = ext4_block_in_group(sb, bmp_inode, bg_ref->index);
+	if (!flex_bg || in_bg)
+		ext4_bmap_bit_set(block_bitmap.data,
+				  (uint32_t)(bmp_inode - first_bg));
+
+        for (i = inode_table; i < inode_table + inode_table_bcnt; i++) {
+		in_bg = ext4_block_in_group(sb, i, bg_ref->index);
+		if (!flex_bg || in_bg)
+			ext4_bmap_bit_set(block_bitmap.data,
+					  (uint32_t)(i - first_bg));
+	}
+        /*
+         * Also if the number of blocks within the group is
+         * less than the blocksize * 8 ( which is the size
+         * of bitmap ), set rest of the block bitmap to 1
+         */
+        ext4_fs_mark_bitmap_end(group_blocks, block_size * 8, block_bitmap.data);
+	ext4_trans_set_block_dirty(block_bitmap.buf);
+
+	ext4_balloc_set_bitmap_csum(sb, bg_ref->block_group, block_bitmap.data);
+	bg_ref->dirty = true;
+
+	/* Save bitmap */
+	return ext4_block_set(bg_ref->fs->bdev, &block_bitmap);
+}
+
+/**@brief Initialize i-node bitmap in block group.
+ * @param bg_ref Reference to block group
+ * @return Error code
+ */
+static int ext4_fs_init_inode_bitmap(struct ext4_block_group_ref *bg_ref)
+{
+	int rc;
+	struct ext4_sblock *sb = &bg_ref->fs->sb;
+	struct ext4_bgroup *bg = bg_ref->block_group;
+
+	/* Load bitmap */
+	ext4_fsblk_t bitmap_block_addr = ext4_bg_get_inode_bitmap(bg, sb);
+
+	struct ext4_block b;
+	rc = ext4_trans_block_get_noread(bg_ref->fs->bdev, &b, bitmap_block_addr);
+	if (rc != EOK)
+		return rc;
+
+	/* Initialize all bitmap bits to zero */
+	uint32_t block_size = ext4_sb_get_block_size(sb);
+	uint32_t inodes_per_group = ext4_get32(sb, inodes_per_group);
+
+	memset(b.data, 0, (inodes_per_group + 7) / 8);
+
+	uint32_t start_bit = inodes_per_group;
+	uint32_t end_bit = block_size * 8;
+
+	uint32_t i;
+	for (i = start_bit; i < ((start_bit + 7) & ~7UL); i++)
+		ext4_bmap_bit_set(b.data, i);
+
+	if (i < end_bit)
+		memset(b.data + (i >> 3), 0xff, (end_bit - i) >> 3);
+
+	ext4_trans_set_block_dirty(b.buf);
+
+	ext4_ialloc_set_bitmap_csum(sb, bg, b.data);
+	bg_ref->dirty = true;
+
+	/* Save bitmap */
+	return ext4_block_set(bg_ref->fs->bdev, &b);
+}
+
+/**@brief Initialize i-node table in block group.
+ * @param bg_ref Reference to block group
+ * @return Error code
+ */
+static int ext4_fs_init_inode_table(struct ext4_block_group_ref *bg_ref)
+{
+	struct ext4_sblock *sb = &bg_ref->fs->sb;
+	struct ext4_bgroup *bg = bg_ref->block_group;
+
+	uint32_t inode_size = ext4_get32(sb, inode_size);
+	uint32_t block_size = ext4_sb_get_block_size(sb);
+	uint32_t inodes_per_block = block_size / inode_size;
+	uint32_t inodes_in_group = ext4_inodes_in_group_cnt(sb, bg_ref->index);
+	uint32_t table_blocks = inodes_in_group / inodes_per_block;
+	ext4_fsblk_t fblock;
+
+	if (inodes_in_group % inodes_per_block)
+		table_blocks++;
+
+	/* Compute initialization bounds */
+	ext4_fsblk_t first_block = ext4_bg_get_inode_table_first_block(bg, sb);
+
+	ext4_fsblk_t last_block = first_block + table_blocks - 1;
+
+	/* Initialization of all itable blocks */
+	for (fblock = first_block; fblock <= last_block; ++fblock) {
+		struct ext4_block b;
+		int rc = ext4_trans_block_get_noread(bg_ref->fs->bdev, &b, fblock);
+		if (rc != EOK)
+			return rc;
+
+		memset(b.data, 0, block_size);
+		ext4_trans_set_block_dirty(b.buf);
+
+		ext4_block_set(bg_ref->fs->bdev, &b);
+		if (rc != EOK)
+			return rc;
+	}
+
+	return EOK;
+}
+
+static ext4_fsblk_t ext4_fs_get_descriptor_block(struct ext4_sblock *s,
+					     uint32_t bgid,
+					     uint32_t dsc_per_block)
+{
+	uint32_t first_meta_bg, dsc_id;
+	int has_super = 0;
+	dsc_id = bgid / dsc_per_block;
+	first_meta_bg = ext4_sb_first_meta_bg(s);
+
+	bool meta_bg = ext4_sb_feature_incom(s, EXT4_FINCOM_META_BG);
+
+	if (!meta_bg || dsc_id < first_meta_bg)
+		return ext4_get32(s, first_data_block) + dsc_id + 1;
+
+	if (ext4_sb_is_super_in_bg(s, bgid))
+		has_super = 1;
+
+	return (has_super + ext4_fs_first_bg_block_no(s, bgid));
+}
+
+/**@brief  Compute checksum of block group descriptor.
+ * @param sb   Superblock
+ * @param bgid Index of block group in the filesystem
+ * @param bg   Block group to compute checksum for
+ * @return Checksum value
+ */
+static uint16_t ext4_fs_bg_checksum(struct ext4_sblock *sb, uint32_t bgid,
+				    struct ext4_bgroup *bg)
+{
+	/* If checksum not supported, 0 will be returned */
+	uint16_t crc = 0;
+#if CONFIG_META_CSUM_ENABLE
+	/* Compute the checksum only if the filesystem supports it */
+	if (ext4_sb_feature_ro_com(sb, EXT4_FRO_COM_METADATA_CSUM)) {
+		/* Use metadata_csum algorithm instead */
+		uint32_t le32_bgid = to_le32(bgid);
+		uint32_t orig_checksum, checksum;
+
+		/* Preparation: temporarily set bg checksum to 0 */
+		orig_checksum = bg->checksum;
+		bg->checksum = 0;
+
+		/* First calculate crc32 checksum against fs uuid */
+		checksum = ext4_crc32c(EXT4_CRC32_INIT, sb->uuid,
+				sizeof(sb->uuid));
+		/* Then calculate crc32 checksum against bgid */
+		checksum = ext4_crc32c(checksum, &le32_bgid, sizeof(bgid));
+		/* Finally calculate crc32 checksum against block_group_desc */
+		checksum = ext4_crc32c(checksum, bg, ext4_sb_get_desc_size(sb));
+		bg->checksum = orig_checksum;
+
+		crc = checksum & 0xFFFF;
+		return crc;
+	}
+#endif
+	if (ext4_sb_feature_ro_com(sb, EXT4_FRO_COM_GDT_CSUM)) {
+		uint8_t *base = (uint8_t *)bg;
+		uint8_t *checksum = (uint8_t *)&bg->checksum;
+
+		uint32_t offset = (uint32_t)(checksum - base);
+
+		/* Convert block group index to little endian */
+		uint32_t group = to_le32(bgid);
+
+		/* Initialization */
+		crc = ext4_bg_crc16(~0, sb->uuid, sizeof(sb->uuid));
+
+		/* Include index of block group */
+		crc = ext4_bg_crc16(crc, (uint8_t *)&group, sizeof(group));
+
+		/* Compute crc from the first part (stop before checksum field)
+		 */
+		crc = ext4_bg_crc16(crc, (uint8_t *)bg, offset);
+
+		/* Skip checksum */
+		offset += sizeof(bg->checksum);
+
+		/* Checksum of the rest of block group descriptor */
+		if ((ext4_sb_feature_incom(sb, EXT4_FINCOM_64BIT)) &&
+		    (offset < ext4_sb_get_desc_size(sb))) {
+
+			const uint8_t *start = ((uint8_t *)bg) + offset;
+			size_t len = ext4_sb_get_desc_size(sb) - offset;
+			crc = ext4_bg_crc16(crc, start, len);
+		}
+	}
+	return crc;
+}
+
+#if CONFIG_META_CSUM_ENABLE
+static bool ext4_fs_verify_bg_csum(struct ext4_sblock *sb,
+				   uint32_t bgid,
+				   struct ext4_bgroup *bg)
+{
+	if (!ext4_sb_feature_ro_com(sb, EXT4_FRO_COM_METADATA_CSUM))
+		return true;
+
+	return ext4_fs_bg_checksum(sb, bgid, bg) == to_le16(bg->checksum);
+}
+#else
+#define ext4_fs_verify_bg_csum(...) true
+#endif
+
+int ext4_fs_get_block_group_ref(struct ext4_fs *fs, uint32_t bgid,
+				struct ext4_block_group_ref *ref)
+{
+	/* Compute number of descriptors, that fits in one data block */
+	uint32_t block_size = ext4_sb_get_block_size(&fs->sb);
+	uint32_t dsc_cnt = block_size / ext4_sb_get_desc_size(&fs->sb);
+
+	/* Block group descriptor table starts at the next block after
+	 * superblock */
+	uint64_t block_id = ext4_fs_get_descriptor_block(&fs->sb, bgid, dsc_cnt);
+
+	uint32_t offset = (bgid % dsc_cnt) * ext4_sb_get_desc_size(&fs->sb);
+
+	int rc = ext4_trans_block_get(fs->bdev, &ref->block, block_id);
+	if (rc != EOK)
+		return rc;
+
+	ref->block_group = (void *)(ref->block.data + offset);
+	ref->fs = fs;
+	ref->index = bgid;
+	ref->dirty = false;
+	struct ext4_bgroup *bg = ref->block_group;
+
+	if (!ext4_fs_verify_bg_csum(&fs->sb, bgid, bg)) {
+		ext4_dbg(DEBUG_FS,
+			 DBG_WARN "Block group descriptor checksum failed."
+			 "Block group index: %" PRIu32"\n",
+			 bgid);
+	}
+
+	if (ext4_bg_has_flag(bg, EXT4_BLOCK_GROUP_BLOCK_UNINIT)) {
+		rc = ext4_fs_init_block_bitmap(ref);
+		if (rc != EOK) {
+			ext4_block_set(fs->bdev, &ref->block);
+			return rc;
+		}
+		ext4_bg_clear_flag(bg, EXT4_BLOCK_GROUP_BLOCK_UNINIT);
+		ref->dirty = true;
+	}
+
+	if (ext4_bg_has_flag(bg, EXT4_BLOCK_GROUP_INODE_UNINIT)) {
+		rc = ext4_fs_init_inode_bitmap(ref);
+		if (rc != EOK) {
+			ext4_block_set(ref->fs->bdev, &ref->block);
+			return rc;
+		}
+
+		ext4_bg_clear_flag(bg, EXT4_BLOCK_GROUP_INODE_UNINIT);
+
+		if (!ext4_bg_has_flag(bg, EXT4_BLOCK_GROUP_ITABLE_ZEROED)) {
+			rc = ext4_fs_init_inode_table(ref);
+			if (rc != EOK) {
+				ext4_block_set(fs->bdev, &ref->block);
+				return rc;
+			}
+
+			ext4_bg_set_flag(bg, EXT4_BLOCK_GROUP_ITABLE_ZEROED);
+		}
+
+		ref->dirty = true;
+	}
+
+	return EOK;
+}
+
+int ext4_fs_put_block_group_ref(struct ext4_block_group_ref *ref)
+{
+	/* Check if reference modified */
+	if (ref->dirty) {
+		/* Compute new checksum of block group */
+		uint16_t cs;
+		cs = ext4_fs_bg_checksum(&ref->fs->sb, ref->index,
+					 ref->block_group);
+		ref->block_group->checksum = to_le16(cs);
+
+		/* Mark block dirty for writing changes to physical device */
+		ext4_trans_set_block_dirty(ref->block.buf);
+	}
+
+	/* Put back block, that contains block group descriptor */
+	return ext4_block_set(ref->fs->bdev, &ref->block);
+}
+
+#if CONFIG_META_CSUM_ENABLE
+static uint32_t ext4_fs_inode_checksum(struct ext4_inode_ref *inode_ref)
+{
+	uint32_t checksum = 0;
+	struct ext4_sblock *sb = &inode_ref->fs->sb;
+	uint16_t inode_size = ext4_get16(sb, inode_size);
+
+	if (ext4_sb_feature_ro_com(sb, EXT4_FRO_COM_METADATA_CSUM)) {
+		uint32_t orig_checksum;
+
+		uint32_t ino_index = to_le32(inode_ref->index);
+		uint32_t ino_gen =
+			to_le32(ext4_inode_get_generation(inode_ref->inode));
+
+		/* Preparation: temporarily set bg checksum to 0 */
+		orig_checksum = ext4_inode_get_csum(sb, inode_ref->inode);
+		ext4_inode_set_csum(sb, inode_ref->inode, 0);
+
+		/* First calculate crc32 checksum against fs uuid */
+		checksum = ext4_crc32c(EXT4_CRC32_INIT, sb->uuid,
+				       sizeof(sb->uuid));
+		/* Then calculate crc32 checksum against inode number
+		 * and inode generation */
+		checksum = ext4_crc32c(checksum, &ino_index, sizeof(ino_index));
+		checksum = ext4_crc32c(checksum, &ino_gen, sizeof(ino_gen));
+		/* Finally calculate crc32 checksum against
+		 * the entire inode */
+		checksum = ext4_crc32c(checksum, inode_ref->inode, inode_size);
+		ext4_inode_set_csum(sb, inode_ref->inode, orig_checksum);
+
+		/* If inode size is not large enough to hold the
+		 * upper 16bit of the checksum */
+		if (inode_size == EXT4_GOOD_OLD_INODE_SIZE)
+			checksum &= 0xFFFF;
+
+	}
+	return checksum;
+}
+#else
+#define ext4_fs_inode_checksum(...) 0
+#endif
+
+static void ext4_fs_set_inode_checksum(struct ext4_inode_ref *inode_ref)
+{
+	struct ext4_sblock *sb = &inode_ref->fs->sb;
+	if (!ext4_sb_feature_ro_com(sb, EXT4_FRO_COM_METADATA_CSUM))
+		return;
+
+	uint32_t csum = ext4_fs_inode_checksum(inode_ref);
+	ext4_inode_set_csum(sb, inode_ref->inode, csum);
+}
+
+#if CONFIG_META_CSUM_ENABLE
+static bool ext4_fs_verify_inode_csum(struct ext4_inode_ref *inode_ref)
+{
+	struct ext4_sblock *sb = &inode_ref->fs->sb;
+	if (!ext4_sb_feature_ro_com(sb, EXT4_FRO_COM_METADATA_CSUM))
+		return true;
+
+	return ext4_inode_get_csum(sb, inode_ref->inode) ==
+		ext4_fs_inode_checksum(inode_ref);
+}
+#else
+#define ext4_fs_verify_inode_csum(...) true
+#endif
+
+static int
+__ext4_fs_get_inode_ref(struct ext4_fs *fs, uint32_t index,
+			struct ext4_inode_ref *ref,
+			bool initialized)
+{
+	/* Compute number of i-nodes, that fits in one data block */
+	uint32_t inodes_per_group = ext4_get32(&fs->sb, inodes_per_group);
+
+	/*
+	 * Inode numbers are 1-based, but it is simpler to work with 0-based
+	 * when computing indices
+	 */
+	index -= 1;
+	uint32_t block_group = index / inodes_per_group;
+	uint32_t offset_in_group = index % inodes_per_group;
+
+	/* Load block group, where i-node is located */
+	struct ext4_block_group_ref bg_ref;
+
+	int rc = ext4_fs_get_block_group_ref(fs, block_group, &bg_ref);
+	if (rc != EOK) {
+		return rc;
+	}
+
+	/* Load block address, where i-node table is located */
+	ext4_fsblk_t inode_table_start =
+	    ext4_bg_get_inode_table_first_block(bg_ref.block_group, &fs->sb);
+
+	/* Put back block group reference (not needed more) */
+	rc = ext4_fs_put_block_group_ref(&bg_ref);
+	if (rc != EOK) {
+		return rc;
+	}
+
+	/* Compute position of i-node in the block group */
+	uint16_t inode_size = ext4_get16(&fs->sb, inode_size);
+	uint32_t block_size = ext4_sb_get_block_size(&fs->sb);
+	uint32_t byte_offset_in_group = offset_in_group * inode_size;
+
+	/* Compute block address */
+	ext4_fsblk_t block_id =
+	    inode_table_start + (byte_offset_in_group / block_size);
+
+	rc = ext4_trans_block_get(fs->bdev, &ref->block, block_id);
+	if (rc != EOK) {
+		return rc;
+	}
+
+	/* Compute position of i-node in the data block */
+	uint32_t offset_in_block = byte_offset_in_group % block_size;
+	ref->inode = (struct ext4_inode *)(ref->block.data + offset_in_block);
+
+	/* We need to store the original value of index in the reference */
+	ref->index = index + 1;
+	ref->fs = fs;
+	ref->dirty = false;
+
+	if (initialized && !ext4_fs_verify_inode_csum(ref)) {
+		ext4_dbg(DEBUG_FS,
+			DBG_WARN "Inode checksum failed."
+			"Inode: %" PRIu32"\n",
+			ref->index);
+	}
+
+	return EOK;
+}
+
+int ext4_fs_get_inode_ref(struct ext4_fs *fs, uint32_t index,
+			  struct ext4_inode_ref *ref)
+{
+	return __ext4_fs_get_inode_ref(fs, index, ref, true);
+}
+
+int ext4_fs_put_inode_ref(struct ext4_inode_ref *ref)
+{
+	/* Check if reference modified */
+	if (ref->dirty) {
+		/* Mark block dirty for writing changes to physical device */
+		ext4_fs_set_inode_checksum(ref);
+		ext4_trans_set_block_dirty(ref->block.buf);
+	}
+
+	/* Put back block, that contains i-node */
+	return ext4_block_set(ref->fs->bdev, &ref->block);
+}
+
+void ext4_fs_inode_blocks_init(struct ext4_fs *fs,
+			       struct ext4_inode_ref *inode_ref)
+{
+	int i;
+	struct ext4_inode *inode = inode_ref->inode;
+
+	for (i = 0; i < EXT4_INODE_BLOCKS; i++)
+		inode->blocks[i] = 0;
+
+	(void)fs;
+#if CONFIG_EXTENT_ENABLE
+	/* Initialize extents if needed */
+	if (ext4_sb_feature_incom(&fs->sb, EXT4_FINCOM_EXTENTS)) {
+		ext4_inode_set_flag(inode, EXT4_INODE_FLAG_EXTENTS);
+
+		/* Initialize extent root header */
+		ext4_extent_tree_init(inode_ref);
+	}
+#endif
+}
+
+uint32_t ext4_fs_correspond_inode_mode(int filetype)
+{
+	switch (filetype) {
+	case EXT4_DE_DIR:
+		return EXT4_INODE_MODE_DIRECTORY;
+	case EXT4_DE_REG_FILE:
+		return EXT4_INODE_MODE_FILE;
+	case EXT4_DE_SYMLINK:
+		return EXT4_INODE_MODE_SOFTLINK;
+	default:
+		/* FIXME: right now we only support 3 file type. */
+		ext4_assert(0);
+	}
+	return 0;
+}
+
+int ext4_fs_alloc_inode(struct ext4_fs *fs, struct ext4_inode_ref *inode_ref,
+			int filetype)
+{
+	/* Check if newly allocated i-node will be a directory */
+	bool is_dir;
+	uint16_t inode_size = ext4_get16(&fs->sb, inode_size);
+
+	is_dir = (filetype == EXT4_DE_DIR);
+
+	/* Allocate inode by allocation algorithm */
+	uint32_t index;
+	int rc = ext4_ialloc_alloc_inode(fs, &index, is_dir);
+	if (rc != EOK)
+		return rc;
+
+	/* Load i-node from on-disk i-node table */
+	rc = __ext4_fs_get_inode_ref(fs, index, inode_ref, false);
+	if (rc != EOK) {
+		ext4_ialloc_free_inode(fs, index, is_dir);
+		return rc;
+	}
+
+	/* Initialize i-node */
+	struct ext4_inode *inode = inode_ref->inode;
+
+	uint32_t mode;
+	if (is_dir) {
+		/*
+		 * Default directory permissions to be compatible with other
+		 * systems
+		 * 0777 (octal) == rwxrwxrwx
+		 */
+
+		mode = 0777;
+		mode |= EXT4_INODE_MODE_DIRECTORY;
+	} else {
+		/*
+		 * Default file permissions to be compatible with other systems
+		 * 0666 (octal) == rw-rw-rw-
+		 */
+
+		mode = 0666;
+		mode |= ext4_fs_correspond_inode_mode(filetype);
+	}
+	ext4_inode_set_mode(&fs->sb, inode, mode);
+
+	ext4_inode_set_links_cnt(inode, 0);
+	ext4_inode_set_uid(inode, 0);
+	ext4_inode_set_gid(inode, 0);
+	ext4_inode_set_size(inode, 0);
+	ext4_inode_set_access_time(inode, 0);
+	ext4_inode_set_change_inode_time(inode, 0);
+	ext4_inode_set_modif_time(inode, 0);
+	ext4_inode_set_del_time(inode, 0);
+	ext4_inode_set_blocks_count(&fs->sb, inode, 0);
+	ext4_inode_set_flags(inode, 0);
+	ext4_inode_set_generation(inode, 0);
+	if (inode_size > EXT4_GOOD_OLD_INODE_SIZE) {
+		uint16_t off = offsetof(struct ext4_inode, extra_isize);
+		uint16_t size = sizeof(struct ext4_inode) - off;
+		ext4_inode_set_extra_isize(inode, size);
+	}
+
+	/* Reset blocks array. For symbolic link inode, just
+	 * fill in blocks with 0 */
+	if (ext4_inode_is_type(&fs->sb, inode, EXT4_INODE_MODE_SOFTLINK)) {
+		for (int i = 0; i < EXT4_INODE_BLOCKS; i++)
+			inode->blocks[i] = 0;
+
+	} else {
+		ext4_fs_inode_blocks_init(fs, inode_ref);
+	}
+
+	inode_ref->dirty = true;
+
+	return EOK;
+}
+
+int ext4_fs_free_inode(struct ext4_inode_ref *inode_ref)
+{
+	struct ext4_fs *fs = inode_ref->fs;
+	uint32_t offset;
+	uint32_t suboff;
+	int rc;
+#if CONFIG_EXTENT_ENABLE
+	/* For extents must be data block destroyed by other way */
+	if ((ext4_sb_feature_incom(&fs->sb, EXT4_FINCOM_EXTENTS)) &&
+	    (ext4_inode_has_flag(inode_ref->inode, EXT4_INODE_FLAG_EXTENTS))) {
+		/* Data structures are released during truncate operation... */
+		goto finish;
+	}
+#endif
+	/* Release all indirect (no data) blocks */
+
+	/* 1) Single indirect */
+	ext4_fsblk_t fblock = ext4_inode_get_indirect_block(inode_ref->inode, 0);
+	if (fblock != 0) {
+		int rc = ext4_balloc_free_block(inode_ref, fblock);
+		if (rc != EOK)
+			return rc;
+
+		ext4_inode_set_indirect_block(inode_ref->inode, 0, 0);
+	}
+
+	uint32_t block_size = ext4_sb_get_block_size(&fs->sb);
+	uint32_t count = block_size / sizeof(uint32_t);
+
+	struct ext4_block block;
+
+	/* 2) Double indirect */
+	fblock = ext4_inode_get_indirect_block(inode_ref->inode, 1);
+	if (fblock != 0) {
+		int rc = ext4_trans_block_get(fs->bdev, &block, fblock);
+		if (rc != EOK)
+			return rc;
+
+		ext4_fsblk_t ind_block;
+		for (offset = 0; offset < count; ++offset) {
+			ind_block = to_le32(((uint32_t *)block.data)[offset]);
+
+			if (ind_block == 0)
+				continue;
+			rc = ext4_balloc_free_block(inode_ref, ind_block);
+			if (rc != EOK) {
+				ext4_block_set(fs->bdev, &block);
+				return rc;
+			}
+
+		}
+
+		ext4_block_set(fs->bdev, &block);
+		rc = ext4_balloc_free_block(inode_ref, fblock);
+		if (rc != EOK)
+			return rc;
+
+		ext4_inode_set_indirect_block(inode_ref->inode, 1, 0);
+	}
+
+	/* 3) Tripple indirect */
+	struct ext4_block subblock;
+	fblock = ext4_inode_get_indirect_block(inode_ref->inode, 2);
+	if (fblock == 0)
+		goto finish;
+	rc = ext4_trans_block_get(fs->bdev, &block, fblock);
+	if (rc != EOK)
+		return rc;
+
+	ext4_fsblk_t ind_block;
+	for (offset = 0; offset < count; ++offset) {
+		ind_block = to_le32(((uint32_t *)block.data)[offset]);
+
+		if (ind_block == 0)
+			continue;
+		rc = ext4_trans_block_get(fs->bdev, &subblock,
+				ind_block);
+		if (rc != EOK) {
+			ext4_block_set(fs->bdev, &block);
+			return rc;
+		}
+
+		ext4_fsblk_t ind_subblk;
+		for (suboff = 0; suboff < count; ++suboff) {
+			ind_subblk = to_le32(((uint32_t *)subblock.data)[suboff]);
+
+			if (ind_subblk == 0)
+				continue;
+			rc = ext4_balloc_free_block(inode_ref, ind_subblk);
+			if (rc != EOK) {
+				ext4_block_set(fs->bdev, &subblock);
+				ext4_block_set(fs->bdev, &block);
+				return rc;
+			}
+
+		}
+
+		ext4_block_set(fs->bdev, &subblock);
+
+		rc = ext4_balloc_free_block(inode_ref,
+				ind_block);
+		if (rc != EOK) {
+			ext4_block_set(fs->bdev, &block);
+			return rc;
+		}
+
+	}
+
+	ext4_block_set(fs->bdev, &block);
+	rc = ext4_balloc_free_block(inode_ref, fblock);
+	if (rc != EOK)
+		return rc;
+
+	ext4_inode_set_indirect_block(inode_ref->inode, 2, 0);
+finish:
+	/* Mark inode dirty for writing to the physical device */
+	inode_ref->dirty = true;
+
+	/* Free block with extended attributes if present */
+	ext4_fsblk_t xattr_block =
+	    ext4_inode_get_file_acl(inode_ref->inode, &fs->sb);
+	if (xattr_block) {
+		int rc = ext4_balloc_free_block(inode_ref, xattr_block);
+		if (rc != EOK)
+			return rc;
+
+		ext4_inode_set_file_acl(inode_ref->inode, &fs->sb, 0);
+	}
+
+	/* Free inode by allocator */
+	if (ext4_inode_is_type(&fs->sb, inode_ref->inode,
+			       EXT4_INODE_MODE_DIRECTORY))
+		rc = ext4_ialloc_free_inode(fs, inode_ref->index, true);
+	else
+		rc = ext4_ialloc_free_inode(fs, inode_ref->index, false);
+
+	return rc;
+}
+
+
+/**@brief Release data block from i-node
+ * @param inode_ref I-node to release block from
+ * @param iblock    Logical block to be released
+ * @return Error code
+ */
+static int ext4_fs_release_inode_block(struct ext4_inode_ref *inode_ref,
+				uint32_t iblock)
+{
+	ext4_fsblk_t fblock;
+
+	struct ext4_fs *fs = inode_ref->fs;
+
+	/* Extents are handled otherwise = there is not support in this function
+	 */
+	ext4_assert(!(
+	    ext4_sb_feature_incom(&fs->sb, EXT4_FINCOM_EXTENTS) &&
+	    (ext4_inode_has_flag(inode_ref->inode, EXT4_INODE_FLAG_EXTENTS))));
+
+	struct ext4_inode *inode = inode_ref->inode;
+
+	/* Handle simple case when we are dealing with direct reference */
+	if (iblock < EXT4_INODE_DIRECT_BLOCK_COUNT) {
+		fblock = ext4_inode_get_direct_block(inode, iblock);
+
+		/* Sparse file */
+		if (fblock == 0)
+			return EOK;
+
+		ext4_inode_set_direct_block(inode, iblock, 0);
+		return ext4_balloc_free_block(inode_ref, fblock);
+	}
+
+	/* Determine the indirection level needed to get the desired block */
+	unsigned int level = 0;
+	unsigned int i;
+	for (i = 1; i < 4; i++) {
+		if (iblock < fs->inode_block_limits[i]) {
+			level = i;
+			break;
+		}
+	}
+
+	if (level == 0)
+		return EIO;
+
+	/* Compute offsets for the topmost level */
+	uint32_t block_offset_in_level =
+	    iblock - fs->inode_block_limits[level - 1];
+	ext4_fsblk_t current_block =
+	    ext4_inode_get_indirect_block(inode, level - 1);
+	uint32_t offset_in_block =
+	    block_offset_in_level / fs->inode_blocks_per_level[level - 1];
+
+	/*
+	 * Navigate through other levels, until we find the block number
+	 * or find null reference meaning we are dealing with sparse file
+	 */
+	struct ext4_block block;
+
+	while (level > 0) {
+
+		/* Sparse check */
+		if (current_block == 0)
+			return EOK;
+
+		int rc = ext4_trans_block_get(fs->bdev, &block, current_block);
+		if (rc != EOK)
+			return rc;
+
+		current_block =
+		    to_le32(((uint32_t *)block.data)[offset_in_block]);
+
+		/* Set zero if physical data block address found */
+		if (level == 1) {
+			((uint32_t *)block.data)[offset_in_block] = to_le32(0);
+			ext4_trans_set_block_dirty(block.buf);
+		}
+
+		rc = ext4_block_set(fs->bdev, &block);
+		if (rc != EOK)
+			return rc;
+
+		level--;
+
+		/*
+		 * If we are on the last level, break here as
+		 * there is no next level to visit
+		 */
+		if (level == 0)
+			break;
+
+		/* Visit the next level */
+		block_offset_in_level %= fs->inode_blocks_per_level[level];
+		offset_in_block = block_offset_in_level /
+				  fs->inode_blocks_per_level[level - 1];
+	}
+
+	fblock = current_block;
+	if (fblock == 0)
+		return EOK;
+
+	/* Physical block is not referenced, it can be released */
+	return ext4_balloc_free_block(inode_ref, fblock);
+}
+
+int ext4_fs_truncate_inode(struct ext4_inode_ref *inode_ref, uint64_t new_size)
+{
+	struct ext4_sblock *sb = &inode_ref->fs->sb;
+	uint32_t i;
+	int r;
+
+	/* Check flags, if i-node can be truncated */
+	if (!ext4_inode_can_truncate(sb, inode_ref->inode))
+		return EINVAL;
+
+	/* If sizes are equal, nothing has to be done. */
+	uint64_t old_size = ext4_inode_get_size(sb, inode_ref->inode);
+	if (old_size == new_size)
+		return EOK;
+
+	/* It's not supported to make the larger file by truncate operation */
+	if (old_size < new_size)
+		return EINVAL;
+
+	bool v;
+	v = ext4_inode_is_type(sb, inode_ref->inode, EXT4_INODE_MODE_SOFTLINK);
+	if (v && old_size < sizeof(inode_ref->inode->blocks) &&
+	    !ext4_inode_get_blocks_count(sb, inode_ref->inode)) {
+		char *content = (char *)inode_ref->inode->blocks + new_size;
+		memset(content, 0,
+		       sizeof(inode_ref->inode->blocks) - (uint32_t)new_size);
+		ext4_inode_set_size(inode_ref->inode, new_size);
+		inode_ref->dirty = true;
+
+		return EOK;
+	}
+
+	/* Compute how many blocks will be released */
+	uint32_t block_size = ext4_sb_get_block_size(sb);
+	uint32_t new_blocks_cnt = (uint32_t)((new_size + block_size - 1) / block_size);
+	uint32_t old_blocks_cnt = (uint32_t)((old_size + block_size - 1) / block_size);
+	uint32_t diff_blocks_cnt = old_blocks_cnt - new_blocks_cnt;
+#if CONFIG_EXTENT_ENABLE
+	if ((ext4_sb_feature_incom(sb, EXT4_FINCOM_EXTENTS)) &&
+	    (ext4_inode_has_flag(inode_ref->inode, EXT4_INODE_FLAG_EXTENTS))) {
+
+		/* Extents require special operation */
+		if (diff_blocks_cnt) {
+			r = ext4_extent_remove_space(inode_ref, new_blocks_cnt,
+						     EXT_MAX_BLOCKS);
+			if (r != EOK)
+				return r;
+
+		}
+	} else
+#endif
+	{
+		/* Release data blocks from the end of file */
+
+		/* Starting from 1 because of logical blocks are numbered from 0
+		 */
+		for (i = 0; i < diff_blocks_cnt; ++i) {
+			r = ext4_fs_release_inode_block(inode_ref,
+							new_blocks_cnt + i);
+			if (r != EOK)
+				return r;
+		}
+	}
+
+	/* Update i-node */
+	ext4_inode_set_size(inode_ref->inode, new_size);
+	inode_ref->dirty = true;
+
+	return EOK;
+}
+
+/**@brief Compute 'goal' for inode index
+ * @param inode_ref Reference to inode, to allocate block for
+ * @return goal
+ */
+ext4_fsblk_t ext4_fs_inode_to_goal_block(struct ext4_inode_ref *inode_ref)
+{
+	uint32_t grp_inodes = ext4_get32(&inode_ref->fs->sb, inodes_per_group);
+	return (inode_ref->index - 1) / grp_inodes;
+}
+
+/**@brief Compute 'goal' for allocation algorithm (For blockmap).
+ * @param inode_ref Reference to inode, to allocate block for
+ * @param goal
+ * @return error code
+ */
+int ext4_fs_indirect_find_goal(struct ext4_inode_ref *inode_ref,
+			       ext4_fsblk_t *goal)
+{
+	int r;
+	struct ext4_sblock *sb = &inode_ref->fs->sb;
+	*goal = 0;
+
+	uint64_t inode_size = ext4_inode_get_size(sb, inode_ref->inode);
+	uint32_t block_size = ext4_sb_get_block_size(sb);
+	uint32_t iblock_cnt = (uint32_t)(inode_size / block_size);
+
+	if (inode_size % block_size != 0)
+		iblock_cnt++;
+
+	/* If inode has some blocks, get last block address + 1 */
+	if (iblock_cnt > 0) {
+		r = ext4_fs_get_inode_dblk_idx(inode_ref, iblock_cnt - 1,
+					       goal, false);
+		if (r != EOK)
+			return r;
+
+		if (*goal != 0) {
+			(*goal)++;
+			return r;
+		}
+
+		/* If goal == 0, sparse file -> continue */
+	}
+
+	/* Identify block group of inode */
+
+	uint32_t inodes_per_bg = ext4_get32(sb, inodes_per_group);
+	uint32_t block_group = (inode_ref->index - 1) / inodes_per_bg;
+	block_size = ext4_sb_get_block_size(sb);
+
+	/* Load block group reference */
+	struct ext4_block_group_ref bg_ref;
+	r = ext4_fs_get_block_group_ref(inode_ref->fs, block_group, &bg_ref);
+	if (r != EOK)
+		return r;
+
+	struct ext4_bgroup *bg = bg_ref.block_group;
+
+	/* Compute indexes */
+	uint32_t bg_count = ext4_block_group_cnt(sb);
+	ext4_fsblk_t itab_first_block = ext4_bg_get_inode_table_first_block(bg, sb);
+	uint16_t itab_item_size = ext4_get16(sb, inode_size);
+	uint32_t itab_bytes;
+
+	/* Check for last block group */
+	if (block_group < bg_count - 1) {
+		itab_bytes = inodes_per_bg * itab_item_size;
+	} else {
+		/* Last block group could be smaller */
+		uint32_t inodes_cnt = ext4_get32(sb, inodes_count);
+
+		itab_bytes = (inodes_cnt - ((bg_count - 1) * inodes_per_bg));
+		itab_bytes *= itab_item_size;
+	}
+
+	ext4_fsblk_t inode_table_blocks = itab_bytes / block_size;
+
+	if (itab_bytes % block_size)
+		inode_table_blocks++;
+
+	*goal = itab_first_block + inode_table_blocks;
+
+	return ext4_fs_put_block_group_ref(&bg_ref);
+}
+
+static int ext4_fs_get_inode_dblk_idx_internal(struct ext4_inode_ref *inode_ref,
+				       uint64_t iblock, ext4_fsblk_t *fblock,
+				       bool extent_create,
+				       bool support_unwritten __unused)
+{
+	struct ext4_fs *fs = inode_ref->fs;
+
+	/* For empty file is situation simple */
+	if (ext4_inode_get_size(&fs->sb, inode_ref->inode) == 0) {
+		*fblock = 0;
+		return EOK;
+	}
+
+	ext4_fsblk_t current_block;
+
+	(void)extent_create;
+#if CONFIG_EXTENT_ENABLE
+	/* Handle i-node using extents */
+	if ((ext4_sb_feature_incom(&fs->sb, EXT4_FINCOM_EXTENTS)) &&
+	    (ext4_inode_has_flag(inode_ref->inode, EXT4_INODE_FLAG_EXTENTS))) {
+
+		ext4_fsblk_t current_fsblk;
+		int rc = ext4_extent_get_blocks(inode_ref, iblock, 1,
+				&current_fsblk, extent_create, NULL);
+		if (rc != EOK)
+			return rc;
+
+		current_block = current_fsblk;
+		*fblock = current_block;
+
+		ext4_assert(*fblock || support_unwritten);
+		return EOK;
+	}
+#endif
+
+	struct ext4_inode *inode = inode_ref->inode;
+
+	/* Direct block are read directly from array in i-node structure */
+	if (iblock < EXT4_INODE_DIRECT_BLOCK_COUNT) {
+		current_block =
+		    ext4_inode_get_direct_block(inode, (uint32_t)iblock);
+		*fblock = current_block;
+		return EOK;
+	}
+
+	/* Determine indirection level of the target block */
+	unsigned int l = 0;
+	unsigned int i;
+	for (i = 1; i < 4; i++) {
+		if (iblock < fs->inode_block_limits[i]) {
+			l = i;
+			break;
+		}
+	}
+
+	if (l == 0)
+		return EIO;
+
+	/* Compute offsets for the topmost level */
+	uint32_t blk_off_in_lvl =  iblock - fs->inode_block_limits[l - 1];
+	current_block = ext4_inode_get_indirect_block(inode, l - 1);
+	uint32_t off_in_blk = blk_off_in_lvl / fs->inode_blocks_per_level[l - 1];
+
+	/* Sparse file */
+	if (current_block == 0) {
+		*fblock = 0;
+		return EOK;
+	}
+
+	struct ext4_block block;
+
+	/*
+	 * Navigate through other levels, until we find the block number
+	 * or find null reference meaning we are dealing with sparse file
+	 */
+	while (l > 0) {
+		/* Load indirect block */
+		int rc = ext4_trans_block_get(fs->bdev, &block, current_block);
+		if (rc != EOK)
+			return rc;
+
+		/* Read block address from indirect block */
+		current_block =
+		    to_le32(((uint32_t *)block.data)[off_in_blk]);
+
+		/* Put back indirect block untouched */
+		rc = ext4_block_set(fs->bdev, &block);
+		if (rc != EOK)
+			return rc;
+
+		/* Check for sparse file */
+		if (current_block == 0) {
+			*fblock = 0;
+			return EOK;
+		}
+
+		/* Jump to the next level */
+		l--;
+
+		/* Termination condition - we have address of data block loaded
+		 */
+		if (l == 0)
+			break;
+
+		/* Visit the next level */
+		blk_off_in_lvl %= fs->inode_blocks_per_level[l];
+		off_in_blk = blk_off_in_lvl / fs->inode_blocks_per_level[l - 1];
+	}
+
+	*fblock = current_block;
+
+	return EOK;
+}
+
+
+int ext4_fs_get_inode_dblk_idx(struct ext4_inode_ref *inode_ref,
+			       uint64_t iblock, ext4_fsblk_t *fblock,
+			       bool support_unwritten)
+{
+	return ext4_fs_get_inode_dblk_idx_internal(inode_ref, iblock, fblock,
+						   false, support_unwritten);
+}
+
+int ext4_fs_init_inode_dblk_idx(struct ext4_inode_ref *inode_ref,
+				uint64_t iblock, ext4_fsblk_t *fblock)
+{
+	return ext4_fs_get_inode_dblk_idx_internal(inode_ref, iblock, fblock,
+						   true, true);
+}
+
+static int ext4_fs_set_inode_data_block_index(struct ext4_inode_ref *inode_ref,
+				       uint32_t iblock, ext4_fsblk_t fblock)
+{
+	struct ext4_fs *fs = inode_ref->fs;
+
+#if CONFIG_EXTENT_ENABLE
+	/* Handle inode using extents */
+	if ((ext4_sb_feature_incom(&fs->sb, EXT4_FINCOM_EXTENTS)) &&
+	    (ext4_inode_has_flag(inode_ref->inode, EXT4_INODE_FLAG_EXTENTS))) {
+		/* Not reachable */
+		return ENOTSUP;
+	}
+#endif
+
+	/* Handle simple case when we are dealing with direct reference */
+	if (iblock < EXT4_INODE_DIRECT_BLOCK_COUNT) {
+		ext4_inode_set_direct_block(inode_ref->inode, (uint32_t)iblock,
+					    (uint32_t)fblock);
+		inode_ref->dirty = true;
+
+		return EOK;
+	}
+
+	/* Determine the indirection level needed to get the desired block */
+	unsigned int l = 0;
+	unsigned int i;
+	for (i = 1; i < 4; i++) {
+		if (iblock < fs->inode_block_limits[i]) {
+			l = i;
+			break;
+		}
+	}
+
+	if (l == 0)
+		return EIO;
+
+	uint32_t block_size = ext4_sb_get_block_size(&fs->sb);
+
+	/* Compute offsets for the topmost level */
+	uint32_t blk_off_in_lvl =  iblock - fs->inode_block_limits[l - 1];
+	ext4_fsblk_t current_block =
+			ext4_inode_get_indirect_block(inode_ref->inode, l - 1);
+	uint32_t off_in_blk = blk_off_in_lvl / fs->inode_blocks_per_level[l - 1];
+
+	ext4_fsblk_t new_blk;
+
+	struct ext4_block block;
+	struct ext4_block new_block;
+
+	/* Is needed to allocate indirect block on the i-node level */
+	if (current_block == 0) {
+		/* Allocate new indirect block */
+		ext4_fsblk_t goal;
+		int rc = ext4_fs_indirect_find_goal(inode_ref, &goal);
+		if (rc != EOK)
+			return rc;
+
+		rc = ext4_balloc_alloc_block(inode_ref, goal, &new_blk);
+		if (rc != EOK)
+			return rc;
+
+		/* Update i-node */
+		ext4_inode_set_indirect_block(inode_ref->inode, l - 1,
+				(uint32_t)new_blk);
+		inode_ref->dirty = true;
+
+		/* Load newly allocated block */
+		rc = ext4_trans_block_get_noread(fs->bdev, &new_block, new_blk);
+		if (rc != EOK) {
+			ext4_balloc_free_block(inode_ref, new_blk);
+			return rc;
+		}
+
+		/* Initialize new block */
+		memset(new_block.data, 0, block_size);
+		ext4_trans_set_block_dirty(new_block.buf);
+
+		/* Put back the allocated block */
+		rc = ext4_block_set(fs->bdev, &new_block);
+		if (rc != EOK)
+			return rc;
+
+		current_block = new_blk;
+	}
+
+	/*
+	 * Navigate through other levels, until we find the block number
+	 * or find null reference meaning we are dealing with sparse file
+	 */
+	while (l > 0) {
+		int rc = ext4_trans_block_get(fs->bdev, &block, current_block);
+		if (rc != EOK)
+			return rc;
+
+		current_block = to_le32(((uint32_t *)block.data)[off_in_blk]);
+		if ((l > 1) && (current_block == 0)) {
+			ext4_fsblk_t goal;
+			rc = ext4_fs_indirect_find_goal(inode_ref, &goal);
+			if (rc != EOK) {
+				ext4_block_set(fs->bdev, &block);
+				return rc;
+			}
+
+			/* Allocate new block */
+			rc =
+			    ext4_balloc_alloc_block(inode_ref, goal, &new_blk);
+			if (rc != EOK) {
+				ext4_block_set(fs->bdev, &block);
+				return rc;
+			}
+
+			/* Load newly allocated block */
+			rc = ext4_trans_block_get_noread(fs->bdev, &new_block,
+					    new_blk);
+
+			if (rc != EOK) {
+				ext4_block_set(fs->bdev, &block);
+				return rc;
+			}
+
+			/* Initialize allocated block */
+			memset(new_block.data, 0, block_size);
+			ext4_trans_set_block_dirty(new_block.buf);
+
+			rc = ext4_block_set(fs->bdev, &new_block);
+			if (rc != EOK) {
+				ext4_block_set(fs->bdev, &block);
+				return rc;
+			}
+
+			/* Write block address to the parent */
+			uint32_t * p = (uint32_t * )block.data;
+			p[off_in_blk] = to_le32((uint32_t)new_blk);
+			ext4_trans_set_block_dirty(block.buf);
+			current_block = new_blk;
+		}
+
+		/* Will be finished, write the fblock address */
+		if (l == 1) {
+			uint32_t * p = (uint32_t * )block.data;
+			p[off_in_blk] = to_le32((uint32_t)fblock);
+			ext4_trans_set_block_dirty(block.buf);
+		}
+
+		rc = ext4_block_set(fs->bdev, &block);
+		if (rc != EOK)
+			return rc;
+
+		l--;
+
+		/*
+		 * If we are on the last level, break here as
+		 * there is no next level to visit
+		 */
+		if (l == 0)
+			break;
+
+		/* Visit the next level */
+		blk_off_in_lvl %= fs->inode_blocks_per_level[l];
+		off_in_blk = blk_off_in_lvl / fs->inode_blocks_per_level[l - 1];
+	}
+
+	return EOK;
+}
+
+
+int ext4_fs_append_inode_dblk(struct ext4_inode_ref *inode_ref,
+			      ext4_fsblk_t *fblock, uint32_t *iblock)
+{
+#if CONFIG_EXTENT_ENABLE
+	/* Handle extents separately */
+	if ((ext4_sb_feature_incom(&inode_ref->fs->sb, EXT4_FINCOM_EXTENTS)) &&
+	    (ext4_inode_has_flag(inode_ref->inode, EXT4_INODE_FLAG_EXTENTS))) {
+		int rc;
+		ext4_fsblk_t current_fsblk;
+		struct ext4_sblock *sb = &inode_ref->fs->sb;
+		uint64_t inode_size = ext4_inode_get_size(sb, inode_ref->inode);
+		uint32_t block_size = ext4_sb_get_block_size(sb);
+		*iblock = (uint32_t)((inode_size + block_size - 1) / block_size);
+
+		rc = ext4_extent_get_blocks(inode_ref, *iblock, 1,
+						&current_fsblk, true, NULL);
+
+		*fblock = current_fsblk;
+		ext4_assert(*fblock);
+
+		ext4_inode_set_size(inode_ref->inode, inode_size + block_size);
+		inode_ref->dirty = true;
+
+
+		return rc;
+	}
+#endif
+	struct ext4_sblock *sb = &inode_ref->fs->sb;
+
+	/* Compute next block index and allocate data block */
+	uint64_t inode_size = ext4_inode_get_size(sb, inode_ref->inode);
+	uint32_t block_size = ext4_sb_get_block_size(sb);
+
+	/* Align size i-node size */
+	if ((inode_size % block_size) != 0)
+		inode_size += block_size - (inode_size % block_size);
+
+	/* Logical blocks are numbered from 0 */
+	uint32_t new_block_idx = (uint32_t)(inode_size / block_size);
+
+	/* Allocate new physical block */
+	ext4_fsblk_t goal, phys_block;
+	int rc = ext4_fs_indirect_find_goal(inode_ref, &goal);
+	if (rc != EOK)
+		return rc;
+
+	rc = ext4_balloc_alloc_block(inode_ref, goal, &phys_block);
+	if (rc != EOK)
+		return rc;
+
+	/* Add physical block address to the i-node */
+	rc = ext4_fs_set_inode_data_block_index(inode_ref, new_block_idx,
+						phys_block);
+	if (rc != EOK) {
+		ext4_balloc_free_block(inode_ref, phys_block);
+		return rc;
+	}
+
+	/* Update i-node */
+	ext4_inode_set_size(inode_ref->inode, inode_size + block_size);
+	inode_ref->dirty = true;
+
+	*fblock = phys_block;
+	*iblock = new_block_idx;
+
+	return EOK;
+}
+
+void ext4_fs_inode_links_count_inc(struct ext4_inode_ref *inode_ref)
+{
+	uint16_t link;
+	bool is_dx;
+	link = ext4_inode_get_links_cnt(inode_ref->inode);
+	link++;
+	ext4_inode_set_links_cnt(inode_ref->inode, link);
+
+	is_dx = ext4_sb_feature_com(&inode_ref->fs->sb, EXT4_FCOM_DIR_INDEX) &&
+		ext4_inode_has_flag(inode_ref->inode, EXT4_INODE_FLAG_INDEX);
+
+	if (is_dx && link > 1) {
+		if (link >= EXT4_LINK_MAX || link == 2) {
+			ext4_inode_set_links_cnt(inode_ref->inode, 1);
+
+			uint32_t v;
+			v = ext4_get32(&inode_ref->fs->sb, features_read_only);
+			v |= EXT4_FRO_COM_DIR_NLINK;
+			ext4_set32(&inode_ref->fs->sb, features_read_only, v);
+		}
+	}
+}
+
+void ext4_fs_inode_links_count_dec(struct ext4_inode_ref *inode_ref)
+{
+	uint16_t links = ext4_inode_get_links_cnt(inode_ref->inode);
+	if (!ext4_inode_is_type(&inode_ref->fs->sb, inode_ref->inode,
+				EXT4_INODE_MODE_DIRECTORY)) {
+		if (links > 0)
+			ext4_inode_set_links_cnt(inode_ref->inode, links - 1);
+		return;
+	}
+
+	if (links > 2)
+		ext4_inode_set_links_cnt(inode_ref->inode, links - 1);
+}
+
+/**
+ * @}
+ */