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>

4 files changed, 403 insertions, 4 deletions

diff --git a/include/linux/sunrpc/msg_prot.h b/include/linux/sunrpc/msg_prot.h
index 77e624883393..c68a147939a6 100644
--- a/include/linux/sunrpc/msg_prot.h
+++ b/include/linux/sunrpc/msg_prot.h
@@ -145,6 +145,7 @@ typedef __be32	rpc_fraghdr;
 #define RPCBIND_NETID_TCP       "tcp"
 #define RPCBIND_NETID_UDP6      "udp6"
 #define RPCBIND_NETID_TCP6      "tcp6"
+#define RPCBIND_NETID_LOCAL     "local"
 
 /*
  * Note that RFC 1833 does not put any size restrictions on the
diff --git a/include/linux/sunrpc/xprt.h b/include/linux/sunrpc/xprt.h
index a0f998c07c65..81cce3b3ee66 100644
--- a/include/linux/sunrpc/xprt.h
+++ b/include/linux/sunrpc/xprt.h
@@ -141,7 +141,8 @@ enum xprt_transports {
         XPRT_TRANSPORT_UDP      = IPPROTO_UDP,
         XPRT_TRANSPORT_TCP      = IPPROTO_TCP,
         XPRT_TRANSPORT_BC_TCP   = IPPROTO_TCP | XPRT_TRANSPORT_BC,
-        XPRT_TRANSPORT_RDMA     = 256
+        XPRT_TRANSPORT_RDMA     = 256,
+        XPRT_TRANSPORT_LOCAL    = 257,
 };
 
 struct rpc_xprt {
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);
diff --git a/net/sunrpc/xprtsock.c b/net/sunrpc/xprtsock.c
index 079366974e1f..72abb7358933 100644
--- a/net/sunrpc/xprtsock.c
+++ b/net/sunrpc/xprtsock.c
@@ -19,6 +19,7 @@
  */
 
 #include <linux/types.h>
+#include <linux/string.h>
 #include <linux/slab.h>
 #include <linux/module.h>
 #include <linux/capability.h>
@@ -28,6 +29,7 @@
 #include <linux/in.h>
 #include <linux/net.h>
 #include <linux/mm.h>
+#include <linux/un.h>
 #include <linux/udp.h>
 #include <linux/tcp.h>
 #include <linux/sunrpc/clnt.h>
@@ -45,6 +47,9 @@
 #include <net/tcp.h>
 
 #include "sunrpc.h"
+
+static void xs_close(struct rpc_xprt *xprt);
+
 /*
  * xprtsock tunables
  */
@@ -261,6 +266,11 @@ static inline struct sockaddr *xs_addr(struct rpc_xprt *xprt)
         return (struct sockaddr *) &xprt->addr;
 }
 
+static inline struct sockaddr_un *xs_addr_un(struct rpc_xprt *xprt)
+{
+        return (struct sockaddr_un *) &xprt->addr;
+}
+
 static inline struct sockaddr_in *xs_addr_in(struct rpc_xprt *xprt)
 {
         return (struct sockaddr_in *) &xprt->addr;
@@ -276,23 +286,34 @@ static void xs_format_common_peer_addresses(struct rpc_xprt *xprt)
         struct sockaddr *sap = xs_addr(xprt);
         struct sockaddr_in6 *sin6;
         struct sockaddr_in *sin;
+        struct sockaddr_un *sun;
         char buf[128];
 
-        (void)rpc_ntop(sap, buf, sizeof(buf));
-        xprt->address_strings[RPC_DISPLAY_ADDR] = kstrdup(buf, GFP_KERNEL);
-
         switch (sap->sa_family) {
+        case AF_LOCAL:
+                sun = xs_addr_un(xprt);
+                strlcpy(buf, sun->sun_path, sizeof(buf));
+                xprt->address_strings[RPC_DISPLAY_ADDR] =
+                                                kstrdup(buf, GFP_KERNEL);
+                break;
         case AF_INET:
+                (void)rpc_ntop(sap, buf, sizeof(buf));
+                xprt->address_strings[RPC_DISPLAY_ADDR] =
+                                                kstrdup(buf, GFP_KERNEL);
                 sin = xs_addr_in(xprt);
                 snprintf(buf, sizeof(buf), "%08x", ntohl(sin->sin_addr.s_addr));
                 break;
         case AF_INET6:
+                (void)rpc_ntop(sap, buf, sizeof(buf));
+                xprt->address_strings[RPC_DISPLAY_ADDR] =
+                                                kstrdup(buf, GFP_KERNEL);
                 sin6 = xs_addr_in6(xprt);
                 snprintf(buf, sizeof(buf), "%pi6", &sin6->sin6_addr);
                 break;
         default:
                 BUG();
         }
+
         xprt->address_strings[RPC_DISPLAY_HEX_ADDR] = kstrdup(buf, GFP_KERNEL);
 }
 
@@ -506,6 +527,60 @@ static inline void xs_encode_stream_record_marker(struct xdr_buf *buf)
 }
 
 /**
+ * xs_local_send_request - write an RPC request to an AF_LOCAL socket
+ * @task: RPC task that manages the state of an RPC request
+ *
+ * Return values:
+ *        0:    The request has been sent
+ *   EAGAIN:    The socket was blocked, please call again later to
+ *              complete the request
+ * ENOTCONN:    Caller needs to invoke connect logic then call again
+ *    other:    Some other error occured, the request was not sent
+ */
+static int xs_local_send_request(struct rpc_task *task)
+{
+        struct rpc_rqst *req = task->tk_rqstp;
+        struct rpc_xprt *xprt = req->rq_xprt;
+        struct sock_xprt *transport =
+                                container_of(xprt, struct sock_xprt, xprt);
+        struct xdr_buf *xdr = &req->rq_snd_buf;
+        int status;
+
+        xs_encode_stream_record_marker(&req->rq_snd_buf);
+
+        xs_pktdump("packet data:",