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[Serge Hallyn <1402834@xxxxxxxxxxxxxxxxxx>]

My guess is that this has been deemed a non-issue until now because '-o
allow_other' is not the norm.

The kernel code doing this is straightforward:
fs/namespace.;do_umount() calls sb->umount_begin() if MNT_FORCE is
specified;  fs/fuse/inode.c:fuse_umount_begin() calls:
fuse_abort_conn(get_fuse_conn_super(sb))

So the answer presumable is for fuse_umount_begin() to only call
fuse_abort_conn() if the caller is in fact the owner of the sb?  If so,
go ahead.  If not, and if there are other remaining mounts, do nothing.
Or finally, if not, and there are no other remaining mounts, then go
ahead.

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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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