ext2: Factor inode-group deserialization out
diff --git a/src/filo-fs-ext2.ads b/src/filo-fs-ext2.ads
index 6003198..5e6b641 100644
--- a/src/filo-fs-ext2.ads
+++ b/src/filo-fs-ext2.ads
@@ -74,7 +74,7 @@
    type Inode_0_Index is new Unsigned_32;
    subtype Inode_Index is Inode_0_Index range 2 .. Inode_0_Index'Last;
    subtype Inode_Size is Positive range 128 .. Positive (Unsigned_16'Last);
-   subtype Desc_Size  is Positive range  32 .. 2 ** 15; -- power-of-2 that fits in 16 bits
+   subtype Group_Desc_Size  is Positive range  32 .. 2 ** 15; -- power-of-2 that fits in 16 bits
 
    type Inode_Type is (Dir, Regular, Link, Fast_Link);
    type Inode_Length is range 0 .. 2 ** 46;
@@ -89,8 +89,8 @@
 
    type Group_Index is new Inode_0_Index;
    subtype Group_In_Block_Count is Group_Index
-      range 1 .. Group_Index (Block_Size'Last / Desc_Size'First);
-   type Desc_In_Block_Index is new Natural range 0 .. Natural (Group_In_Block_Count'Last - 1);
+      range 1 .. Group_Index (Block_Size'Last / Group_Desc_Size'First);
+   type Group_In_Block_Index is new Natural range 0 .. Natural (Group_In_Block_Count'Last - 1);
 
    subtype Inode_In_Group_Count is Inode_0_Index range 1 .. Inode_0_Index'Last;
    type Inode_In_Group_Index is new Inode_0_Index range 0 .. Inode_In_Group_Count'Last - 1;
@@ -106,8 +106,8 @@
       Inodes_Per_Group     : Inode_In_Group_Count := Inode_In_Group_Count'First;
       Inode_Size           : Ext2.Inode_Size := Ext2.Inode_Size'First;
       Inodes_Per_Block     : Inode_In_Block_Count := Inode_In_Block_Count'First;
-      Desc_Size            : Ext2.Desc_Size := Ext2.Desc_Size'First;
-      Desc_Per_Block       : Group_In_Block_Count := Group_In_Block_Count'First;
+      Group_Desc_Size      : Ext2.Group_Desc_Size := Ext2.Group_Desc_Size'First;
+      Group_Desc_Per_Block : Group_In_Block_Count := Group_In_Block_Count'First;
       Feature_Extents      : Boolean := False;
       Feature_64Bit        : Boolean := False;
    end record;