Bug#549691: lvm2: can't remove unmounted snapshot volume

[Celejar]

Package: lvm2
Version: 2.02.62-1
Severity: normal


I'm seeing the same problem trying to remove a snapshot volume.  It is not
mounted, but it can't be removed:

~# lvremove /dev/lizzie/var_backup 
  Can't remove open logical volume "var_backup"

~# lvchange -a n /dev/lizzie/var_backup 
  Can't change snapshot logical volume "var_backup"

~# mount
/dev/mapper/lizzie-root on / type ext3 (rw,errors=remount-ro)
tmpfs on /lib/init/rw type tmpfs (rw,nosuid,mode=0755)
proc on /proc type proc (rw,noexec,nosuid,nodev)
sysfs on /sys type sysfs (rw,noexec,nosuid,nodev)
udev on /dev type tmpfs (rw,mode=0755)
tmpfs on /dev/shm type tmpfs (rw,nosuid,nodev)
devpts on /dev/pts type devpts (rw,noexec,nosuid,gid=5,mode=620)
/dev/sda3 on /boot type ext3 (rw)
/dev/mapper/lizzie-home on /home type ext3 (rw)
/dev/mapper/lizzie-usr on /usr type ext3 (rw)
/dev/mapper/lizzie-var on /var type ext3 (rw)
none on /tmp type tmpfs (rw)

Eventually, I noticed that after a suspend / resume cycle, mount now shows that
the snapshot volume is mounted where the original should be:

~# mount
/dev/mapper/lizzie-root_backup on / type ext3 (rw,errors=remount-ro)
tmpfs on /lib/init/rw type tmpfs (rw,nosuid,mode=0755)
proc on /proc type proc (rw,noexec,nosuid,nodev)
sysfs on /sys type sysfs (rw,noexec,nosuid,nodev)
udev on /dev type tmpfs (rw,mode=0755)
tmpfs on /dev/shm type tmpfs (rw,nosuid,nodev)
devpts on /dev/pts type devpts (rw,noexec,nosuid,gid=5,mode=620)
/dev/sda3 on /boot type ext3 (rw)
/dev/mapper/lizzie-home on /home type ext3 (rw)
/dev/mapper/lizzie-usr on /usr type ext3 (rw)
/dev/mapper/lizzie-var_backup on /var type ext3 (rw)
none on /tmp type tmpfs (rw)

[Note that root / root_backup is now messed up, too.]

What on earth is going wrong here?  How is the snapshot usurping the place of
the origin volume?  And I have no idea what the trigger is.  This doesn't
generally happen - I've seen it once before, and now again, after using this
backup system for several months.  The last time, I resolved the problem by
going to runlevel 1 and remounting correctly, and then returning to runlevel 2.

-- System Information:
Debian Release: squeeze/sid
  APT prefers unstable
  APT policy: (500, 'unstable')
Architecture: i386 (i686)

Kernel: Linux 2.6.34-rc2-lizzie-00052-gae6be51
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash

Versions of packages lvm2 depends on:
ii  dmsetup                      2:1.02.45-1 The Linux Kernel Device Mapper use
ii  libc6                        2.10.2-6    Embedded GNU C Library: Shared lib
ii  libdevmapper1.02.1           2:1.02.45-1 The Linux Kernel Device Mapper use
ii  lsb-base                     3.2-23      Linux Standard Base 3.2 init scrip

lvm2 recommends no packages.

lvm2 suggests no packages.

-- no debconf information