Add a retry to create_iscsi_target for LVM

There's a bug in the tgt driver where under certain
conditions where a race condition is present that can
result in tgtadm attempting re-use a target ID.

Testing this it seems that a retry will address this nicely
and cause tgtd to grab a new target ID and things are ok.

This patch adds a simple check/retry mechanism around the
iscsi_target_create in the LVM driver to catch this issue and
deal with it.

There are a number of bugs that it appears can be attributed to
this, but this patch is associated with the most predominant
clear cut version.

Closes-Bug #1223469

Change-Id: I5126009f196adcafad55e73ff99a59262dd93dfe
Fix issues with failed lvremove

There are some race conditions that
can cause problems with lvremove commands.  In
most cases these seem to recover nicely just
with a simple retry of the lvremove.  Adding
a udev settle seems to elimate the rest of them.

This is a difficult issue to reproduce, and there's
a suspiscion that it relates to failed target
creeates.

The patch adds a catch on the lvremove failure,
followed by a udevadm settle and a retry of the
lvremove.  With the setup that I've been able
to reproduce this issue these changes have eliminated
any force delete failures.

The other option that had been proposed was using dmsetup remove
but there are concerns that this may cause problems.

Change-Id: I2a2b0d0f4fefd0daf9424ab96aaf87ba53ebc171
Closes-Bug: #1191960
Merge "Fix issues with failed lvremove"
Merge "Add a retry to create_iscsi_target for LVM"