Description of problem: Export Ceph RBD via LIO
Cannot execute ls once a block device is created in targetcli.

Version-Release number of selected component (if applicable):
targetcli-2.1.fb26-2.fc19.noarch
ceph-0.61.7-0.fc19.x86_64
kernel-3.10.3-300.fc19.x86_64


How reproducible:


Steps to Reproduce:
[root@cephgw ~]# rbd showmapped
id pool       image        snap device    
1  iscsi-ssd  test-ssd  -    /dev/rbd1 
[root@cephgw ~]# targetcli
targetcli shell version 2.1.26
Copyright 2011 by RisingTide Systems LLC and others.
For help on commands, type 'help'.

/> ls
o- / ......................................................................................................................... [...]
  o- backstores .............................................................................................................. [...]
  | o- block .................................................................................................. [Storage Objects: 0]
  | o- fileio ................................................................................................. [Storage Objects: 0]
  | o- pscsi .................................................................................................. [Storage Objects: 0]
  | o- ramdisk ................................................................................................ [Storage Objects: 0]
  o- iscsi ............................................................................................................ [Targets: 0]
  o- loopback ......................................................................................................... [Targets: 0]
  o- vhost ............................................................................................................ [Targets: 0]
/> cd backstores
/backstores> dc block
Command not found dc
/backstores> cd block
/backstores/block> create name=bashfulssd dev=/dev/rbd1
Created block storage object bashfulssd using /dev/rbd1.
/backstores/block> ls
Traceback (most recent call last):
  File "/usr/lib/python2.7/site-packages/configshell/shell.py", line 990, in run_interactive
    self._cli_loop()
  File "/usr/lib/python2.7/site-packages/configshell/shell.py", line 813, in _cli_loop
    self.run_cmdline(cmdline)
  File "/usr/lib/python2.7/site-packages/configshell/shell.py", line 934, in run_cmdline
    self._execute_command(path, command, pparams, kparams)
  File "/usr/lib/python2.7/site-packages/configshell/shell.py", line 909, in _execute_command
    result = target.execute_command(command, pparams, kparams)
  File "/usr/lib/python2.7/site-packages/targetcli/ui_node.py", line 87, in execute_command
    pparams, kparams)
  File "/usr/lib/python2.7/site-packages/configshell/node.py", line 1416, in execute_command
    result = method(*pparams, **kparams)
  File "/usr/lib/python2.7/site-packages/configshell/node.py", line 714, in ui_command_ls
    tree = self._render_tree(target, depth=depth)
  File "/usr/lib/python2.7/site-packages/configshell/node.py", line 865, in _render_tree
    + self._render_tree(children[i], margin, depth)
  File "/usr/lib/python2.7/site-packages/configshell/node.py", line 769, in _render_tree
    (description, is_healthy) = root.summary()
  File "/usr/lib/python2.7/site-packages/targetcli/ui_backstore.py", line 423, in summary
    return ("%s (%s) %s%s %s" % (so.udev_path, bytes_to_human(so.size),
  File "/usr/lib/python2.7/site-packages/rtslib/tcm.py", line 707, in _get_size
    return get_blockdev_size(self._parse_info('device')) * int(self._parse_info('SectorSize'))
  File "/usr/lib/python2.7/site-packages/rtslib/utils.py", line 122, in get_blockdev_size
    return int(fread("/sys/block/%s/%s/size" % (m.groups()[0], m.group())))
  File "/usr/lib/python2.7/site-packages/rtslib/utils.py", line 88, in fread
    with open(path, 'r') as file_fd:
IOError: [Errno 2] No such file or directory: '/sys/block/rbd/rbd1/size'
/backstores/block> delete name=bashfulssd              
Deleted storage object bashfulssd.
/backstores/block> exit
Global pref auto_save_on_exit=true
Last 10 configs saved in /etc/target/backup.
Configuration saved to /etc/target/saveconfig.json

1.
2.
3.

Actual results:
There is no /sys/block/rbd/rbd1/size, actual is /sys/block/rbd1/size

Expected results:
No python errors in targetcli


Additional info: