missing y2038 support

missing y2038 support

I don't think you can convert between those in place without a full backup/restore. One way to find out the inode format is to use the "stats" command in debugfs. It appears that at least in e2fsprogs version 1.45.7, the default in mkfs is still to use small inodes for smaller file system images, regardless of the file system type, so an ext2 file system image over 512MB is not actually compatible with the ext2 format unless you manually set the inode size, and smaller ext4 images continue having the y2038 problem:

$ truncate --size=511M ext4.img
$ mkfs -t ext4  -q  ext4.img
$ echo stats | debugfs ext4.img 2>&1 | grep "Inode size"
Inode size:	          128

$ truncate --size=512M ext2.img
$ mkfs -t ext2  -q ext2.img
$ echo stats | debugfs ext2.img 2>&1 | grep "Inode size"
Inode size:	          256

        small = {
                inode_size = 128
                inode_ratio = 4096
        }