dropping the non-inline mode for fscrypt?

After just having run into another issue with missing testing for one of
the path, I'd like to ask if we should look into dropping the non-inline
mode for block based fscrypt?

I did a few simple fio based benchmarks, and writes are a minimal amount
fast for the inline mode, while the reverse is true for reads.

The big blocker seems to be this comment in fscrypt_select_encryption_impl:

        /*
         * When a page contains multiple logically contiguous filesystem blocks,
         * some filesystem code only calls fscrypt_mergeable_bio() for the first
         * block in the page. This is fine for most of fscrypt's IV generation
         * strategies, where contiguous blocks imply contiguous IVs. But it
         * doesn't work with IV_INO_LBLK_32. For now, simply exclude
         * IV_INO_LBLK_32 with blocksize != PAGE_SIZE from inline encryption.
         */

from touching the file system callers lately, the only obvious place
for this is fscrypt_zeroout_range_inline_crypt helper, or did I miss
anything else?  Does anyone have a good xfstests setup for the
IV_INO_LBLK_32 mode?