multipathd: trigger all devices on startup

During startup multipathd might race with udev and device discovery.
During that time any information from libudev might not be fully
available, leading to spurious multipathd failures during startup.
So instead of scanning all devices on our own we should just
re-trigger the existing devices; with that we'll read _all_
devices via uevents during startup and avoid the race condition.

References: bnc#901465

Signed-off-by: Hannes Reinecke <hare@suse.de>
Separate out vpd parsing functions

Signed-off-by: Hannes Reinecke <hare@suse.de>
multipathd: use SG_IO as fallback to generate uid

If both udev attribute and sysfs vpd fails to generate a valid
WWID fallback to use SG_IO directly.

Signed-off-by: Hannes Reinecke <hare@suse.de>
Do not automatically fall back to vpd uid generation

When a wwid via uid_attribute cannot be generated we should
not fall back to using sysfs vpd attributes automatically.
The uid_attribute can be set to virtually anything and an
automatic fallback will then generated a different wwid,
leading to an incorrect setup.
A fallback is only valid if the uid_attribute value
is the default setting of 'ID_SERIAL', for which the
format is fixed.

Signed-off-by: Hannes Reinecke <hare@suse.de>
- Update Changelog.