diff --git a/fs/ext4/dev.c b/fs/ext4/dev.c
index 464a67d..7b6fd16 100644
--- a/fs/ext4/dev.c
+++ b/fs/ext4/dev.c
@@ -40,6 +40,7 @@
 #include <config.h>
 #include <ext4fs.h>
 #include <ext_common.h>
+#include "ext4_common.h"
 
 unsigned long part_offset;
 
@@ -48,37 +49,41 @@ static disk_partition_t *part_info;
 
 void ext4fs_set_blk_dev(block_dev_desc_t *rbdd, disk_partition_t *info)
 {
+	assert(rbdd->blksz == (1 << rbdd->log2blksz));
 	ext4fs_block_dev_desc = rbdd;
 	part_info = info;
 	part_offset = info->start;
-	get_fs()->total_sect = (info->size * info->blksz) / SECTOR_SIZE;
+	get_fs()->total_sect = (info->size * info->blksz) >>
+		get_fs()->dev_desc->log2blksz;
 	get_fs()->dev_desc = rbdd;
 }
 
 int ext4fs_devread(int sector, int byte_offset, int byte_len, char *buf)
 {
-	ALLOC_CACHE_ALIGN_BUFFER(char, sec_buf, SECTOR_SIZE);
 	unsigned block_len;
+	int log2blksz = ext4fs_block_dev_desc->log2blksz;
+	ALLOC_CACHE_ALIGN_BUFFER(char, sec_buf, (ext4fs_block_dev_desc ?
+						 ext4fs_block_dev_desc->blksz :
+						 0));
+	if (ext4fs_block_dev_desc == NULL) {
+		printf("** Invalid Block Device Descriptor (NULL)\n");
+		return 0;
+	}
 
 	/* Check partition boundaries */
 	if ((sector < 0)
-	    || ((sector + ((byte_offset + byte_len - 1) >> SECTOR_BITS)) >=
-		part_info->size)) {
+	    || ((sector + ((byte_offset + byte_len - 1) >> log2blksz))
+		>= part_info->size)) {
 		printf("%s read outside partition %d\n", __func__, sector);
 		return 0;
 	}
 
 	/* Get the read to the beginning of a partition */
-	sector += byte_offset >> SECTOR_BITS;
-	byte_offset &= SECTOR_SIZE - 1;
+	sector += byte_offset >> log2blksz;
+	byte_offset &= ext4fs_block_dev_desc->blksz - 1;
 
 	debug(" <%d, %d, %d>\n", sector, byte_offset, byte_len);
 
-	if (ext4fs_block_dev_desc == NULL) {
-		printf("** Invalid Block Device Descriptor (NULL)\n");
-		return 0;
-	}
-
 	if (byte_offset != 0) {
 		/* read first part which isn't aligned with start of sector */
 		if (ext4fs_block_dev_desc->
@@ -89,9 +94,12 @@ int ext4fs_devread(int sector, int byte_offset, int byte_len, char *buf)
 			return 0;
 		}
 		memcpy(buf, sec_buf + byte_offset,
-			min(SECTOR_SIZE - byte_offset, byte_len));
-		buf += min(SECTOR_SIZE - byte_offset, byte_len);
-		byte_len -= min(SECTOR_SIZE - byte_offset, byte_len);
+			min(ext4fs_block_dev_desc->blksz
+			    - byte_offset, byte_len));
+		buf += min(ext4fs_block_dev_desc->blksz
+			   - byte_offset, byte_len);
+		byte_len -= min(ext4fs_block_dev_desc->blksz
+				- byte_offset, byte_len);
 		sector++;
 	}
 
@@ -99,12 +107,12 @@ int ext4fs_devread(int sector, int byte_offset, int byte_len, char *buf)
 		return 1;
 
 	/* read sector aligned part */
-	block_len = byte_len & ~(SECTOR_SIZE - 1);
+	block_len = byte_len & ~(ext4fs_block_dev_desc->blksz - 1);
 
 	if (block_len == 0) {
-		ALLOC_CACHE_ALIGN_BUFFER(u8, p, SECTOR_SIZE);
+		ALLOC_CACHE_ALIGN_BUFFER(u8, p, ext4fs_block_dev_desc->blksz);
 
-		block_len = SECTOR_SIZE;
+		block_len = ext4fs_block_dev_desc->blksz;
 		ext4fs_block_dev_desc->block_read(ext4fs_block_dev_desc->dev,
 						  part_info->start + sector,
 						  1, (unsigned long *)p);
@@ -114,16 +122,16 @@ int ext4fs_devread(int sector, int byte_offset, int byte_len, char *buf)
 
 	if (ext4fs_block_dev_desc->block_read(ext4fs_block_dev_desc->dev,
 					       part_info->start + sector,
-					       block_len / SECTOR_SIZE,
+					       block_len >> log2blksz,
 					       (unsigned long *) buf) !=
-					       block_len / SECTOR_SIZE) {
+					       block_len >> log2blksz) {
 		printf(" ** %s read error - block\n", __func__);
 		return 0;
 	}
-	block_len = byte_len & ~(SECTOR_SIZE - 1);
+	block_len = byte_len & ~(ext4fs_block_dev_desc->blksz - 1);
 	buf += block_len;
 	byte_len -= block_len;
-	sector += block_len / SECTOR_SIZE;
+	sector += block_len / ext4fs_block_dev_desc->blksz;
 
 	if (byte_len != 0) {
 		/* read rest of data which are not in whole sector */
@@ -138,3 +146,13 @@ int ext4fs_devread(int sector, int byte_offset, int byte_len, char *buf)
 	}
 	return 1;
 }
+
+int ext4_read_superblock(char *buffer)
+{
+	struct ext_filesystem *fs = get_fs();
+	int sect = SUPERBLOCK_START >> fs->dev_desc->log2blksz;
+	int off = SUPERBLOCK_START % fs->dev_desc->blksz;
+
+	return ext4fs_devread(sect, off, SUPERBLOCK_SIZE,
+				buffer);
+}
diff --git a/fs/ext4/ext4_common.c b/fs/ext4/ext4_common.c
index f12b805..38c9603 100644
--- a/fs/ext4/ext4_common.c
+++ b/fs/ext4/ext4_common.c
@@ -71,18 +71,18 @@ void put_ext4(uint64_t off, void *buf, uint32_t size)
 	uint64_t startblock;
 	uint64_t remainder;
 	unsigned char *temp_ptr = NULL;
-	ALLOC_CACHE_ALIGN_BUFFER(unsigned char, sec_buf, SECTOR_SIZE);
 	struct ext_filesystem *fs = get_fs();
+	int log2blksz = fs->dev_desc->log2blks;
+	ALLOC_CACHE_ALIGN_BUFFER(unsigned char, sec_buf, fs->dev_desc->blksz);
 
-	startblock = off / (uint64_t)SECTOR_SIZE;
+	startblock = off >> log2blksz;
 	startblock += part_offset;
-	remainder = off % (uint64_t)SECTOR_SIZE;
-	remainder &= SECTOR_SIZE - 1;
+	remainder = off & (uint64_t)(fs->dev_desc->blksz - 1);
 
 	if (fs->dev_desc == NULL)
 		return;
 
-	if ((startblock + (size / SECTOR_SIZE)) >
+	if ((startblock + (size >> log2blksz)) >
 	    (part_offset + fs->total_sect)) {
 		printf("part_offset is %lu\n", part_offset);
 		printf("total_sector is %llu\n", fs->total_sect);
@@ -101,10 +101,10 @@ void put_ext4(uint64_t off, void *buf, uint32_t size)
 						  startblock, 1, sec_buf);
 		}
 	} else {
-		if (size / SECTOR_SIZE != 0) {
+		if (size >> log2blksz != 0) {
 			fs->dev_desc->block_write(fs->dev_desc->dev,
 						  startblock,
-						  size / SECTOR_SIZE,
+						  size >> log2blksz,
 						  (unsigned long *)buf);
 		} else {
 			fs->dev_desc->block_read(fs->dev_desc->dev,
@@ -1459,6 +1459,7 @@ static int ext4fs_blockgroup
 {
 	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);
 
@@ -1469,7 +1470,7 @@ static int ext4fs_blockgroup
 	debug("ext4fs read %d group descriptor (blkno %ld blkoff %u)\n",
 	      group, blkno, blkoff);
 
-	return ext4fs_devread(blkno << LOG2_EXT2_BLOCK_SIZE(data),
+	return ext4fs_devread(blkno << (LOG2_BLOCK_SIZE(data) - log2blksz),
 			      blkoff, sizeof(struct ext2_block_group),
 			      (char *)blkgrp);
 }
@@ -1479,6 +1480,7 @@ 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;
@@ -1495,7 +1497,8 @@ int ext4fs_read_inode(struct ext2_data *data, int ino, struct ext2_inode *inode)
 	    (ino % __le32_to_cpu(sblock->inodes_per_group)) / inodes_per_block;
 	blkoff = (ino % inodes_per_block) * fs->inodesz;
 	/* Read the inode. */
-	status = ext4fs_devread(blkno << LOG2_EXT2_BLOCK_SIZE(data), blkoff,
+	status = ext4fs_devread(blkno << (LOG2_BLOCK_SIZE(data) - log2blksz),
+				blkoff,
 				sizeof(struct ext2_inode), (char *)inode);
 	if (status == 0)
 		return 0;
@@ -1515,7 +1518,9 @@ long int read_allocated_block(struct ext2_inode *inode, int fileblock)
 	unsigned long long start;
 	/* get the blocksize of the filesystem */
 	blksz = EXT2_BLOCK_SIZE(ext4fs_root);
-	log2_blksz = LOG2_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)
@@ -1523,11 +1528,11 @@ long int read_allocated_block(struct ext2_inode *inode, int fileblock)
 		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);
+		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);
@@ -1839,7 +1844,7 @@ long int read_allocated_block(struct ext2_inode *inode, int fileblock)
 		blknr = __le32_to_cpu(ext4fs_indir3_block
 				      [rblock % perblock_child]);
 	}
-	debug("ext4fs_read_block %ld\n", blknr);
+	debug("read_allocated_block %ld\n", blknr);
 
 	return blknr;
 }
@@ -2193,13 +2198,12 @@ int ext4fs_mount(unsigned part_length)
 	struct ext2_data *data;
 	int status;
 	struct ext_filesystem *fs = get_fs();
-	data = zalloc(sizeof(struct ext2_data));
+	data = zalloc(SUPERBLOCK_SIZE);
 	if (!data)
 		return 0;
 
 	/* Read the superblock. */
-	status = ext4fs_devread(1 * 2, 0, sizeof(struct ext2_sblock),
-				(char *)&data->sblock);
+	status = ext4_read_superblock((char *)&data->sblock);
 
 	if (status == 0)
 		goto fail;
diff --git a/fs/ext4/ext4_common.h b/fs/ext4/ext4_common.h
index 87cab16..5fc0ce9 100644
--- a/fs/ext4/ext4_common.h
+++ b/fs/ext4/ext4_common.h
@@ -51,7 +51,7 @@
 
 #define S_IFLNK		0120000		/* symbolic link */
 #define BLOCK_NO_ONE		1
-#define SUPERBLOCK_SECTOR	2
+#define SUPERBLOCK_START	(2 * 512)
 #define SUPERBLOCK_SIZE	1024
 #define F_FILE			1
 
diff --git a/fs/ext4/ext4_journal.c b/fs/ext4/ext4_journal.c
index 9f01708..4a84384 100644
--- a/fs/ext4/ext4_journal.c
+++ b/fs/ext4/ext4_journal.c
@@ -534,16 +534,14 @@ end:
 		jsb->s_start = cpu_to_be32(1);
 		jsb->s_sequence = cpu_to_be32(be32_to_cpu(jsb->s_sequence) + 1);
 		/* get the superblock */
-		ext4fs_devread(SUPERBLOCK_SECTOR, 0, SUPERBLOCK_SIZE,
-			       (char *)fs->sb);
+		ext4_read_superblock((char *)fs->sb);
 		fs->sb->feature_incompat |= EXT3_FEATURE_INCOMPAT_RECOVER;
 
 		/* Update the super block */
 		put_ext4((uint64_t) (SUPERBLOCK_SIZE),
 			 (struct ext2_sblock *)fs->sb,
 			 (uint32_t) SUPERBLOCK_SIZE);
-		ext4fs_devread(SUPERBLOCK_SECTOR, 0, SUPERBLOCK_SIZE,
-			       (char *)fs->sb);
+		ext4_read_superblock((char *)fs->sb);
 
 		blknr = read_allocated_block(&inode_journal,
 					 EXT2_JOURNAL_SUPERBLOCK);
diff --git a/fs/ext4/ext4_write.c b/fs/ext4/ext4_write.c
index c4e399c..f76a464 100644
--- a/fs/ext4/ext4_write.c
+++ b/fs/ext4/ext4_write.c
@@ -614,14 +614,13 @@ int ext4fs_init(void)
 	/* populate fs */
 	fs->blksz = EXT2_BLOCK_SIZE(ext4fs_root);
 	fs->inodesz = INODE_SIZE_FILESYSTEM(ext4fs_root);
-	fs->sect_perblk = fs->blksz / SECTOR_SIZE;
+	fs->sect_perblk = fs->blksz >> fs->dev_desc->log2blksz;
 
 	/* get the superblock */
 	fs->sb = zalloc(SUPERBLOCK_SIZE);
 	if (!fs->sb)
 		return -ENOMEM;
-	if (!ext4fs_devread(SUPERBLOCK_SECTOR, 0, SUPERBLOCK_SIZE,
-			(char *)fs->sb))
+	if (!ext4_read_superblock((char *)fs->sb))
 		goto fail;
 
 	/* init journal */
@@ -722,7 +721,7 @@ void ext4fs_deinit(void)
 	ext4fs_free_journal();
 
 	/* get the superblock */
-	ext4fs_devread(SUPERBLOCK_SECTOR, 0, SUPERBLOCK_SIZE, (char *)fs->sb);
+	ext4_read_superblock((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);
@@ -766,7 +765,8 @@ static int ext4fs_write_file(struct ext2_inode *file_inode,
 {
 	int i;
 	int blockcnt;
-	int log2blocksize = LOG2_EXT2_BLOCK_SIZE(ext4fs_root);
+	int log2blksz = fs->dev_desc->log2blksz;
+	int log2_fs_blocksize = LOG2_BLOCK_SIZE(ext4fs_root) - log2blksz;
 	unsigned int filesize = __le32_to_cpu(file_inode->size);
 	struct ext_filesystem *fs = get_fs();
 	int previous_block_number = -1;
@@ -789,16 +789,16 @@ static int ext4fs_write_file(struct ext2_inode *file_inode,
 		if (blknr < 0)
 			return -1;
 
-		blknr = blknr << log2blocksize;
+		blknr = blknr << log2_fs_blocksize;
 
 		if (blknr) {
 			if (previous_block_number != -1) {
 				if (delayed_next == blknr) {
 					delayed_extent += blockend;
-					delayed_next += blockend >> SECTOR_BITS;
+					delayed_next += blockend >> log2blksz;
 				} else {	/* spill */
-					put_ext4((uint64_t) (delayed_start *
-							     SECTOR_SIZE),
+					put_ext4((uint64_t)
+						 (delayed_start << log2blksz),
 						 delayed_buf,
 						 (uint32_t) delayed_extent);
 					previous_block_number = blknr;
@@ -806,7 +806,7 @@ static int ext4fs_write_file(struct ext2_inode *file_inode,
 					delayed_extent = blockend;
 					delayed_buf = buf;
 					delayed_next = blknr +
-					    (blockend >> SECTOR_BITS);
+					    (blockend >> log2blksz);
 				}
 			} else {
 				previous_block_number = blknr;
@@ -814,13 +814,14 @@ static int ext4fs_write_file(struct ext2_inode *file_inode,
 				delayed_extent = blockend;
 				delayed_buf = buf;
 				delayed_next = blknr +
-				    (blockend >> SECTOR_BITS);
+				    (blockend >> log2blksz);
 			}
 		} else {
 			if (previous_block_number != -1) {
 				/* spill */
-				put_ext4((uint64_t) (delayed_start *
-						     SECTOR_SIZE), delayed_buf,
+				put_ext4((uint64_t) (delayed_start <<
+						     log2blksz),
+					 delayed_buf,
 					 (uint32_t) delayed_extent);
 				previous_block_number = -1;
 			}
@@ -830,7 +831,7 @@ static int ext4fs_write_file(struct ext2_inode *file_inode,
 	}
 	if (previous_block_number != -1) {
 		/* spill */
-		put_ext4((uint64_t) (delayed_start * SECTOR_SIZE),
+		put_ext4((uint64_t) (delayed_start << log2blksz),
 			 delayed_buf, (uint32_t) delayed_extent);
 		previous_block_number = -1;
 	}
@@ -921,7 +922,8 @@ int ext4fs_write(const char *fname, unsigned char *buffer,
 	/* 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;
+	file_inode->blockcnt = (blks_reqd_for_file * fs->blksz) >>
+		fs->dev_desc->log2blksz;
 
 	temp_ptr = zalloc(fs->blksz);
 	if (!temp_ptr)
diff --git a/fs/ext4/ext4fs.c b/fs/ext4/ext4fs.c
index 4dddde2..1954afb 100644
--- a/fs/ext4/ext4fs.c
+++ b/fs/ext4/ext4fs.c
@@ -60,10 +60,12 @@ void ext4fs_free_node(struct ext2fs_node *node, struct ext2fs_node *currroot)
 int ext4fs_read_file(struct ext2fs_node *node, int pos,
 		unsigned int len, char *buf)
 {
+	struct ext_filesystem *fs = get_fs();
 	int i;
 	int blockcnt;
-	int log2blocksize = LOG2_EXT2_BLOCK_SIZE(node->data);
-	int blocksize = 1 << (log2blocksize + DISK_SECTOR_BITS);
+	int log2blksz = fs->dev_desc->log2blksz;
+	int log2_fs_blocksize = LOG2_BLOCK_SIZE(node->data) - log2blksz;
+	int blocksize = (1 << (log2_fs_blocksize + log2blksz));
 	unsigned int filesize = __le32_to_cpu(node->inode.size);
 	int previous_block_number = -1;
 	int delayed_start = 0;
@@ -88,7 +90,7 @@ int ext4fs_read_file(struct ext2fs_node *node, int pos,
 		if (blknr < 0)
 			return -1;
 
-		blknr = blknr << log2blocksize;
+		blknr = blknr << log2_fs_blocksize;
 
 		/* Last block.  */
 		if (i == blockcnt - 1) {
@@ -110,7 +112,7 @@ int ext4fs_read_file(struct ext2fs_node *node, int pos,
 			if (previous_block_number != -1) {
 				if (delayed_next == blknr) {
 					delayed_extent += blockend;
-					delayed_next += blockend >> SECTOR_BITS;
+					delayed_next += blockend >> log2blksz;
 				} else {	/* spill */
 					status = ext4fs_devread(delayed_start,
 							delayed_skipfirst,
@@ -124,7 +126,7 @@ int ext4fs_read_file(struct ext2fs_node *node, int pos,
 					delayed_skipfirst = skipfirst;
 					delayed_buf = buf;
 					delayed_next = blknr +
-						(blockend >> SECTOR_BITS);
+						(blockend >> log2blksz);
 				}
 			} else {
 				previous_block_number = blknr;
@@ -133,7 +135,7 @@ int ext4fs_read_file(struct ext2fs_node *node, int pos,
 				delayed_skipfirst = skipfirst;
 				delayed_buf = buf;
 				delayed_next = blknr +
-					(blockend >> SECTOR_BITS);
+					(blockend >> log2blksz);
 			}
 		} else {
 			if (previous_block_number != -1) {
diff --git a/include/ext4fs.h b/include/ext4fs.h
index 025a2e8..379f7eb 100644
--- a/include/ext4fs.h
+++ b/include/ext4fs.h
@@ -141,4 +141,5 @@ long int read_allocated_block(struct ext2_inode *inode, int fileblock);
 int ext4fs_probe(block_dev_desc_t *fs_dev_desc,
 		 disk_partition_t *fs_partition);
 int ext4_read_file(const char *filename, void *buf, int offset, int len);
+int ext4_read_superblock(char *buffer);
 #endif
diff --git a/include/ext_common.h b/include/ext_common.h
index 86373a6..78a7808 100644
--- a/include/ext_common.h
+++ b/include/ext_common.h
@@ -34,7 +34,6 @@
 #define __EXT_COMMON__
 #include <command.h>
 #define SECTOR_SIZE		0x200
-#define SECTOR_BITS		9
 
 /* Magic value used to identify an ext2 filesystem.  */
 #define	EXT2_MAGIC			0xEF53
@@ -58,18 +57,13 @@
 #define FILETYPE_INO_SYMLINK		0120000
 #define EXT2_ROOT_INO			2 /* Root inode */
 
-/* Bits used as offset in sector */
-#define DISK_SECTOR_BITS		9
 /* The size of an ext2 block in bytes.  */
 #define EXT2_BLOCK_SIZE(data)	   (1 << LOG2_BLOCK_SIZE(data))
 
-/* Log2 size of ext2 block in 512 blocks.  */
-#define LOG2_EXT2_BLOCK_SIZE(data) (__le32_to_cpu \
-				(data->sblock.log2_block_size) + 1)
-
 /* Log2 size of ext2 block in bytes.  */
-#define LOG2_BLOCK_SIZE(data)	   (__le32_to_cpu \
-		(data->sblock.log2_block_size) + 10)
+#define LOG2_BLOCK_SIZE(data)	   (__le32_to_cpu		   \
+				    (data->sblock.log2_block_size) \
+				    + EXT2_MIN_BLOCK_LOG_SIZE)
 #define INODE_SIZE_FILESYSTEM(data)	(__le32_to_cpu \
 			(data->sblock.inode_size))
 
