io_uring: add support for shutdown(2)

This adds support for the shutdown(2) system call, which is useful for
dealing with sockets.

shutdown(2) may block, so we have to punt it to async context.
Suggested-by: NNorman Maurer <norman.maurer@googlemail.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

fs/io_uring.c

@@ -541,6 +541,11 @@ struct io_statx {
 	struct statx __user		*buffer;
 };
 
+struct io_shutdown {
+	struct file			*file;
+	int				how;
+};
+
 struct io_completion {
 	struct file			*file;
 	struct list_head		list;
@@ -667,6 +672,7 @@ struct io_kiocb {
 		struct io_splice	splice;
 		struct io_provide_buf	pbuf;
 		struct io_statx		statx;
+		struct io_shutdown	shutdown;
 		/* use only after cleaning per-op data, see io_clean_op() */
 		struct io_completion	compl;
 	};
@@ -934,6 +940,9 @@ static const struct io_op_def io_op_defs[] = {
 		.hash_reg_file		= 1,
 		.unbound_nonreg_file	= 1,
 	},
+	[IORING_OP_SHUTDOWN] = {
+		.needs_file		= 1,
+	},
 };
 
 enum io_mem_account {
@@ -3591,6 +3600,44 @@ static int io_write(struct io_kiocb *req, bool force_nonblock,
 	return ret;
 }
 
+static int io_shutdown_prep(struct io_kiocb *req,
+			    const struct io_uring_sqe *sqe)
+{
+#if defined(CONFIG_NET)
+	if (unlikely(req->ctx->flags & IORING_SETUP_IOPOLL))
+		return -EINVAL;
+	if (sqe->ioprio || sqe->off || sqe->addr || sqe->rw_flags ||
+	    sqe->buf_index)
+		return -EINVAL;
+
+	req->shutdown.how = READ_ONCE(sqe->len);
+	return 0;
+#else
+	return -EOPNOTSUPP;
+#endif
+}
+
+static int io_shutdown(struct io_kiocb *req, bool force_nonblock)
+{
+#if defined(CONFIG_NET)
+	struct socket *sock;
+	int ret;
+
+	if (force_nonblock)
+		return -EAGAIN;
+
+	sock = sock_from_file(req->file, &ret);
+	if (unlikely(!sock))
+		return ret;
+
+	ret = __sys_shutdown_sock(sock, req->shutdown.how);
+	io_req_complete(req, ret);
+	return 0;
+#else
+	return -EOPNOTSUPP;
+#endif
+}
+
 static int __io_splice_prep(struct io_kiocb *req,
 			    const struct io_uring_sqe *sqe)
 {
@@ -5775,6 +5822,8 @@ static int io_req_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
 		return io_remove_buffers_prep(req, sqe);
 	case IORING_OP_TEE:
 		return io_tee_prep(req, sqe);
+	case IORING_OP_SHUTDOWN:
+		return io_shutdown_prep(req, sqe);
 	}
 
 	printk_once(KERN_WARNING "io_uring: unhandled opcode %d\n",
@@ -6018,6 +6067,9 @@ static int io_issue_sqe(struct io_kiocb *req, bool force_nonblock,
 	case IORING_OP_TEE:
 		ret = io_tee(req, force_nonblock);
 		break;
+	case IORING_OP_SHUTDOWN:
+		ret = io_shutdown(req, force_nonblock);
+		break;
 	default:
 		ret = -EINVAL;
 		break;

include/uapi/linux/io_uring.h

@@ -132,6 +132,7 @@ enum {
 	IORING_OP_PROVIDE_BUFFERS,
 	IORING_OP_REMOVE_BUFFERS,
 	IORING_OP_TEE,
+	IORING_OP_SHUTDOWN,
 
 	/* this goes last, obviously */
 	IORING_OP_LAST,