Index: uspace/lib/ext4/libext4_extent.c
===================================================================
--- uspace/lib/ext4/libext4_extent.c	(revision 2d1f7a218402b3374cc95dd5db29a27e5e87ec3a)
+++ uspace/lib/ext4/libext4_extent.c	(revision cb7056ae1da753c448596f60b309940133614bba)
@@ -41,4 +41,9 @@
 #include "libext4.h"
 
+/** Get logical number of the block covered extent.
+ *
+ * @param extent	extent to load number from
+ * @return			logical number of the first block covered by extent
+ */
 uint32_t ext4_extent_get_first_block(ext4_extent_t *extent)
 {
@@ -46,9 +51,19 @@
 }
 
-void ext4_extent_set_first_block(ext4_extent_t *extent, uint32_t first_block)
-{
-	extent->first_block = host2uint32_t_le(first_block);
-}
-
+/** Set logical number of the first block covered by extent.
+ *
+ * @param extent	extent to load number from
+ * @param iblock	logical number of the first block covered by extent
+ */
+void ext4_extent_set_first_block(ext4_extent_t *extent, uint32_t iblock)
+{
+	extent->first_block = host2uint32_t_le(iblock);
+}
+
+/** Get number of blocks covered by extent.
+ *
+ * @param extent	extent to load count from
+ * @return			number of blocks covered by extent
+ */
 uint16_t ext4_extent_get_block_count(ext4_extent_t *extent)
 {
@@ -56,9 +71,19 @@
 }
 
-void ext4_extent_set_block_count(ext4_extent_t *extent, uint16_t block_count)
-{
-	extent->block_count = host2uint16_t_le(block_count);
-}
-
+/** Set number of blocks covered by extent.
+ *
+ * @param extent	extent to load count from
+ * @param count 	number of blocks covered by extent
+ */
+void ext4_extent_set_block_count(ext4_extent_t *extent, uint16_t count)
+{
+	extent->block_count = host2uint16_t_le(count);
+}
+
+/** Get physical number of the first block covered by extent.
+ *
+ * @param extent 	extent to load number
+ * @return			physical number of the first block covered by extent
+ */
 uint64_t ext4_extent_get_start(ext4_extent_t *extent)
 {
@@ -67,9 +92,16 @@
 }
 
-void ext4_extent_set_start(ext4_extent_t *extent, uint64_t start)
-{
-	extent->start_lo = host2uint32_t_le((start << 32) >> 32);
-	extent->start_hi = host2uint16_t_le((uint16_t)(start >> 32));
-}
+/** Set physical number of the first block covered by extent.
+ *
+ * @param extent 	extent to load number
+ * @param fblock	physical number of the first block covered by extent
+ */
+void ext4_extent_set_start(ext4_extent_t *extent, uint64_t fblock)
+{
+	extent->start_lo = host2uint32_t_le((fblock << 32) >> 32);
+	extent->start_hi = host2uint16_t_le((uint16_t)(fblock >> 32));
+}
+
+// TODO start comments here
 
 uint32_t ext4_extent_index_get_first_block(ext4_extent_index_t *index)