build_library/disk_util: Switch default ext4 inode size to 256 bytes

Inode sizes smaller than 256:
- don't support extended metadata (nanosecond timestamp resolution)
- cannot handle dates beyond 2038
- are deprecated

Change the default from 128 to 256. There is no way to apply this change on a
mounted filesystem so this change will only apply to new deployments.

Fixes: flatcar/Flatcar#1082
Signed-off-by: Jeremi Piotrowski <[email protected]>

build_library/disk_util

@@ -403,7 +403,7 @@ def FormatExt(part, device):
                   '-t', part['fs_type'],
                   '-b', part['fs_block_size'],
                   '-i', part.get('fs_bytes_per_inode', part['fs_block_size']),
-                  '-I', part.get('fs_inode_size', 128),
+                  '-I', part.get('fs_inode_size', 256),
                   device,
                   part['fs_blocks']])