nilfs2 cannot umount, device is always busy

[dan]

nilfs-tools 2.1.5-1 on a fresh install ubuntu 13.10 x86_64

The filesystem mounts and seems to be working correctly (also lscp, mkcp and others seem to work as expected), but when trying to umount the device (be it a real partition, loop device or luks device) the result is always this one:

# umount /mnt/nilfs/
umount.nilfs2: /dev/loop0: device is busy
umount.nilfs2: /dev/loop0: device is busy

# umount /dev/loop0
umount.nilfs2: /dev/loop0: device is busy
umount.nilfs2: /dev/loop0: device is busy

# lsof /mnt/nilfs/
      Output information may be incomplete.
COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME
nilfs_cle 2777 root 5r DIR 7,0 4096 2 /mnt/nilfs

# ps aux | grep 2777
root 2777 0.0 0.0 14824 904 ? Ss 19:59 0:00 /sbin/nilfs_cleanerd -n /dev/loop0 /mnt/nilfs

# kill -9 2777
# umount /mnt/nilfs/ <-- Works

So, it seems like nilfs_cleanered prevents the device from being umounted at all times. This bug is reproducible 100% of the times for me.
Killing the deamon seems to be the only way to umount a nilfs2 mounted partition.

--EDIT--
This is also reproducible when booting from the live CD image of ubuntu 13.10_64 (I booted from liveCD image, added community repository and "apt-get update && apt-get install nilfs-tools")

--EDIT2--
Version 2.1.0-1 of nilfs-tools on Ubuntu 12.04.3 LTS was unaffected from this bug, just tested it.

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Curtis Gedak (gedakc)]

This problem also occurs on a fresh install of Ubuntu 13.10 i386 from the ubuntu-13.10-desktop-i386.iso file.

A sample session demonstrating this problem follows:

root@saucy:~# gparted /dev/sdb # Create 512 MiB nilfs2 sdb1
======================
libparted : 2.3
======================
root@saucy:~# mount -t nilfs2 /dev/sdb1 /mnt
root@saucy:~# umount /mnt
umount.nilfs2: /dev/sdb1: device is busy
umount.nilfs2: /dev/sdb1: device is busy
root@saucy:~# ps -e | grep nilfs
 2242 ? 00:00:00 nilfs_cleanerd
root@saucy:~# kill 2242
root@saucy:~# umount /mnt
root@saucy:~#

[Akhilesh Chaganti (akhilesh-chg)]

Hitting this issue on Fresh install of Ubuntu Server 14.04 LTS x86_64.

====================================================
root@gr3:~# mkfs.nilfs2 -f /dev/sdb1
mkfs.nilfs2 (nilfs-utils 2.1.5)
Start writing file system initial data to the device
       Blocksize:4096 Device:/dev/sdb1 Device Size:146162057216
File system initialization succeeded !!
root@gr3:~# mount /dev/sd
sda sda1 sda2 sda5 sdb sdb1 sdc sdc1 sdd sdd1
root@gr3:~# mount /dev/sd
sda sda1 sda2 sda5 sdb sdb1 sdc sdc1 sdd sdd1
root@gr3:~# mount /dev/sdb1 /test/root/
root@gr3:~# umount /test/root
umount.nilfs2: /dev/sdb1: device is busy
umount.nilfs2: /dev/sdb1: device is busy
root@gr3:~# ps -A | grep nilfs
 1313 ? 00:00:00 nilfs_cleanerd
root@gr3:~# kill -9 1313
root@gr3:~# umount /test/root
root@gr3:~# lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 14.04 LTS
Release: 14.04
Codename: trusty
====================================================

[J. Stockburger (j-t-stockburger)]

I found a workaround, at least for removable drives:

* initiate unmount from nautilus (will hang)
* ask nilfs_cleanerd to stop: sudo nilfs-clean -q
* pending unmount will proceed

Why does umount.nilfs2 fail to perform this operation?

Note that this workaround may not be appropriate if several nilfs file systems are in use.