FSCRYPT Adding Direct I/O Support For Encrypted Files In Linux 5.18

It's been a while since having any shiny new features to talk about for FSCRYPT, the Linux kernel's file-system encryption framework that is used by the likes of EXT4 and F2FS. With Linux 5.18 that changes with FSCRYPT adding direct I/O support.

Google's Eric Biggers sent in the FSCRYPT feature pull this morning for the newly-started Linux 5.18 merge window. The big feature there is adding support for direct I/O on encrypted files, which works when blk-crypto is activated for inline encryption handling of the encrypted file contents.

Direct I/O to this point hadn't been supported with FSCRYPT file-system encryption while now it can be but with fallback support to buffered I/O in the event of issues. The "inlinecrypt" mount option must be in use and the system having hardware inline encryption or otherwise have the fallback inline encryption mode enabled.

This direct I/O support with FSCRYPT has been successfully tested with the EXT4 and F2FS file-systems under the above-mentioned criteria.

More details via the FSCRYPT pull request for Linux 5.18.