EXT4 On Linux 5.5 To Support Encryption On Smaller Block Sizes

[starshipeleven]

p.s. and remember, security and convenience are worst enemies. If something is very convenient, most likely it highly insecure. "Usable security" is holy grail of crypto ... and at the end of day, if you don't have idea how it works... there could be nasty surprises. Hey, how many users do you think can use, say, SSL/TLS/HTTPS in anyhow secure manner?

Sadly true, but it's not a physical law. Convenient and safe can coexist, it's just unlikely

[xorbe]

Typo:

> For the past four years going back to Linux 5.5

Linux 4.4

[ebiggers]

Don't some POWER systems use 64k page sizes?

Yes, that's the main reason for this change: it makes it possible to use ext4 encryption on PowerPC.

The other reason is that it eliminates the special case where ext4 encryption didn't work with block size less than 4K on architectures with 4K pages such as x86 and ARM. Though this limitation was rarely encountered in practice as the ext4 block size is normally 4K, it was still annoying to have to document.