Re: [PATCH V3 02/16] io_uring: add IORING_OP_FUSED_CMD

[Jens Axboe <axboe@kernel.dk>]

On 3/14/23 6:57?AM, Ming Lei wrote:
> Add IORING_OP_FUSED_CMD, it is one special URING_CMD, which has to
> be SQE128. The 1st SQE(master) is one 64byte URING_CMD, and the 2nd
> 64byte SQE(slave) is another normal 64byte OP. For any OP which needs
> to support slave OP, io_issue_defs[op].fused_slave has to be set as 1,
> and its ->issue() needs to retrieve buffer from master request's
> fused_cmd_kbuf.

Since we'd be introducing this as a new concept, probably makes sense to
name it something other than master/slave. What about primary and
secondary? Producer/consumer?

> +static inline bool io_fused_slave_write_to_buf(u8 op)
> +{
> +	switch (op) {
> +	case IORING_OP_READ:
> +	case IORING_OP_READV:
> +	case IORING_OP_READ_FIXED:
> +	case IORING_OP_RECVMSG:
> +	case IORING_OP_RECV:
> +		return 1;
> +	default:
> +		return 0;
> +	}
> +}

Maybe add a data direction bit to the hot opdef part? Any command that
has fused support should ensure that it is set correctly.

> +int io_import_kbuf_for_slave(unsigned long buf_off, unsigned int len, int dir,
> +		struct iov_iter *iter, struct io_kiocb *slave)
> +{

The kbuf naming should probably also change, as it kind of overlaps with
the kbufs we already have and which are not really related.

-- 
Jens Axboe