ext4fs write support

Signed-off-by: Uma Shankar <uma.shankar@samsung.com>
Signed-off-by: Manjunatha C Achar <a.manjunatha@samsung.com>
Signed-off-by: Iqbal Shareef <iqbal.ams@samsung.com>
Signed-off-by: Hakgoo Lee <goodguy.lee@samsung.com>

1 files changed, 961 insertions, 0 deletions

diff --git a/fs/ext4/ext4fs.c b/fs/ext4/ext4fs.c
index 1287bf0e1..114c2a214 100644
--- a/fs/ext4/ext4fs.c
+++ b/fs/ext4/ext4fs.c
@@ -16,6 +16,8 @@
  * GRUB  --  GRand Unified Bootloader
  * Copyright (C) 2003, 2004  Free Software Foundation, Inc.
  *
+ * ext4write : Based on generic ext4 protocol.
+ *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
  * the Free Software Foundation; either version 2 of the License, or
@@ -226,3 +228,962 @@ int ext4fs_read(char *buf, unsigned len)
 
 	return ext4fs_read_file(ext4fs_file, 0, len, buf);
 }
+
+#if defined(CONFIG_CMD_EXT4_WRITE)
+static void ext4fs_update(void)
+{
+	short i;
+	ext4fs_update_journal();
+	struct ext_filesystem *fs = get_fs();
+
+	/* update  super block */
+	put_ext4((uint64_t)(SUPERBLOCK_SIZE),
+		 (struct ext2_sblock *)fs->sb, (uint32_t)SUPERBLOCK_SIZE);
+
+	/* update block groups */
+	for (i = 0; i < fs->no_blkgrp; i++) {
+		fs->gd[i].bg_checksum = ext4fs_checksum_update(i);
+		put_ext4((uint64_t)(fs->gd[i].block_id * fs->blksz),
+			 fs->blk_bmaps[i], fs->blksz);
+	}
+
+	/* update inode table groups */
+	for (i = 0; i < fs->no_blkgrp; i++) {
+		put_ext4((uint64_t) (fs->gd[i].inode_id * fs->blksz),
+			 fs->inode_bmaps[i], fs->blksz);
+	}
+
+	/* update the block group descriptor table */
+	put_ext4((uint64_t)(fs->gdtable_blkno * fs->blksz),
+		 (struct ext2_block_group *)fs->gdtable,
+		 (fs->blksz * fs->no_blk_pergdt));
+
+	ext4fs_dump_metadata();
+
+	gindex = 0;
+	gd_index = 0;
+}
+
+int ext4fs_get_bgdtable(void)
+{
+	int status;
+	int grp_desc_size;
+	struct ext_filesystem *fs = get_fs();
+	grp_desc_size = sizeof(struct ext2_block_group);
+	fs->no_blk_pergdt = (fs->no_blkgrp * grp_desc_size) / fs->blksz;
+	if ((fs->no_blkgrp * grp_desc_size) % fs->blksz)
+		fs->no_blk_pergdt++;
+
+	/* allocate memory for gdtable */
+	fs->gdtable = zalloc(fs->blksz * fs->no_blk_pergdt);
+	if (!fs->gdtable)
+		return -ENOMEM;
+	/* read the group descriptor table */
+	status = ext4fs_devread(fs->gdtable_blkno * fs->sect_perblk, 0,
+				fs->blksz * fs->no_blk_pergdt, fs->gdtable);
+	if (status == 0)
+		goto fail;
+
+	if (ext4fs_log_gdt(fs->gdtable)) {
+		printf("Error in ext4fs_log_gdt\n");
+		return -1;
+	}
+
+	return 0;
+fail:
+	free(fs->gdtable);
+	fs->gdtable = NULL;
+
+	return -1;
+}
+
+static void delete_single_indirect_block(struct ext2_inode *inode)
+{
+	struct ext2_block_group *gd = NULL;
+	static int prev_bg_bmap_idx = -1;
+	long int blknr;
+	int remainder;
+	int bg_idx;
+	int status;
+	unsigned int blk_per_grp = ext4fs_root->sblock.blocks_per_group;
+	struct ext_filesystem *fs = get_fs();
+	char *journal_buffer = zalloc(fs->blksz);
+	if (!journal_buffer) {
+		printf("No memory\n");
+		return;
+	}
+	/* get  block group descriptor table */
+	gd = (struct ext2_block_group *)fs->gdtable;
+
+	/* deleting the single indirect block associated with inode */
+	if (inode->b.blocks.indir_block != 0) {
+		debug("SIPB releasing %u\n", inode->b.blocks.indir_block);
+		blknr = inode->b.blocks.indir_block;
+		if (fs->blksz != 1024) {
+			bg_idx = blknr / blk_per_grp;
+		} else {
+			bg_idx = blknr / blk_per_grp;
+			remainder = blknr % blk_per_grp;
+			if (!remainder)
+				bg_idx--;
+		}
+		ext4fs_reset_block_bmap(blknr, fs->blk_bmaps[bg_idx], bg_idx);
+		gd[bg_idx].free_blocks++;
+		fs->sb->free_blocks++;
+		/* journal backup */
+		if (prev_bg_bmap_idx != bg_idx) {
+			status =
+			    ext4fs_devread(gd[bg_idx].block_id *
+					   fs->sect_perblk, 0, fs->blksz,
+					   journal_buffer);
+			if (status == 0)
+				goto fail;
+			if (ext4fs_log_journal
+			    (journal_buffer, gd[bg_idx].block_id))
+				goto fail;
+			prev_bg_bmap_idx = bg_idx;
+		}
+	}
+fail:
+	free(journal_buffer);
+}
+
+static void delete_double_indirect_block(struct ext2_inode *inode)
+{
+	int i;
+	short status;
+	static int prev_bg_bmap_idx = -1;
+	long int blknr;
+	int remainder;
+	int bg_idx;
+	unsigned int blk_per_grp = ext4fs_root->sblock.blocks_per_group;
+	unsigned int *di_buffer = NULL;
+	unsigned int *DIB_start_addr = NULL;
+	struct ext2_block_group *gd = NULL;
+	struct ext_filesystem *fs = get_fs();
+	char *journal_buffer = zalloc(fs->blksz);
+	if (!journal_buffer) {
+		printf("No memory\n");
+		return;
+	}
+	/* get the block group descriptor table */
+	gd = (struct ext2_block_group *)fs->gdtable;
+
+	if (inode->b.blocks.double_indir_block != 0) {
+		di_buffer = zalloc(fs->blksz);
+		if (!di_buffer) {
+			printf("No memory\n");
+			return;
+		}
+		DIB_start_addr = (unsigned int *)di_buffer;
+		blknr = inode->b.blocks.double_indir_block;
+		status = ext4fs_devread(blknr * fs->sect_perblk, 0, fs->blksz,
+					(char *)di_buffer);
+		for (i = 0; i < fs->blksz / sizeof(int); i++) {
+			if (*di_buffer == 0)
+				break;
+
+			debug("DICB releasing %u\n", *di_buffer);
+			if (fs->blksz != 1024) {
+				bg_idx = (*di_buffer) / blk_per_grp;
+			} else {
+				bg_idx = (*di_buffer) / blk_per_grp;
+				remainder = (*di_buffer) % blk_per_grp;
+				if (!remainder)
+					bg_idx--;
+			}
+			ext4fs_reset_block_bmap(*di_buffer,
+					fs->blk_bmaps[bg_idx], bg_idx);
+			di_buffer++;
+			gd[bg_idx].free_blocks++;
+			fs->sb->free_blocks++;
+			/* journal backup */
+			if (prev_bg_bmap_idx != bg_idx) {
+				status = ext4fs_devread(gd[bg_idx].block_id
+							* fs->sect_perblk, 0,
+							fs->blksz,
+							journal_buffer);
+				if (status == 0)
+					goto fail;
+
+				if (ext4fs_log_journal(journal_buffer,
+							gd[bg_idx].block_id))
+					goto fail;
+				prev_bg_bmap_idx = bg_idx;
+			}
+		}
+
+		/* removing the parent double indirect block */
+		blknr = inode->b.blocks.double_indir_block;
+		if (fs->blksz != 1024) {
+			bg_idx = blknr / blk_per_grp;
+		} else {
+			bg_idx = blknr / blk_per_grp;
+			remainder = blknr % blk_per_grp;
+			if (!remainder)
+				bg_idx--;
+		}
+		ext4fs_reset_block_bmap(blknr, fs->blk_bmaps[bg_idx], bg_idx);
+		gd[bg_idx].free_blocks++;
+		fs->sb->free_blocks++;
+		/* journal backup */
+		if (prev_bg_bmap_idx != bg_idx) {
+			memset(journal_buffer, '\0', fs->blksz);
+			status = ext4fs_devread(gd[bg_idx].block_id *
+						fs->sect_perblk, 0, fs->blksz,
+						journal_buffer);
+			if (status == 0)
+				goto fail;
+
+			if (ext4fs_log_journal(journal_buffer,
+						gd[bg_idx].block_id))
+				goto fail;
+			prev_bg_bmap_idx = bg_idx;
+		}
+		debug("DIPB releasing %ld\n", blknr);
+	}
+fail:
+	free(DIB_start_addr);
+	free(journal_buffer);
+}
+
+static void delete_triple_indirect_block(struct ext2_inode *inode)
+{
+	int i, j;
+	short status;
+	static int prev_bg_bmap_idx = -1;
+	long int blknr;
+	int remainder;
+	int bg_idx;
+	unsigned int blk_per_grp = ext4fs_root->sblock.blocks_per_group;
+	unsigned int *tigp_buffer = NULL;
+	unsigned int *tib_start_addr = NULL;
+	unsigned int *tip_buffer = NULL;
+	unsigned int *tipb_start_addr = NULL;
+	struct ext2_block_group *gd = NULL;
+	struct ext_filesystem *fs = get_fs();
+	char *journal_buffer = zalloc(fs->blksz);
+	if (!journal_buffer) {
+		printf("No memory\n");
+		return;
+	}
+	/* get block group descriptor table */
+	gd = (struct ext2_block_group *)fs->gdtable;
+
+	if (inode->b.blocks.triple_indir_block != 0) {
+		tigp_buffer = zalloc(fs->blksz);
+		if (!tigp_buffer) {
+			printf("No memory\n");
+			return;
+		}
+		tib_start_addr = (unsigned int *)tigp_buffer;
+		blknr = inode->b.blocks.triple_indir_block;
+		status = ext4fs_devread(blknr * fs->sect_perblk, 0, fs->blksz,
+					(char *)tigp_buffer);
+		for (i = 0; i < fs->blksz / sizeof(int); i++) {
+			if (*tigp_buffer == 0)
+				break;
+			debug("tigp buffer releasing %u\n", *tigp_buffer);
+
+			tip_buffer = zalloc(fs->blksz);
+			if (!tip_buffer)
+				goto fail;
+			tipb_start_addr = (unsigned int *)tip_buffer;
+			status = ext4fs_devread((*tigp_buffer) *
+						fs->sect_perblk, 0, fs->blksz,
+						(char *)tip_buffer);
+			for (j = 0; j < fs->blksz / sizeof(int); j++) {
+				if (*tip_buffer == 0)
+					break;
+				if (fs->blksz != 1024) {
+					bg_idx = (*tip_buffer) / blk_per_grp;
+				} else {
+					bg_idx = (*tip_buffer) / blk_per_grp;
+
+					remainder = (*tip_buffer) % blk_per_grp;
+					if (!remainder)
+						bg_idx--;
+				}
+
+				ext4fs_reset_block_bmap(*tip_buffer,
+							fs->blk_bmaps[bg_idx],
+							bg_idx);
+
+				tip_buffer++;
+				gd[bg_idx].free_blocks++;
+				fs->sb->free_blocks++;
+				/* journal backup */
+				if (prev_bg_bmap_idx != bg_idx) {
+					status =
+					    ext4fs_devread(gd[bg_idx].block_id *
+							   fs->sect_perblk, 0,
+							   fs->blksz,
+							   journal_buffer);
+					if (status == 0)
+						goto fail;
+
+					if (ext4fs_log_journal(journal_buffer,
+							       gd[bg_idx].
+							       block_id))
+						goto fail;
+					prev_bg_bmap_idx = bg_idx;
+				}
+			}
+			free(tipb_start_addr);
+			tipb_start_addr = NULL;
+
+			/*
+			 * removing the grand parent blocks
+			 * which is connected to inode
+			 */
+			if (fs->blksz != 1024) {
+				bg_idx = (*tigp_buffer) / blk_per_grp;
+			} else {
+				bg_idx = (*tigp_buffer) / blk_per_grp;
+
+				remainder = (*tigp_buffer) % blk_per_grp;
+				if (!remainder)
+					bg_idx--;
+			}
+			ext4fs_reset_block_bmap(*tigp_buffer,
+						fs->blk_bmaps[bg_idx], bg_idx);
+
+			tigp_buffer++;
+			gd[bg_idx].free_blocks++;
+			fs->sb->free_blocks++;
+			/* journal backup */
+			if (prev_bg_bmap_idx != bg_idx) {
+				memset(journal_buffer, '\0', fs->blksz);
+				status =
+				    ext4fs_devread(gd[bg_idx].block_id *
+						   fs->sect_perblk, 0,
+						   fs->blksz, journal_buffer);
+				if (status == 0)
+					goto fail;
+
+				if (ext4fs_log_journal(journal_buffer,
+							gd[bg_idx].block_id))
+					goto fail;
+				prev_bg_bmap_idx = bg_idx;
+			}
+		}
+
+		/* removing the grand parent triple indirect block */
+		blknr = inode->b.blocks.triple_indir_block;
+		if (fs->blksz != 1024) {
+			bg_idx = blknr / blk_per_grp;
+		} else {
+			bg_idx = blknr / blk_per_grp;
+			remainder = blknr % blk_per_grp;
+			if (!remainder)
+				bg_idx--;
+		}
+		ext4fs_reset_block_bmap(blknr, fs->blk_bmaps[bg_idx], bg_idx);
+		gd[bg_idx].free_blocks++;
+		fs->sb->free_blocks++;
+		/* journal backup */
+		if (prev_bg_bmap_idx != bg_idx) {
+			memset(journal_buffer, '\0', fs->blksz);
+			status = ext4fs_devread(gd[bg_idx].block_id *
+						fs->sect_perblk, 0, fs->blksz,
+						journal_buffer);
+			if (status == 0)
+				goto fail;
+
+			if (ext4fs_log_journal(journal_buffer,
+						gd[bg_idx].block_id))
+				goto fail;
+			prev_bg_bmap_idx = bg_idx;
+		}
+		debug("tigp buffer itself releasing %ld\n", blknr);
+	}
+fail:
+	free(tib_start_addr);
+	free(tipb_start_addr);
+	free(journal_buffer);
+}
+
+static int ext4fs_delete_file(int inodeno)
+{
+	struct ext2_inode inode;
+	short status;
+	int i;
+	int remainder;
+	long int blknr;
+	int bg_idx;
+	int ibmap_idx;
+	char *read_buffer = NULL;
+	char *start_block_address = NULL;
+	unsigned int no_blocks;
+
+	static int prev_bg_bmap_idx = -1;
+	unsigned int inodes_per_block;
+	long int blkno;
+	unsigned int blkoff;
+	unsigned int blk_per_grp = ext4fs_root->sblock.blocks_per_group;
+	unsigned int inode_per_grp = ext4fs_root->sblock.inodes_per_group;
+	struct ext2_inode *inode_buffer = NULL;
+	struct ext2_block_group *gd = NULL;
+	struct ext_filesystem *fs = get_fs();
+	char *journal_buffer = zalloc(fs->blksz);
+	if (!journal_buffer)
+		return -ENOMEM;
+	/* get the block group descriptor table */
+	gd = (struct ext2_block_group *)fs->gdtable;
+	status = ext4fs_read_inode(ext4fs_root, inodeno, &inode);
+	if (status == 0)
+		goto fail;
+
+	/* read the block no allocated to a file */
+	no_blocks = inode.size / fs->blksz;
+	if (inode.size % fs->blksz)
+		no_blocks++;
+
+	if (le32_to_cpu(inode.flags) & EXT4_EXTENTS_FL) {
+		struct ext2fs_node *node_inode =
+		    zalloc(sizeof(struct ext2fs_node));
+		if (!node_inode)
+			goto fail;
+		node_inode->data = ext4fs_root;
+		node_inode->ino = inodeno;
+		node_inode->inode_read = 0;
+		memcpy(&(node_inode->inode), &inode, sizeof(struct ext2_inode));
+
+		for (i = 0; i < no_blocks; i++) {
+			blknr = read_allocated_block(&(node_inode->inode), i);
+			if (fs->blksz != 1024) {
+				bg_idx = blknr / blk_per_grp;
+			} else {
+				bg_idx = blknr / blk_per_grp;
+				remainder = blknr % blk_per_grp;
+				if (!remainder)
+					bg_idx--;
+			}
+			ext4fs_reset_block_bmap(blknr, fs->blk_bmaps[bg_idx],
+						bg_idx);
+			debug("EXT4_EXTENTS Block releasing %ld: %d\n",
+			      blknr, bg_idx);
+
+			gd[bg_idx].free_blocks++;
+			fs->sb->free_blocks++;
+
+			/* journal backup */
+			if (prev_bg_bmap_idx != bg_idx) {
+				status =
+				    ext4fs_devread(gd[bg_idx].block_id *
+						   fs->sect_perblk, 0,
+						   fs->blksz, journal_buffer);
+				if (status == 0)
+					goto fail;
+				if (ext4fs_log_journal(journal_buffer,
+							gd[bg_idx].block_id))
+					goto fail;
+				prev_bg_bmap_idx = bg_idx;
+			}
+		}
+		if (node_inode) {
+			free(node_inode);
+			node_inode = NULL;
+		}
+	} else {
+
+		delete_single_indirect_block(&inode);
+		delete_double_indirect_block(&inode);
+		delete_triple_indirect_block(&inode);
+
+		/* read the block no allocated to a file */
+		no_blocks = inode.size / fs->blksz;
+		if (inode.size % fs->blksz)
+			no_blocks++;
+		for (i = 0; i < no_blocks; i++) {
+			blknr = read_allocated_block(&inode, i);
+			if (fs->blksz != 1024) {
+				bg_idx = blknr / blk_per_grp;
+			} else {
+				bg_idx = blknr / blk_per_grp;
+				remainder = blknr % blk_per_grp;
+				if (!remainder)
+					bg_idx--;
+			}
+			ext4fs_reset_block_bmap(blknr, fs->blk_bmaps[bg_idx],
+						bg_idx);
+			debug("ActualB releasing %ld: %d\n", blknr, bg_idx);
+
+			gd[bg_idx].free_blocks++;
+			fs->sb->free_blocks++;
+			/* journal backup */
+			if (prev_bg_bmap_idx != bg_idx) {
+				memset(journal_buffer, '\0', fs->blksz);
+				status = ext4fs_devread(gd[bg_idx].block_id
+							* fs->sect_perblk,
+							0, fs->blksz,
+							journal_buffer);
+				if (status == 0)
+					goto fail;
+				if (ext4fs_log_journal(journal_buffer,
+						gd[bg_idx].block_id))
+					goto fail;
+				prev_bg_bmap_idx = bg_idx;
+			}
+		}
+	}
+
+	/* from the inode no to blockno */
+	inodes_per_block = fs->blksz / fs->inodesz;
+	ibmap_idx = inodeno / inode_per_grp;
+
+	/* get the block no */
+	inodeno--;
+	blkno = __le32_to_cpu(gd[ibmap_idx].inode_table_id) +
+		(inodeno % __le32_to_cpu(inode_per_grp)) / inodes_per_block;
+
+	/* get the offset of the inode */
+	blkoff = ((inodeno) % inodes_per_block) * fs->inodesz;
+
+	/* read the block no containing the inode */
+	read_buffer = zalloc(fs->blksz);
+	if (!read_buffer)
+		goto fail;
+	start_block_address = read_buffer;
+	status = ext4fs_devread(blkno * fs->sect_perblk,
+				0, fs->blksz, read_buffer);
+	if (status == 0)
+		goto fail;
+
+	if (ext4fs_log_journal(read_buffer, blkno))
+		goto fail;
+
+	read_buffer = read_buffer + blkoff;
+	inode_buffer = (struct ext2_inode *)read_buffer;
+	memset(inode_buffer, '\0', sizeof(struct ext2_inode));
+
+	/* write the inode to original position in inode table */
+	if (ext4fs_put_metadata(start_block_address, blkno))
+		goto fail;
+
+	/* update the respective inode bitmaps */
+	inodeno++;
+	ext4fs_reset_inode_bmap(inodeno, fs->inode_bmaps[ibmap_idx], ibmap_idx);
+	gd[ibmap_idx].free_inodes++;
+	fs->sb->free_inodes++;
+	/* journal backup */
+	memset(journal_buffer, '\0', fs->blksz);
+	status = ext4fs_devread(gd[ibmap_idx].inode_id *
+				fs->sect_perblk, 0, fs->blksz, journal_buffer);
+	if (status == 0)
+		goto fail;
+	if (ext4fs_log_journal(journal_buffer, gd[ibmap_idx].inode_id))
+		goto fail;
+
+	ext4fs_update();
+	ext4fs_deinit();
+
+	if (ext4fs_init() != 0) {
+		printf("error in File System init\n");
+		goto fail;
+	}
+
+	free(start_block_address);
+	free(journal_buffer);
+
+	return 0;
+fail:
+	free(start_block_address);
+	free(journal_buffer);
+
+	return -1;
+}
+
+int ext4fs_init(void)
+{
+	short status;
+	int i;
+	unsigned int real_free_blocks = 0;
+	struct ext_filesystem *fs = get_fs();
+
+	/* populate fs */
+	fs->blksz = EXT2_BLOCK_SIZE(ext4fs_root);
+	fs->inodesz = INODE_SIZE_FILESYSTEM(ext4fs_root);
+	fs->sect_perblk = fs->blksz / SECTOR_SIZE;
+
+	/* get the superblock */
+	fs->sb = zalloc(SUPERBLOCK_SIZE);
+	if (!fs->sb)
+		return -ENOMEM;
+	if (!ext4fs_devread(SUPERBLOCK_SECTOR, 0, SUPERBLOCK_SIZE,
+			(char *)fs->sb))
+		goto fail;
+
+	/* init journal */
+	if (ext4fs_init_journal())
+		goto fail;
+
+	/* get total no of blockgroups */
+	fs->no_blkgrp = (uint32_t)ext4fs_div_roundup(
+			(ext4fs_root->sblock.total_blocks -
+			ext4fs_root->sblock.first_data_block),
+			ext4fs_root->sblock.blocks_per_group);
+
+	/* get the block group descriptor table */
+	fs->gdtable_blkno = ((EXT2_MIN_BLOCK_SIZE == fs->blksz) + 1);
+	if (ext4fs_get_bgdtable() == -1) {
+		printf("Error in getting the block group descriptor table\n");
+		goto fail;
+	}
+	fs->gd = (struct ext2_block_group *)fs->gdtable;
+
+	/* load all the available bitmap block of the partition */
+	fs->blk_bmaps = zalloc(fs->no_blkgrp * sizeof(char *));
+	if (!fs->blk_bmaps)
+		goto fail;
+	for (i = 0; i < fs->no_blkgrp; i++) {
+		fs->blk_bmaps[i] = zalloc(fs->blksz);
+		if (!fs->blk_bmaps[i])
+			goto fail;
+	}
+
+	for (i = 0; i < fs->no_blkgrp; i++) {
+		status =
+		    ext4fs_devread(fs->gd[i].block_id * fs->sect_perblk, 0,
+				   fs->blksz, (char *)fs->blk_bmaps[i]);
+		if (status == 0)
+			goto fail;
+	}
+
+	/* load all the available inode bitmap of the partition */
+	fs->inode_bmaps = zalloc(fs->no_blkgrp * sizeof(unsigned char *));
+	if (!fs->inode_bmaps)
+		goto fail;
+	for (i = 0; i < fs->no_blkgrp; i++) {
+		fs->inode_bmaps[i] = zalloc(fs->blksz);
+		if (!fs->inode_bmaps[i])
+			goto fail;
+	}
+
+	for (i = 0; i < fs->no_blkgrp; i++) {
+		status = ext4fs_devread(fs->gd[i].inode_id * fs->sect_perblk,
+					0, fs->blksz,
+					(char *)fs->inode_bmaps[i]);
+		if (status == 0)
+			goto fail;
+	}
+
+	/*
+	 * check filesystem consistency with free blocks of file system
+	 * some time we observed that superblock freeblocks does not match
+	 * with the  blockgroups freeblocks when improper
+	 * reboot of a linux kernel
+	 */
+	for (i = 0; i < fs->no_blkgrp; i++)
+		real_free_blocks = real_free_blocks + fs->gd[i].free_blocks;
+	if (real_free_blocks != fs->sb->free_blocks)
+		fs->sb->free_blocks = real_free_blocks;
+
+	return 0;
+fail:
+	ext4fs_deinit();
+
+	return -1;
+}
+
+void ext4fs_deinit(void)
+{
+	int i;
+	struct ext2_inode inode_journal;
+	struct journal_superblock_t *jsb;
+	long int blknr;
+	struct ext_filesystem *fs = get_fs();
+
+	/* free journal */
+	char *temp_buff = zalloc(fs->blksz);
+	if (temp_buff) {
+		ext4fs_read_inode(ext4fs_root, EXT2_JOURNAL_INO,
+				  &inode_journal);
+		blknr = read_allocated_block(&inode_journal,
+					EXT2_JOURNAL_SUPERBLOCK);
+		ext4fs_devread(blknr * fs->sect_perblk, 0, fs->blksz,
+			       temp_buff);
+		jsb = (struct journal_superblock_t *)temp_buff;
+		jsb->s_start = cpu_to_be32(0);
+		put_ext4((uint64_t) (blknr * fs->blksz),
+			 (struct journal_superblock_t *)temp_buff, fs->blksz);
+		free(temp_buff);
+	}
+	ext4fs_free_journal();
+
+	/* get the superblock */
+	ext4fs_devread(SUPERBLOCK_SECTOR, 0, SUPERBLOCK_SIZE, (char *)fs->sb);
+	fs->sb->feature_incompat &= ~EXT3_FEATURE_INCOMPAT_RECOVER;
+	put_ext4((uint64_t)(SUPERBLOCK_SIZE),
+		 (struct ext2_sblock *)fs->sb, (uint32_t)SUPERBLOCK_SIZE);
+	free(fs->sb);
+	fs->sb = NULL;
+
+	if (fs->blk_bmaps) {
+		for (i = 0; i < fs->no_blkgrp; i++) {
+			free(fs->blk_bmaps[i]);
+			fs->blk_bmaps[i] = NULL;
+		}
+		free(fs->blk_bmaps);
+		fs->blk_bmaps = NULL;
+	}
+
+	if (fs->inode_bmaps) {
+		for (i = 0; i < fs->no_blkgrp; i++) {
+			free(fs->inode_bmaps[i]);
+			fs->inode_bmaps[i] = NULL;
+		}
+		free(fs->inode_bmaps);
+		fs->inode_bmaps = NULL;
+	}
+
+
+	free(fs->gdtable);
+	fs->gdtable = NULL;
+	fs->gd = NULL;
+	/*
+	 * reinitiliazed the global inode and
+	 * block bitmap first execution check variables
+	 */
+	fs->first_pass_ibmap = 0;
+	fs->first_pass_bbmap = 0;
+	fs->curr_inode_no = 0;
+	fs->curr_blkno = 0;
+}
+
+static int ext4fs_write_file(struct ext2_inode *file_inode,
+			     int pos, unsigned int len, char *buf)
+{
+	int i;
+	int blockcnt;
+	int log2blocksize = LOG2_EXT2_BLOCK_SIZE(ext4fs_root);
+	unsigned int filesize = __le32_to_cpu(file_inode->size);
+	struct ext_filesystem *fs = get_fs();
+	int previous_block_number = -1;
+	int delayed_start = 0;
+	int delayed_extent = 0;
+	int delayed_skipfirst = 0;
+	int delayed_next = 0;
+	char *delayed_buf = NULL;
+
+	/* Adjust len so it we can't read past the end of the file. */
+	if (len > filesize)
+		len = filesize;
+
+	blockcnt = ((len + pos) + fs->blksz - 1) / fs->blksz;
+
+	for (i = pos / fs->blksz; i < blockcnt; i++) {
+		long int blknr;
+		int blockend = fs->blksz;
+		int skipfirst = 0;
+		blknr = read_allocated_block(file_inode, i);
+		if (blknr < 0)
+			return -1;
+
+		blknr = blknr << log2blocksize;
+
+		if (blknr) {
+			if (previous_block_number != -1) {
+				if (delayed_next == blknr) {
+					delayed_extent += blockend;
+					delayed_next += blockend >> SECTOR_BITS;
+				} else {	/* spill */
+					put_ext4((uint64_t) (delayed_start *
+							     SECTOR_SIZE),
+						 delayed_buf,
+						 (uint32_t) delayed_extent);
+					previous_block_number = blknr;
+					delayed_start = blknr;
+					delayed_extent = blockend;
+					delayed_skipfirst = skipfirst;
+					delayed_buf = buf;
+					delayed_next = blknr +
+					    (blockend >> SECTOR_BITS);
+				}
+			} else {
+				previous_block_number = blknr;
+				delayed_start = blknr;
+				delayed_extent = blockend;
+				delayed_skipfirst = skipfirst;
+				delayed_buf = buf;
+				delayed_next = blknr +
+				    (blockend >> SECTOR_BITS);
+			}
+		} else {
+			if (previous_block_number != -1) {
+				/* spill */
+				put_ext4((uint64_t) (delayed_start *
+						     SECTOR_SIZE), delayed_buf,
+					 (uint32_t) delayed_extent);
+				previous_block_number = -1;
+			}
+			memset(buf, 0, fs->blksz - skipfirst);
+		}
+		buf += fs->blksz - skipfirst;
+	}
+	if (previous_block_number != -1) {
+		/* spill */
+		put_ext4((uint64_t) (delayed_start * SECTOR_SIZE),
+			 delayed_buf, (uint32_t) delayed_extent);
+		previous_block_number = -1;
+	}
+
+	return len;
+}
+
+int ext4fs_write(const char *fname, unsigned char *buffer,
+					unsigned long sizebytes)
+{
+	int ret = 0;
+	struct ext2_inode *file_inode = NULL;
+	unsigned char *inode_buffer = NULL;
+	int parent_inodeno;
+	int inodeno;
+	time_t timestamp = 0;
+
+	uint64_t bytes_reqd_for_file;
+	unsigned int blks_reqd_for_file;
+	unsigned int blocks_remaining;
+	int existing_file_inodeno;
+	char filename[256];
+
+	char *temp_ptr = NULL;
+	long int itable_blkno;
+	long int parent_itable_blkno;
+	long int blkoff;
+	struct ext2_sblock *sblock = &(ext4fs_root->sblock);
+	unsigned int inodes_per_block;
+	unsigned int ibmap_idx;
+	struct ext_filesystem *fs = get_fs();
+	g_parent_inode = zalloc(sizeof(struct ext2_inode));
+	if (!g_parent_inode)
+		goto fail;
+
+	if (ext4fs_init() != 0) {
+		printf("error in File System init\n");
+		return -1;
+	}
+	inodes_per_block = fs->blksz / fs->inodesz;
+	parent_inodeno = ext4fs_get_parent_inode_num(fname, filename, F_FILE);
+	if (parent_inodeno == -1)
+		goto fail;
+	if (ext4fs_iget(parent_inodeno, g_parent_inode))
+		goto fail;
+	/* check if the filename is already present in root */
+	existing_file_inodeno = ext4fs_filename_check(filename);
+	if (existing_file_inodeno != -1) {
+		ret = ext4fs_delete_file(existing_file_inodeno);
+		fs->first_pass_bbmap = 0;
+		fs->curr_blkno = 0;
+
+		fs->first_pass_ibmap = 0;
+		fs->curr_inode_no = 0;
+		if (ret)
+			goto fail;
+	}
+	/* calucalate how many blocks required */
+	bytes_reqd_for_file = sizebytes;
+	blks_reqd_for_file = bytes_reqd_for_file / fs->blksz;
+	if (bytes_reqd_for_file % fs->blksz != 0) {
+		blks_reqd_for_file++;
+		debug("total bytes for a file %u\n", blks_reqd_for_file);
+	}
+	blocks_remaining = blks_reqd_for_file;
+	/* test for available space in partition */
+	if (fs->sb->free_blocks < blks_reqd_for_file) {
+		printf("Not enough space on partition !!!\n");
+		goto fail;
+	}
+
+	ext4fs_update_parent_dentry(filename, &inodeno, FILETYPE_REG);
+	/* prepare file inode */
+	inode_buffer = zalloc(fs->inodesz);
+	if (!inode_buffer)
+		goto fail;
+	file_inode = (struct ext2_inode *)inode_buffer;
+	file_inode->mode = S_IFREG | S_IRWXU |
+	    S_IRGRP | S_IROTH | S_IXGRP | S_IXOTH;
+	/* ToDo: Update correct time */
+	file_inode->mtime = timestamp;
+	file_inode->atime = timestamp;
+	file_inode->ctime = timestamp;
+	file_inode->nlinks = 1;
+	file_inode->size = sizebytes;
+
+	/* Allocate data blocks */
+	ext4fs_allocate_blocks(file_inode, blocks_remaining,
+			       &blks_reqd_for_file);
+	file_inode->blockcnt = (blks_reqd_for_file * fs->blksz) / SECTOR_SIZE;
+
+	temp_ptr = zalloc(fs->blksz);
+	if (!temp_ptr)
+		goto fail;
+	ibmap_idx = inodeno / ext4fs_root->sblock.inodes_per_group;
+	inodeno--;
+	itable_blkno = __le32_to_cpu(fs->gd[ibmap_idx].inode_table_id) +
+			(inodeno % __le32_to_cpu(sblock->inodes_per_group)) /
+			inodes_per_block;
+	blkoff = (inodeno % inodes_per_block) * fs->inodesz;
+	ext4fs_devread(itable_blkno * fs->sect_perblk, 0, fs->blksz, temp_ptr);
+	if (ext4fs_log_journal(temp_ptr, itable_blkno))
+		goto fail;
+
+	memcpy(temp_ptr + blkoff, inode_buffer, fs->inodesz);
+	if (ext4fs_put_metadata(temp_ptr, itable_blkno))
+		goto fail;
+	/* copy the file content into data blocks */
+	if (ext4fs_write_file(file_inode, 0, sizebytes, (char *)buffer) == -1) {
+		printf("Error in copying content\n");
+		goto fail;
+	}
+	ibmap_idx = parent_inodeno / ext4fs_root->sblock.inodes_per_group;
+	parent_inodeno--;
+	parent_itable_blkno = __le32_to_cpu(fs->gd[ibmap_idx].inode_table_id) +
+	    (parent_inodeno %
+	     __le32_to_cpu(sblock->inodes_per_group)) / inodes_per_block;
+	blkoff = (parent_inodeno % inodes_per_block) * fs->inodesz;
+	if (parent_itable_blkno != itable_blkno) {
+		memset(temp_ptr, '\0', fs->blksz);
+		ext4fs_devread(parent_itable_blkno * fs->sect_perblk,
+			       0, fs->blksz, temp_ptr);
+		if (ext4fs_log_journal(temp_ptr, parent_itable_blkno))
+			goto fail;
+
+		memcpy(temp_ptr + blkoff, g_parent_inode,
+			sizeof(struct ext2_inode));
+		if (ext4fs_put_metadata(temp_ptr, parent_itable_blkno))
+			goto fail;
+		free(temp_ptr);
+	} else {
+		/*
+		 * If parent and child fall in same inode table block
+		 * both should be kept in 1 buffer
+		 */
+		memcpy(temp_ptr + blkoff, g_parent_inode,
+		       sizeof(struct ext2_inode));
+		gd_index--;
+		if (ext4fs_put_metadata(temp_ptr, itable_blkno))
+			goto fail;
+		free(temp_ptr);
+	}
+	ext4fs_update();
+	ext4fs_deinit();
+
+	fs->first_pass_bbmap = 0;
+	fs->curr_blkno = 0;
+	fs->first_pass_ibmap = 0;
+	fs->curr_inode_no = 0;
+	free(inode_buffer);
+	free(g_parent_inode);
+	g_parent_inode = NULL;
+
+	return 0;
+fail:
+	ext4fs_deinit();
+	free(inode_buffer);
+	free(g_parent_inode);
+	g_parent_inode = NULL;
+
+	return -1;
+}
+#endif