[PATCH 14/17] io_uring: add polling support for uring-cmd

[Christoph Hellwig]

On Tue, Mar 08, 2022 at 08:51:02PM +0530, Kanchan Joshi wrote:
> +		if (req->opcode == IORING_OP_URING_CMD ||
> +		    req->opcode == IORING_OP_URING_CMD_FIXED) {
> +			/* uring_cmd structure does not contain kiocb struct */
> +			struct kiocb kiocb_uring_cmd;
> +
> +			kiocb_uring_cmd.private = req->uring_cmd.bio;
> +			kiocb_uring_cmd.ki_filp = req->uring_cmd.file;
> +			ret = req->uring_cmd.file->f_op->iopoll(&kiocb_uring_cmd,
> +			      &iob, poll_flags);
> +		} else {
> +			ret = kiocb->ki_filp->f_op->iopoll(kiocb, &iob,
> +							   poll_flags);
> +		}

This is just completely broken.  You absolutely do need the iocb
in struct uring_cmd for ->iopoll to work.