[Adding util-linux@vger and Michael Kerrisk] On Wed, Jan 17, 2018 at 5:17 AM, Al Viro <viro@xxxxxxxxxxxxxxxxxx> wrote: > On Tue, Jan 16, 2018 at 05:41:46PM +0100, Miklos Szeredi wrote: > >> Right. >> >> Still, those two (propagation and flags) are properties of the mount. >> No fundamental difference in how to handle them, that I see. Okay, we >> have MS_REC handling in the propagation and not in the flags, but >> that's something that might make sense for flags as well. >> >> What's more interesting is how MS_PRIVATE + MS_REC semantics are >> complete failure in the real world: the logical thing would be to mark >> a mount private on the supplied mount AND propagate an umount event to >> everywhere else. > > This is utter nonsense. Most of the time it's "Fedora, in its infinite > bogo^Wwisdom has made everything shared; I don't fucking need that > idiocy, so please unshare this, this and that". You really don't want > (or have permissions for) unmounting e.g. /mnt in namespace of init > when you do that. > > Sure, we get tons of bug reports. Due to idiotic Fedora setup, with > everything shared. The same setup that would go up in flames on the > semantics change you propose. I wouldn't propose to change existing --make-private, as this would not be backward compatible. The new semantics would mean a new op, obviously. Documenting --make-private thing properly would also help. To me the wording "make private" strongly implies "I want to make submounts private to this instance". See for example rhbz#1432211. > If anything, "private bind on itself" would be a useful operation. > Turning given location into a mountpoint, and having everything > under it looking as it used to, but with no propagation at all. > Without bothering anybody else, even if location currently happens > to be on a shared/master mount. > > I can slap that together for mount(2), but I'm not sure what a sane > combination of flags for that would look like ;-) For fsmount > I think it would be very useful thing to have. Yes, I think such an operation would be pretty useful. Not sure if it's the whole story, though. Thanks, Miklos
