Index: uspace/lib/ext4/Makefile
===================================================================
--- uspace/lib/ext4/Makefile	(revision 7b9381bffbfa6ad5040dcd4c616370abc46b95a4)
+++ uspace/lib/ext4/Makefile	(revision 829d23834992f037805099f7df69f6fa5f1141e1)
@@ -35,4 +35,5 @@
 	libext4_block_group.c \
 	libext4_directory.c \
+	libext4_extent.c \
 	libext4_filesystem.c \
 	libext4_inode.c \
Index: uspace/lib/ext4/libext4.h
===================================================================
--- uspace/lib/ext4/libext4.h	(revision 7b9381bffbfa6ad5040dcd4c616370abc46b95a4)
+++ uspace/lib/ext4/libext4.h	(revision 829d23834992f037805099f7df69f6fa5f1141e1)
@@ -36,4 +36,5 @@
 #include "libext4_block_group.h"
 #include "libext4_directory.h"
+#include "libext4_extent.h"
 #include "libext4_filesystem.h"
 #include "libext4_inode.h"
Index: uspace/lib/ext4/libext4_extent.c
===================================================================
--- uspace/lib/ext4/libext4_extent.c	(revision 829d23834992f037805099f7df69f6fa5f1141e1)
+++ uspace/lib/ext4/libext4_extent.c	(revision 829d23834992f037805099f7df69f6fa5f1141e1)
@@ -0,0 +1,42 @@
+/*
+ * Copyright (c) 2011 Frantisek Princ
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * - Redistributions of source code must retain the above copyright
+ *   notice, this list of conditions and the following disclaimer.
+ * - Redistributions in binary form must reproduce the above copyright
+ *   notice, this list of conditions and the following disclaimer in the
+ *   documentation and/or other materials provided with the distribution.
+ * - The name of the author may not be used to endorse or promote products
+ *   derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+/** @addtogroup libext4
+ * @{
+ */ 
+
+/**
+ * @file	libext4_extent.c
+ * @brief	TODO
+ */
+
+
+
+/**
+ * @}
+ */ 
Index: uspace/lib/ext4/libext4_extent.h
===================================================================
--- uspace/lib/ext4/libext4_extent.h	(revision 829d23834992f037805099f7df69f6fa5f1141e1)
+++ uspace/lib/ext4/libext4_extent.h	(revision 829d23834992f037805099f7df69f6fa5f1141e1)
@@ -0,0 +1,76 @@
+/*
+ * Copyright (c) 2011 Frantisek Princ
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * - Redistributions of source code must retain the above copyright
+ *   notice, this list of conditions and the following disclaimer.
+ * - Redistributions in binary form must reproduce the above copyright
+ *   notice, this list of conditions and the following disclaimer in the
+ *   documentation and/or other materials provided with the distribution.
+ * - The name of the author may not be used to endorse or promote products
+ *   derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+/** @addtogroup libext4
+ * @{
+ */ 
+
+#ifndef LIBEXT4_LIBEXT4_EXTENT_H_
+#define LIBEXT4_LIBEXT4_EXTENT_H_
+
+/*
+ * This is the extent on-disk structure.
+ * It's used at the bottom of the tree.
+ */
+typedef struct ext4_extent {
+	uint32_t first_block; // First logical block extent covers
+	uint16_t block_count; // Number of blocks covered by extent
+	uint16_t start_hi;    // High 16 bits of physical block
+	uint32_t start_lo;    // Low 32 bits of physical block
+} ext4_extent_t;
+
+/*
+ * This is index on-disk structure.
+ * It's used at all the levels except the bottom.
+ */
+typedef struct ext4_extent_idx {
+	uint32_t block; // Index covers logical blocks from 'block'
+	uint32_t leaf_lo; /* Pointer to the physical block of the next
+	 	 	 	 	   * level. leaf or next index could be there */
+	uint16_t leaf_hi;     /* high 16 bits of physical block */
+	uint16_t padding;
+} ext4_extent_idx_t;
+
+/*
+ * Each block (leaves and indexes), even inode-stored has header.
+ */
+typedef struct ext4_extent_header {
+	uint16_t magic;
+	uint16_t entries_count; // Number of valid entries
+	uint16_t max_entries_count; // Capacity of store in entries
+	uint16_t depth; // Has tree real underlying blocks?
+	uint32_t generation; // generation of the tree
+} ext4_extent_header_t;
+
+#define EXT4_EXTENT_MAGIC host2uint16_t_le(0xF30A)
+
+#endif
+
+/**
+ * @}
+ */
Index: uspace/lib/ext4/libext4_filesystem.c
===================================================================
--- uspace/lib/ext4/libext4_filesystem.c	(revision 7b9381bffbfa6ad5040dcd4c616370abc46b95a4)
+++ uspace/lib/ext4/libext4_filesystem.c	(revision 829d23834992f037805099f7df69f6fa5f1141e1)
@@ -196,4 +196,14 @@
 }
 
+int ext4_filesystem_put_block_group_ref(ext4_block_group_ref_t *ref)
+{
+	int rc;
+
+	rc = block_put(ref->block);
+	free(ref);
+
+	return rc;
+}
+
 int ext4_filesystem_get_inode_ref(ext4_filesystem_t *fs, uint32_t index,
     ext4_inode_ref_t **ref)
@@ -235,4 +245,10 @@
 	    bg_ref->block_group);
 
+	rc = ext4_filesystem_put_block_group_ref(bg_ref);
+	if (rc != EOK) {
+		free(newref);
+		return rc;
+	}
+
 	inode_size = ext4_superblock_get_inode_size(fs->superblock);
 	block_size = ext4_superblock_get_block_size(fs->superblock);
Index: uspace/lib/ext4/libext4_filesystem.h
===================================================================
--- uspace/lib/ext4/libext4_filesystem.h	(revision 7b9381bffbfa6ad5040dcd4c616370abc46b95a4)
+++ uspace/lib/ext4/libext4_filesystem.h	(revision 829d23834992f037805099f7df69f6fa5f1141e1)
@@ -109,4 +109,5 @@
 extern int ext4_filesystem_get_block_group_ref(ext4_filesystem_t *, uint32_t,
     ext4_block_group_ref_t **);
+extern int ext4_filesystem_put_block_group_ref(ext4_block_group_ref_t *);
 extern int ext4_filesystem_get_inode_ref(ext4_filesystem_t *, uint32_t,
 		ext4_inode_ref_t **);