/*
 * 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  extent.c
 * @brief Ext4 extent structures operations.
 */

#include <byteorder.h>
#include <errno.h>
#include <mem.h>
#include <stdlib.h>
#include "ext4/balloc.h"
#include "ext4/extent.h"
#include "ext4/inode.h"
#include "ext4/superblock.h"

/** Get logical number of the block covered by extent.
 *
 * @param extent Extent to load number from
 *
 * @return Logical number of the first block covered by extent
 *
 */
uint32_t ext4_extent_get_first_block(ext4_extent_t *extent)
{
	return uint32_t_le2host(extent->first_block);
}

/** Set logical number of the first block covered by extent.
 *
 * @param extent Extent to set number to
 * @param iblock Logical number of the first block covered by extent
 *
 */
void ext4_extent_set_first_block(ext4_extent_t *extent, uint32_t iblock)
{
	extent->first_block = host2uint32_t_le(iblock);
}

/** Get number of blocks covered by extent.
 *
 * @param extent Extent to load count from
 *
 * @return Number of blocks covered by extent
 *
 */
uint16_t ext4_extent_get_block_count(ext4_extent_t *extent)
{
	return uint16_t_le2host(extent->block_count);
}

/** Set number of blocks covered by extent.
 *
 * @param extent Extent to load count from
 * @param count  Number of blocks covered by extent
 *
 */
void ext4_extent_set_block_count(ext4_extent_t *extent, uint16_t count)
{
	extent->block_count = host2uint16_t_le(count);
}

/** Get physical number of the first block covered by extent.
 *
 * @param extent Extent to load number
 *
 * @return Physical number of the first block covered by extent
 *
 */
uint64_t ext4_extent_get_start(ext4_extent_t *extent)
{
	return ((uint64_t)uint16_t_le2host(extent->start_hi)) << 32 |
	    ((uint64_t)uint32_t_le2host(extent->start_lo));
}

/** Set physical number of the first block covered by extent.
 *
 * @param extent Extent to load number
 * @param fblock Physical number of the first block covered by extent
 *
 */
void ext4_extent_set_start(ext4_extent_t *extent, uint64_t fblock)
{
	extent->start_lo = host2uint32_t_le((fblock << 32) >> 32);
	extent->start_hi = host2uint16_t_le((uint16_t)(fblock >> 32));
}

/** Get logical number of the block covered by extent index.
 *
 * @param index Extent index to load number from
 *
 * @return Logical number of the first block covered by extent index
 *
 */
uint32_t ext4_extent_index_get_first_block(ext4_extent_index_t *index)
{
	return uint32_t_le2host(index->first_block);
}

/** Set logical number of the block covered by extent index.
 *
 * @param index  Extent index to set number to
 * @param iblock Logical number of the first block covered by extent index
 *
 */
void ext4_extent_index_set_first_block(ext4_extent_index_t *index,
    uint32_t iblock)
{
	index->first_block = host2uint32_t_le(iblock);
}

/** Get physical number of block where the child node is located.
 *
 * @param index Extent index to load number from
 *
 * @return Physical number of the block with child node
 *
 */
uint64_t ext4_extent_index_get_leaf(ext4_extent_index_t *index)
{
	return ((uint64_t) uint16_t_le2host(index->leaf_hi)) << 32 |
	    ((uint64_t)uint32_t_le2host(index->leaf_lo));
}

/** Set physical number of block where the child node is located.
 *
 * @param index  Extent index to set number to
 * @param fblock Ohysical number of the block with child node
 *
 */
void ext4_extent_index_set_leaf(ext4_extent_index_t *index, uint64_t fblock)
{
	index->leaf_lo = host2uint32_t_le((fblock << 32) >> 32);
	index->leaf_hi = host2uint16_t_le((uint16_t) (fblock >> 32));
}

/** Get magic value from extent header.
 *
 * @param header Extent header to load value from
 *
 * @return Magic value of extent header
 *
 */
uint16_t ext4_extent_header_get_magic(ext4_extent_header_t *header)
{
	return uint16_t_le2host(header->magic);
}

/** Set magic value to extent header.
 *
 * @param header Extent header to set value to
 * @param magic  Magic value of extent header
 *
 */
void ext4_extent_header_set_magic(ext4_extent_header_t *header, uint16_t magic)
{
	header->magic = host2uint16_t_le(magic);
}

/** Get number of entries from extent header
 *
 * @param header Extent header to get value from
 *
 * @return Number of entries covered by extent header
 *
 */
uint16_t ext4_extent_header_get_entries_count(ext4_extent_header_t *header)
{
	return uint16_t_le2host(header->entries_count);
}

/** Set number of entries to extent header
 *
 * @param header Extent header to set value to
 * @param count  Number of entries covered by extent header
 *
 */
void ext4_extent_header_set_entries_count(ext4_extent_header_t *header,
    uint16_t count)
{
	header->entries_count = host2uint16_t_le(count);
}

/** Get maximum number of entries from extent header
 *
 * @param header Extent header to get value from
 *
 * @return Maximum number of entries covered by extent header
 *
 */
uint16_t ext4_extent_header_get_max_entries_count(ext4_extent_header_t *header)
{
	return uint16_t_le2host(header->max_entries_count);
}

/** Set maximum number of entries to extent header
 *
 * @param header    Extent header to set value to
 * @param max_count Maximum number of entries covered by extent header
 *
 */
void ext4_extent_header_set_max_entries_count(ext4_extent_header_t *header,
    uint16_t max_count)
{
	header->max_entries_count = host2uint16_t_le(max_count);
}

/** Get depth of extent subtree.
 *
 * @param header Extent header to get value from
 *
 * @return Depth of extent subtree
 *
 */
uint16_t ext4_extent_header_get_depth(ext4_extent_header_t *header)
{
	return uint16_t_le2host(header->depth);
}

/** Set depth of extent subtree.
 *
 * @param header Extent header to set value to
 * @param depth  Depth of extent subtree
 *
 */
void ext4_extent_header_set_depth(ext4_extent_header_t *header, uint16_t depth)
{
	header->depth = host2uint16_t_le(depth);
}

/** Get generation from extent header
 *
 * @param header Extent header to get value from
 *
 * @return Generation
 *
 */
uint32_t ext4_extent_header_get_generation(ext4_extent_header_t *header)
{
	return uint32_t_le2host(header->generation);
}

/** Set generation to extent header
 *
 * @param header     Extent header to set value to
 * @param generation Generation
 *
 */
void ext4_extent_header_set_generation(ext4_extent_header_t *header,
    uint32_t generation)
{
	header->generation = host2uint32_t_le(generation);
}

/** Binary search in extent index node.
 *
 * @param header Extent header of index node
 * @param index  Output value - found index will be set here
 * @param iblock Logical block number to find in index node
 *
 */
static void ext4_extent_binsearch_idx(ext4_extent_header_t *header,
    ext4_extent_index_t **index, uint32_t iblock)
{
	ext4_extent_index_t *r;
	ext4_extent_index_t *l;
	ext4_extent_index_t *m;
	
	uint16_t entries_count =
	    ext4_extent_header_get_entries_count(header);
	
	/* Initialize bounds */
	l = EXT4_EXTENT_FIRST_INDEX(header) + 1;
	r = EXT4_EXTENT_FIRST_INDEX(header) + entries_count - 1;
	
	/* Do binary search */
	while (l <= r) {
		m = l + (r - l) / 2;
		uint32_t first_block = ext4_extent_index_get_first_block(m);
		
		if (iblock < first_block)
			r = m - 1;
		else
			l = m + 1;
	}
	
	/* Set output value */
	*index = l - 1;
}

/** Binary search in extent leaf node.
 *
 * @param header Extent header of leaf node
 * @param extent Output value - found extent will be set here,
 *               or NULL if node is empty
 * @param iblock Logical block number to find in leaf node
 *
 */
static void ext4_extent_binsearch(ext4_extent_header_t *header,
    ext4_extent_t **extent, uint32_t iblock)
{
	ext4_extent_t *r;
	ext4_extent_t *l;
	ext4_extent_t *m;
	
	uint16_t entries_count =
	    ext4_extent_header_get_entries_count(header);
	
	if (entries_count == 0) {
		/* this leaf is empty */
		*extent = NULL;
		return;
	}
	
	/* Initialize bounds */
	l = EXT4_EXTENT_FIRST(header) + 1;
	r = EXT4_EXTENT_FIRST(header) + entries_count - 1;
	
	/* Do binary search */
	while (l <= r) {
		m = l + (r - l) / 2;
		uint32_t first_block = ext4_extent_get_first_block(m);
		
		if (iblock < first_block)
			r = m - 1;
		else
			l = m + 1;
	}
	
	/* Set output value */
	*extent = l - 1;
}

/** Find physical block in the extent tree by logical block number.
 *
 * There is no need to save path in the tree during this algorithm.
 *
 * @param inode_ref I-node to load block from
 * @param iblock    Logical block number to find
 * @param fblock    Output value for physical block number
 *
 * @return Error code
 *
 */
errno_t ext4_extent_find_block(ext4_inode_ref_t *inode_ref, uint32_t iblock,
    uint32_t *fblock)
{
	errno_t rc = EOK;
	/* Compute bound defined by i-node size */
	uint64_t inode_size =
	    ext4_inode_get_size(inode_ref->fs->superblock, inode_ref->inode);
	
	uint32_t block_size =
	    ext4_superblock_get_block_size(inode_ref->fs->superblock);
	
	uint32_t last_idx = (inode_size - 1) / block_size;
	
	/* Check if requested iblock is not over size of i-node */
	if (iblock > last_idx) {
		*fblock = 0;
		return EOK;
	}
	
	block_t *block = NULL;
	
	/* Walk through extent tree */
	ext4_extent_header_t *header =
	    ext4_inode_get_extent_header(inode_ref->inode);
	
	while (ext4_extent_header_get_depth(header) != 0) {
		/* Search index in node */
		ext4_extent_index_t *index;
		ext4_extent_binsearch_idx(header, &index, iblock);
		
		/* Load child node and set values for the next iteration */
		uint64_t child = ext4_extent_index_get_leaf(index);
		
		if (block != NULL) {
			rc = block_put(block);
			if (rc != EOK)
				return rc;
		}
		
		rc = block_get(&block, inode_ref->fs->device, child,
		    BLOCK_FLAGS_NONE);
		if (rc != EOK)
			return rc;
		
		header = (ext4_extent_header_t *)block->data;
	}
	
	/* Search extent in the leaf block */
	ext4_extent_t* extent = NULL;
	ext4_extent_binsearch(header, &extent, iblock);
	
	/* Prevent empty leaf */
	if (extent == NULL) {
		*fblock = 0;
	} else {
		/* Compute requested physical block address */
		uint32_t phys_block;
		uint32_t first = ext4_extent_get_first_block(extent);
		phys_block = ext4_extent_get_start(extent) + iblock - first;
		
		*fblock = phys_block;
	}
	
	/* Cleanup */
	if (block != NULL)
		rc = block_put(block);
	
	return rc;
}

/** Find extent for specified iblock.
 *
 * This function is used for finding block in the extent tree with
 * saving the path through the tree for possible future modifications.
 *
 * @param inode_ref I-node to read extent tree from
 * @param iblock    Iblock to find extent for
 * @param ret_path  Output value for loaded path from extent tree
 *
 * @return Error code
 *
 */
static errno_t ext4_extent_find_extent(ext4_inode_ref_t *inode_ref, uint32_t iblock,
    ext4_extent_path_t **ret_path)
{
	ext4_extent_header_t *eh =
	    ext4_inode_get_extent_header(inode_ref->inode);
	
	uint16_t depth = ext4_extent_header_get_depth(eh);
	
	ext4_extent_path_t *tmp_path;
	
	/* Added 2 for possible tree growing */
	tmp_path = malloc(sizeof(ext4_extent_path_t) * (depth + 2));
	if (tmp_path == NULL)
		return ENOMEM;
	
	/* Initialize structure for algorithm start */
	tmp_path[0].block = inode_ref->block;
	tmp_path[0].header = eh;
	
	/* Walk through the extent tree */
	uint16_t pos = 0;
	errno_t rc;
	while (ext4_extent_header_get_depth(eh) != 0) {
		/* Search index in index node by iblock */
		ext4_extent_binsearch_idx(tmp_path[pos].header,
		    &tmp_path[pos].index, iblock);
		
		tmp_path[pos].depth = depth;
		tmp_path[pos].extent = NULL;
		
		assert(tmp_path[pos].index != NULL);
		
		/* Load information for the next iteration */
		uint64_t fblock = ext4_extent_index_get_leaf(tmp_path[pos].index);
		
		block_t *block;
		rc = block_get(&block, inode_ref->fs->device, fblock,
		    BLOCK_FLAGS_NONE);
		if (rc != EOK)
			goto cleanup;
		
		pos++;
		
		eh = (ext4_extent_header_t *)block->data;
		tmp_path[pos].block = block;
		tmp_path[pos].header = eh;
	}
	
	tmp_path[pos].depth = 0;
	tmp_path[pos].extent = NULL;
	tmp_path[pos].index = NULL;
	
	/* Find extent in the leaf node */
	ext4_extent_binsearch(tmp_path[pos].header, &tmp_path[pos].extent, iblock);
	*ret_path = tmp_path;
	
	return EOK;
	
cleanup:
	;

	errno_t rc2 = EOK;

	/*
	 * Put loaded blocks
	 * From 1: 0 is a block with inode data
	 */
	for (uint16_t i = 1; i < tmp_path->depth; ++i) {
		if (tmp_path[i].block) {
			rc2 = block_put(tmp_path[i].block);
			if (rc == EOK && rc2 != EOK)
				rc = rc2;
		}
	}
	
	/* Destroy temporary data structure */
	free(tmp_path);
	
	return rc;
}

/** Release extent and all data blocks covered by the extent.
 *
 * @param inode_ref I-node to release extent and block from
 * @param extent    Extent to release
 *
 * @return Error code
 *
 */
static errno_t ext4_extent_release(ext4_inode_ref_t *inode_ref,
    ext4_extent_t *extent)
{
	/* Compute number of the first physical block to release */
	uint64_t start = ext4_extent_get_start(extent);
	uint16_t block_count = ext4_extent_get_block_count(extent);
	
	return ext4_balloc_free_blocks(inode_ref, start, block_count);
}

/** Recursively release the whole branch of the extent tree.
 *
 * For each entry of the node release the subbranch and finally release
 * the node. In the leaf node all extents will be released.
 *
 * @param inode_ref I-node where the branch is released
 * @param index     Index in the non-leaf node to be released
 *                  with the whole subtree
 *
 * @return Error code
 *
 */
static errno_t ext4_extent_release_branch(ext4_inode_ref_t *inode_ref,
		ext4_extent_index_t *index)
{
	uint32_t fblock = ext4_extent_index_get_leaf(index);
	
	block_t* block;
	errno_t rc = block_get(&block, inode_ref->fs->device, fblock, BLOCK_FLAGS_NONE);
	if (rc != EOK)
		return rc;
	
	ext4_extent_header_t *header = block->data;
	
	if (ext4_extent_header_get_depth(header)) {
		/* The node is non-leaf, do recursion */
		ext4_extent_index_t *idx = EXT4_EXTENT_FIRST_INDEX(header);
		
		/* Release all subbranches */
		for (uint32_t i = 0;
		    i < ext4_extent_header_get_entries_count(header);
		    ++i, ++idx) {
			rc = ext4_extent_release_branch(inode_ref, idx);
			if (rc != EOK)
				return rc;
		}
	} else {
		/* Leaf node reached */
		ext4_extent_t *ext = EXT4_EXTENT_FIRST(header);
		
		/* Release all extents and stop recursion */
		for (uint32_t i = 0;
		    i < ext4_extent_header_get_entries_count(header);
		    ++i, ++ext) {
			rc = ext4_extent_release(inode_ref, ext);
			if (rc != EOK)
				return rc;
		}
	}
	
	/* Release data block where the node was stored */
	
	rc = block_put(block);
	if (rc != EOK)
		return rc;
	
	return ext4_balloc_free_block(inode_ref, fblock);
}

/** Release all data blocks starting from specified logical block.
 *
 * @param inode_ref   I-node to release blocks from
 * @param iblock_from First logical block to release
 *
 */
errno_t ext4_extent_release_blocks_from(ext4_inode_ref_t *inode_ref,
    uint32_t iblock_from)
{
	/* Find the first extent to modify */
	ext4_extent_path_t *path;
	errno_t rc = ext4_extent_find_extent(inode_ref, iblock_from, &path);
	if (rc != EOK)
		return rc;
	
	/* Jump to last item of the path (extent) */
	ext4_extent_path_t *path_ptr = path;
	while (path_ptr->depth != 0)
		path_ptr++;
	
	assert(path_ptr->extent != NULL);
	
	/* First extent maybe released partially */
	uint32_t first_iblock =
	    ext4_extent_get_first_block(path_ptr->extent);
	uint32_t first_fblock =
	    ext4_extent_get_start(path_ptr->extent) + iblock_from - first_iblock;
	
	uint16_t block_count = ext4_extent_get_block_count(path_ptr->extent);
	
	uint16_t delete_count = block_count -
	    (ext4_extent_get_start(path_ptr->extent) - first_fblock);
	
	/* Release all blocks */
	rc = ext4_balloc_free_blocks(inode_ref, first_fblock, delete_count);
	if (rc != EOK)
		goto cleanup;
	
	/* Correct counter */
	block_count -= delete_count;
	ext4_extent_set_block_count(path_ptr->extent, block_count);
	
	/* Initialize the following loop */
	uint16_t entries =
	    ext4_extent_header_get_entries_count(path_ptr->header);
	ext4_extent_t *tmp_ext = path_ptr->extent + 1;
	ext4_extent_t *stop_ext = EXT4_EXTENT_FIRST(path_ptr->header) + entries;
	
	/* If first extent empty, release it */
	if (block_count == 0)
		entries--;
	
	/* Release all successors of the first extent in the same node */
	while (tmp_ext < stop_ext) {
		first_fblock = ext4_extent_get_start(tmp_ext);
		delete_count = ext4_extent_get_block_count(tmp_ext);
		
		rc = ext4_balloc_free_blocks(inode_ref, first_fblock, delete_count);
		if (rc != EOK)
			goto cleanup;
		
		entries--;
		tmp_ext++;
	}
	
	ext4_extent_header_set_entries_count(path_ptr->header, entries);
	path_ptr->block->dirty = true;
	
	/* If leaf node is empty, parent entry must be modified */
	bool remove_parent_record = false;
	
	/* Don't release root block (including inode data) !!! */
	if ((path_ptr != path) && (entries == 0)) {
		rc = ext4_balloc_free_block(inode_ref, path_ptr->block->lba);
		if (rc != EOK)
			goto cleanup;
		
		remove_parent_record = true;
	}
	
	/* Jump to the parent */
	--path_ptr;
	
	/* Release all successors in all tree levels */
	while (path_ptr >= path) {
		entries = ext4_extent_header_get_entries_count(path_ptr->header);
		ext4_extent_index_t *index = path_ptr->index + 1;
		ext4_extent_index_t *stop =
		    EXT4_EXTENT_FIRST_INDEX(path_ptr->header) + entries;
		
		/* Correct entries count because of changes in the previous iteration */
		if (remove_parent_record)
			entries--;
		
		/* Iterate over all entries and release the whole subtrees */
		while (index < stop) {
			rc = ext4_extent_release_branch(inode_ref, index);
			if (rc != EOK)
				goto cleanup;
			
			++index;
			--entries;
		}
		
		ext4_extent_header_set_entries_count(path_ptr->header, entries);
		path_ptr->block->dirty = true;
		
		/* Free the node if it is empty */
		if ((entries == 0) && (path_ptr != path)) {
			rc = ext4_balloc_free_block(inode_ref, path_ptr->block->lba);
			if (rc != EOK)
				goto cleanup;
			
			/* Mark parent to be checked */
			remove_parent_record = true;
		} else
			remove_parent_record = false;
		
		--path_ptr;
	}
	
cleanup:
	;

	errno_t rc2 = EOK;

	/*
	 * Put loaded blocks
	 * starting from 1: 0 is a block with inode data
	 */
	for (uint16_t i = 1; i <= path->depth; ++i) {
		if (path[i].block) {
			rc2 = block_put(path[i].block);
			if (rc == EOK && rc2 != EOK)
				rc = rc2;
		}
	}
	
	/* Destroy temporary data structure */
	free(path);
	
	return rc;
}

/** Append new extent to the i-node and do some splitting if necessary.
 *
 * @param inode_ref      I-node to append extent to
 * @param path           Path in the extent tree for possible splitting
 * @param last_path_item Input/output parameter for pointer to the last
 *                       valid item in the extent tree path
 * @param iblock         Logical index of block to append extent for
 *
 * @return Error code
 *
 */
static errno_t ext4_extent_append_extent(ext4_inode_ref_t *inode_ref,
    ext4_extent_path_t *path, uint32_t iblock)
{
	ext4_extent_path_t *path_ptr = path + path->depth;
	
	uint32_t block_size =
	    ext4_superblock_get_block_size(inode_ref->fs->superblock);
	
	/* Start splitting */
	while (path_ptr > path) {
		uint16_t entries =
		    ext4_extent_header_get_entries_count(path_ptr->header);
		uint16_t limit =
		    ext4_extent_header_get_max_entries_count(path_ptr->header);
		
		if (entries == limit) {
			/* Full node - allocate block for new one */
			uint32_t fblock;
			errno_t rc = ext4_balloc_alloc_block(inode_ref, &fblock);
			if (rc != EOK)
				return rc;
			
			block_t *block;
			rc = block_get(&block, inode_ref->fs->device, fblock,
			    BLOCK_FLAGS_NOREAD);
			if (rc != EOK) {
				ext4_balloc_free_block(inode_ref, fblock);
				return rc;
			}
			
			/* Put back not modified old block */
			rc = block_put(path_ptr->block);
			if (rc != EOK) {
				ext4_balloc_free_block(inode_ref, fblock);
				block_put(block);
				return rc;
			}
			
			/* Initialize newly allocated block and remember it */
			memset(block->data, 0, block_size);
			path_ptr->block = block;
			
			/* Update pointers in extent path structure */
			path_ptr->header = block->data;
			if (path_ptr->depth) {
				path_ptr->index = EXT4_EXTENT_FIRST_INDEX(path_ptr->header);
				ext4_extent_index_set_first_block(path_ptr->index, iblock);
				ext4_extent_index_set_leaf(path_ptr->index, (path_ptr + 1)->block->lba);
				limit = (block_size - sizeof(ext4_extent_header_t)) /
				    sizeof(ext4_extent_index_t);
			} else {
				path_ptr->extent = EXT4_EXTENT_FIRST(path_ptr->header);
				ext4_extent_set_first_block(path_ptr->extent, iblock);
				limit = (block_size - sizeof(ext4_extent_header_t)) /
				    sizeof(ext4_extent_t);
			}
			
			/* Initialize on-disk structure (header) */
			ext4_extent_header_set_entries_count(path_ptr->header, 1);
			ext4_extent_header_set_max_entries_count(path_ptr->header, limit);
			ext4_extent_header_set_magic(path_ptr->header, EXT4_EXTENT_MAGIC);
			ext4_extent_header_set_depth(path_ptr->header, path_ptr->depth);
			ext4_extent_header_set_generation(path_ptr->header, 0);
			
			path_ptr->block->dirty = true;
			
			/* Jump to the preceeding item */
			path_ptr--;
		} else {
			/* Node with free space */
			if (path_ptr->depth) {
				path_ptr->index = EXT4_EXTENT_FIRST_INDEX(path_ptr->header) + entries;
				ext4_extent_index_set_first_block(path_ptr->index, iblock);
				ext4_extent_index_set_leaf(path_ptr->index, (path_ptr + 1)->block->lba);
			} else {
				path_ptr->extent = EXT4_EXTENT_FIRST(path_ptr->header) + entries;
				ext4_extent_set_first_block(path_ptr->extent, iblock);
			}
			
			ext4_extent_header_set_entries_count(path_ptr->header, entries + 1);
			path_ptr->block->dirty = true;
			
			/* No more splitting needed */
			return EOK;
		}
	}
	
	assert(path_ptr == path);
	
	/* Should be the root split too? */
	
	uint16_t entries = ext4_extent_header_get_entries_count(path->header);
	uint16_t limit = ext4_extent_header_get_max_entries_count(path->header);
	
	if (entries == limit) {
		uint32_t new_fblock;
		errno_t rc = ext4_balloc_alloc_block(inode_ref, &new_fblock);
		if (rc != EOK)
			return rc;
		
		block_t *block;
		rc = block_get(&block, inode_ref->fs->device, new_fblock,
		    BLOCK_FLAGS_NOREAD);
		if (rc != EOK)
			return rc;
		
		/* Initialize newly allocated block */
		memset(block->data, 0, block_size);
		
		/* Move data from root to the new block */
		memcpy(block->data, inode_ref->inode->blocks,
		    EXT4_INODE_BLOCKS * sizeof(uint32_t));
		
		/* Data block is initialized */
		
		block_t *root_block = path->block;
		uint16_t root_depth = path->depth;
		ext4_extent_header_t *root_header = path->header;
		
		/* Make space for tree growing */
		ext4_extent_path_t *new_root = path;
		ext4_extent_path_t *old_root = path + 1;
		
		size_t nbytes = sizeof(ext4_extent_path_t) * (path->depth + 1);
		memmove(old_root, new_root, nbytes);
		memset(new_root, 0, sizeof(ext4_extent_path_t));
		
		/* Update old root structure */
		old_root->block = block;
		old_root->header = (ext4_extent_header_t *)block->data;
		
		/* Add new entry and update limit for entries */
		if (old_root->depth) {
			limit = (block_size - sizeof(ext4_extent_header_t)) /
			    sizeof(ext4_extent_index_t);
			old_root->index = EXT4_EXTENT_FIRST_INDEX(old_root->header) + entries;
			ext4_extent_index_set_first_block(old_root->index, iblock);
			ext4_extent_index_set_leaf(old_root->index, (old_root + 1)->block->lba);
			old_root->extent = NULL;
		} else {
			limit = (block_size - sizeof(ext4_extent_header_t)) /
			    sizeof(ext4_extent_t);
			old_root->extent = EXT4_EXTENT_FIRST(old_root->header) + entries;
			ext4_extent_set_first_block(old_root->extent, iblock);
			old_root->index = NULL;
		}
		
		ext4_extent_header_set_entries_count(old_root->header, entries + 1);
		ext4_extent_header_set_max_entries_count(old_root->header, limit);
		
		old_root->block->dirty = true;
		
		/* Re-initialize new root metadata */
		new_root->depth = root_depth + 1;
		new_root->block = root_block;
		new_root->header = root_header;
		new_root->extent = NULL;
		new_root->index = EXT4_EXTENT_FIRST_INDEX(new_root->header);
		
		ext4_extent_header_set_depth(new_root->header, new_root->depth);
		
		/* Create new entry in root */
		ext4_extent_header_set_entries_count(new_root->header, 1);
		ext4_extent_index_set_first_block(new_root->index, 0);
		ext4_extent_index_set_leaf(new_root->index, new_fblock);
		
		new_root->block->dirty = true;
	} else {
		if (path->depth) {
			path->index = EXT4_EXTENT_FIRST_INDEX(path->header) + entries;
			ext4_extent_index_set_first_block(path->index, iblock);
			ext4_extent_index_set_leaf(path->index, (path + 1)->block->lba);
		} else {
			path->extent = EXT4_EXTENT_FIRST(path->header) + entries;
			ext4_extent_set_first_block(path->extent, iblock);
		}
		
		ext4_extent_header_set_entries_count(path->header, entries + 1);
		path->block->dirty = true;
	}
	
	return EOK;
}

/** Append data block to the i-node.
 *
 * This function allocates data block, tries to append it
 * to some existing extent or creates new extents.
 * It includes possible extent tree modifications (splitting).
 *<
 * @param inode_ref I-node to append block to
 * @param iblock    Output logical number of newly allocated block
 * @param fblock    Output physical block address of newly allocated block
 *
 * @return Error code
 *
 */
errno_t ext4_extent_append_block(ext4_inode_ref_t *inode_ref, uint32_t *iblock,
    uint32_t *fblock, bool update_size)
{
	ext4_superblock_t *sb = inode_ref->fs->superblock;
	uint64_t inode_size = ext4_inode_get_size(sb, inode_ref->inode);
	uint32_t block_size = ext4_superblock_get_block_size(sb);
	
	/* Calculate number of new logical block */
	uint32_t new_block_idx = 0;
	if (inode_size > 0) {
		if ((inode_size % block_size) != 0)
			inode_size += block_size - (inode_size % block_size);
		
		new_block_idx = inode_size / block_size;
	}
	
	/* Load the nearest leaf (with extent) */
	ext4_extent_path_t *path;
	errno_t rc = ext4_extent_find_extent(inode_ref, new_block_idx, &path);
	if (rc != EOK)
		return rc;
	
	/* Jump to last item of the path (extent) */
	ext4_extent_path_t *path_ptr = path;
	while (path_ptr->depth != 0)
		path_ptr++;
	
	/* Add new extent to the node if not present */
	if (path_ptr->extent == NULL)
		goto append_extent;
	
	uint16_t block_count = ext4_extent_get_block_count(path_ptr->extent);
	uint16_t block_limit = (1 << 15);
	
	uint32_t phys_block = 0;
	if (block_count < block_limit) {
		/* There is space for new block in the extent */
		if (block_count == 0) {
			/* Existing extent is empty */
			rc = ext4_balloc_alloc_block(inode_ref, &phys_block);
			if (rc != EOK)
				goto finish;
			
			/* Initialize extent */
			ext4_extent_set_first_block(path_ptr->extent, new_block_idx);
			ext4_extent_set_start(path_ptr->extent, phys_block);
			ext4_extent_set_block_count(path_ptr->extent, 1);
			
			/* Update i-node */
			if (update_size) {
				ext4_inode_set_size(inode_ref->inode, inode_size + block_size);
				inode_ref->dirty = true;
			}
			
			path_ptr->block->dirty = true;
			
			goto finish;
		} else {
			/* Existing extent contains some blocks */
			phys_block = ext4_extent_get_start(path_ptr->extent);
			phys_block += ext4_extent_get_block_count(path_ptr->extent);
			
			/* Check if the following block is free for allocation */
			bool free;
			rc = ext4_balloc_try_alloc_block(inode_ref, phys_block, &free);
			if (rc != EOK)
				goto finish;
			
			if (!free) {
				/* Target is not free, new block must be appended to new extent */
				goto append_extent;
			}
			
			/* Update extent */
			ext4_extent_set_block_count(path_ptr->extent, block_count + 1);
			
			/* Update i-node */
			if (update_size) {
				ext4_inode_set_size(inode_ref->inode, inode_size + block_size);
				inode_ref->dirty = true;
			}
			
			path_ptr->block->dirty = true;
			
			goto finish;
		}
	}
	
	
append_extent:
	/* Append new extent to the tree */
	phys_block = 0;
	
	/* Allocate new data block */
	rc = ext4_balloc_alloc_block(inode_ref, &phys_block);
	if (rc != EOK)
		goto finish;
	
	/* Append extent for new block (includes tree splitting if needed) */
	rc = ext4_extent_append_extent(inode_ref, path, new_block_idx);
	if (rc != EOK) {
		ext4_balloc_free_block(inode_ref, phys_block);
		goto finish;
	}
	
	uint32_t tree_depth = ext4_extent_header_get_depth(path->header);
	path_ptr = path + tree_depth;
	
	/* Initialize newly created extent */
	ext4_extent_set_block_count(path_ptr->extent, 1);
	ext4_extent_set_first_block(path_ptr->extent, new_block_idx);
	ext4_extent_set_start(path_ptr->extent, phys_block);
	
	/* Update i-node */
	if (update_size) {
		ext4_inode_set_size(inode_ref->inode, inode_size + block_size);
		inode_ref->dirty = true;
	}
	
	path_ptr->block->dirty = true;
	
finish:
	;

	errno_t rc2 = EOK;

	/* Set return values */
	*iblock = new_block_idx;
	*fblock = phys_block;
	
	/*
	 * Put loaded blocks
	 * starting from 1: 0 is a block with inode data
	 */
	for (uint16_t i = 1; i <= path->depth; ++i) {
		if (path[i].block) {
			rc2 = block_put(path[i].block);
			if (rc == EOK && rc2 != EOK)
				rc = rc2;
		}
	}
	
	/* Destroy temporary data structure */
	free(path);
	
	return rc;
}

/**
 * @}
 */
