[PATCH v4 4/5] nvme: wire-up uring-cmd support for io-passthru on char-device.

[Christoph Hellwig]

On Fri, May 06, 2022 at 07:37:55AM -0600, Jens Axboe wrote:
> Folded most of it, but I left your two meta data related patches as
> separate as I they really should be separate. However, they need a
> proper commit message and signed-off-by from you. It's these two:
> 
> https://git.kernel.dk/cgit/linux-block/commit/?h=for-5.19/io_uring-passthrough&id=b855a4458068722235bdf69688448820c8ddae8e

This one should be folded into "nvme: refactor nvme_submit_user_cmd()",
which is the patch just before it that adds nvme_meta_from_bio.

> https://git.kernel.dk/cgit/linux-block/commit/?h=for-5.19/io_uring-passthrough&id=2be698bdd668daeb1aad2ecd516484a62e948547

Just add this:

"Add a small helper to act as the counterpart to nvme_add_user_metadata."

with my signoff:

Signed-off-by: Christoph Hellwig <hch at lst.de>

> I did not do your async_size changes, I think you're jetlagged eyes
> missed that this isn't a sizeof thing on a flexible array, it's just the
> offset of it. Hence for non-sqe128, the the async size is io_uring_sqe -
> offsetof where pdu starts, and so forth.

Hmm, this still seems a bit odd to me.  So without sqe128 you don't even
get the cmd data that would fit into the 64-bit SQE?