Re: [PATCH v2 3/4] io_uring: Introduce IORING_OP_BIND

[Kuniyuki Iwashima <kuniyu@amazon.com>]

From: Gabriel Krisman Bertazi <krisman@suse.de>
Date: Fri, 14 Jun 2024 12:30:46 -0400
> IORING_OP_BIND provides the semantic of bind(2) via io_uring.  While
> this is an essentially synchronous system call, the main point is to
> enable a network path to execute fully with io_uring registered and
> descriptorless files.
> 
> Signed-off-by: Gabriel Krisman Bertazi <krisman@suse.de>
> 
> ---
> changes since v1:
> - drop explocit error handling for move_addr_to_kernel (jens)
> - Remove empty line ahead of return;
> ---
>  include/uapi/linux/io_uring.h |  1 +
>  io_uring/net.c                | 36 +++++++++++++++++++++++++++++++++++
>  io_uring/net.h                |  3 +++
>  io_uring/opdef.c              | 13 +++++++++++++
>  4 files changed, 53 insertions(+)
> 
> diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h
> index 994bf7af0efe..4ef153d95c87 100644
> --- a/include/uapi/linux/io_uring.h
> +++ b/include/uapi/linux/io_uring.h
> @@ -257,6 +257,7 @@ enum io_uring_op {
>  	IORING_OP_FUTEX_WAITV,
>  	IORING_OP_FIXED_FD_INSTALL,
>  	IORING_OP_FTRUNCATE,
> +	IORING_OP_BIND,
>  
>  	/* this goes last, obviously */
>  	IORING_OP_LAST,
> diff --git a/io_uring/net.c b/io_uring/net.c
> index 0a48596429d9..8cbc29aff15c 100644
> --- a/io_uring/net.c
> +++ b/io_uring/net.c
> @@ -51,6 +51,11 @@ struct io_connect {
>  	bool				seen_econnaborted;
>  };
>  
> +struct io_bind {
> +	struct file			*file;
> +	int				addr_len;
> +};
> +
>  struct io_sr_msg {
>  	struct file			*file;
>  	union {
> @@ -1715,6 +1720,37 @@ int io_connect(struct io_kiocb *req, unsigned int issue_flags)
>  	return IOU_OK;
>  }
>  
> +int io_bind_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
> +{
> +	struct io_bind *bind = io_kiocb_to_cmd(req, struct io_bind);
> +	struct sockaddr __user *uaddr;
> +	struct io_async_msghdr *io;
> +
> +	if (sqe->len || sqe->buf_index || sqe->rw_flags || sqe->splice_fd_in)
> +		return -EINVAL;
> +
> +	uaddr = u64_to_user_ptr(READ_ONCE(sqe->addr));
> +	bind->addr_len =  READ_ONCE(sqe->addr2);
                        ^^
nit: double space


> +
> +	io = io_msg_alloc_async(req);
> +	if (unlikely(!io))
> +		return -ENOMEM;
> +	return move_addr_to_kernel(uaddr, bind->addr_len, &io->addr);
> +}
> +
> +int io_bind(struct io_kiocb *req, unsigned int issue_flags)
> +{
> +	struct io_bind *bind = io_kiocb_to_cmd(req, struct io_bind);
> +	struct io_async_msghdr *io = req->async_data;
> +	int ret;
> +
> +	ret = __sys_bind_socket(sock_from_file(req->file),  &io->addr, bind->addr_len);
                                                          ^^
ditto


> +	if (ret < 0)
> +		req_set_fail(req);
> +	io_req_set_res(req, ret, 0);
> +	return 0;
> +}
> +
>  void io_netmsg_cache_free(const void *entry)
>  {
>  	struct io_async_msghdr *kmsg = (struct io_async_msghdr *) entry;
> diff --git a/io_uring/net.h b/io_uring/net.h
> index 0eb1c1920fc9..49f9a7bc1113 100644
> --- a/io_uring/net.h
> +++ b/io_uring/net.h
> @@ -49,6 +49,9 @@ int io_sendmsg_zc(struct io_kiocb *req, unsigned int issue_flags);
>  int io_send_zc_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe);
>  void io_send_zc_cleanup(struct io_kiocb *req);
>  
> +int io_bind_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe);
> +int io_bind(struct io_kiocb *req, unsigned int issue_flags);
> +
>  void io_netmsg_cache_free(const void *entry);
>  #else
>  static inline void io_netmsg_cache_free(const void *entry)
> diff --git a/io_uring/opdef.c b/io_uring/opdef.c
> index 2de5cca9504e..19ee9445f024 100644
> --- a/io_uring/opdef.c
> +++ b/io_uring/opdef.c
> @@ -495,6 +495,16 @@ const struct io_issue_def io_issue_defs[] = {
>  		.prep			= io_ftruncate_prep,
>  		.issue			= io_ftruncate,
>  	},
> +	[IORING_OP_BIND] = {
> +#if defined(CONFIG_NET)
> +		.needs_file		= 1,
> +		.prep			= io_bind_prep,
> +		.issue			= io_bind,
> +		.async_size		= sizeof(struct io_async_msghdr),
> +#else
> +		.prep			= io_eopnotsupp_prep,
> +#endif
> +	},
>  };
>  
>  const struct io_cold_def io_cold_defs[] = {
> @@ -711,6 +721,9 @@ const struct io_cold_def io_cold_defs[] = {
>  	[IORING_OP_FTRUNCATE] = {
>  		.name			= "FTRUNCATE",
>  	},
> +	[IORING_OP_BIND] = {
> +		.name			= "BIND",
> +	},
>  };
>  
>  const char *io_uring_get_opcode(u8 opcode)
> -- 
> 2.45.2