Index: uspace/srv/fs/mfs/mfs_rw.c
===================================================================
--- uspace/srv/fs/mfs/mfs_rw.c	(revision 77ec4d957785c9a7f9fd828f7b07940f947d04e2)
+++ uspace/srv/fs/mfs/mfs_rw.c	(revision 980671e76738926c06f7db7f11620871f6f563d9)
@@ -53,5 +53,10 @@
  *bytes, this function returns the on-disk block
  *relative to that position.
- *Returns zero if the block does not exist.
+ *
+ * @param b	Pointer to a 32bit number where the block number will be stored
+ * @param mnode	Pointer to a generic MINIX inode in memory.
+ * @param pos	Position in file.
+ *
+ * @return	EOK on success or a negative error code.
  */
 int
@@ -227,5 +232,11 @@
 }
 
-/*Free unused indirect zones*/
+/**Free unused indirect zones from a MINIX inode according to it's new size.
+ *
+ * @param mnode		Pointer to a generic MINIX inode in memory.
+ * @param new_size	The new size of the inode.
+ *
+ * @return		EOK on success or a negative error code.
+ */
 int
 mfs_prune_ind_zones(struct mfs_node *mnode, size_t new_size)
@@ -239,4 +250,6 @@
 	mfs_version_t fs_version = sbi->fs_version;
 	
+	assert(new_size <= ino_i->i_size);
+
 	if (fs_version == MFS_VERSION_V1) {
 		nr_direct = V1_NR_DIRECT_ZONES;