[PATCH] sanitize __user_walk_fd() et.al.

* do not pass nameidata; struct path is all the callers want.
* switch to new helpers:
	user_path_at(dfd, pathname, flags, &path)
	user_path(pathname, &path)
	user_lpath(pathname, &path)
	user_path_dir(pathname, &path)  (fail if not a directory)
  The last 3 are trivial macro wrappers for the first one.
* remove nameidata in callers.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/xfs/linux-2.6/xfs_ioctl.c b/fs/xfs/linux-2.6/xfs_ioctl.c
index a42ba9d..01939ba 100644
--- a/fs/xfs/linux-2.6/xfs_ioctl.c
+++ b/fs/xfs/linux-2.6/xfs_ioctl.c
@@ -84,17 +84,15 @@
 	switch (cmd) {
 	case XFS_IOC_PATH_TO_FSHANDLE:
 	case XFS_IOC_PATH_TO_HANDLE: {
-		struct nameidata	nd;
-		int			error;
-
-		error = user_path_walk_link((const char __user *)hreq.path, &nd);
+		struct path path;
+		int error = user_lpath((const char __user *)hreq.path, &path);
 		if (error)
 			return error;
 
-		ASSERT(nd.path.dentry);
-		ASSERT(nd.path.dentry->d_inode);
-		inode = igrab(nd.path.dentry->d_inode);
-		path_put(&nd.path);
+		ASSERT(path.dentry);
+		ASSERT(path.dentry->d_inode);
+		inode = igrab(path.dentry->d_inode);
+		path_put(&path);
 		break;
 	}