EXT4 On Linux 5.5 To Support Encryption On Smaller Block Sizes

For the past four years going back to Linux 4.4 has been EXT4 native file-system encryption making use of the kernel's FSCRYPT framework that is shared between several file-systems. That support has continued to improve with time and with Linux 5.5 another limitation will be dropped.

One of the lingering limitations of the EXT4 encryption code is that it hasn't worked where the file-system block size is different from the system's page size. But beginning with Linux 5.5, a different block size compared to the kernel's page size will be supported while still allowing encryption to be enabled. Namely this will help those preferring non-default block sizes for better efficiency on different storage devices or other reasons.

The limitation was overcome after they added support for sub-page-sized blocks. The work is currently queued in the EXT4 development branch ahead of the Linux 5.5 kernel merge window opening later this month.