Volume can't be deleted if tgt has had a reconnect.

During heavy read/write operations, we are seeing reconnect issues from the connecting machine when using tgt:

Mar 24 20:06:24 node009-cont001 iscsid: Kernel reported iSCSI connection 44:0 error (1021 - ISCSI_ERR_SCSI_EH_SESSION_RST: Session was dropped as a result of SCSI error recovery) state (3)

The system seems to recover correctly but tgt still thinks there is a connection open:

arget 2: iqn.2010-10.org.openstack:volume-23603703-c801-41c7-b357-ab8e802033af
    System information:
        Driver: iscsi
        State: ready
    I_T nexus information:
        I_T nexus: 2
            Initiator: iqn.1993-08.org.debian:01:19cd983643f alias: node009-cont001
            Connection: 0
                IP Address: 172.18.1.9
        I_T nexus: 3
            Initiator: iqn.1993-08.org.debian:01:19cd983643f alias: node009-cont001
            Connection: 0
                IP Address: 172.18.1.9

This means the volume can't be deleted correctly:

2013-03-24 21:49:03 DEBUG cinder.volume.manager [req-dd6b1079-a9f0-45e6-8c3c-12bc6be46007 533801293fbe4b528db3a01ff70c2cc0 d3c7b21c21844e4e862abc894ef0b14c] volume volume-23603703-c801-41c7-b357-ab8e802033af: removing export delete_volume /usr/lib/python2.7/dist-packages/cinder/volume/manager.py:192
2013-03-24 21:49:03 DEBUG cinder.utils [req-dd6b1079-a9f0-45e6-8c3c-12bc6be46007 533801293fbe4b528db3a01ff70c2cc0 d3c7b21c21844e4e862abc894ef0b14c] Running cmd (subprocess): sudo cinder-rootwrap /etc/cinder/rootwrap.conf tgt-admin --show execute /usr/lib/python2.7/dist-packages/cinder/utils.py:163
2013-03-24 21:49:03 INFO cinder.volume.iscsi [req-dd6b1079-a9f0-45e6-8c3c-12bc6be46007 533801293fbe4b528db3a01ff70c2cc0 d3c7b21c21844e4e862abc894ef0b14c] Removing volume: 23603703-c801-41c7-b357-ab8e802033af
2013-03-24 21:49:03 DEBUG cinder.utils [req-dd6b1079-a9f0-45e6-8c3c-12bc6be46007 533801293fbe4b528db3a01ff70c2cc0 d3c7b21c21844e4e862abc894ef0b14c] Running cmd (subprocess): sudo cinder-rootwrap /etc/cinder/rootwrap.conf tgt-admin --delete iqn.2010-10.org.openstack:volume-23603703-c801-41c7-b357-ab8e802033af execute /usr/lib/python2.7/dist-packages/cinder/utils.py:163
2013-03-24 21:49:03 DEBUG cinder.volume.manager [req-dd6b1079-a9f0-45e6-8c3c-12bc6be46007 533801293fbe4b528db3a01ff70c2cc0 d3c7b21c21844e4e862abc894ef0b14c] volume volume-23603703-c801-41c7-b357-ab8e802033af: deleting delete_volume /usr/lib/python2.7/dist-packages/cinder/volume/manager.py:194
2013-03-24 21:49:03 DEBUG cinder.utils [req-dd6b1079-a9f0-45e6-8c3c-12bc6be46007 533801293fbe4b528db3a01ff70c2cc0 d3c7b21c21844e4e862abc894ef0b14c] Running cmd (subprocess): sudo cinder-rootwrap /etc/cinder/rootwrap.conf lvdisplay vg.nebula.openstack/volume-23603703-c801-41c7-b357-ab8e802033af execute /usr/lib/python2.7/dist-packages/cinder/utils.py:163
2013-03-24 21:49:03 DEBUG cinder.utils [req-dd6b1079-a9f0-45e6-8c3c-12bc6be46007 533801293fbe4b528db3a01ff70c2cc0 d3c7b21c21844e4e862abc894ef0b14c] Running cmd (subprocess): sudo cinder-rootwrap /etc/cinder/rootwrap.conf lvdisplay --noheading -C -o Attr vg.nebula.openstack/volume-23603703-c801-41c7-b357-ab8e802033af execute /usr/lib/python2.7/dist-packages/cinder/utils.py:163
2013-03-24 21:49:03 DEBUG cinder.utils [req-dd6b1079-a9f0-45e6-8c3c-12bc6be46007 533801293fbe4b528db3a01ff70c2cc0 d3c7b21c21844e4e862abc894ef0b14c] Running cmd (subprocess): sudo cinder-rootwrap /etc/cinder/rootwrap.conf dmsetup remove -f /dev/mapper/vg.nebula.openstack-volume--23603703--c801--41c7--b357--ab8e802033af execute /usr/lib/python2.7/dist-packages/cinder/utils.py:163
2013-03-24 21:49:03 DEBUG cinder.utils [req-dd6b1079-a9f0-45e6-8c3c-12bc6be46007 533801293fbe4b528db3a01ff70c2cc0 d3c7b21c21844e4e862abc894ef0b14c] Result was 1 execute /usr/lib/python2.7/dist-packages/cinder/utils.py:180
2013-03-24 21:49:03 ERROR cinder.volume.driver [req-dd6b1079-a9f0-45e6-8c3c-12bc6be46007 533801293fbe4b528db3a01ff70c2cc0 d3c7b21c21844e4e862abc894ef0b14c] Recovering from a failed execute. Try number 1
2013-03-24 21:49:03 19996 TRACE cinder.volume.driver Traceback (most recent call last):
2013-03-24 21:49:03 19996 TRACE cinder.volume.driver File "/usr/lib/python2.7/dist-packages/cinder/volume/driver.py", line 105, in _try_execute
2013-03-24 21:49:03 19996 TRACE cinder.volume.driver self._execute(*command, **kwargs)
2013-03-24 21:49:03 19996 TRACE cinder.volume.driver File "/usr/lib/python2.7/dist-packages/cinder/utils.py", line 187, in execute
2013-03-24 21:49:03 19996 TRACE cinder.volume.driver cmd=' '.join(cmd))
2013-03-24 21:49:03 19996 TRACE cinder.volume.driver ProcessExecutionError: Unexpected error while running command.
2013-03-24 21:49:03 19996 TRACE cinder.volume.driver Command: sudo cinder-rootwrap /etc/cinder/rootwrap.conf dmsetup remove -f /dev/mapper/vg.nebula.openstack-volume--23603703--c801--41c7--b357--ab8e802033af
2013-03-24 21:49:03 19996 TRACE cinder.volume.driver Exit code: 1
2013-03-24 21:49:03 19996 TRACE cinder.volume.driver Stdout: ''
2013-03-24 21:49:03 19996 TRACE cinder.volume.driver Stderr: 'device-mapper: remove ioctl on vg.nebula.openstack-volume--23603703--c801--41c7--b357--ab8e802033af failed: Device or resource busy\nCommand failed\n'