SUNRPC: Add a structure to track multiple transports

In order to support multipathing/trunking we will need the ability to
track multiple transports. This patch sets up a basic structure for
doing so.

Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>

2 files changed, 74 insertions, 0 deletions

diff --git a/include/linux/sunrpc/xprt.h b/include/linux/sunrpc/xprt.h
index 83218129ff28..fb0d212e0d3a 100644
--- a/include/linux/sunrpc/xprt.h
+++ b/include/linux/sunrpc/xprt.h
@@ -198,6 +198,11 @@ struct rpc_xprt {
         unsigned int            bind_index;     /* bind function index */
 
         /*
+         * Multipath
+         */
+        struct list_head        xprt_switch;
+
+        /*
          * Connection of transports
          */
         unsigned long           bind_timeout,
diff --git a/include/linux/sunrpc/xprtmultipath.h b/include/linux/sunrpc/xprtmultipath.h
new file mode 100644
index 000000000000..5a9acffa41be
--- /dev/null
+++ b/include/linux/sunrpc/xprtmultipath.h
@@ -0,0 +1,69 @@
+/*
+ * RPC client multipathing definitions
+ *
+ * Copyright (c) 2015, 2016, Primary Data, Inc. All rights reserved.
+ *
+ * Trond Myklebust <trond.myklebust@primarydata.com>
+ */
+#ifndef _NET_SUNRPC_XPRTMULTIPATH_H
+#define _NET_SUNRPC_XPRTMULTIPATH_H
+
+struct rpc_xprt_iter_ops;
+struct rpc_xprt_switch {
+        spinlock_t              xps_lock;
+        struct kref             xps_kref;
+
+        unsigned int            xps_nxprts;
+        struct list_head        xps_xprt_list;
+
+        struct net *            xps_net;
+
+        const struct rpc_xprt_iter_ops *xps_iter_ops;
+
+        struct rcu_head         xps_rcu;
+};
+
+struct rpc_xprt_iter {
+        struct rpc_xprt_switch __rcu *xpi_xpswitch;
+        struct rpc_xprt *       xpi_cursor;
+
+        const struct rpc_xprt_iter_ops *xpi_ops;
+};
+
+
+struct rpc_xprt_iter_ops {
+        void (*xpi_rewind)(struct rpc_xprt_iter *);
+        struct rpc_xprt *(*xpi_xprt)(struct rpc_xprt_iter *);
+        struct rpc_xprt *(*xpi_next)(struct rpc_xprt_iter *);
+};
+
+extern struct rpc_xprt_switch *xprt_switch_alloc(struct rpc_xprt *xprt,
+                gfp_t gfp_flags);
+
+extern struct rpc_xprt_switch *xprt_switch_get(struct rpc_xprt_switch *xps);
+extern void xprt_switch_put(struct rpc_xprt_switch *xps);
+
+extern void rpc_xprt_switch_set_roundrobin(struct rpc_xprt_switch *xps);
+
+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);
+
+extern void xprt_iter_init(struct rpc_xprt_iter *xpi,
+                struct rpc_xprt_switch *xps);
+
+extern void xprt_iter_init_listall(struct rpc_xprt_iter *xpi,
+                struct rpc_xprt_switch *xps);
+
+extern void xprt_iter_destroy(struct rpc_xprt_iter *xpi);
+
+extern struct rpc_xprt_switch *xprt_iter_xchg_switch(
+                struct rpc_xprt_iter *xpi,
+                struct rpc_xprt_switch *newswitch);
+
+extern struct rpc_xprt *xprt_iter_xprt(struct rpc_xprt_iter *xpi);
+extern struct rpc_xprt *xprt_iter_get_xprt(struct rpc_xprt_iter *xpi);
+extern struct rpc_xprt *xprt_iter_get_next(struct rpc_xprt_iter *xpi);
+
+#endif