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[Serge Hallyn <1402834@xxxxxxxxxxxxxxxxxx>]

> The other question is whether or not lxc acutally needs to use MNT_FORCE
> when unmounting. What's the reason for doing so?

lxc doesn't.  Ubuntu does.  But the point is that any user can disconnect
any other user's fuse connections, so this now looks much more serious
than it did at first.  Joe can disconnect my sshfs.

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https://bugs.launchpad.net/bugs/1402834

Title:
  fuse filesystems get disconnected on container exit

Status in linux package in Ubuntu:
  Confirmed

Bug description:
  When bind-mounting a directory from a fuse filesytems into a container,
  then when the container is shut down, the userspace process serving the
  fuse fs is terminated.  The original fuse mountpoint remains busy until it
  is manually unmounted.

  I've tested this with sshfs, git://github.com/stgraber/cgmanagerfs,
  the bbfs example fs from http://www.cs.nmsu.edu/~pfeiffer/fuse-tutorial/,
  or git://github.com/lxc/lxcfs.

  To reproduce:

  Mount a fusefs - say sshfs - with -o allow_other, let's say onto
  /tmp/d.

  sshfs -f -d -o allow_other somehost:$HOME /tmp/d

  Bind that into a container by adding

  lxc.mount.entry = /tmp/d freezer none bind,create=dir 0 0

  to the container's config.

  start the container, stop it.

  the fuse program stops (exits 0 in fact)

  the mount is not cleaned up - ls /tmp/d on the host henceforth
  complains:

  	ls: cannot access /tmp/d Transport endpoint is not connected"
  	
  (sudo umount /tmp/d cleans it up)

  I don't know for sure whether this is a kernel or libfuse bug.

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