All LVM actions in the devicemapper library are asyncronous, involving a call to
a task enqueue function (dm_run_task) and a wait on a resultant udev event
(UdevWait). Currently devmapper.go defers all calls to UdevWait, which discards
the return value. While it still generates an error message in the log (if
debugging is enabled), the calling thread is still allowed to continue as if no
error has occured, leading to subsequent errors, and significant confusion when
debugging, due to those subsequent errors. Given that there is no risk of panic
between the task submission and the wait operation, it seems more reasonable to
preform the UdevWait inline at the end of any given lvm action so that errors
can be caught and returned before docker can continue and create additional
failures.
Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
5206d45e70