sunrpc: add a debugfs rpc_xprt directory with an info file in it

Add a new directory heirarchy under the debugfs sunrpc/ directory:

    sunrpc/
        rpc_xprt/
            <xprt id>/

Within that directory, we can put files that give info about the
xprts. We do have the (minor) problem that there is no succinct,
unique identifier for rpc_xprts. So we generate them synthetically
with a static atomic_t counter.

For now, this directory just holds an "info" file, but we may add
other files to it in the future.

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

2 files changed, 18 insertions, 0 deletions

diff --git a/include/linux/sunrpc/debug.h b/include/linux/sunrpc/debug.h
index 835339707094..c57d8ea0716c 100644
--- a/include/linux/sunrpc/debug.h
+++ b/include/linux/sunrpc/debug.h
@@ -55,6 +55,7 @@ extern unsigned int		nlm_debug;
  */
 
 struct rpc_clnt;
+struct rpc_xprt;
 
 #if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
 void            rpc_register_sysctl(void);
@@ -63,6 +64,8 @@ int		sunrpc_debugfs_init(void);
 void            sunrpc_debugfs_exit(void);
 int             rpc_clnt_debugfs_register(struct rpc_clnt *);
 void            rpc_clnt_debugfs_unregister(struct rpc_clnt *);
+int             rpc_xprt_debugfs_register(struct rpc_xprt *);
+void            rpc_xprt_debugfs_unregister(struct rpc_xprt *);
 #else
 static inline int
 sunrpc_debugfs_init(void)
@@ -87,6 +90,18 @@ rpc_clnt_debugfs_unregister(struct rpc_clnt *clnt)
 {
         return;
 }
+
+static inline int
+rpc_xprt_debugfs_register(struct rpc_xprt *xprt)
+{
+        return 0;
+}
+
+static inline void
+rpc_xprt_debugfs_unregister(struct rpc_xprt *xprt)
+{
+        return;
+}
 #endif
 
 #endif /* _LINUX_SUNRPC_DEBUG_H_ */
diff --git a/include/linux/sunrpc/xprt.h b/include/linux/sunrpc/xprt.h
index cf391eef2e6d..9d27ac45b909 100644
--- a/include/linux/sunrpc/xprt.h
+++ b/include/linux/sunrpc/xprt.h
@@ -239,6 +239,9 @@ struct rpc_xprt {
         struct net              *xprt_net;
         const char              *servername;
         const char              *address_strings[RPC_DISPLAY_MAX];
+#if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
+        struct dentry           *debugfs;               /* debugfs directory */
+#endif
 };
 
 #if defined(CONFIG_SUNRPC_BACKCHANNEL)