SUNRPC: Support for RPC over AF_LOCAL transports

TI-RPC introduces the capability of performing RPC over AF_LOCAL
sockets.  It uses this mainly for registering and unregistering
local RPC services securely with the local rpcbind, but we could
also conceivably use it as a generic upcall mechanism.

This patch provides a client-side only implementation for the moment.
We might also consider a server-side implementation to provide
AF_LOCAL access to NLM (for statd downcalls, and such like).

Autobinding is not supported on kernel AF_LOCAL transports at this
time.  Kernel ULPs must specify the pathname of the remote endpoint
when an AF_LOCAL transport is created.  rpcbind supports registering
services available via AF_LOCAL, so the kernel could handle it with
some adjustment to ->rpcbind and ->set_port.  But we don't need this
feature for doing upcalls via well-known named sockets.

This has not been tested with ULPs that move a substantial amount of
data.  Thus, I can't attest to how robust the write_space and
congestion management logic is.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

1 files changed, 8 insertions, 0 deletions

diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c
index 08ed49629b86..b84d7395535e 100644
--- a/net/sunrpc/clnt.c
+++ b/net/sunrpc/clnt.c
@@ -28,7 +28,9 @@
 #include <linux/slab.h>
 #include <linux/utsname.h>
 #include <linux/workqueue.h>
+#include <linux/in.h>
 #include <linux/in6.h>
+#include <linux/un.h>
 
 #include <linux/sunrpc/clnt.h>
 #include <linux/sunrpc/rpc_pipe_fs.h>
@@ -294,6 +296,8 @@ struct rpc_clnt *rpc_create(struct rpc_create_args *args)
          * up a string representation of the passed-in address.
          */
         if (args->servername == NULL) {
+                struct sockaddr_un *sun =
+                                (struct sockaddr_un *)args->address;
                 struct sockaddr_in *sin =
                                 (struct sockaddr_in *)args->address;
                 struct sockaddr_in6 *sin6 =
@@ -301,6 +305,10 @@ struct rpc_clnt *rpc_create(struct rpc_create_args *args)
 
                 servername[0] = '\0';
                 switch (args->address->sa_family) {
+                case AF_LOCAL:
+                        snprintf(servername, sizeof(servername), "%s",
+                                 sun->sun_path);
+                        break;
                 case AF_INET:
                         snprintf(servername, sizeof(servername), "%pI4",
                                  &sin->sin_addr.s_addr);