[PATCH] RPC,NFS: new rpc_pipefs patch

Currently rpc_mkdir/rpc_rmdir and rpc_mkpipe/mk_unlink have an API that's
 a little unfortunate.  They take a path relative to the rpc_pipefs root and
 thus need to perform a full lookup.  If you look at debugfs or usbfs they
 always store the dentry for directories they created and thus can pass in
 a dentry + single pathname component pair into their equivalents of the
 above functions.

 And in fact rpc_pipefs actually stores a dentry for all but one component so
 this change not only simplifies the core rpc_pipe code but also the callers.

 Unfortuntately this code path is only used by the NFS4 idmapper and
 AUTH_GSSAPI for which I don't have a test enviroment.  Could someone give
 it a spin?  It's the last bit needed before we can rework the
 lookup_hash API

 Signed-off-by: Christoph Hellwig <hch@lst.de>
 Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

net/sunrpc/clnt.c

@@ -67,26 +67,42 @@ static u32 *	call_verify(struct rpc_task *task);
 static int
 rpc_setup_pipedir(struct rpc_clnt *clnt, char *dir_name)
 {
-	static uint32_t clntid;
+	static unsigned int clntid;
+	char name[128];
 	int error;
 
 	if (dir_name == NULL)
 		return 0;
-	for (;;) {
-		snprintf(clnt->cl_pathname, sizeof(clnt->cl_pathname),
-				"%s/clnt%x", dir_name,
-				(unsigned int)clntid++);
-		clnt->cl_pathname[sizeof(clnt->cl_pathname) - 1] = '\0';
-		clnt->cl_dentry = rpc_mkdir(clnt->cl_pathname, clnt);
-		if (!IS_ERR(clnt->cl_dentry))
-			return 0;
-		error = PTR_ERR(clnt->cl_dentry);
-		if (error != -EEXIST) {
-			printk(KERN_INFO "RPC: Couldn't create pipefs entry %s, error %d\n",
-					clnt->cl_pathname, error);
-			return error;
-		}
+
+ retry_parent:
+	clnt->__cl_parent_dentry = rpc_mkdir(NULL, dir_name, NULL);
+	if (IS_ERR(clnt->__cl_parent_dentry)) {
+		error = PTR_ERR(clnt->__cl_parent_dentry);
+		if (error == -EEXIST)
+			goto retry_parent; /* XXX(hch): WTF? */
+	
+		printk(KERN_INFO "RPC: Couldn't create pipefs entry %s, error %d\n",
+				dir_name, error);
+		return error;
 	}
+
+
+ retry_child:
+	snprintf(name, sizeof(name), "clnt%x", clntid++);
+	name[sizeof(name) - 1] = '\0';
+
+	clnt->cl_dentry = rpc_mkdir(clnt->__cl_parent_dentry, name, clnt);
+	if (IS_ERR(clnt->cl_dentry)) {
+		error = PTR_ERR(clnt->cl_dentry);
+		if (error == -EEXIST)
+			goto retry_child;
+		printk(KERN_INFO "RPC: Couldn't create pipefs entry %s, error %d\n",
+				name, error);
+		rpc_rmdir(clnt->__cl_parent_dentry);
+		return error;
+	}
+
+	return 0;
 }
 
 /*
@@ -174,7 +190,8 @@ rpc_new_client(struct rpc_xprt *xprt, char *servname,
 	return clnt;
 
 out_no_auth:
-	rpc_rmdir(clnt->cl_pathname);
+	rpc_rmdir(clnt->cl_dentry);
+	rpc_rmdir(clnt->__cl_parent_dentry);
 out_no_path:
 	if (clnt->cl_server != clnt->cl_inline_name)
 		kfree(clnt->cl_server);
@@ -302,8 +319,10 @@ rpc_destroy_client(struct rpc_clnt *clnt)
 		rpc_destroy_client(clnt->cl_parent);
 		goto out_free;
 	}
-	if (clnt->cl_pathname[0])
-		rpc_rmdir(clnt->cl_pathname);
+	if (clnt->cl_dentry)
+		rpc_rmdir(clnt->cl_dentry);
+	if (clnt->__cl_parent_dentry)
+		rpc_rmdir(clnt->__cl_parent_dentry);
 	if (clnt->cl_xprt) {
 		xprt_destroy(clnt->cl_xprt);
 		clnt->cl_xprt = NULL;