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fdt_ro.c

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    ext4_common.c 56.22 KiB
    /*
     * (C) Copyright 2011 - 2012 Samsung Electronics
     * EXT4 filesystem implementation in Uboot by
     * Uma Shankar <uma.shankar@samsung.com>
     * Manjunatha C Achar <a.manjunatha@samsung.com>
     *
     * ext4ls and ext4load : Based on ext2 ls load support in Uboot.
     *
     * (C) Copyright 2004
     * esd gmbh <www.esd-electronics.com>
     * Reinhard Arlt <reinhard.arlt@esd-electronics.com>
     *
     * based on code from grub2 fs/ext2.c and fs/fshelp.c by
     * GRUB  --  GRand Unified Bootloader
     * Copyright (C) 2003, 2004  Free Software Foundation, Inc.
     *
     * ext4write : Based on generic ext4 protocol.
     *
     * SPDX-License-Identifier:	GPL-2.0+
     */
    
    #include <common.h>
    #include <ext_common.h>
    #include <ext4fs.h>
    #include <inttypes.h>
    #include <malloc.h>
    #include <memalign.h>
    #include <stddef.h>
    #include <linux/stat.h>
    #include <linux/time.h>
    #include <asm/byteorder.h>
    #include "ext4_common.h"
    
    struct ext2_data *ext4fs_root;
    struct ext2fs_node *ext4fs_file;
    __le32 *ext4fs_indir1_block;
    int ext4fs_indir1_size;
    int ext4fs_indir1_blkno = -1;
    __le32 *ext4fs_indir2_block;
    int ext4fs_indir2_size;
    int ext4fs_indir2_blkno = -1;
    
    __le32 *ext4fs_indir3_block;
    int ext4fs_indir3_size;
    int ext4fs_indir3_blkno = -1;
    struct ext2_inode *g_parent_inode;
    static int symlinknest;
    
    #if defined(CONFIG_EXT4_WRITE)
    static inline void ext4fs_sb_free_inodes_dec(struct ext2_sblock *sb)
    {
    	sb->free_inodes = cpu_to_le32(le32_to_cpu(sb->free_inodes) - 1);
    }
    
    static inline void ext4fs_sb_free_blocks_dec(struct ext2_sblock *sb)
    {
    	sb->free_blocks = cpu_to_le32(le32_to_cpu(sb->free_blocks) - 1);
    }
    
    static inline void ext4fs_bg_free_inodes_dec(struct ext2_block_group *bg)
    {
    	bg->free_inodes = cpu_to_le16(le16_to_cpu(bg->free_inodes) - 1);
    }
    
    static inline void ext4fs_bg_free_blocks_dec(struct ext2_block_group *bg)
    {
    	bg->free_blocks = cpu_to_le16(le16_to_cpu(bg->free_blocks) - 1);
    }
    
    static inline void ext4fs_bg_itable_unused_dec(struct ext2_block_group *bg)
    {
    	bg->bg_itable_unused = cpu_to_le16(le16_to_cpu(bg->bg_itable_unused) - 1);
    }
    
    uint32_t ext4fs_div_roundup(uint32_t size, uint32_t n)
    {
    	uint32_t res = size / n;
    	if (res * n != size)
    		res++;
    
    	return res;
    }
    
    void put_ext4(uint64_t off, void *buf, uint32_t size)
    {
    	uint64_t startblock;
    	uint64_t remainder;
    	unsigned char *temp_ptr = NULL;
    	struct ext_filesystem *fs = get_fs();
    	int log2blksz = fs->dev_desc->log2blksz;
    	ALLOC_CACHE_ALIGN_BUFFER(unsigned char, sec_buf, fs->dev_desc->blksz);
    
    	startblock = off >> log2blksz;
    	startblock += part_offset;
    	remainder = off & (uint64_t)(fs->dev_desc->blksz - 1);
    
    	if (fs->dev_desc == NULL)
    		return;
    
    	if ((startblock + (size >> log2blksz)) >
    	    (part_offset + fs->total_sect)) {
    		printf("part_offset is " LBAFU "\n", part_offset);
    		printf("total_sector is %" PRIu64 "\n", fs->total_sect);
    		printf("error: overflow occurs\n");
    		return;
    	}
    
    	if (remainder) {
    		blk_dread(fs->dev_desc, startblock, 1, sec_buf);
    		temp_ptr = sec_buf;
    		memcpy((temp_ptr + remainder), (unsigned char *)buf, size);
    		blk_dwrite(fs->dev_desc, startblock, 1, sec_buf);
    	} else {
    		if (size >> log2blksz != 0) {
    			blk_dwrite(fs->dev_desc, startblock, size >> log2blksz,
    				   (unsigned long *)buf);
    		} else {
    			blk_dread(fs->dev_desc, startblock, 1, sec_buf);
    			temp_ptr = sec_buf;
    			memcpy(temp_ptr, buf, size);
    			blk_dwrite(fs->dev_desc, startblock, 1,
    				   (unsigned long *)sec_buf);
    		}
    	}
    }
    
    static int _get_new_inode_no(unsigned char *buffer)
    {
    	struct ext_filesystem *fs = get_fs();
    	unsigned char input;
    	int operand, status;
    	int count = 1;
    	int j = 0;
    
    	/* get the blocksize of the filesystem */
    	unsigned char *ptr = buffer;
    	while (*ptr == 255) {
    		ptr++;
    		count += 8;
    		if (count > le32_to_cpu(ext4fs_root->sblock.inodes_per_group))
    			return -1;
    	}
    
    	for (j = 0; j < fs->blksz; j++) {
    		input = *ptr;
    		int i = 0;
    		while (i <= 7) {
    			operand = 1 << i;
    			status = input & operand;
    			if (status) {
    				i++;
    				count++;
    			} else {
    				*ptr |= operand;
    				return count;
    			}
    		}
    		ptr = ptr + 1;
    	}
    
    	return -1;
    }
    
    static int _get_new_blk_no(unsigned char *buffer)
    {
    	int operand;
    	int count = 0;
    	int i;
    	unsigned char *ptr = buffer;
    	struct ext_filesystem *fs = get_fs();
    
    	while (*ptr == 255) {
    		ptr++;
    		count += 8;
    		if (count == (fs->blksz * 8))
    			return -1;
    	}
    
    	if (fs->blksz == 1024)
    		count += 1;
    
    	for (i = 0; i <= 7; i++) {
    		operand = 1 << i;
    		if (*ptr & operand) {
    			count++;
    		} else {
    			*ptr |= operand;
    			return count;
    		}
    	}
    
    	return -1;
    }
    
    int ext4fs_set_block_bmap(long int blockno, unsigned char *buffer, int index)
    {
    	int i, remainder, status;
    	unsigned char *ptr = buffer;
    	unsigned char operand;
    	i = blockno / 8;
    	remainder = blockno % 8;
    	int blocksize = EXT2_BLOCK_SIZE(ext4fs_root);
    
    	i = i - (index * blocksize);
    	if (blocksize != 1024) {
    		ptr = ptr + i;
    		operand = 1 << remainder;
    		status = *ptr & operand;
    		if (status)
    			return -1;
    
    		*ptr = *ptr | operand;
    		return 0;
    	} else {
    		if (remainder == 0) {
    			ptr = ptr + i - 1;
    			operand = (1 << 7);
    		} else {
    			ptr = ptr + i;
    			operand = (1 << (remainder - 1));
    		}
    		status = *ptr & operand;
    		if (status)
    			return -1;
    
    		*ptr = *ptr | operand;
    		return 0;
    	}
    }
    
    void ext4fs_reset_block_bmap(long int blockno, unsigned char *buffer, int index)
    {
    	int i, remainder, status;
    	unsigned char *ptr = buffer;
    	unsigned char operand;
    	i = blockno / 8;
    	remainder = blockno % 8;
    	int blocksize = EXT2_BLOCK_SIZE(ext4fs_root);
    
    	i = i - (index * blocksize);
    	if (blocksize != 1024) {
    		ptr = ptr + i;
    		operand = (1 << remainder);
    		status = *ptr & operand;
    		if (status)
    			*ptr = *ptr & ~(operand);
    	} else {
    		if (remainder == 0) {
    			ptr = ptr + i - 1;
    			operand = (1 << 7);
    		} else {
    			ptr = ptr + i;
    			operand = (1 << (remainder - 1));
    		}
    		status = *ptr & operand;
    		if (status)
    			*ptr = *ptr & ~(operand);
    	}
    }
    
    int ext4fs_set_inode_bmap(int inode_no, unsigned char *buffer, int index)
    {
    	int i, remainder, status;
    	unsigned char *ptr = buffer;
    	unsigned char operand;
    
    	inode_no -= (index * le32_to_cpu(ext4fs_root->sblock.inodes_per_group));
    	i = inode_no / 8;
    	remainder = inode_no % 8;
    	if (remainder == 0) {
    		ptr = ptr + i - 1;
    		operand = (1 << 7);
    	} else {
    		ptr = ptr + i;
    		operand = (1 << (remainder - 1));
    	}
    	status = *ptr & operand;
    	if (status)
    		return -1;
    
    	*ptr = *ptr | operand;
    
    	return 0;
    }
    
    void ext4fs_reset_inode_bmap(int inode_no, unsigned char *buffer, int index)
    {
    	int i, remainder, status;
    	unsigned char *ptr = buffer;
    	unsigned char operand;
    
    	inode_no -= (index * le32_to_cpu(ext4fs_root->sblock.inodes_per_group));
    	i = inode_no / 8;
    	remainder = inode_no % 8;
    	if (remainder == 0) {
    		ptr = ptr + i - 1;
    		operand = (1 << 7);
    	} else {
    		ptr = ptr + i;
    		operand = (1 << (remainder - 1));
    	}
    	status = *ptr & operand;
    	if (status)
    		*ptr = *ptr & ~(operand);
    }
    
    uint16_t ext4fs_checksum_update(uint32_t i)
    {
    	struct ext2_block_group *desc;
    	struct ext_filesystem *fs = get_fs();
    	uint16_t crc = 0;
    	__le32 le32_i = cpu_to_le32(i);
    
    	desc = (struct ext2_block_group *)&fs->bgd[i];
    	if (le32_to_cpu(fs->sb->feature_ro_compat) & EXT4_FEATURE_RO_COMPAT_GDT_CSUM) {
    		int offset = offsetof(struct ext2_block_group, bg_checksum);
    
    		crc = ext2fs_crc16(~0, fs->sb->unique_id,
    				   sizeof(fs->sb->unique_id));
    		crc = ext2fs_crc16(crc, &le32_i, sizeof(le32_i));
    		crc = ext2fs_crc16(crc, desc, offset);
    		offset += sizeof(desc->bg_checksum);	/* skip checksum */
    		assert(offset == sizeof(*desc));
    	}
    
    	return crc;
    }
    
    static int check_void_in_dentry(struct ext2_dirent *dir, char *filename)
    {
    	int dentry_length;
    	int sizeof_void_space;
    	int new_entry_byte_reqd;
    	short padding_factor = 0;
    
    	if (dir->namelen % 4 != 0)
    		padding_factor = 4 - (dir->namelen % 4);
    
    	dentry_length = sizeof(struct ext2_dirent) +
    			dir->namelen + padding_factor;
    	sizeof_void_space = le16_to_cpu(dir->direntlen) - dentry_length;
    	if (sizeof_void_space == 0)
    		return 0;
    
    	padding_factor = 0;
    	if (strlen(filename) % 4 != 0)
    		padding_factor = 4 - (strlen(filename) % 4);
    
    	new_entry_byte_reqd = strlen(filename) +
    	    sizeof(struct ext2_dirent) + padding_factor;
    	if (sizeof_void_space >= new_entry_byte_reqd) {
    		dir->direntlen = cpu_to_le16(dentry_length);
    		return sizeof_void_space;
    	}
    
    	return 0;
    }
    
    int ext4fs_update_parent_dentry(char *filename, int file_type)
    {
    	unsigned int *zero_buffer = NULL;
    	char *root_first_block_buffer = NULL;
    	int blk_idx;
    	long int first_block_no_of_root = 0;
    	int totalbytes = 0;
    	unsigned int new_entry_byte_reqd;
    	int sizeof_void_space = 0;
    	int templength = 0;
    	int inodeno = -1;
    	int status;
    	struct ext_filesystem *fs = get_fs();
    	/* directory entry */
    	struct ext2_dirent *dir;
    	char *temp_dir = NULL;
    	uint32_t new_blk_no;
    	uint32_t new_size;
    	uint32_t new_blockcnt;
    	uint32_t directory_blocks;
    
    	zero_buffer = zalloc(fs->blksz);
    	if (!zero_buffer) {
    		printf("No Memory\n");
    		return -1;
    	}
    	root_first_block_buffer = zalloc(fs->blksz);
    	if (!root_first_block_buffer) {
    		free(zero_buffer);
    		printf("No Memory\n");
    		return -1;
    	}
    	new_entry_byte_reqd = ROUND(strlen(filename) +
    				    sizeof(struct ext2_dirent), 4);
    restart:
    	directory_blocks = le32_to_cpu(g_parent_inode->size) >>
    		LOG2_BLOCK_SIZE(ext4fs_root);
    	blk_idx = directory_blocks - 1;
    
    restart_read:
    	/* read the block no allocated to a file */
    	first_block_no_of_root = read_allocated_block(g_parent_inode, blk_idx);
    	if (first_block_no_of_root <= 0)
    		goto fail;
    
    	status = ext4fs_devread((lbaint_t)first_block_no_of_root
    				* fs->sect_perblk,
    				0, fs->blksz, root_first_block_buffer);
    	if (status == 0)
    		goto fail;
    
    	if (ext4fs_log_journal(root_first_block_buffer, first_block_no_of_root))
    		goto fail;
    	dir = (struct ext2_dirent *)root_first_block_buffer;
    	totalbytes = 0;
    
    	while (le16_to_cpu(dir->direntlen) > 0) {
    		unsigned short used_len = ROUND(dir->namelen +
    		    sizeof(struct ext2_dirent), 4);
    
    		/* last entry of block */
    		if (fs->blksz - totalbytes == le16_to_cpu(dir->direntlen)) {
    
    			/* check if new entry fits */
    			if ((used_len + new_entry_byte_reqd) <=
    			    le16_to_cpu(dir->direntlen)) {
    				dir->direntlen = cpu_to_le16(used_len);
    				break;
    			} else {
    				if (blk_idx > 0) {
    					printf("Block full, trying previous\n");
    					blk_idx--;
    					goto restart_read;
    				}
    				printf("All blocks full: Allocate new\n");
    
    				if (le32_to_cpu(g_parent_inode->flags) &
    						EXT4_EXTENTS_FL) {
    					printf("Directory uses extents\n");
    					goto fail;
    				}
    				if (directory_blocks >= INDIRECT_BLOCKS) {
    					printf("Directory exceeds limit\n");
    					goto fail;
    				}
    				new_blk_no = ext4fs_get_new_blk_no();
    				if (new_blk_no == -1) {
    					printf("no block left to assign\n");
    					goto fail;
    				}
    				put_ext4((uint64_t)new_blk_no * fs->blksz, zero_buffer, fs->blksz);
    				g_parent_inode->b.blocks.
    					dir_blocks[directory_blocks] =
    					cpu_to_le32(new_blk_no);
    
    				new_size = le32_to_cpu(g_parent_inode->size);
    				new_size += fs->blksz;
    				g_parent_inode->size = cpu_to_le32(new_size);
    
    				new_blockcnt = le32_to_cpu(g_parent_inode->blockcnt);
    				new_blockcnt += fs->sect_perblk;
    				g_parent_inode->blockcnt = cpu_to_le32(new_blockcnt);
    
    				if (ext4fs_put_metadata
    				    (root_first_block_buffer,
    				     first_block_no_of_root))
    					goto fail;
    				goto restart;
    			}
    		}
    
    		templength = le16_to_cpu(dir->direntlen);
    		totalbytes = totalbytes + templength;
    		sizeof_void_space = check_void_in_dentry(dir, filename);
    		if (sizeof_void_space)
    			break;
    
    		dir = (struct ext2_dirent *)((char *)dir + templength);
    	}
    
    	/* make a pointer ready for creating next directory entry */
    	templength = le16_to_cpu(dir->direntlen);
    	totalbytes = totalbytes + templength;
    	dir = (struct ext2_dirent *)((char *)dir + templength);
    
    	/* get the next available inode number */
    	inodeno = ext4fs_get_new_inode_no();
    	if (inodeno == -1) {
    		printf("no inode left to assign\n");
    		goto fail;
    	}
    	dir->inode = cpu_to_le32(inodeno);
    	if (sizeof_void_space)
    		dir->direntlen = cpu_to_le16(sizeof_void_space);
    	else
    		dir->direntlen = cpu_to_le16(fs->blksz - totalbytes);
    
    	dir->namelen = strlen(filename);
    	dir->filetype = FILETYPE_REG;	/* regular file */
    	temp_dir = (char *)dir;
    	temp_dir = temp_dir + sizeof(struct ext2_dirent);
    	memcpy(temp_dir, filename, strlen(filename));
    
    	/* update or write  the 1st block of root inode */
    	if (ext4fs_put_metadata(root_first_block_buffer,
    				first_block_no_of_root))
    		goto fail;
    
    fail:
    	free(zero_buffer);
    	free(root_first_block_buffer);
    
    	return inodeno;
    }
    
    static int search_dir(struct ext2_inode *parent_inode, char *dirname)
    {
    	int status;
    	int inodeno = 0;
    	int offset;
    	int blk_idx;
    	long int blknr;
    	char *block_buffer = NULL;
    	struct ext2_dirent *dir = NULL;
    	struct ext_filesystem *fs = get_fs();
    	uint32_t directory_blocks;
    	char *direntname;
    
    	directory_blocks = le32_to_cpu(parent_inode->size) >>
    		LOG2_BLOCK_SIZE(ext4fs_root);
    
    	block_buffer = zalloc(fs->blksz);
    	if (!block_buffer)
    		goto fail;
    
    	/* get the block no allocated to a file */
    	for (blk_idx = 0; blk_idx < directory_blocks; blk_idx++) {
    		blknr = read_allocated_block(parent_inode, blk_idx);
    		if (blknr == 0)
    			goto fail;
    
    		/* read the directory block */
    		status = ext4fs_devread((lbaint_t)blknr * fs->sect_perblk,
    					0, fs->blksz, (char *)block_buffer);
    		if (status == 0)
    			goto fail;
    
    		offset = 0;
    		do {
    			dir = (struct ext2_dirent *)(block_buffer + offset);
    			direntname = (char*)(dir) + sizeof(struct ext2_dirent);
    
    			int direntlen = le16_to_cpu(dir->direntlen);
    			if (direntlen < sizeof(struct ext2_dirent))
    				break;
    
    			if (dir->inode && (strlen(dirname) == dir->namelen) &&
    			    (strncmp(dirname, direntname, dir->namelen) == 0)) {
    				inodeno = le32_to_cpu(dir->inode);
    				break;
    			}
    
    			offset += direntlen;
    
    		} while (offset < fs->blksz);
    
    		if (inodeno > 0) {
    			free(block_buffer);
    			return inodeno;
    		}
    	}
    
    fail:
    	free(block_buffer);
    
    	return -1;
    }
    
    static int find_dir_depth(char *dirname)
    {
    	char *token = strtok(dirname, "/");
    	int count = 0;
    	while (token != NULL) {
    		token = strtok(NULL, "/");
    		count++;
    	}
    	return count + 1 + 1;
    	/*
    	 * for example  for string /home/temp
    	 * depth=home(1)+temp(1)+1 extra for NULL;
    	 * so count is 4;
    	 */
    }
    
    static int parse_path(char **arr, char *dirname)
    {
    	char *token = strtok(dirname, "/");
    	int i = 0;
    
    	/* add root */
    	arr[i] = zalloc(strlen("/") + 1);
    	if (!arr[i])
    		return -ENOMEM;
    	memcpy(arr[i++], "/", strlen("/"));
    
    	/* add each path entry after root */
    	while (token != NULL) {
    		arr[i] = zalloc(strlen(token) + 1);
    		if (!arr[i])
    			return -ENOMEM;
    		memcpy(arr[i++], token, strlen(token));
    		token = strtok(NULL, "/");
    	}
    	arr[i] = NULL;
    
    	return 0;
    }
    
    int ext4fs_iget(int inode_no, struct ext2_inode *inode)
    {
    	if (ext4fs_read_inode(ext4fs_root, inode_no, inode) == 0)
    		return -1;
    
    	return 0;
    }
    
    /*
     * Function: ext4fs_get_parent_inode_num
     * Return Value: inode Number of the parent directory of  file/Directory to be
     * created
     * dirname : Input parmater, input path name of the file/directory to be created
     * dname : Output parameter, to be filled with the name of the directory
     * extracted from dirname
     */
    int ext4fs_get_parent_inode_num(const char *dirname, char *dname, int flags)
    {
    	int i;
    	int depth = 0;
    	int matched_inode_no;
    	int result_inode_no = -1;
    	char **ptr = NULL;
    	char *depth_dirname = NULL;
    	char *parse_dirname = NULL;
    	struct ext2_inode *parent_inode = NULL;
    	struct ext2_inode *first_inode = NULL;
    	struct ext2_inode temp_inode;
    
    	if (*dirname != '/') {
    		printf("Please supply Absolute path\n");
    		return -1;
    	}
    
    	/* TODO: input validation make equivalent to linux */
    	depth_dirname = zalloc(strlen(dirname) + 1);
    	if (!depth_dirname)
    		return -ENOMEM;
    
    	memcpy(depth_dirname, dirname, strlen(dirname));
    	depth = find_dir_depth(depth_dirname);
    	parse_dirname = zalloc(strlen(dirname) + 1);
    	if (!parse_dirname)
    		goto fail;
    	memcpy(parse_dirname, dirname, strlen(dirname));
    
    	/* allocate memory for each directory level */
    	ptr = zalloc((depth) * sizeof(char *));
    	if (!ptr)
    		goto fail;
    	if (parse_path(ptr, parse_dirname))
    		goto fail;
    	parent_inode = zalloc(sizeof(struct ext2_inode));
    	if (!parent_inode)
    		goto fail;
    	first_inode = zalloc(sizeof(struct ext2_inode));
    	if (!first_inode)
    		goto fail;
    	memcpy(parent_inode, ext4fs_root->inode, sizeof(struct ext2_inode));
    	memcpy(first_inode, parent_inode, sizeof(struct ext2_inode));
    	if (flags & F_FILE)
    		result_inode_no = EXT2_ROOT_INO;
    	for (i = 1; i < depth; i++) {
    		matched_inode_no = search_dir(parent_inode, ptr[i]);
    		if (matched_inode_no == -1) {
    			if (ptr[i + 1] == NULL && i == 1) {
    				result_inode_no = EXT2_ROOT_INO;
    				goto end;
    			} else {
    				if (ptr[i + 1] == NULL)
    					break;
    				printf("Invalid path\n");
    				result_inode_no = -1;
    				goto fail;
    			}
    		} else {
    			if (ptr[i + 1] != NULL) {
    				memset(parent_inode, '\0',
    				       sizeof(struct ext2_inode));
    				if (ext4fs_iget(matched_inode_no,
    						parent_inode)) {
    					result_inode_no = -1;
    					goto fail;
    				}
    				result_inode_no = matched_inode_no;
    			} else {
    				break;
    			}
    		}
    	}
    
    end:
    	if (i == 1)
    		matched_inode_no = search_dir(first_inode, ptr[i]);
    	else
    		matched_inode_no = search_dir(parent_inode, ptr[i]);
    
    	if (matched_inode_no != -1) {
    		ext4fs_iget(matched_inode_no, &temp_inode);
    		if (le16_to_cpu(temp_inode.mode) & S_IFDIR) {
    			printf("It is a Directory\n");
    			result_inode_no = -1;
    			goto fail;
    		}
    	}
    
    	if (strlen(ptr[i]) > 256) {
    		result_inode_no = -1;
    		goto fail;
    	}
    	memcpy(dname, ptr[i], strlen(ptr[i]));
    
    fail:
    	free(depth_dirname);
    	free(parse_dirname);
    	for (i = 0; i < depth; i++) {
    		if (!ptr[i])
    			break;
    		free(ptr[i]);
    	}
    	free(ptr);
    	free(parent_inode);
    	free(first_inode);
    
    	return result_inode_no;
    }
    
    static int unlink_filename(char *filename, unsigned int blknr)
    {
    	int totalbytes = 0;
    	int templength = 0;
    	int status, inodeno;
    	int found = 0;
    	char *root_first_block_buffer = NULL;
    	struct ext2_dirent *dir = NULL;
    	struct ext2_dirent *previous_dir = NULL;
    	char *ptr = NULL;
    	struct ext_filesystem *fs = get_fs();
    	int ret = -1;
    
    	/* get the first block of root */
    	root_first_block_buffer = zalloc(fs->blksz);
    	if (!root_first_block_buffer)
    		return -ENOMEM;
    	status = ext4fs_devread((lbaint_t)blknr * fs->sect_perblk, 0,
    				fs->blksz, root_first_block_buffer);
    	if (status == 0)
    		goto fail;
    
    	if (ext4fs_log_journal(root_first_block_buffer, blknr))
    		goto fail;
    	dir = (struct ext2_dirent *)root_first_block_buffer;
    	ptr = (char *)dir;
    	totalbytes = 0;
    	while (le16_to_cpu(dir->direntlen) >= 0) {
    		/*
    		 * blocksize-totalbytes because last
    		 * directory length i.e., *dir->direntlen
    		 * is free availble space in the block that
    		 * means it is a last entry of directory entry
    		 */
    		if (dir->inode && (strlen(filename) == dir->namelen) &&
    		    (strncmp(ptr + sizeof(struct ext2_dirent),
    			     filename, dir->namelen) == 0)) {
    			printf("file found, deleting\n");
    			inodeno = le32_to_cpu(dir->inode);
    			if (previous_dir) {
    				uint16_t new_len;
    				new_len = le16_to_cpu(previous_dir->direntlen);
    				new_len += le16_to_cpu(dir->direntlen);
    				previous_dir->direntlen = cpu_to_le16(new_len);
    			} else {
    				dir->inode = 0;
    			}
    			found = 1;
    			break;
    		}
    
    		if (fs->blksz - totalbytes == le16_to_cpu(dir->direntlen))
    			break;
    
    		/* traversing the each directory entry */
    		templength = le16_to_cpu(dir->direntlen);
    		totalbytes = totalbytes + templength;
    		previous_dir = dir;
    		dir = (struct ext2_dirent *)((char *)dir + templength);
    		ptr = (char *)dir;
    	}
    
    
    	if (found == 1) {
    		if (ext4fs_put_metadata(root_first_block_buffer, blknr))
    			goto fail;
    		ret = inodeno;
    	}
    fail:
    	free(root_first_block_buffer);
    
    	return ret;
    }
    
    int ext4fs_filename_unlink(char *filename)
    {
    	int blk_idx;
    	long int blknr = -1;
    	int inodeno = -1;
    	uint32_t directory_blocks;
    
    	directory_blocks = le32_to_cpu(g_parent_inode->size) >>
    		LOG2_BLOCK_SIZE(ext4fs_root);
    
    	/* read the block no allocated to a file */
    	for (blk_idx = 0; blk_idx < directory_blocks; blk_idx++) {
    		blknr = read_allocated_block(g_parent_inode, blk_idx);
    		if (blknr == 0)
    			break;
    		inodeno = unlink_filename(filename, blknr);
    		if (inodeno != -1)
    			return inodeno;
    	}
    
    	return -1;
    }
    
    uint32_t ext4fs_get_new_blk_no(void)
    {
    	short i;
    	short status;
    	int remainder;
    	unsigned int bg_idx;
    	static int prev_bg_bitmap_index = -1;
    	unsigned int blk_per_grp = le32_to_cpu(ext4fs_root->sblock.blocks_per_group);
    	struct ext_filesystem *fs = get_fs();
    	char *journal_buffer = zalloc(fs->blksz);
    	char *zero_buffer = zalloc(fs->blksz);
    	if (!journal_buffer || !zero_buffer)
    		goto fail;
    	struct ext2_block_group *bgd = (struct ext2_block_group *)fs->gdtable;
    
    	if (fs->first_pass_bbmap == 0) {
    		for (i = 0; i < fs->no_blkgrp; i++) {
    			if (le16_to_cpu(bgd[i].free_blocks)) {
    				if (le16_to_cpu(bgd[i].bg_flags) & EXT4_BG_BLOCK_UNINIT) {
    					uint16_t new_flags;
    					put_ext4((uint64_t)le32_to_cpu(bgd[i].block_id) * fs->blksz,
    						 zero_buffer, fs->blksz);
    					new_flags = le16_to_cpu(bgd[i].bg_flags) & ~EXT4_BG_BLOCK_UNINIT;
    					bgd[i].bg_flags = cpu_to_le16(new_flags);
    					memcpy(fs->blk_bmaps[i], zero_buffer,
    					       fs->blksz);
    				}
    				fs->curr_blkno =
    				    _get_new_blk_no(fs->blk_bmaps[i]);
    				if (fs->curr_blkno == -1)
    					/* if block bitmap is completely fill */
    					continue;
    				fs->curr_blkno = fs->curr_blkno +
    						(i * fs->blksz * 8);
    				fs->first_pass_bbmap++;
    				ext4fs_bg_free_blocks_dec(&bgd[i]);
    				ext4fs_sb_free_blocks_dec(fs->sb);
    				status = ext4fs_devread(
    							(lbaint_t)le32_to_cpu(bgd[i].block_id) *
    							fs->sect_perblk, 0,
    							fs->blksz,
    							journal_buffer);
    				if (status == 0)
    					goto fail;
    				if (ext4fs_log_journal(journal_buffer,
    							le32_to_cpu(bgd[i].block_id)))
    					goto fail;
    				goto success;
    			} else {
    				debug("no space left on block group %d\n", i);
    			}
    		}
    
    		goto fail;
    	} else {
    		fs->curr_blkno++;
    restart:
    		/* get the blockbitmap index respective to blockno */
    		bg_idx = fs->curr_blkno / blk_per_grp;
    		if (fs->blksz == 1024) {
    			remainder = fs->curr_blkno % blk_per_grp;
    			if (!remainder)
    				bg_idx--;
    		}
    
    		/*
    		 * To skip completely filled block group bitmaps
    		 * Optimize the block allocation
    		 */
    		if (bg_idx >= fs->no_blkgrp)
    			goto fail;
    
    		if (bgd[bg_idx].free_blocks == 0) {
    			debug("block group %u is full. Skipping\n", bg_idx);
    			fs->curr_blkno = (bg_idx + 1) * blk_per_grp;
    			if (fs->blksz == 1024)
    				fs->curr_blkno += 1;
    			goto restart;
    		}
    
    		if (le16_to_cpu(bgd[bg_idx].bg_flags) & EXT4_BG_BLOCK_UNINIT) {
    			uint16_t new_flags;
    			put_ext4((uint64_t)le32_to_cpu(bgd[bg_idx].block_id) * fs->blksz,
    				 zero_buffer, fs->blksz);
    			memcpy(fs->blk_bmaps[bg_idx], zero_buffer, fs->blksz);
    			new_flags = le16_to_cpu(bgd[bg_idx].bg_flags) & ~EXT4_BG_BLOCK_UNINIT;
    			bgd[bg_idx].bg_flags = cpu_to_le16(new_flags);
    		}
    
    		if (ext4fs_set_block_bmap(fs->curr_blkno, fs->blk_bmaps[bg_idx],
    				   bg_idx) != 0) {
    			debug("going for restart for the block no %ld %u\n",
    			      fs->curr_blkno, bg_idx);
    			fs->curr_blkno++;
    			goto restart;
    		}
    
    		/* journal backup */
    		if (prev_bg_bitmap_index != bg_idx) {
    			status = ext4fs_devread(
    						(lbaint_t)le32_to_cpu(bgd[bg_idx].block_id)
    						* fs->sect_perblk,
    						0, fs->blksz, journal_buffer);
    			if (status == 0)
    				goto fail;
    			if (ext4fs_log_journal(journal_buffer,
    						le32_to_cpu(bgd[bg_idx].block_id)))
    				goto fail;
    
    			prev_bg_bitmap_index = bg_idx;
    		}
    		ext4fs_bg_free_blocks_dec(&bgd[bg_idx]);
    		ext4fs_sb_free_blocks_dec(fs->sb);
    		goto success;
    	}
    success:
    	free(journal_buffer);
    	free(zero_buffer);
    
    	return fs->curr_blkno;
    fail:
    	free(journal_buffer);
    	free(zero_buffer);
    
    	return -1;
    }
    
    int ext4fs_get_new_inode_no(void)
    {
    	short i;
    	short status;
    	unsigned int ibmap_idx;
    	static int prev_inode_bitmap_index = -1;
    	unsigned int inodes_per_grp = le32_to_cpu(ext4fs_root->sblock.inodes_per_group);
    	struct ext_filesystem *fs = get_fs();
    	char *journal_buffer = zalloc(fs->blksz);
    	char *zero_buffer = zalloc(fs->blksz);
    	if (!journal_buffer || !zero_buffer)
    		goto fail;
    	struct ext2_block_group *bgd = (struct ext2_block_group *)fs->gdtable;
    	int has_gdt_chksum = le32_to_cpu(fs->sb->feature_ro_compat) &
    		EXT4_FEATURE_RO_COMPAT_GDT_CSUM ? 1 : 0;
    
    	if (fs->first_pass_ibmap == 0) {
    		for (i = 0; i < fs->no_blkgrp; i++) {
    			if (bgd[i].free_inodes) {
    				if (has_gdt_chksum)
    					bgd[i].bg_itable_unused =
    						bgd[i].free_inodes;
    				if (le16_to_cpu(bgd[i].bg_flags) & EXT4_BG_INODE_UNINIT) {
    					int new_flags;
    					put_ext4((uint64_t)le32_to_cpu(bgd[i].inode_id) * fs->blksz,
    						 zero_buffer, fs->blksz);
    					new_flags = le16_to_cpu(bgd[i].bg_flags) & ~EXT4_BG_INODE_UNINIT;
    					bgd[i].bg_flags = cpu_to_le16(new_flags);
    					memcpy(fs->inode_bmaps[i],
    					       zero_buffer, fs->blksz);
    				}
    				fs->curr_inode_no =
    				    _get_new_inode_no(fs->inode_bmaps[i]);
    				if (fs->curr_inode_no == -1)
    					/* if block bitmap is completely fill */
    					continue;
    				fs->curr_inode_no = fs->curr_inode_no +
    							(i * inodes_per_grp);
    				fs->first_pass_ibmap++;
    				ext4fs_bg_free_inodes_dec(&bgd[i]);
    				if (has_gdt_chksum)
    					ext4fs_bg_itable_unused_dec(&bgd[i]);
    				ext4fs_sb_free_inodes_dec(fs->sb);
    				status = ext4fs_devread(
    							(lbaint_t)le32_to_cpu(bgd[i].inode_id) *
    							fs->sect_perblk, 0,
    							fs->blksz,
    							journal_buffer);
    				if (status == 0)
    					goto fail;
    				if (ext4fs_log_journal(journal_buffer,
    							le32_to_cpu(bgd[i].inode_id)))
    					goto fail;
    				goto success;
    			} else
    				debug("no inode left on block group %d\n", i);
    		}
    		goto fail;
    	} else {
    restart:
    		fs->curr_inode_no++;
    		/* get the blockbitmap index respective to blockno */
    		ibmap_idx = fs->curr_inode_no / inodes_per_grp;
    		if (le16_to_cpu(bgd[ibmap_idx].bg_flags) & EXT4_BG_INODE_UNINIT) {
    			int new_flags;
    			put_ext4((uint64_t)le32_to_cpu(bgd[ibmap_idx].inode_id) * fs->blksz,
    				 zero_buffer, fs->blksz);
    			new_flags = le16_to_cpu(bgd[ibmap_idx].bg_flags) & ~EXT4_BG_INODE_UNINIT;
    			bgd[ibmap_idx].bg_flags = cpu_to_le16(new_flags);
    			memcpy(fs->inode_bmaps[ibmap_idx], zero_buffer,
    				fs->blksz);
    		}
    
    		if (ext4fs_set_inode_bmap(fs->curr_inode_no,
    					  fs->inode_bmaps[ibmap_idx],
    					  ibmap_idx) != 0) {
    			debug("going for restart for the block no %d %u\n",
    			      fs->curr_inode_no, ibmap_idx);
    			goto restart;
    		}
    
    		/* journal backup */
    		if (prev_inode_bitmap_index != ibmap_idx) {
    			memset(journal_buffer, '\0', fs->blksz);
    			status = ext4fs_devread(
    						(lbaint_t)le32_to_cpu(bgd[ibmap_idx].inode_id)
    						* fs->sect_perblk,
    						0, fs->blksz, journal_buffer);
    			if (status == 0)
    				goto fail;
    			if (ext4fs_log_journal(journal_buffer,
    						le32_to_cpu(bgd[ibmap_idx].inode_id)))
    				goto fail;
    			prev_inode_bitmap_index = ibmap_idx;
    		}
    		ext4fs_bg_free_inodes_dec(&bgd[ibmap_idx]);
    		if (has_gdt_chksum)
    			bgd[ibmap_idx].bg_itable_unused =
    					bgd[ibmap_idx].free_inodes;
    		ext4fs_sb_free_inodes_dec(fs->sb);
    		goto success;
    	}
    
    success:
    	free(journal_buffer);
    	free(zero_buffer);
    
    	return fs->curr_inode_no;
    fail:
    	free(journal_buffer);
    	free(zero_buffer);
    
    	return -1;
    
    }
    
    
    static void alloc_single_indirect_block(struct ext2_inode *file_inode,
    					unsigned int *total_remaining_blocks,
    					unsigned int *no_blks_reqd)
    {
    	short i;
    	short status;
    	long int actual_block_no;
    	long int si_blockno;
    	/* si :single indirect */
    	__le32 *si_buffer = NULL;
    	__le32 *si_start_addr = NULL;
    	struct ext_filesystem *fs = get_fs();
    
    	if (*total_remaining_blocks != 0) {
    		si_buffer = zalloc(fs->blksz);
    		if (!si_buffer) {
    			printf("No Memory\n");
    			return;
    		}
    		si_start_addr = si_buffer;
    		si_blockno = ext4fs_get_new_blk_no();
    		if (si_blockno == -1) {
    			printf("no block left to assign\n");
    			goto fail;
    		}
    		(*no_blks_reqd)++;
    		debug("SIPB %ld: %u\n", si_blockno, *total_remaining_blocks);
    
    		status = ext4fs_devread((lbaint_t)si_blockno * fs->sect_perblk,
    					0, fs->blksz, (char *)si_buffer);
    		memset(si_buffer, '\0', fs->blksz);
    		if (status == 0)
    			goto fail;
    
    		for (i = 0; i < (fs->blksz / sizeof(int)); i++) {
    			actual_block_no = ext4fs_get_new_blk_no();
    			if (actual_block_no == -1) {
    				printf("no block left to assign\n");
    				goto fail;
    			}
    			*si_buffer = cpu_to_le32(actual_block_no);
    			debug("SIAB %u: %u\n", *si_buffer,
    				*total_remaining_blocks);
    
    			si_buffer++;
    			(*total_remaining_blocks)--;
    			if (*total_remaining_blocks == 0)
    				break;
    		}
    
    		/* write the block to disk */
    		put_ext4(((uint64_t) ((uint64_t)si_blockno * (uint64_t)fs->blksz)),
    			 si_start_addr, fs->blksz);
    		file_inode->b.blocks.indir_block = cpu_to_le32(si_blockno);
    	}
    fail:
    	free(si_start_addr);
    }
    
    static void alloc_double_indirect_block(struct ext2_inode *file_inode,
    					unsigned int *total_remaining_blocks,
    					unsigned int *no_blks_reqd)
    {
    	short i;
    	short j;
    	short status;
    	long int actual_block_no;
    	/* di:double indirect */
    	long int di_blockno_parent;
    	long int di_blockno_child;
    	__le32 *di_parent_buffer = NULL;
    	__le32 *di_child_buff = NULL;
    	__le32 *di_block_start_addr = NULL;
    	__le32 *di_child_buff_start = NULL;
    	struct ext_filesystem *fs = get_fs();
    
    	if (*total_remaining_blocks != 0) {
    		/* double indirect parent block connecting to inode */
    		di_blockno_parent = ext4fs_get_new_blk_no();
    		if (di_blockno_parent == -1) {
    			printf("no block left to assign\n");
    			goto fail;
    		}
    		di_parent_buffer = zalloc(fs->blksz);
    		if (!di_parent_buffer)
    			goto fail;
    
    		di_block_start_addr = di_parent_buffer;
    		(*no_blks_reqd)++;
    		debug("DIPB %ld: %u\n", di_blockno_parent,
    		      *total_remaining_blocks);
    
    		status = ext4fs_devread((lbaint_t)di_blockno_parent *
    					fs->sect_perblk, 0,
    					fs->blksz, (char *)di_parent_buffer);
    
    		if (!status) {
    			printf("%s: Device read error!\n", __func__);
    			goto fail;
    		}
    		memset(di_parent_buffer, '\0', fs->blksz);
    
    		/*
    		 * start:for each double indirect parent
    		 * block create one more block
    		 */
    		for (i = 0; i < (fs->blksz / sizeof(int)); i++) {
    			di_blockno_child = ext4fs_get_new_blk_no();
    			if (di_blockno_child == -1) {
    				printf("no block left to assign\n");
    				goto fail;
    			}
    			di_child_buff = zalloc(fs->blksz);
    			if (!di_child_buff)
    				goto fail;
    
    			di_child_buff_start = di_child_buff;
    			*di_parent_buffer = cpu_to_le32(di_blockno_child);
    			di_parent_buffer++;
    			(*no_blks_reqd)++;
    			debug("DICB %ld: %u\n", di_blockno_child,
    			      *total_remaining_blocks);
    
    			status = ext4fs_devread((lbaint_t)di_blockno_child *
    						fs->sect_perblk, 0,
    						fs->blksz,
    						(char *)di_child_buff);
    
    			if (!status) {
    				printf("%s: Device read error!\n", __func__);
    				goto fail;
    			}
    			memset(di_child_buff, '\0', fs->blksz);
    			/* filling of actual datablocks for each child */
    			for (j = 0; j < (fs->blksz / sizeof(int)); j++) {
    				actual_block_no = ext4fs_get_new_blk_no();
    				if (actual_block_no == -1) {
    					printf("no block left to assign\n");
    					goto fail;
    				}
    				*di_child_buff = cpu_to_le32(actual_block_no);
    				debug("DIAB %ld: %u\n", actual_block_no,
    				      *total_remaining_blocks);
    
    				di_child_buff++;
    				(*total_remaining_blocks)--;
    				if (*total_remaining_blocks == 0)
    					break;
    			}
    			/* write the block  table */
    			put_ext4(((uint64_t) ((uint64_t)di_blockno_child * (uint64_t)fs->blksz)),
    				 di_child_buff_start, fs->blksz);
    			free(di_child_buff_start);
    			di_child_buff_start = NULL;
    
    			if (*total_remaining_blocks == 0)
    				break;
    		}
    		put_ext4(((uint64_t) ((uint64_t)di_blockno_parent * (uint64_t)fs->blksz)),
    			 di_block_start_addr, fs->blksz);
    		file_inode->b.blocks.double_indir_block = cpu_to_le32(di_blockno_parent);
    	}
    fail:
    	free(di_block_start_addr);
    }
    
    static void alloc_triple_indirect_block(struct ext2_inode *file_inode,
    					unsigned int *total_remaining_blocks,
    					unsigned int *no_blks_reqd)
    {
    	short i;
    	short j;
    	short k;
    	long int actual_block_no;
    	/* ti: Triple Indirect */
    	long int ti_gp_blockno;
    	long int ti_parent_blockno;
    	long int ti_child_blockno;
    	__le32 *ti_gp_buff = NULL;
    	__le32 *ti_parent_buff = NULL;
    	__le32 *ti_child_buff = NULL;
    	__le32 *ti_gp_buff_start_addr = NULL;
    	__le32 *ti_pbuff_start_addr = NULL;
    	__le32 *ti_cbuff_start_addr = NULL;
    	struct ext_filesystem *fs = get_fs();
    	if (*total_remaining_blocks != 0) {
    		/* triple indirect grand parent block connecting to inode */
    		ti_gp_blockno = ext4fs_get_new_blk_no();
    		if (ti_gp_blockno == -1) {
    			printf("no block left to assign\n");
    			return;
    		}
    		ti_gp_buff = zalloc(fs->blksz);
    		if (!ti_gp_buff)
    			return;
    
    		ti_gp_buff_start_addr = ti_gp_buff;
    		(*no_blks_reqd)++;
    		debug("TIGPB %ld: %u\n", ti_gp_blockno,
    		      *total_remaining_blocks);
    
    		/* for each 4 byte grand parent entry create one more block */
    		for (i = 0; i < (fs->blksz / sizeof(int)); i++) {
    			ti_parent_blockno = ext4fs_get_new_blk_no();
    			if (ti_parent_blockno == -1) {
    				printf("no block left to assign\n");
    				goto fail;
    			}
    			ti_parent_buff = zalloc(fs->blksz);
    			if (!ti_parent_buff)
    				goto fail;
    
    			ti_pbuff_start_addr = ti_parent_buff;
    			*ti_gp_buff = cpu_to_le32(ti_parent_blockno);
    			ti_gp_buff++;
    			(*no_blks_reqd)++;
    			debug("TIPB %ld: %u\n", ti_parent_blockno,
    			      *total_remaining_blocks);
    
    			/* for each 4 byte entry parent create one more block */
    			for (j = 0; j < (fs->blksz / sizeof(int)); j++) {
    				ti_child_blockno = ext4fs_get_new_blk_no();
    				if (ti_child_blockno == -1) {
    					printf("no block left assign\n");
    					goto fail1;
    				}
    				ti_child_buff = zalloc(fs->blksz);
    				if (!ti_child_buff)
    					goto fail1;
    
    				ti_cbuff_start_addr = ti_child_buff;
    				*ti_parent_buff = cpu_to_le32(ti_child_blockno);
    				ti_parent_buff++;
    				(*no_blks_reqd)++;
    				debug("TICB %ld: %u\n", ti_parent_blockno,
    				      *total_remaining_blocks);
    
    				/* fill actual datablocks for each child */
    				for (k = 0; k < (fs->blksz / sizeof(int));
    					k++) {
    					actual_block_no =
    					    ext4fs_get_new_blk_no();
    					if (actual_block_no == -1) {
    						printf("no block left\n");
    						free(ti_cbuff_start_addr);
    						goto fail1;
    					}
    					*ti_child_buff = cpu_to_le32(actual_block_no);
    					debug("TIAB %ld: %u\n", actual_block_no,
    					      *total_remaining_blocks);
    
    					ti_child_buff++;
    					(*total_remaining_blocks)--;
    					if (*total_remaining_blocks == 0)
    						break;
    				}
    				/* write the child block */
    				put_ext4(((uint64_t) ((uint64_t)ti_child_blockno *
    						      (uint64_t)fs->blksz)),
    					 ti_cbuff_start_addr, fs->blksz);
    				free(ti_cbuff_start_addr);
    
    				if (*total_remaining_blocks == 0)
    					break;
    			}
    			/* write the parent block */
    			put_ext4(((uint64_t) ((uint64_t)ti_parent_blockno * (uint64_t)fs->blksz)),
    				 ti_pbuff_start_addr, fs->blksz);
    			free(ti_pbuff_start_addr);
    
    			if (*total_remaining_blocks == 0)
    				break;
    		}
    		/* write the grand parent block */
    		put_ext4(((uint64_t) ((uint64_t)ti_gp_blockno * (uint64_t)fs->blksz)),
    			 ti_gp_buff_start_addr, fs->blksz);
    		file_inode->b.blocks.triple_indir_block = cpu_to_le32(ti_gp_blockno);
    		free(ti_gp_buff_start_addr);
    		return;
    	}
    fail1:
    	free(ti_pbuff_start_addr);
    fail:
    	free(ti_gp_buff_start_addr);
    }
    
    void ext4fs_allocate_blocks(struct ext2_inode *file_inode,
    				unsigned int total_remaining_blocks,
    				unsigned int *total_no_of_block)
    {
    	short i;
    	long int direct_blockno;
    	unsigned int no_blks_reqd = 0;
    
    	/* allocation of direct blocks */
    	for (i = 0; total_remaining_blocks && i < INDIRECT_BLOCKS; i++) {
    		direct_blockno = ext4fs_get_new_blk_no();
    		if (direct_blockno == -1) {
    			printf("no block left to assign\n");
    			return;
    		}
    		file_inode->b.blocks.dir_blocks[i] = cpu_to_le32(direct_blockno);
    		debug("DB %ld: %u\n", direct_blockno, total_remaining_blocks);
    
    		total_remaining_blocks--;
    	}
    
    	alloc_single_indirect_block(file_inode, &total_remaining_blocks,
    				    &no_blks_reqd);
    	alloc_double_indirect_block(file_inode, &total_remaining_blocks,
    				    &no_blks_reqd);
    	alloc_triple_indirect_block(file_inode, &total_remaining_blocks,
    				    &no_blks_reqd);
    	*total_no_of_block += no_blks_reqd;
    }
    
    #endif
    
    static struct ext4_extent_header *ext4fs_get_extent_block
    	(struct ext2_data *data, char *buf,
    		struct ext4_extent_header *ext_block,
    		uint32_t fileblock, int log2_blksz)
    {
    	struct ext4_extent_idx *index;
    	unsigned long long block;
    	int blksz = EXT2_BLOCK_SIZE(data);
    	int i;
    
    	while (1) {
    		index = (struct ext4_extent_idx *)(ext_block + 1);
    
    		if (le16_to_cpu(ext_block->eh_magic) != EXT4_EXT_MAGIC)
    			return NULL;
    
    		if (ext_block->eh_depth == 0)
    			return ext_block;
    		i = -1;
    		do {
    			i++;
    			if (i >= le16_to_cpu(ext_block->eh_entries))
    				break;
    		} while (fileblock >= le32_to_cpu(index[i].ei_block));
    
    		if (--i < 0)
    			return NULL;
    
    		block = le16_to_cpu(index[i].ei_leaf_hi);
    		block = (block << 32) + le32_to_cpu(index[i].ei_leaf_lo);
    
    		if (ext4fs_devread((lbaint_t)block << log2_blksz, 0, blksz,
    				   buf))
    			ext_block = (struct ext4_extent_header *)buf;
    		else
    			return NULL;
    	}
    }
    
    static int ext4fs_blockgroup
    	(struct ext2_data *data, int group, struct ext2_block_group *blkgrp)
    {
    	long int blkno;
    	unsigned int blkoff, desc_per_blk;
    	int log2blksz = get_fs()->dev_desc->log2blksz;
    
    	desc_per_blk = EXT2_BLOCK_SIZE(data) / sizeof(struct ext2_block_group);
    
    	blkno = le32_to_cpu(data->sblock.first_data_block) + 1 +
    			group / desc_per_blk;
    	blkoff = (group % desc_per_blk) * sizeof(struct ext2_block_group);
    
    	debug("ext4fs read %d group descriptor (blkno %ld blkoff %u)\n",
    	      group, blkno, blkoff);
    
    	return ext4fs_devread((lbaint_t)blkno <<
    			      (LOG2_BLOCK_SIZE(data) - log2blksz),
    			      blkoff, sizeof(struct ext2_block_group),
    			      (char *)blkgrp);
    }
    
    int ext4fs_read_inode(struct ext2_data *data, int ino, struct ext2_inode *inode)
    {
    	struct ext2_block_group blkgrp;
    	struct ext2_sblock *sblock = &data->sblock;
    	struct ext_filesystem *fs = get_fs();
    	int log2blksz = get_fs()->dev_desc->log2blksz;
    	int inodes_per_block, status;
    	long int blkno;
    	unsigned int blkoff;
    
    	/* It is easier to calculate if the first inode is 0. */
    	ino--;
    	status = ext4fs_blockgroup(data, ino / le32_to_cpu
    				   (sblock->inodes_per_group), &blkgrp);
    	if (status == 0)
    		return 0;
    
    	inodes_per_block = EXT2_BLOCK_SIZE(data) / fs->inodesz;
    	blkno = le32_to_cpu(blkgrp.inode_table_id) +
    	    (ino % le32_to_cpu(sblock->inodes_per_group)) / inodes_per_block;
    	blkoff = (ino % inodes_per_block) * fs->inodesz;
    	/* Read the inode. */
    	status = ext4fs_devread((lbaint_t)blkno << (LOG2_BLOCK_SIZE(data) -
    				log2blksz), blkoff,
    				sizeof(struct ext2_inode), (char *)inode);
    	if (status == 0)
    		return 0;
    
    	return 1;
    }
    
    long int read_allocated_block(struct ext2_inode *inode, int fileblock)
    {
    	long int blknr;
    	int blksz;
    	int log2_blksz;
    	int status;
    	long int rblock;
    	long int perblock_parent;
    	long int perblock_child;
    	unsigned long long start;
    	/* get the blocksize of the filesystem */
    	blksz = EXT2_BLOCK_SIZE(ext4fs_root);
    	log2_blksz = LOG2_BLOCK_SIZE(ext4fs_root)
    		- get_fs()->dev_desc->log2blksz;
    
    	if (le32_to_cpu(inode->flags) & EXT4_EXTENTS_FL) {
    		char *buf = zalloc(blksz);
    		if (!buf)
    			return -ENOMEM;
    		struct ext4_extent_header *ext_block;
    		struct ext4_extent *extent;
    		int i = -1;
    		ext_block =
    			ext4fs_get_extent_block(ext4fs_root, buf,
    						(struct ext4_extent_header *)
    						inode->b.blocks.dir_blocks,
    						fileblock, log2_blksz);
    		if (!ext_block) {
    			printf("invalid extent block\n");
    			free(buf);
    			return -EINVAL;
    		}
    
    		extent = (struct ext4_extent *)(ext_block + 1);
    
    		do {
    			i++;
    			if (i >= le16_to_cpu(ext_block->eh_entries))
    				break;
    		} while (fileblock >= le32_to_cpu(extent[i].ee_block));
    		if (--i >= 0) {
    			fileblock -= le32_to_cpu(extent[i].ee_block);
    			if (fileblock >= le16_to_cpu(extent[i].ee_len)) {
    				free(buf);
    				return 0;
    			}
    
    			start = le16_to_cpu(extent[i].ee_start_hi);
    			start = (start << 32) +
    					le32_to_cpu(extent[i].ee_start_lo);
    			free(buf);
    			return fileblock + start;
    		}
    
    		printf("Extent Error\n");
    		free(buf);
    		return -1;
    	}
    
    	/* Direct blocks. */
    	if (fileblock < INDIRECT_BLOCKS)
    		blknr = le32_to_cpu(inode->b.blocks.dir_blocks[fileblock]);
    
    	/* Indirect. */
    	else if (fileblock < (INDIRECT_BLOCKS + (blksz / 4))) {
    		if (ext4fs_indir1_block == NULL) {
    			ext4fs_indir1_block = zalloc(blksz);
    			if (ext4fs_indir1_block == NULL) {
    				printf("** SI ext2fs read block (indir 1)"
    					"malloc failed. **\n");
    				return -1;
    			}
    			ext4fs_indir1_size = blksz;
    			ext4fs_indir1_blkno = -1;
    		}
    		if (blksz != ext4fs_indir1_size) {
    			free(ext4fs_indir1_block);
    			ext4fs_indir1_block = NULL;
    			ext4fs_indir1_size = 0;
    			ext4fs_indir1_blkno = -1;
    			ext4fs_indir1_block = zalloc(blksz);
    			if (ext4fs_indir1_block == NULL) {
    				printf("** SI ext2fs read block (indir 1):"
    					"malloc failed. **\n");
    				return -1;
    			}
    			ext4fs_indir1_size = blksz;
    		}
    		if ((le32_to_cpu(inode->b.blocks.indir_block) <<
    		     log2_blksz) != ext4fs_indir1_blkno) {
    			status =
    			    ext4fs_devread((lbaint_t)le32_to_cpu
    					   (inode->b.blocks.
    					    indir_block) << log2_blksz, 0,
    					   blksz, (char *)ext4fs_indir1_block);
    			if (status == 0) {
    				printf("** SI ext2fs read block (indir 1)"
    					"failed. **\n");
    				return 0;
    			}
    			ext4fs_indir1_blkno =
    				le32_to_cpu(inode->b.blocks.
    					       indir_block) << log2_blksz;
    		}
    		blknr = le32_to_cpu(ext4fs_indir1_block
    				      [fileblock - INDIRECT_BLOCKS]);
    	}
    	/* Double indirect. */
    	else if (fileblock < (INDIRECT_BLOCKS + (blksz / 4 *
    					(blksz / 4 + 1)))) {
    
    		long int perblock = blksz / 4;
    		long int rblock = fileblock - (INDIRECT_BLOCKS + blksz / 4);
    
    		if (ext4fs_indir1_block == NULL) {
    			ext4fs_indir1_block = zalloc(blksz);
    			if (ext4fs_indir1_block == NULL) {
    				printf("** DI ext2fs read block (indir 2 1)"
    					"malloc failed. **\n");
    				return -1;
    			}
    			ext4fs_indir1_size = blksz;
    			ext4fs_indir1_blkno = -1;
    		}
    		if (blksz != ext4fs_indir1_size) {
    			free(ext4fs_indir1_block);
    			ext4fs_indir1_block = NULL;
    			ext4fs_indir1_size = 0;
    			ext4fs_indir1_blkno = -1;
    			ext4fs_indir1_block = zalloc(blksz);
    			if (ext4fs_indir1_block == NULL) {
    				printf("** DI ext2fs read block (indir 2 1)"
    					"malloc failed. **\n");
    				return -1;
    			}
    			ext4fs_indir1_size = blksz;
    		}
    		if ((le32_to_cpu(inode->b.blocks.double_indir_block) <<
    		     log2_blksz) != ext4fs_indir1_blkno) {
    			status =
    			    ext4fs_devread((lbaint_t)le32_to_cpu
    					   (inode->b.blocks.
    					    double_indir_block) << log2_blksz,
    					   0, blksz,
    					   (char *)ext4fs_indir1_block);
    			if (status == 0) {
    				printf("** DI ext2fs read block (indir 2 1)"
    					"failed. **\n");
    				return -1;
    			}
    			ext4fs_indir1_blkno =
    			    le32_to_cpu(inode->b.blocks.double_indir_block) <<
    			    log2_blksz;
    		}
    
    		if (ext4fs_indir2_block == NULL) {
    			ext4fs_indir2_block = zalloc(blksz);
    			if (ext4fs_indir2_block == NULL) {
    				printf("** DI ext2fs read block (indir 2 2)"
    					"malloc failed. **\n");
    				return -1;
    			}
    			ext4fs_indir2_size = blksz;
    			ext4fs_indir2_blkno = -1;
    		}
    		if (blksz != ext4fs_indir2_size) {
    			free(ext4fs_indir2_block);
    			ext4fs_indir2_block = NULL;
    			ext4fs_indir2_size = 0;
    			ext4fs_indir2_blkno = -1;
    			ext4fs_indir2_block = zalloc(blksz);
    			if (ext4fs_indir2_block == NULL) {
    				printf("** DI ext2fs read block (indir 2 2)"
    					"malloc failed. **\n");
    				return -1;
    			}
    			ext4fs_indir2_size = blksz;
    		}
    		if ((le32_to_cpu(ext4fs_indir1_block[rblock / perblock]) <<
    		     log2_blksz) != ext4fs_indir2_blkno) {
    			status = ext4fs_devread((lbaint_t)le32_to_cpu
    						(ext4fs_indir1_block
    						 [rblock /
    						  perblock]) << log2_blksz, 0,
    						blksz,
    						(char *)ext4fs_indir2_block);
    			if (status == 0) {
    				printf("** DI ext2fs read block (indir 2 2)"
    					"failed. **\n");
    				return -1;
    			}
    			ext4fs_indir2_blkno =
    			    le32_to_cpu(ext4fs_indir1_block[rblock
    							      /
    							      perblock]) <<
    			    log2_blksz;
    		}
    		blknr = le32_to_cpu(ext4fs_indir2_block[rblock % perblock]);
    	}
    	/* Tripple indirect. */
    	else {
    		rblock = fileblock - (INDIRECT_BLOCKS + blksz / 4 +
    				      (blksz / 4 * blksz / 4));
    		perblock_child = blksz / 4;
    		perblock_parent = ((blksz / 4) * (blksz / 4));
    
    		if (ext4fs_indir1_block == NULL) {
    			ext4fs_indir1_block = zalloc(blksz);
    			if (ext4fs_indir1_block == NULL) {
    				printf("** TI ext2fs read block (indir 2 1)"
    					"malloc failed. **\n");
    				return -1;
    			}
    			ext4fs_indir1_size = blksz;
    			ext4fs_indir1_blkno = -1;
    		}
    		if (blksz != ext4fs_indir1_size) {
    			free(ext4fs_indir1_block);
    			ext4fs_indir1_block = NULL;
    			ext4fs_indir1_size = 0;
    			ext4fs_indir1_blkno = -1;
    			ext4fs_indir1_block = zalloc(blksz);
    			if (ext4fs_indir1_block == NULL) {
    				printf("** TI ext2fs read block (indir 2 1)"
    					"malloc failed. **\n");
    				return -1;
    			}
    			ext4fs_indir1_size = blksz;
    		}
    		if ((le32_to_cpu(inode->b.blocks.triple_indir_block) <<
    		     log2_blksz) != ext4fs_indir1_blkno) {
    			status = ext4fs_devread
    			    ((lbaint_t)
    			     le32_to_cpu(inode->b.blocks.triple_indir_block)
    			     << log2_blksz, 0, blksz,
    			     (char *)ext4fs_indir1_block);
    			if (status == 0) {
    				printf("** TI ext2fs read block (indir 2 1)"
    					"failed. **\n");
    				return -1;
    			}
    			ext4fs_indir1_blkno =
    			    le32_to_cpu(inode->b.blocks.triple_indir_block) <<
    			    log2_blksz;
    		}
    
    		if (ext4fs_indir2_block == NULL) {
    			ext4fs_indir2_block = zalloc(blksz);
    			if (ext4fs_indir2_block == NULL) {
    				printf("** TI ext2fs read block (indir 2 2)"
    					"malloc failed. **\n");
    				return -1;
    			}
    			ext4fs_indir2_size = blksz;
    			ext4fs_indir2_blkno = -1;
    		}
    		if (blksz != ext4fs_indir2_size) {
    			free(ext4fs_indir2_block);
    			ext4fs_indir2_block = NULL;
    			ext4fs_indir2_size = 0;
    			ext4fs_indir2_blkno = -1;
    			ext4fs_indir2_block = zalloc(blksz);
    			if (ext4fs_indir2_block == NULL) {
    				printf("** TI ext2fs read block (indir 2 2)"
    					"malloc failed. **\n");
    				return -1;
    			}
    			ext4fs_indir2_size = blksz;
    		}
    		if ((le32_to_cpu(ext4fs_indir1_block[rblock /
    						       perblock_parent]) <<
    		     log2_blksz)
    		    != ext4fs_indir2_blkno) {
    			status = ext4fs_devread((lbaint_t)le32_to_cpu
    						(ext4fs_indir1_block
    						 [rblock /
    						  perblock_parent]) <<
    						log2_blksz, 0, blksz,
    						(char *)ext4fs_indir2_block);
    			if (status == 0) {
    				printf("** TI ext2fs read block (indir 2 2)"
    					"failed. **\n");
    				return -1;
    			}
    			ext4fs_indir2_blkno =
    			    le32_to_cpu(ext4fs_indir1_block[rblock /
    							      perblock_parent])
    			    << log2_blksz;
    		}
    
    		if (ext4fs_indir3_block == NULL) {
    			ext4fs_indir3_block = zalloc(blksz);
    			if (ext4fs_indir3_block == NULL) {
    				printf("** TI ext2fs read block (indir 2 2)"
    					"malloc failed. **\n");
    				return -1;
    			}
    			ext4fs_indir3_size = blksz;
    			ext4fs_indir3_blkno = -1;
    		}
    		if (blksz != ext4fs_indir3_size) {
    			free(ext4fs_indir3_block);
    			ext4fs_indir3_block = NULL;
    			ext4fs_indir3_size = 0;
    			ext4fs_indir3_blkno = -1;
    			ext4fs_indir3_block = zalloc(blksz);
    			if (ext4fs_indir3_block == NULL) {
    				printf("** TI ext2fs read block (indir 2 2)"
    					"malloc failed. **\n");
    				return -1;
    			}
    			ext4fs_indir3_size = blksz;
    		}
    		if ((le32_to_cpu(ext4fs_indir2_block[rblock
    						       /
    						       perblock_child]) <<
    		     log2_blksz) != ext4fs_indir3_blkno) {
    			status =
    			    ext4fs_devread((lbaint_t)le32_to_cpu
    					   (ext4fs_indir2_block
    					    [(rblock / perblock_child)
    					     % (blksz / 4)]) << log2_blksz, 0,
    					   blksz, (char *)ext4fs_indir3_block);
    			if (status == 0) {
    				printf("** TI ext2fs read block (indir 2 2)"
    				       "failed. **\n");
    				return -1;
    			}
    			ext4fs_indir3_blkno =
    			    le32_to_cpu(ext4fs_indir2_block[(rblock /
    							       perblock_child) %
    							      (blksz /
    							       4)]) <<
    			    log2_blksz;
    		}
    
    		blknr = le32_to_cpu(ext4fs_indir3_block
    				      [rblock % perblock_child]);
    	}
    	debug("read_allocated_block %ld\n", blknr);
    
    	return blknr;
    }
    
    /**
     * ext4fs_reinit_global() - Reinitialize values of ext4 write implementation's
     *			    global pointers
     *
     * This function assures that for a file with the same name but different size
     * the sequential store on the ext4 filesystem will be correct.
     *
     * In this function the global data, responsible for internal representation
     * of the ext4 data are initialized to the reset state. Without this, during
     * replacement of the smaller file with the bigger truncation of new file was
     * performed.
     */
    void ext4fs_reinit_global(void)
    {
    	if (ext4fs_indir1_block != NULL) {
    		free(ext4fs_indir1_block);
    		ext4fs_indir1_block = NULL;
    		ext4fs_indir1_size = 0;
    		ext4fs_indir1_blkno = -1;
    	}
    	if (ext4fs_indir2_block != NULL) {
    		free(ext4fs_indir2_block);
    		ext4fs_indir2_block = NULL;
    		ext4fs_indir2_size = 0;
    		ext4fs_indir2_blkno = -1;
    	}
    	if (ext4fs_indir3_block != NULL) {
    		free(ext4fs_indir3_block);
    		ext4fs_indir3_block = NULL;
    		ext4fs_indir3_size = 0;
    		ext4fs_indir3_blkno = -1;
    	}
    }
    void ext4fs_close(void)
    {
    	if ((ext4fs_file != NULL) && (ext4fs_root != NULL)) {
    		ext4fs_free_node(ext4fs_file, &ext4fs_root->diropen);
    		ext4fs_file = NULL;
    	}
    	if (ext4fs_root != NULL) {
    		free(ext4fs_root);
    		ext4fs_root = NULL;
    	}
    
    	ext4fs_reinit_global();
    }
    
    int ext4fs_iterate_dir(struct ext2fs_node *dir, char *name,
    				struct ext2fs_node **fnode, int *ftype)
    {
    	unsigned int fpos = 0;
    	int status;
    	loff_t actread;
    	struct ext2fs_node *diro = (struct ext2fs_node *) dir;
    
    #ifdef DEBUG
    	if (name != NULL)
    		printf("Iterate dir %s\n", name);
    #endif /* of DEBUG */
    	if (!diro->inode_read) {
    		status = ext4fs_read_inode(diro->data, diro->ino, &diro->inode);
    		if (status == 0)
    			return 0;
    	}
    	/* Search the file.  */
    	while (fpos < le32_to_cpu(diro->inode.size)) {
    		struct ext2_dirent dirent;
    
    		status = ext4fs_read_file(diro, fpos,
    					   sizeof(struct ext2_dirent),
    					   (char *)&dirent, &actread);
    		if (status < 0)
    			return 0;
    
    		if (dirent.direntlen == 0) {
    			printf("Failed to iterate over directory %s\n", name);
    			return 0;
    		}
    
    		if (dirent.namelen != 0) {
    			char filename[dirent.namelen + 1];
    			struct ext2fs_node *fdiro;
    			int type = FILETYPE_UNKNOWN;
    
    			status = ext4fs_read_file(diro,
    						  fpos +
    						  sizeof(struct ext2_dirent),
    						  dirent.namelen, filename,
    						  &actread);
    			if (status < 0)
    				return 0;
    
    			fdiro = zalloc(sizeof(struct ext2fs_node));
    			if (!fdiro)
    				return 0;
    
    			fdiro->data = diro->data;
    			fdiro->ino = le32_to_cpu(dirent.inode);
    
    			filename[dirent.namelen] = '\0';
    
    			if (dirent.filetype != FILETYPE_UNKNOWN) {
    				fdiro->inode_read = 0;
    
    				if (dirent.filetype == FILETYPE_DIRECTORY)
    					type = FILETYPE_DIRECTORY;
    				else if (dirent.filetype == FILETYPE_SYMLINK)
    					type = FILETYPE_SYMLINK;
    				else if (dirent.filetype == FILETYPE_REG)
    					type = FILETYPE_REG;
    			} else {
    				status = ext4fs_read_inode(diro->data,
    							   le32_to_cpu
    							   (dirent.inode),
    							   &fdiro->inode);
    				if (status == 0) {
    					free(fdiro);
    					return 0;
    				}
    				fdiro->inode_read = 1;
    
    				if ((le16_to_cpu(fdiro->inode.mode) &
    				     FILETYPE_INO_MASK) ==
    				    FILETYPE_INO_DIRECTORY) {
    					type = FILETYPE_DIRECTORY;
    				} else if ((le16_to_cpu(fdiro->inode.mode)
    					    & FILETYPE_INO_MASK) ==
    					   FILETYPE_INO_SYMLINK) {
    					type = FILETYPE_SYMLINK;
    				} else if ((le16_to_cpu(fdiro->inode.mode)
    					    & FILETYPE_INO_MASK) ==
    					   FILETYPE_INO_REG) {
    					type = FILETYPE_REG;
    				}
    			}
    #ifdef DEBUG
    			printf("iterate >%s<\n", filename);
    #endif /* of DEBUG */
    			if ((name != NULL) && (fnode != NULL)
    			    && (ftype != NULL)) {
    				if (strcmp(filename, name) == 0) {
    					*ftype = type;
    					*fnode = fdiro;
    					return 1;
    				}
    			} else {
    				if (fdiro->inode_read == 0) {
    					status = ext4fs_read_inode(diro->data,
    								 le32_to_cpu(
    								 dirent.inode),
    								 &fdiro->inode);
    					if (status == 0) {
    						free(fdiro);
    						return 0;
    					}
    					fdiro->inode_read = 1;
    				}
    				switch (type) {
    				case FILETYPE_DIRECTORY:
    					printf("<DIR> ");
    					break;
    				case FILETYPE_SYMLINK:
    					printf("<SYM> ");
    					break;
    				case FILETYPE_REG:
    					printf("      ");
    					break;
    				default:
    					printf("< ? > ");
    					break;
    				}
    				printf("%10u %s\n",
    				       le32_to_cpu(fdiro->inode.size),
    					filename);
    			}
    			free(fdiro);
    		}
    		fpos += le16_to_cpu(dirent.direntlen);
    	}
    	return 0;
    }
    
    static char *ext4fs_read_symlink(struct ext2fs_node *node)
    {
    	char *symlink;
    	struct ext2fs_node *diro = node;
    	int status;
    	loff_t actread;
    
    	if (!diro->inode_read) {
    		status = ext4fs_read_inode(diro->data, diro->ino, &diro->inode);
    		if (status == 0)
    			return NULL;
    	}
    	symlink = zalloc(le32_to_cpu(diro->inode.size) + 1);
    	if (!symlink)
    		return NULL;
    
    	if (le32_to_cpu(diro->inode.size) < sizeof(diro->inode.b.symlink)) {
    		strncpy(symlink, diro->inode.b.symlink,
    			 le32_to_cpu(diro->inode.size));
    	} else {
    		status = ext4fs_read_file(diro, 0,
    					   le32_to_cpu(diro->inode.size),
    					   symlink, &actread);
    		if ((status < 0) || (actread == 0)) {
    			free(symlink);
    			return NULL;
    		}
    	}
    	symlink[le32_to_cpu(diro->inode.size)] = '\0';
    	return symlink;
    }
    
    static int ext4fs_find_file1(const char *currpath,
    			     struct ext2fs_node *currroot,
    			     struct ext2fs_node **currfound, int *foundtype)
    {
    	char fpath[strlen(currpath) + 1];
    	char *name = fpath;
    	char *next;
    	int status;
    	int type = FILETYPE_DIRECTORY;
    	struct ext2fs_node *currnode = currroot;
    	struct ext2fs_node *oldnode = currroot;
    
    	strncpy(fpath, currpath, strlen(currpath) + 1);
    
    	/* Remove all leading slashes. */
    	while (*name == '/')
    		name++;
    
    	if (!*name) {
    		*currfound = currnode;
    		return 1;
    	}
    
    	for (;;) {
    		int found;
    
    		/* Extract the actual part from the pathname. */
    		next = strchr(name, '/');
    		if (next) {
    			/* Remove all leading slashes. */
    			while (*next == '/')
    				*(next++) = '\0';
    		}
    
    		if (type != FILETYPE_DIRECTORY) {
    			ext4fs_free_node(currnode, currroot);
    			return 0;
    		}
    
    		oldnode = currnode;
    
    		/* Iterate over the directory. */
    		found = ext4fs_iterate_dir(currnode, name, &currnode, &type);
    		if (found == 0)
    			return 0;
    
    		if (found == -1)
    			break;
    
    		/* Read in the symlink and follow it. */
    		if (type == FILETYPE_SYMLINK) {
    			char *symlink;
    
    			/* Test if the symlink does not loop. */
    			if (++symlinknest == 8) {
    				ext4fs_free_node(currnode, currroot);
    				ext4fs_free_node(oldnode, currroot);
    				return 0;
    			}
    
    			symlink = ext4fs_read_symlink(currnode);
    			ext4fs_free_node(currnode, currroot);
    
    			if (!symlink) {
    				ext4fs_free_node(oldnode, currroot);
    				return 0;
    			}
    
    			debug("Got symlink >%s<\n", symlink);
    
    			if (symlink[0] == '/') {
    				ext4fs_free_node(oldnode, currroot);
    				oldnode = &ext4fs_root->diropen;
    			}
    
    			/* Lookup the node the symlink points to. */
    			status = ext4fs_find_file1(symlink, oldnode,
    						    &currnode, &type);
    
    			free(symlink);
    
    			if (status == 0) {
    				ext4fs_free_node(oldnode, currroot);
    				return 0;
    			}
    		}
    
    		ext4fs_free_node(oldnode, currroot);
    
    		/* Found the node! */
    		if (!next || *next == '\0') {
    			*currfound = currnode;
    			*foundtype = type;
    			return 1;
    		}
    		name = next;
    	}
    	return -1;
    }
    
    int ext4fs_find_file(const char *path, struct ext2fs_node *rootnode,
    	struct ext2fs_node **foundnode, int expecttype)
    {
    	int status;
    	int foundtype = FILETYPE_DIRECTORY;
    
    	symlinknest = 0;
    	if (!path)
    		return 0;
    
    	status = ext4fs_find_file1(path, rootnode, foundnode, &foundtype);
    	if (status == 0)
    		return 0;
    
    	/* Check if the node that was found was of the expected type. */
    	if ((expecttype == FILETYPE_REG) && (foundtype != expecttype))
    		return 0;
    	else if ((expecttype == FILETYPE_DIRECTORY)
    		   && (foundtype != expecttype))
    		return 0;
    
    	return 1;
    }
    
    int ext4fs_open(const char *filename, loff_t *len)
    {
    	struct ext2fs_node *fdiro = NULL;
    	int status;
    
    	if (ext4fs_root == NULL)
    		return -1;
    
    	ext4fs_file = NULL;
    	status = ext4fs_find_file(filename, &ext4fs_root->diropen, &fdiro,
    				  FILETYPE_REG);
    	if (status == 0)
    		goto fail;
    
    	if (!fdiro->inode_read) {
    		status = ext4fs_read_inode(fdiro->data, fdiro->ino,
    				&fdiro->inode);
    		if (status == 0)
    			goto fail;
    	}
    	*len = le32_to_cpu(fdiro->inode.size);
    	ext4fs_file = fdiro;
    
    	return 0;
    fail:
    	ext4fs_free_node(fdiro, &ext4fs_root->diropen);
    
    	return -1;
    }
    
    int ext4fs_mount(unsigned part_length)
    {
    	struct ext2_data *data;
    	int status;
    	struct ext_filesystem *fs = get_fs();
    	data = zalloc(SUPERBLOCK_SIZE);
    	if (!data)
    		return 0;
    
    	/* Read the superblock. */
    	status = ext4_read_superblock((char *)&data->sblock);
    
    	if (status == 0)
    		goto fail;
    
    	/* Make sure this is an ext2 filesystem. */
    	if (le16_to_cpu(data->sblock.magic) != EXT2_MAGIC)
    		goto fail;
    
    	/*
    	 * The 64bit feature was enabled when metadata_csum was enabled
    	 * and we do not support metadata_csum (and cannot reliably find
    	 * files when it is set.  Refuse to mount.
    	 */
    	if (le32_to_cpu(data->sblock.feature_incompat) & EXT4_FEATURE_INCOMPAT_64BIT) {
    		printf("Unsupported feature found (64bit, possibly metadata_csum), not mounting\n");
    		goto fail;
    	}
    
    	if (le32_to_cpu(data->sblock.revision_level) == 0)
    		fs->inodesz = 128;
    	else
    		fs->inodesz = le16_to_cpu(data->sblock.inode_size);
    
    	debug("EXT2 rev %d, inode_size %d\n",
    	       le32_to_cpu(data->sblock.revision_level), fs->inodesz);
    
    	data->diropen.data = data;
    	data->diropen.ino = 2;
    	data->diropen.inode_read = 1;
    	data->inode = &data->diropen.inode;
    
    	status = ext4fs_read_inode(data, 2, data->inode);
    	if (status == 0)
    		goto fail;
    
    	ext4fs_root = data;
    
    	return 1;
    fail:
    	printf("Failed to mount ext2 filesystem...\n");
    	free(data);
    	ext4fs_root = NULL;
    
    	return 0;
    }