[PATCH v4 3/7] xen/9pfs: introduce Xen 9pfs transport driver

[Stefano Stabellini]

Introduce the Xen 9pfs transport driver: add struct xenbus_driver to
register as a xenbus driver and add struct p9_trans_module to register
as v9fs driver.

All functions are empty stubs for now.

Signed-off-by: Stefano Stabellini <stefano@xxxxxxxxxxx>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
CC: groug@xxxxxxxx
CC: jgross@xxxxxxxx
CC: Eric Van Hensbergen <ericvh@xxxxxxxxx>
CC: Ron Minnich <rminnich@xxxxxxxxxx>
CC: Latchesar Ionkov <lucho@xxxxxxxxxx>
CC: v9fs-developer@xxxxxxxxxxxxxxxxxxxxx
---
 net/9p/trans_xen.c | 125 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 125 insertions(+)
 create mode 100644 net/9p/trans_xen.c

diff --git a/net/9p/trans_xen.c b/net/9p/trans_xen.c
new file mode 100644
index 0000000..b1333b2
--- /dev/null
+++ b/net/9p/trans_xen.c
@@ -0,0 +1,125 @@
+/*
+ * linux/fs/9p/trans_xen
+ *
+ * Xen transport layer.
+ *
+ * Copyright (C) 2017 by Stefano Stabellini <stefano@xxxxxxxxxxx>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License version 2
+ * as published by the Free Software Foundation; or, when distributed
+ * separately from the Linux kernel or incorporated into other
+ * software packages, subject to the following license:
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this source file (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use, copy, modify,
+ * merge, publish, distribute, sublicense, and/or sell copies of the Software,
+ * and to permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ */
+
+#include <xen/events.h>
+#include <xen/grant_table.h>
+#include <xen/xen.h>
+#include <xen/xenbus.h>
+#include <xen/interface/io/9pfs.h>
+
+#include <linux/module.h>
+#include <net/9p/9p.h>
+#include <net/9p/client.h>
+#include <net/9p/transport.h>
+
+static int p9_xen_cancel(struct p9_client *client, struct p9_req_t *req)
+{
+	return 0;
+}
+
+static int p9_xen_create(struct p9_client *client, const char *addr, char *args)
+{
+	return 0;
+}
+
+static void p9_xen_close(struct p9_client *client)
+{
+}
+
+static int p9_xen_request(struct p9_client *client, struct p9_req_t *p9_req)
+{
+	return 0;
+}
+
+static struct p9_trans_module p9_xen_trans = {
+	.name = "xen",
+	.maxsize = 1 << (XEN_9PFS_RING_ORDER + XEN_PAGE_SHIFT),
+	.def = 1,
+	.create = p9_xen_create,
+	.close = p9_xen_close,
+	.request = p9_xen_request,
+	.cancel = p9_xen_cancel,
+	.owner = THIS_MODULE,
+};
+
+static const struct xenbus_device_id xen_9pfs_front_ids[] = {
+	{ "9pfs" },
+	{ "" }
+};
+
+static int xen_9pfs_front_remove(struct xenbus_device *dev)
+{
+	return 0;
+}
+
+static int xen_9pfs_front_probe(struct xenbus_device *dev,
+		const struct xenbus_device_id *id)
+{
+	return 0;
+}
+
+static int xen_9pfs_front_resume(struct xenbus_device *dev)
+{
+	return 0;
+}
+
+static void xen_9pfs_front_changed(struct xenbus_device *dev,
+			    enum xenbus_state backend_state)
+{
+}
+
+static struct xenbus_driver xen_9pfs_front_driver = {
+	.ids = xen_9pfs_front_ids,
+	.probe = xen_9pfs_front_probe,
+	.remove = xen_9pfs_front_remove,
+	.resume = xen_9pfs_front_resume,
+	.otherend_changed = xen_9pfs_front_changed,
+};
+
+int p9_trans_xen_init(void)
+{
+	if (!xen_domain())
+		return -ENODEV;
+
+	pr_info("Initialising Xen transport for 9pfs\n");
+
+	v9fs_register_trans(&p9_xen_trans);
+	return xenbus_register_frontend(&xen_9pfs_front_driver);
+}
+module_init(p9_trans_xen_init);
+
+void p9_trans_xen_exit(void)
+{
+	v9fs_unregister_trans(&p9_xen_trans);
+	return xenbus_unregister_driver(&xen_9pfs_front_driver);
+}
+module_exit(p9_trans_xen_exit);
-- 
1.9.1