new helper: file_inode(file)

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/arch/s390/kernel/debug.c b/arch/s390/kernel/debug.c
index 4e8215e..19dcf13 100644
--- a/arch/s390/kernel/debug.c
+++ b/arch/s390/kernel/debug.c
@@ -611,7 +611,7 @@
 	debug_info_t *debug_info, *debug_info_snapshot;
 
 	mutex_lock(&debug_mutex);
-	debug_info = file->f_path.dentry->d_inode->i_private;
+	debug_info = file_inode(file)->i_private;
 	/* find debug view */
 	for (i = 0; i < DEBUG_MAX_VIEWS; i++) {
 		if (!debug_info->views[i])