vfs: add path_put_init()

This one initializes the struct path to all zeroes so that multiple
path_put_init() on the path is safe.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

include/linux/path.h

@@ -18,4 +18,10 @@ static inline int path_equal(const struct path *path1, const struct path *path2)
 	return path1->mnt == path2->mnt && path1->dentry == path2->dentry;
 }
 
+static inline void path_put_init(struct path *path)
+{
+	path_put(path);
+	*path = (struct path) { };
+}
+
 #endif  /* _LINUX_PATH_H */