On Sun, Jun 03, 2018 at 01:55:37AM +0100, Al Viro wrote: > +SYSCALL_DEFINE3(open_tree, int, dfd, const char *, filename, unsigned, flags) > +{ > + struct file *file; > + struct path path; > + int lookup_flags = LOOKUP_AUTOMOUNT | LOOKUP_FOLLOW; > + bool detached = flags & OPEN_TREE_CLONE; > + int error; > + int fd; > + > + BUILD_BUG_ON(OPEN_TREE_CLOEXEC != O_CLOEXEC); Why do we need OPEN_TREE_CLOEXEC? Wouldn't we be better off just making the fd returned by open_tree implicitly close-on-exec? I can think of no good reason for these file descriptors to be inherited across exec() and if someone comes up with such a reason, fcntl(F_SETFD) is not an expensive call to make.