Comment 10 for bug 995645

I have pretty much the same problem. Once a snapshot is on the volume, the system fails to boot.

the problem is exactly as described here: http://www.redhat.com/archives/linux-lvm/2012-February/msg00028.html and the people on the mailing list suggest broken udev rules.

fstab is pretty normal:

# <file system> <mount point> <type> <options> <dump> <pass>
proc /proc proc nodev,noexec,nosuid 0 0
/dev/mapper/helpc--13-system / btrfs defaults,subvol=@,compress,discard,space_cache,inode_cache 0 1
# /boot was on /dev/sdb2 during installation
UUID=084c2f84-902f-4fa9-aadd-e7c4e19cd6bb /boot ext3 defaults 0 2
/dev/mapper/helpc--13-system /home btrfs defaults,subvol=@home,compress,discard,space_cache,inode_cache 0 2
/dev/mapper/helpc--13-swap none swap sw 0 0
/dev/mapper/bigstor-vms /home/hel/vms ext4 defaults 0 2
/dev/mapper/bigstor-archive /home/hel/archive ext4 defaults 0 2