diff --git a/fs/ext4/ext4_common.c b/fs/ext4/ext4_common.c
index b745d8d..90e7602 100644
--- a/fs/ext4/ext4_common.c
+++ b/fs/ext4/ext4_common.c
@@ -393,7 +393,7 @@
 	uint16_t crc = 0;
 	__le32 le32_i = cpu_to_le32(i);
 
-	desc = (struct ext2_block_group *)&fs->bgd[i];
+	desc = ext4fs_get_group_descriptor(fs, 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);
 
@@ -933,39 +933,41 @@
 	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);
+			struct ext2_block_group *bgd = NULL;
+			bgd = ext4fs_get_group_descriptor(fs, i);
+			if (ext4fs_bg_get_free_blocks(bgd, fs)) {
+				uint16_t bg_flags = ext4fs_bg_get_flags(bgd);
+				uint64_t b_bitmap_blk =
+					ext4fs_bg_get_block_id(bgd, fs);
+				if (bg_flags & EXT4_BG_BLOCK_UNINIT) {
 					memcpy(fs->blk_bmaps[i], zero_buffer,
 					       fs->blksz);
+					put_ext4(b_bitmap_blk * fs->blksz,
+						 fs->blk_bmaps[i], fs->blksz);
+					bg_flags &= ~EXT4_BG_BLOCK_UNINIT;
+					ext4fs_bg_set_flags(bgd, bg_flags);
 				}
 				fs->curr_blkno =
 				    _get_new_blk_no(fs->blk_bmaps[i]);
 				if (fs->curr_blkno == -1)
-					/* if block bitmap is completely fill */
+					/* block bitmap is completely filled */
 					continue;
 				fs->curr_blkno = fs->curr_blkno +
 						(i * fs->blksz * 8);
 				fs->first_pass_bbmap++;
-				ext4fs_bg_free_blocks_dec(&bgd[i]);
+				ext4fs_bg_free_blocks_dec(bgd);
 				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,
+				status = ext4fs_devread(b_bitmap_blk *
+							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)))
+						       b_bitmap_blk))
 					goto fail;
 				goto success;
 			} else {
@@ -992,7 +994,9 @@
 		if (bg_idx >= fs->no_blkgrp)
 			goto fail;
 
-		if (bgd[bg_idx].free_blocks == 0) {
+		struct ext2_block_group *bgd = NULL;
+		bgd = ext4fs_get_group_descriptor(fs, bg_idx);
+		if (ext4fs_bg_get_free_blocks(bgd, fs) == 0) {
 			debug("block group %u is full. Skipping\n", bg_idx);
 			fs->curr_blkno = (bg_idx + 1) * blk_per_grp;
 			if (fs->blksz == 1024)
@@ -1000,13 +1004,14 @@
 			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);
+		uint16_t bg_flags = ext4fs_bg_get_flags(bgd);
+		uint64_t b_bitmap_blk = ext4fs_bg_get_block_id(bgd, fs);
+		if (bg_flags & EXT4_BG_BLOCK_UNINIT) {
 			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);
+			put_ext4(b_bitmap_blk * fs->blksz,
+				 zero_buffer, fs->blksz);
+			bg_flags &= ~EXT4_BG_BLOCK_UNINIT;
+			ext4fs_bg_set_flags(bgd, bg_flags);
 		}
 
 		if (ext4fs_set_block_bmap(fs->curr_blkno, fs->blk_bmaps[bg_idx],
@@ -1019,19 +1024,16 @@
 
 		/* 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,
+			status = ext4fs_devread(b_bitmap_blk * 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)))
+			if (ext4fs_log_journal(journal_buffer, b_bitmap_blk))
 				goto fail;
 
 			prev_bg_bitmap_index = bg_idx;
 		}
-		ext4fs_bg_free_blocks_dec(&bgd[bg_idx]);
+		ext4fs_bg_free_blocks_dec(bgd);
 		ext4fs_sb_free_blocks_dec(fs->sb);
 		goto success;
 	}
@@ -1059,46 +1061,49 @@
 	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) {
+			uint32_t free_inodes;
+			struct ext2_block_group *bgd = NULL;
+			bgd = ext4fs_get_group_descriptor(fs, i);
+			free_inodes = ext4fs_bg_get_free_inodes(bgd, fs);
+			if (free_inodes) {
+				uint16_t bg_flags = ext4fs_bg_get_flags(bgd);
+				uint64_t i_bitmap_blk =
+					ext4fs_bg_get_inode_id(bgd, fs);
 				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,
+					bgd->bg_itable_unused = free_inodes;
+				if (bg_flags & EXT4_BG_INODE_UNINIT) {
+					put_ext4(i_bitmap_blk * 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);
+					bg_flags &= ~EXT4_BG_INODE_UNINIT;
+					ext4fs_bg_set_flags(bgd, bg_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 */
+					/* inode bitmap is completely filled */
 					continue;
 				fs->curr_inode_no = fs->curr_inode_no +
 							(i * inodes_per_grp);
 				fs->first_pass_ibmap++;
-				ext4fs_bg_free_inodes_dec(&bgd[i]);
+				ext4fs_bg_free_inodes_dec(bgd);
 				if (has_gdt_chksum)
-					ext4fs_bg_itable_unused_dec(&bgd[i]);
+					ext4fs_bg_itable_unused_dec(bgd);
 				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,
+				status = ext4fs_devread(i_bitmap_blk *
+							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)))
+						       i_bitmap_blk))
 					goto fail;
 				goto success;
 			} else
@@ -1110,12 +1115,16 @@
 		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,
+		struct ext2_block_group *bgd =
+			ext4fs_get_group_descriptor(fs, ibmap_idx);
+		uint16_t bg_flags = ext4fs_bg_get_flags(bgd);
+		uint64_t i_bitmap_blk = ext4fs_bg_get_inode_id(bgd, fs);
+
+		if (bg_flags & EXT4_BG_INODE_UNINIT) {
+			put_ext4(i_bitmap_blk * 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);
+			bg_flags &= ~EXT4_BG_INODE_UNINIT;
+			ext4fs_bg_set_flags(bgd, bg_flags);
 			memcpy(fs->inode_bmaps[ibmap_idx], zero_buffer,
 				fs->blksz);
 		}
@@ -1130,22 +1139,18 @@
 
 		/* 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,
+			status = ext4fs_devread(i_bitmap_blk * 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)))
+						le32_to_cpu(bgd->inode_id)))
 				goto fail;
 			prev_inode_bitmap_index = ibmap_idx;
 		}
-		ext4fs_bg_free_inodes_dec(&bgd[ibmap_idx]);
+		ext4fs_bg_free_inodes_dec(bgd);
 		if (has_gdt_chksum)
-			bgd[ibmap_idx].bg_itable_unused =
-					bgd[ibmap_idx].free_inodes;
+			bgd->bg_itable_unused = bgd->free_inodes;
 		ext4fs_sb_free_inodes_dec(fs->sb);
 		goto success;
 	}
@@ -1561,7 +1566,7 @@
 		return 0;
 
 	inodes_per_block = EXT2_BLOCK_SIZE(data) / fs->inodesz;
-	blkno = le32_to_cpu(blkgrp.inode_table_id) +
+	blkno = ext4fs_bg_get_inode_table_id(&blkgrp, fs) +
 	    (ino % le32_to_cpu(sblock->inodes_per_group)) / inodes_per_block;
 	blkoff = (ino % inodes_per_block) * fs->inodesz;
 	/* Read the inode. */
diff --git a/fs/ext4/ext4_write.c b/fs/ext4/ext4_write.c
index e4f0905..2c123e3 100644
--- a/fs/ext4/ext4_write.c
+++ b/fs/ext4/ext4_write.c
@@ -53,21 +53,26 @@
 	short i;
 	ext4fs_update_journal();
 	struct ext_filesystem *fs = get_fs();
+	struct ext2_block_group *bgd = NULL;
 
 	/* update  super block */
 	put_ext4((uint64_t)(SUPERBLOCK_SIZE),
 		 (struct ext2_sblock *)fs->sb, (uint32_t)SUPERBLOCK_SIZE);
 
-	/* update block groups */
+	/* update block bitmaps */
 	for (i = 0; i < fs->no_blkgrp; i++) {
-		fs->bgd[i].bg_checksum = cpu_to_le16(ext4fs_checksum_update(i));
-		put_ext4((uint64_t)le32_to_cpu(fs->bgd[i].block_id) * fs->blksz,
+		bgd = ext4fs_get_group_descriptor(fs, i);
+		bgd->bg_checksum = cpu_to_le16(ext4fs_checksum_update(i));
+		uint64_t b_bitmap_blk = ext4fs_bg_get_block_id(bgd, fs);
+		put_ext4(b_bitmap_blk * fs->blksz,
 			 fs->blk_bmaps[i], fs->blksz);
 	}
 
-	/* update inode table groups */
+	/* update inode bitmaps */
 	for (i = 0; i < fs->no_blkgrp; i++) {
-		put_ext4((uint64_t)le32_to_cpu(fs->bgd[i].inode_id) * fs->blksz,
+		bgd = ext4fs_get_group_descriptor(fs, i);
+		uint64_t i_bitmap_blk = ext4fs_bg_get_inode_id(bgd, fs);
+		put_ext4(i_bitmap_blk * fs->blksz,
 			 fs->inode_bmaps[i], fs->blksz);
 	}
 
@@ -85,15 +90,12 @@
 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++;
+	int gdsize_total = ROUND(fs->no_blkgrp * fs->gdsize, fs->blksz);
+	fs->no_blk_pergdt = gdsize_total / fs->blksz;
 
 	/* allocate memory for gdtable */
-	fs->gdtable = zalloc(fs->blksz * fs->no_blk_pergdt);
+	fs->gdtable = zalloc(gdsize_total);
 	if (!fs->gdtable)
 		return -ENOMEM;
 	/* read the group descriptor table */
@@ -130,8 +132,6 @@
 		printf("No memory\n");
 		return;
 	}
-	/* get  block group descriptor table */
-	bgd = (struct ext2_block_group *)fs->gdtable;
 
 	/* deleting the single indirect block associated with inode */
 	if (inode->b.blocks.indir_block != 0) {
@@ -144,18 +144,19 @@
 				bg_idx--;
 		}
 		ext4fs_reset_block_bmap(blknr, fs->blk_bmaps[bg_idx], bg_idx);
-		ext4fs_bg_free_blocks_inc(&bgd[bg_idx]);
+		/* get  block group descriptor table */
+		bgd = ext4fs_get_group_descriptor(fs, bg_idx);
+		ext4fs_bg_free_blocks_inc(bgd);
 		ext4fs_sb_free_blocks_inc(fs->sb);
 		/* journal backup */
 		if (prev_bg_bmap_idx != bg_idx) {
+			uint64_t b_bitmap_blk = ext4fs_bg_get_block_id(bgd, fs);
 			status = ext4fs_devread(
-					   (lbaint_t)le32_to_cpu(bgd[bg_idx].block_id) *
-					   fs->sect_perblk, 0, fs->blksz,
-					   journal_buffer);
+					   b_bitmap_blk * 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)))
+			if (ext4fs_log_journal(journal_buffer, b_bitmap_blk))
 				goto fail;
 			prev_bg_bmap_idx = bg_idx;
 		}
@@ -182,8 +183,6 @@
 		printf("No memory\n");
 		return;
 	}
-	/* get the block group descriptor table */
-	bgd = (struct ext2_block_group *)fs->gdtable;
 
 	if (inode->b.blocks.double_indir_block != 0) {
 		di_buffer = zalloc(fs->blksz);
@@ -206,15 +205,18 @@
 				if (!remainder)
 					bg_idx--;
 			}
+			/* get  block group descriptor table */
+			bgd = ext4fs_get_group_descriptor(fs, bg_idx);
 			ext4fs_reset_block_bmap(le32_to_cpu(*di_buffer),
 					fs->blk_bmaps[bg_idx], bg_idx);
 			di_buffer++;
-			ext4fs_bg_free_blocks_inc(&bgd[bg_idx]);
+			ext4fs_bg_free_blocks_inc(bgd);
 			ext4fs_sb_free_blocks_inc(fs->sb);
 			/* journal backup */
 			if (prev_bg_bmap_idx != bg_idx) {
-				status = ext4fs_devread(
-							(lbaint_t)le32_to_cpu(bgd[bg_idx].block_id)
+				uint64_t b_bitmap_blk =
+					ext4fs_bg_get_block_id(bgd, fs);
+				status = ext4fs_devread(b_bitmap_blk
 							* fs->sect_perblk, 0,
 							fs->blksz,
 							journal_buffer);
@@ -222,7 +224,7 @@
 					goto fail;
 
 				if (ext4fs_log_journal(journal_buffer,
-							le32_to_cpu(bgd[bg_idx].block_id)))
+						       b_bitmap_blk))
 					goto fail;
 				prev_bg_bmap_idx = bg_idx;
 			}
@@ -236,20 +238,20 @@
 			if (!remainder)
 				bg_idx--;
 		}
+		/* get  block group descriptor table */
+		bgd = ext4fs_get_group_descriptor(fs, bg_idx);
 		ext4fs_reset_block_bmap(blknr, fs->blk_bmaps[bg_idx], bg_idx);
-		ext4fs_bg_free_blocks_inc(&bgd[bg_idx]);
+		ext4fs_bg_free_blocks_inc(bgd);
 		ext4fs_sb_free_blocks_inc(fs->sb);
 		/* journal backup */
 		if (prev_bg_bmap_idx != bg_idx) {
-			memset(journal_buffer, '\0', fs->blksz);
-			status = ext4fs_devread((lbaint_t)le32_to_cpu(bgd[bg_idx].block_id) *
-						fs->sect_perblk, 0, fs->blksz,
-						journal_buffer);
+			uint64_t b_bitmap_blk = ext4fs_bg_get_block_id(bgd, fs);
+			status = ext4fs_devread(b_bitmap_blk * 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)))
+			if (ext4fs_log_journal(journal_buffer, b_bitmap_blk))
 				goto fail;
 			prev_bg_bmap_idx = bg_idx;
 		}
@@ -280,8 +282,6 @@
 		printf("No memory\n");
 		return;
 	}
-	/* get block group descriptor table */
-	bgd = (struct ext2_block_group *)fs->gdtable;
 
 	if (inode->b.blocks.triple_indir_block != 0) {
 		tigp_buffer = zalloc(fs->blksz);
@@ -320,13 +320,17 @@
 							bg_idx);
 
 				tip_buffer++;
-				ext4fs_bg_free_blocks_inc(&bgd[bg_idx]);
+				/* get  block group descriptor table */
+				bgd = ext4fs_get_group_descriptor(fs, bg_idx);
+				ext4fs_bg_free_blocks_inc(bgd);
 				ext4fs_sb_free_blocks_inc(fs->sb);
 				/* journal backup */
 				if (prev_bg_bmap_idx != bg_idx) {
+					uint64_t b_bitmap_blk =
+						ext4fs_bg_get_block_id(bgd, fs);
 					status =
 					    ext4fs_devread(
-							(lbaint_t)le32_to_cpu(bgd[bg_idx].block_id) *
+							b_bitmap_blk *
 							fs->sect_perblk, 0,
 							fs->blksz,
 							journal_buffer);
@@ -334,7 +338,7 @@
 						goto fail;
 
 					if (ext4fs_log_journal(journal_buffer,
-							       le32_to_cpu(bgd[bg_idx].block_id)))
+							       b_bitmap_blk))
 						goto fail;
 					prev_bg_bmap_idx = bg_idx;
 				}
@@ -356,21 +360,24 @@
 						fs->blk_bmaps[bg_idx], bg_idx);
 
 			tigp_buffer++;
-			ext4fs_bg_free_blocks_inc(&bgd[bg_idx]);
+			/* get  block group descriptor table */
+			bgd = ext4fs_get_group_descriptor(fs, bg_idx);
+			ext4fs_bg_free_blocks_inc(bgd);
 			ext4fs_sb_free_blocks_inc(fs->sb);
 			/* journal backup */
 			if (prev_bg_bmap_idx != bg_idx) {
+				uint64_t b_bitmap_blk =
+					ext4fs_bg_get_block_id(bgd, fs);
 				memset(journal_buffer, '\0', fs->blksz);
-				status =
-				    ext4fs_devread(
-						   (lbaint_t)le32_to_cpu(bgd[bg_idx].block_id) *
-						   fs->sect_perblk, 0,
-						   fs->blksz, journal_buffer);
+				status = ext4fs_devread(b_bitmap_blk *
+							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)))
+						       b_bitmap_blk))
 					goto fail;
 				prev_bg_bmap_idx = bg_idx;
 			}
@@ -385,20 +392,19 @@
 				bg_idx--;
 		}
 		ext4fs_reset_block_bmap(blknr, fs->blk_bmaps[bg_idx], bg_idx);
-		ext4fs_bg_free_blocks_inc(&bgd[bg_idx]);
+		/* get  block group descriptor table */
+		bgd = ext4fs_get_group_descriptor(fs, bg_idx);
+		ext4fs_bg_free_blocks_inc(bgd);
 		ext4fs_sb_free_blocks_inc(fs->sb);
 		/* journal backup */
 		if (prev_bg_bmap_idx != bg_idx) {
-			memset(journal_buffer, '\0', fs->blksz);
-			status = ext4fs_devread(
-						(lbaint_t)le32_to_cpu(bgd[bg_idx].block_id) *
-						fs->sect_perblk, 0, fs->blksz,
-						journal_buffer);
+			uint64_t b_bitmap_blk = ext4fs_bg_get_block_id(bgd, fs);
+			status = ext4fs_devread(b_bitmap_blk * 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)))
+			if (ext4fs_log_journal(journal_buffer, b_bitmap_blk))
 				goto fail;
 			prev_bg_bmap_idx = bg_idx;
 		}
@@ -435,8 +441,6 @@
 	char *journal_buffer = zalloc(fs->blksz);
 	if (!journal_buffer)
 		return -ENOMEM;
-	/* get the block group descriptor table */
-	bgd = (struct ext2_block_group *)fs->gdtable;
 	status = ext4fs_read_inode(ext4fs_root, inodeno, &inode);
 	if (status == 0)
 		goto fail;
@@ -475,18 +479,19 @@
 					bg_idx);
 		debug("EXT4 Block releasing %ld: %d\n", blknr, bg_idx);
 
-		ext4fs_bg_free_blocks_inc(&bgd[bg_idx]);
+		/* get  block group descriptor table */
+		bgd = ext4fs_get_group_descriptor(fs, bg_idx);
+		ext4fs_bg_free_blocks_inc(bgd);
 		ext4fs_sb_free_blocks_inc(fs->sb);
 		/* journal backup */
 		if (prev_bg_bmap_idx != bg_idx) {
-			uint32_t bgd_blknr = le32_to_cpu(bgd[bg_idx].block_id);
-			status = ext4fs_devread((lbaint_t)bgd_blknr *
-						fs->sect_perblk,
+			uint64_t b_bitmap_blk = ext4fs_bg_get_block_id(bgd, fs);
+			status = ext4fs_devread(b_bitmap_blk * fs->sect_perblk,
 						0, fs->blksz,
 						journal_buffer);
 			if (status == 0)
 				goto fail;
-			if (ext4fs_log_journal(journal_buffer, bgd_blknr))
+			if (ext4fs_log_journal(journal_buffer, b_bitmap_blk))
 				goto fail;
 			prev_bg_bmap_idx = bg_idx;
 		}
@@ -499,7 +504,9 @@
 
 	/* get the block no */
 	inodeno--;
-	blkno = le32_to_cpu(bgd[ibmap_idx].inode_table_id) +
+	/* get  block group descriptor table */
+	bgd = ext4fs_get_group_descriptor(fs, ibmap_idx);
+	blkno = ext4fs_bg_get_inode_table_id(bgd, fs) +
 		(inodeno % inode_per_grp) / inodes_per_block;
 
 	/* get the offset of the inode */
@@ -529,15 +536,15 @@
 	/* update the respective inode bitmaps */
 	inodeno++;
 	ext4fs_reset_inode_bmap(inodeno, fs->inode_bmaps[ibmap_idx], ibmap_idx);
-	ext4fs_bg_free_inodes_inc(&bgd[ibmap_idx]);
+	ext4fs_bg_free_inodes_inc(bgd);
 	ext4fs_sb_free_inodes_inc(fs->sb);
 	/* journal backup */
 	memset(journal_buffer, '\0', fs->blksz);
-	status = ext4fs_devread((lbaint_t)le32_to_cpu(bgd[ibmap_idx].inode_id) *
+	status = ext4fs_devread(ext4fs_bg_get_inode_id(bgd, fs) *
 				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)))
+	if (ext4fs_log_journal(journal_buffer, ext4fs_bg_get_inode_id(bgd, fs)))
 		goto fail;
 
 	ext4fs_update();
@@ -594,7 +601,6 @@
 		printf("Error in getting the block group descriptor table\n");
 		goto fail;
 	}
-	fs->bgd = (struct ext2_block_group *)fs->gdtable;
 
 	/* load all the available bitmap block of the partition */
 	fs->blk_bmaps = zalloc(fs->no_blkgrp * sizeof(char *));
@@ -607,9 +613,9 @@
 	}
 
 	for (i = 0; i < fs->no_blkgrp; i++) {
-		status =
-		    ext4fs_devread(
-				   (lbaint_t)le32_to_cpu(fs->bgd[i].block_id) *
+		struct ext2_block_group *bgd =
+			ext4fs_get_group_descriptor(fs, i);
+		status = ext4fs_devread(ext4fs_bg_get_block_id(bgd, fs) *
 				   fs->sect_perblk, 0,
 				   fs->blksz, (char *)fs->blk_bmaps[i]);
 		if (status == 0)
@@ -627,8 +633,9 @@
 	}
 
 	for (i = 0; i < fs->no_blkgrp; i++) {
-		status = ext4fs_devread(
-					(lbaint_t)le32_to_cpu(fs->bgd[i].inode_id) *
+		struct ext2_block_group *bgd =
+			ext4fs_get_group_descriptor(fs, i);
+		status = ext4fs_devread(ext4fs_bg_get_inode_id(bgd, fs) *
 					fs->sect_perblk,
 					0, fs->blksz,
 					(char *)fs->inode_bmaps[i]);
@@ -642,10 +649,14 @@
 	 * 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 + le16_to_cpu(fs->bgd[i].free_blocks);
-	if (real_free_blocks != le32_to_cpu(fs->sb->free_blocks))
-		fs->sb->free_blocks = cpu_to_le32(real_free_blocks);
+	for (i = 0; i < fs->no_blkgrp; i++) {
+		struct ext2_block_group *bgd =
+			ext4fs_get_group_descriptor(fs, i);
+		real_free_blocks = real_free_blocks +
+			ext4fs_bg_get_free_blocks(bgd, fs);
+	}
+	if (real_free_blocks != ext4fs_sb_get_free_blocks(fs->sb))
+		ext4fs_sb_set_free_blocks(fs->sb, real_free_blocks);
 
 	return 0;
 fail:
@@ -711,7 +722,6 @@
 
 	free(fs->gdtable);
 	fs->gdtable = NULL;
-	fs->bgd = NULL;
 	/*
 	 * reinitiliazed the global inode and
 	 * block bitmap first execution check variables
@@ -826,6 +836,7 @@
 	struct ext2_sblock *sblock = &(ext4fs_root->sblock);
 	unsigned int inodes_per_block;
 	unsigned int ibmap_idx;
+	struct ext2_block_group *bgd = NULL;
 	struct ext_filesystem *fs = get_fs();
 	ALLOC_CACHE_ALIGN_BUFFER(char, filename, 256);
 	memset(filename, 0x00, 256);
@@ -903,7 +914,8 @@
 		goto fail;
 	ibmap_idx = inodeno / le32_to_cpu(ext4fs_root->sblock.inodes_per_group);
 	inodeno--;
-	itable_blkno = le32_to_cpu(fs->bgd[ibmap_idx].inode_table_id) +
+	bgd = ext4fs_get_group_descriptor(fs, ibmap_idx);
+	itable_blkno = ext4fs_bg_get_inode_table_id(bgd, fs) +
 			(inodeno % le32_to_cpu(sblock->inodes_per_group)) /
 			inodes_per_block;
 	blkoff = (inodeno % inodes_per_block) * fs->inodesz;
@@ -923,7 +935,8 @@
 	}
 	ibmap_idx = parent_inodeno / le32_to_cpu(ext4fs_root->sblock.inodes_per_group);
 	parent_inodeno--;
-	parent_itable_blkno = le32_to_cpu(fs->bgd[ibmap_idx].inode_table_id) +
+	bgd = ext4fs_get_group_descriptor(fs, ibmap_idx);
+	parent_itable_blkno = ext4fs_bg_get_inode_table_id(bgd, fs) +
 	    (parent_inodeno %
 	     le32_to_cpu(sblock->inodes_per_group)) / inodes_per_block;
 	blkoff = (parent_inodeno % inodes_per_block) * fs->inodesz;