SUNRPC: add xprt switch API for printing formatted remote peer addresses

Add a new method to the transport switch API to provide a way to convert
the opaque contents of xprt->addr to a human-readable string.

Test plan:
Compile kernel with CONFIG_NFS enabled.

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

2 files changed, 82 insertions, 8 deletions

diff --git a/include/linux/sunrpc/xprt.h b/include/linux/sunrpc/xprt.h
index 84122559fa17..8372ab8fc9b5 100644
--- a/include/linux/sunrpc/xprt.h
+++ b/include/linux/sunrpc/xprt.h
@@ -51,6 +51,14 @@ struct rpc_timeout {
         unsigned char           to_exponential;
 };
 
+enum rpc_display_format_t {
+        RPC_DISPLAY_ADDR = 0,
+        RPC_DISPLAY_PORT,
+        RPC_DISPLAY_PROTO,
+        RPC_DISPLAY_ALL,
+        RPC_DISPLAY_MAX,
+};
+
 struct rpc_task;
 struct rpc_xprt;
 struct seq_file;
@@ -103,6 +111,7 @@ struct rpc_rqst {
 
 struct rpc_xprt_ops {
         void            (*set_buffer_size)(struct rpc_xprt *xprt, size_t sndsize, size_t rcvsize);
+        char *          (*print_addr)(struct rpc_xprt *xprt, enum rpc_display_format_t format);
         int             (*reserve_xprt)(struct rpc_task *task);
         void            (*release_xprt)(struct rpc_xprt *xprt, struct rpc_task *task);
         void            (*rpcbind)(struct rpc_task *task);
@@ -207,6 +216,8 @@ struct rpc_xprt {
         void                    (*old_data_ready)(struct sock *, int);
         void                    (*old_state_change)(struct sock *);
         void                    (*old_write_space)(struct sock *);
+
+        char *                  address_strings[RPC_DISPLAY_MAX];
 };
 
 #define XPRT_LAST_FRAG          (1 << 0)
diff --git a/net/sunrpc/xprtsock.c b/net/sunrpc/xprtsock.c
index 4c98b89a5b48..cb8e6c34e12f 100644
--- a/net/sunrpc/xprtsock.c
+++ b/net/sunrpc/xprtsock.c
@@ -125,6 +125,47 @@ static inline void xs_pktdump(char *msg, u32 *packet, unsigned int count)
 }
 #endif
 
+static void xs_format_peer_addresses(struct rpc_xprt *xprt)
+{
+        struct sockaddr_in *addr = (struct sockaddr_in *) &xprt->addr;
+        char *buf;
+
+        buf = kzalloc(20, GFP_KERNEL);
+        if (buf) {
+                snprintf(buf, 20, "%u.%u.%u.%u",
+                                NIPQUAD(addr->sin_addr.s_addr));
+        }
+        xprt->address_strings[RPC_DISPLAY_ADDR] = buf;
+
+        buf = kzalloc(8, GFP_KERNEL);
+        if (buf) {
+                snprintf(buf, 8, "%u",
+                                ntohs(addr->sin_port));
+        }
+        xprt->address_strings[RPC_DISPLAY_PORT] = buf;
+
+        if (xprt->prot == IPPROTO_UDP)
+                xprt->address_strings[RPC_DISPLAY_PROTO] = "udp";
+        else
+                xprt->address_strings[RPC_DISPLAY_PROTO] = "tcp";
+
+        buf = kzalloc(48, GFP_KERNEL);
+        if (buf) {
+                snprintf(buf, 48, "addr=%u.%u.%u.%u port=%u proto=%s",
+                        NIPQUAD(addr->sin_addr.s_addr),
+                        ntohs(addr->sin_port),
+                        xprt->prot == IPPROTO_UDP ? "udp" : "tcp");
+        }
+        xprt->address_strings[RPC_DISPLAY_ALL] = buf;
+}
+
+static void xs_free_peer_addresses(struct rpc_xprt *xprt)
+{
+        kfree(xprt->address_strings[RPC_DISPLAY_ADDR]);
+        kfree(xprt->address_strings[RPC_DISPLAY_PORT]);
+        kfree(xprt->address_strings[RPC_DISPLAY_ALL]);
+}
+
 #define XS_SENDMSG_FLAGS        (MSG_DONTWAIT | MSG_NOSIGNAL)
 
 static inline int xs_send_head(struct socket *sock, struct sockaddr *addr, int addrlen, struct xdr_buf *xdr, unsigned int base, unsigned int len)
@@ -490,6 +531,7 @@ static void xs_destroy(struct rpc_xprt *xprt)
 
         xprt_disconnect(xprt);
         xs_close(xprt);
+        xs_free_peer_addresses(xprt);
         kfree(xprt->slot);
 }
 
@@ -965,6 +1007,19 @@ static unsigned short xs_get_random_port(void)
 }
 
 /**
+ * xs_print_peer_address - format an IPv4 address for printing
+ * @xprt: generic transport
+ * @format: flags field indicating which parts of the address to render
+ */
+static char *xs_print_peer_address(struct rpc_xprt *xprt, enum rpc_display_format_t format)
+{
+        if (xprt->address_strings[format] != NULL)
+                return xprt->address_strings[format];
+        else
+                return "unprintable";
+}
+
+/**
  * xs_set_port - reset the port number in the remote endpoint address
  * @xprt: generic transport
  * @port: new port number
@@ -1019,8 +1074,6 @@ static void xs_udp_connect_worker(void *args)
         if (xprt->shutdown || !xprt_bound(xprt))
                 goto out;
 
-        dprintk("RPC:      xs_udp_connect_worker for xprt %p\n", xprt);
-
         /* Start by resetting any existing state */
         xs_close(xprt);
 
@@ -1034,6 +1087,9 @@ static void xs_udp_connect_worker(void *args)
                 goto out;
         }
 
+        dprintk("RPC:      worker connecting xprt %p to address: %s\n",
+                        xprt, xs_print_peer_address(xprt, RPC_DISPLAY_ALL));
+
         if (!xprt->inet) {
                 struct sock *sk = sock->sk;
 
@@ -1102,8 +1158,6 @@ static void xs_tcp_connect_worker(void *args)
         if (xprt->shutdown || !xprt_bound(xprt))
                 goto out;
 
-        dprintk("RPC:      xs_tcp_connect_worker for xprt %p\n", xprt);
-
         if (!xprt->sock) {
                 /* start from scratch */
                 if ((err = sock_create_kern(PF_INET, SOCK_STREAM, IPPROTO_TCP, &sock)) < 0) {
@@ -1119,6 +1173,9 @@ static void xs_tcp_connect_worker(void *args)
                 /* "close" the socket, preserving the local port */
                 xs_tcp_reuse_connection(xprt);
 
+        dprintk("RPC:      worker connecting xprt %p to address: %s\n",
+                        xprt, xs_print_peer_address(xprt, RPC_DISPLAY_ALL));
+
         if (!xprt->inet) {
                 struct sock *sk = sock->sk;
 
@@ -1260,6 +1317,7 @@ static void xs_tcp_print_stats(struct rpc_xprt *xprt, struct seq_file *seq)
 
 static struct rpc_xprt_ops xs_udp_ops = {
         .set_buffer_size        = xs_udp_set_buffer_size,
+        .print_addr             = xs_print_peer_address,
         .reserve_xprt           = xprt_reserve_xprt_cong,
         .release_xprt           = xprt_release_xprt_cong,
         .rpcbind                = rpc_getport,
@@ -1277,6 +1335,7 @@ static struct rpc_xprt_ops xs_udp_ops = {
 };
 
 static struct rpc_xprt_ops xs_tcp_ops = {
+        .print_addr             = xs_print_peer_address,
         .reserve_xprt           = xprt_reserve_xprt,
         .release_xprt           = xs_tcp_release_xprt,
         .rpcbind                = rpc_getport,
@@ -1301,8 +1360,6 @@ int xs_setup_udp(struct rpc_xprt *xprt, struct rpc_timeout *to)
 {
         size_t slot_table_size;
 
-        dprintk("RPC:      setting up udp-ipv4 transport...\n");
-
         xprt->max_reqs = xprt_udp_slot_table_entries;
         slot_table_size = xprt->max_reqs * sizeof(xprt->slot[0]);
         xprt->slot = kzalloc(slot_table_size, GFP_KERNEL);
@@ -1332,6 +1389,10 @@ int xs_setup_udp(struct rpc_xprt *xprt, struct rpc_timeout *to)
         else
                 xprt_set_timeout(&xprt->timeout, 5, 5 * HZ);
 
+        xs_format_peer_addresses(xprt);
+        dprintk("RPC:      set up transport to address %s\n",
+                        xs_print_peer_address(xprt, RPC_DISPLAY_ALL));
+
         return 0;
 }
 
@@ -1345,8 +1406,6 @@ int xs_setup_tcp(struct rpc_xprt *xprt, struct rpc_timeout *to)
 {
         size_t slot_table_size;
 
-        dprintk("RPC:      setting up tcp-ipv4 transport...\n");
-
         xprt->max_reqs = xprt_tcp_slot_table_entries;
         slot_table_size = xprt->max_reqs * sizeof(xprt->slot[0]);
         xprt->slot = kzalloc(slot_table_size, GFP_KERNEL);
@@ -1375,5 +1434,9 @@ int xs_setup_tcp(struct rpc_xprt *xprt, struct rpc_timeout *to)
         else
                 xprt_set_timeout(&xprt->timeout, 2, 60 * HZ);
 
+        xs_format_peer_addresses(xprt);
+        dprintk("RPC:      set up transport to address %s\n",
+                        xs_print_peer_address(xprt, RPC_DISPLAY_ALL));
+
         return 0;
 }