On Mon, Sep 29, 2014 at 5:29 PM, Al Viro <viro@xxxxxxxxxxxxxxxxxx> wrote: > On Mon, Sep 29, 2014 at 05:14:55PM -0700, Andy Lutomirski wrote: >> I understand that: >> >> # mount --make-rshared / >> # mount --rbind / /mnt >> # umount - /mnt/dev >> >> should unmount /dev. That's the whole point. But why does unmounting >> */mnt* propagate like that? It doesn't unmount /. To me, this makes >> about as much sense as having 'umount -l /mnt/dev' unmount /dev/pts >> but *not* /dev would make. > > Aha. And what, pray tell, does umount -l /mnt do to mounts deeper in > the tree? Forget about shared, etc. - what, in your opinion, does umount -l > mean wrt the stuff mounted on /mnt? /mnt/dev, for example... Ideally it would leave them around until the whole subtree had no references, at which point /mnt and everything under it would disappear with no side effects, because it has no references. I suspect it detaches them immediately, especially after reading the rest of your email. > >> > What for? >> >> Simplicity and comprehensibility. > > Such an elegant way to say "I can't be arsed to read"... For what it's > worth: MNT_DETACH is *not* "detach the subtree as whole, busy or not". > It's "unmount all mounts within the subtree, busy or not". At which point > the self-LART you keep describing becomes quite easy to comprehend, doesn't > it? Again, *I have no problem with the current semantics of umount -l*, except insofar as they interact really nastily with shared subtrees. I have a problem with bidirectional shared subtrees *in general*. --Andy -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
