On Mon, Oct 28, 2019 at 12:20:26AM -0700, Satya Tangirala wrote:

We introduce blk-crypto, which manages programming keyslots for struct
bios. With blk-crypto, filesystems only need to call bio_crypt_set_ctx with
the encryption key, algorithm and data_unit_num; they don't have to worry
about getting a keyslot for each encryption context, as blk-crypto handles
that. Blk-crypto also makes it possible for layered devices like device
mapper to make use of inline encryption hardware.

Blk-crypto delegates crypto operations to inline encryption hardware when
available, and also contains a software fallback to the kernel crypto API.
For more details, refer to Documentation/block/inline-encryption.rst.

Can you explain why we need this software fallback that basically just
duplicates logic already in fscrypt?  As far as I can tell this fallback
logic actually is more code than the actual inline encryption, and nasty
code at that, e.g. the whole crypt_iter thing.