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

[Jens Axboe <axboe@kernel.dk>]

On 5/6/22 8:50 AM, Christoph Hellwig wrote:
> 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@lst.de>

Both done, thanks.

>> 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?

You do. Without sqe128, you get sizeof(sqe) - offsetof(cmd) == 16 bytes.
With, you get 16 + 64, 80.

-- 
Jens Axboe