Commit 4f57f06c authored by Jens Axboe's avatar Jens Axboe
Browse files

io_uring: add support for IORING_OP_MSG_RING command 



This adds support for IORING_OP_MSG_RING, which allows an SQE to signal
another ring. That allows either waking up someone waiting on the ring,
or even passing a 64-bit value via the user_data field in the CQE.

sqe->fd must contain the fd of a ring that should receive the CQE.
sqe->off will be propagated to the cqe->user_data on the target ring,
and sqe->len will be propagated to cqe->res. The results CQE will have
IORING_CQE_F_MSG set in its flags, to indicate that this CQE was generated
from a messaging request rather than a SQE issued locally on that ring.
This effectively allows passing a 64-bit and a 32-bit quantify between
the two rings.

This request type has the following request specific error cases:

- -EBADFD. Set if the sqe->fd doesn't point to a file descriptor that is
  of the io_uring type.
- -EOVERFLOW. Set if we were not able to deliver a request to the target
  ring.

Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent cc3cec83

fs/io_uring.c

+55 −0
Original line number Diff line number Diff line
@@ -706,6 +706,12 @@ struct io_hardlink { 
	int				flags;

};



struct io_msg {

	struct file			*file;

	u64 user_data;

	u32 len;

};



struct io_async_connect {

	struct sockaddr_storage		address;

};
@@ -871,6 +877,7 @@ struct io_kiocb { 
		struct io_mkdir		mkdir;

		struct io_symlink	symlink;

		struct io_hardlink	hardlink;

		struct io_msg		msg;

	};



	u8				opcode;
@@ -1121,6 +1128,9 @@ static const struct io_op_def io_op_defs[] = { 
	[IORING_OP_MKDIRAT] = {},

	[IORING_OP_SYMLINKAT] = {},

	[IORING_OP_LINKAT] = {},

	[IORING_OP_MSG_RING] = {

		.needs_file		= 1,

	},

};



/* requests with any of those set should undergo io_disarm_next() */
@@ -4322,6 +4332,46 @@ static int io_nop(struct io_kiocb *req, unsigned int issue_flags) 
	return 0;

}



static int io_msg_ring_prep(struct io_kiocb *req,

			    const struct io_uring_sqe *sqe)

{

	if (unlikely(sqe->addr || sqe->ioprio || sqe->buf_index ||

		     sqe->rw_flags || sqe->splice_fd_in || sqe->buf_index ||

		     sqe->personality))

		return -EINVAL;



	if (req->file->f_op != &io_uring_fops)

		return -EBADFD;



	req->msg.user_data = READ_ONCE(sqe->off);

	req->msg.len = READ_ONCE(sqe->len);

	return 0;

}



static int io_msg_ring(struct io_kiocb *req, unsigned int issue_flags)

{

	struct io_ring_ctx *target_ctx;

	struct io_msg *msg = &req->msg;

	int ret = -EOVERFLOW;

	bool filled;



	target_ctx = req->file->private_data;



	spin_lock(&target_ctx->completion_lock);

	filled = io_fill_cqe_aux(target_ctx, msg->user_data, msg->len,

					IORING_CQE_F_MSG);

	io_commit_cqring(target_ctx);

	spin_unlock(&target_ctx->completion_lock);



	if (filled) {

		io_cqring_ev_posted(target_ctx);

		ret = 0;

	}



	__io_req_complete(req, issue_flags, ret, 0);

	return 0;

}



static int io_fsync_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)

{

	struct io_ring_ctx *ctx = req->ctx;
@@ -6700,6 +6750,8 @@ static int io_req_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe) 
		return io_symlinkat_prep(req, sqe);

	case IORING_OP_LINKAT:

		return io_linkat_prep(req, sqe);

	case IORING_OP_MSG_RING:

		return io_msg_ring_prep(req, sqe);

	}



	printk_once(KERN_WARNING "io_uring: unhandled opcode %d\n",
@@ -6983,6 +7035,9 @@ static int io_issue_sqe(struct io_kiocb *req, unsigned int issue_flags) 
	case IORING_OP_LINKAT:

		ret = io_linkat(req, issue_flags);

		break;

	case IORING_OP_MSG_RING:

		ret = io_msg_ring(req, issue_flags);

		break;

	default:

		ret = -EINVAL;

		break;

include/uapi/linux/io_uring.h

+3 −0
Original line number Diff line number Diff line
@@ -143,6 +143,7 @@ enum { 
	IORING_OP_MKDIRAT,

	IORING_OP_SYMLINKAT,

	IORING_OP_LINKAT,

	IORING_OP_MSG_RING,



	/* this goes last, obviously */

	IORING_OP_LAST,
@@ -199,9 +200,11 @@ struct io_uring_cqe { 
 *

 * IORING_CQE_F_BUFFER	If set, the upper 16 bits are the buffer ID

 * IORING_CQE_F_MORE	If set, parent SQE will generate more CQE entries

 * IORING_CQE_F_MSG	If set, CQE was generated with IORING_OP_MSG_RING

 */

#define IORING_CQE_F_BUFFER		(1U << 0)

#define IORING_CQE_F_MORE		(1U << 1)

#define IORING_CQE_F_MSG		(1U << 2)



enum {

	IORING_CQE_BUFFER_SHIFT		= 16,