On Tue, 2012-08-21 at 20:21 -0600, Bob Proulx wrote: > Ross Boylan wrote: > > I setup a chroot on a snapshot. Part of the setup was > > mount --rbind /dev /mnt/chrtest/dev > > Why did you choose "rbind" over "bind". Just curious. My reply is > the one I would give if you had used bind. I have never used rbind. > The result may be wrong for rbind. But it would be right for bind. I started with nothing mounted under /dev (and maybe /proc and /sys too) in the chroot and kept adding things that I needed to make screen and aptitude, and the package installers (e.g., some needed df to work) happy inside the chroot. At first I just mounted /dev/pts, but found that was not enough. rbind picks up /dev/pts and /dev/shm.
It's certainly not something to take as a model; it's just what sort of worked for me. > > > I have exited the chroot and, I believe, ended the processes I started. > > umount /mnt/chrtest/dev > > gives umount: /mnt/chrtest/dev: device is busy > > > > How can I get this to work? > > Unmount that path. Look at /proc/mounts for the path to anything > mounted in that directory tree and unmount it. You will see something > like this bind mount. > > udev /srv/chroot/sid/dev devtmpfs > rw,relatime,size=10240k,nr_inodes=493001,mode=755 0 0 my host system shows udev /mnt/chrtest/dev tmpfs rw,size=10240k,mode=755 0 0 > > In which case the umount command would be: > > # umount /srv/chroot/sid/dev The corresponding command is the one I tried. That failed with "device is busy". > > > After reviewing the output of mount I umounted the mounts below /dev, > > which seems to be the main advice on the net for undoing rbinds. > > I think instead of unmounting below /dev you needed to unmount below > /mnt/chartest/dev instead. I was speaking loosely; I meant below /dev in the chroot, i.e., /mnt/chrtest/dev/pts and the shm directory. Those mounts are now gone, as verified by /proc/mounts (/proc/mounts on the host system). /dev/pts is still mounted on the host. > > If you really get stuck then rebooting should restore things to a sane > state since those mounts will not exist after a reboot. But you > should be able to recover without rebooting. That's my hope. It might be relevant that I began with a logical volume mounted at /mnt/chroot, with various submounts including /mnt/chroot/dev. I created a snapshot of the first logical volume and mounted it at /mnt/chrtest. I mounted stuff under it, ran some tests, shut down what I could in the /mnt/chrtest chroot, and umounted what I could. But I can't seem to umount /mnt/chrtest/dev or (as a result, I think) /mnt/chrtest itseelf. Ross -- To UNSUBSCRIBE, email to debian-user-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org Archive: http://lists.debian.org/1345611934.9282.117.ca...@corn.betterworld.us
