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

[Stefano Stabellini <sstabellini@kernel.org>]

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@aporeto.com>
CC: boris.ostrovsky@oracle.com
CC: jgross@suse.com
CC: Eric Van Hensbergen <ericvh@gmail.com>
CC: Ron Minnich <rminnich@sandia.gov>
CC: Latchesar Ionkov <lucho@ionkov.net>
CC: v9fs-developer@lists.sourceforge.net
---
 net/9p/trans_xen.c | 101 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 101 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..877dfd0
--- /dev/null
+++ b/net/9p/trans_xen.c
@@ -0,0 +1,101 @@
+/*
+ * linux/fs/9p/trans_xen
+ *
+ * Xen transport layer.
+ *
+ * Copyright (C) 2017 by Stefano Stabellini <stefano@aporeto.com>
+ */ 
+
+#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