[PATCH v2 4/5] sunrpc: Add a sysfs file for adding a new xprt

[Anna Schumaker <anna@kernel.org>]

From: Anna Schumaker <anna.schumaker@oracle.com>

Writing to this file will clone the 'main' xprt of an xprt_switch and
add it to be used as an additional connection.

Signed-off-by: Anna Schumaker <anna.schumaker@oracle.com>
--
v2: Rename the new file to add_xprt
---
 include/linux/sunrpc/xprtmultipath.h |  1 +
 net/sunrpc/sysfs.c                   | 54 ++++++++++++++++++++++++++++
 net/sunrpc/xprtmultipath.c           | 21 +++++++++++
 3 files changed, 76 insertions(+)

diff --git a/include/linux/sunrpc/xprtmultipath.h b/include/linux/sunrpc/xprtmultipath.h
index c0514c684b2c..c827c6ef0bc5 100644
--- a/include/linux/sunrpc/xprtmultipath.h
+++ b/include/linux/sunrpc/xprtmultipath.h
@@ -56,6 +56,7 @@ extern void rpc_xprt_switch_add_xprt(struct rpc_xprt_switch *xps,
 		struct rpc_xprt *xprt);
 extern void rpc_xprt_switch_remove_xprt(struct rpc_xprt_switch *xps,
 		struct rpc_xprt *xprt, bool offline);
+extern struct rpc_xprt *rpc_xprt_switch_get_main_xprt(struct rpc_xprt_switch *xps);
 
 extern void xprt_iter_init(struct rpc_xprt_iter *xpi,
 		struct rpc_xprt_switch *xps);
diff --git a/net/sunrpc/sysfs.c b/net/sunrpc/sysfs.c
index 0d382ab24f1f..a9d155a2b0ea 100644
--- a/net/sunrpc/sysfs.c
+++ b/net/sunrpc/sysfs.c
@@ -305,6 +305,55 @@ static ssize_t rpc_sysfs_xprt_switch_info_show(struct kobject *kobj,
 	return ret;
 }
 
+static ssize_t rpc_sysfs_xprt_switch_add_xprt_show(struct kobject *kobj,
+						   struct kobj_attribute *attr,
+						   char *buf)
+{
+	return sprintf(buf, "# add one xprt to this xprt_switch\n");
+}
+
+static ssize_t rpc_sysfs_xprt_switch_add_xprt_store(struct kobject *kobj,
+						    struct kobj_attribute *attr,
+						    const char *buf, size_t count)
+{
+	struct rpc_xprt_switch *xprt_switch =
+		rpc_sysfs_xprt_switch_kobj_get_xprt(kobj);
+	struct xprt_create xprt_create_args;
+	struct rpc_xprt *xprt, *new;
+
+	if (!xprt_switch)
+		return 0;
+
+	xprt = rpc_xprt_switch_get_main_xprt(xprt_switch);
+	if (!xprt)
+		goto out;
+
+	xprt_create_args.ident = xprt->xprt_class->ident;
+	xprt_create_args.net = xprt->xprt_net;
+	xprt_create_args.dstaddr = (struct sockaddr *)&xprt->addr;
+	xprt_create_args.addrlen = xprt->addrlen;
+	xprt_create_args.servername = xprt->servername;
+	xprt_create_args.bc_xprt = xprt->bc_xprt;
+	xprt_create_args.xprtsec = xprt->xprtsec;
+	xprt_create_args.connect_timeout = xprt->connect_timeout;
+	xprt_create_args.reconnect_timeout = xprt->max_reconnect_timeout;
+
+	new = xprt_create_transport(&xprt_create_args);
+	if (IS_ERR_OR_NULL(new)) {
+		count = PTR_ERR(new);
+		goto out_put_xprt;
+	}
+
+	rpc_xprt_switch_add_xprt(xprt_switch, new);
+	xprt_put(new);
+
+out_put_xprt:
+	xprt_put(xprt);
+out:
+	xprt_switch_put(xprt_switch);
+	return count;
+}
+
 static ssize_t rpc_sysfs_xprt_dstaddr_store(struct kobject *kobj,
 					    struct kobj_attribute *attr,
 					    const char *buf, size_t count)
@@ -523,8 +572,13 @@ ATTRIBUTE_GROUPS(rpc_sysfs_xprt);
 static struct kobj_attribute rpc_sysfs_xprt_switch_info =
 	__ATTR(xprt_switch_info, 0444, rpc_sysfs_xprt_switch_info_show, NULL);
 
+static struct kobj_attribute rpc_sysfs_xprt_switch_add_xprt =
+	__ATTR(add_xprt, 0644, rpc_sysfs_xprt_switch_add_xprt_show,
+		rpc_sysfs_xprt_switch_add_xprt_store);
+
 static struct attribute *rpc_sysfs_xprt_switch_attrs[] = {
 	&rpc_sysfs_xprt_switch_info.attr,
+	&rpc_sysfs_xprt_switch_add_xprt.attr,
 	NULL,
 };
 ATTRIBUTE_GROUPS(rpc_sysfs_xprt_switch);
diff --git a/net/sunrpc/xprtmultipath.c b/net/sunrpc/xprtmultipath.c
index 720d3ba742ec..a07b81ce93c3 100644
--- a/net/sunrpc/xprtmultipath.c
+++ b/net/sunrpc/xprtmultipath.c
@@ -92,6 +92,27 @@ void rpc_xprt_switch_remove_xprt(struct rpc_xprt_switch *xps,
 	xprt_put(xprt);
 }
 
+/**
+ * rpc_xprt_switch_get_main_xprt - Get the 'main' xprt for an xprt switch.
+ * @xps: pointer to struct rpc_xprt_switch.
+ */
+struct rpc_xprt *rpc_xprt_switch_get_main_xprt(struct rpc_xprt_switch *xps)
+{
+	struct rpc_xprt_iter xpi;
+	struct rpc_xprt *xprt;
+
+	xprt_iter_init_listall(&xpi, xps);
+
+	xprt = xprt_iter_get_xprt(&xpi);
+	while (xprt && !xprt->main) {
+		xprt_put(xprt);
+		xprt = xprt_iter_get_next(&xpi);
+	}
+
+	xprt_iter_destroy(&xpi);
+	return xprt;
+}
+
 static DEFINE_IDA(rpc_xprtswitch_ids);
 
 void xprt_multipath_cleanup_ids(void)
-- 
2.48.1