CA-121481: Ensure root disk is not blacklisted if booting from SAN

By default, every device is blacklisted, unless explicitly managed
by the Storage Manager.
When the root disk is managed by multipath, this happens at boot
time and the initrd must be able to add the device to multipath.
This patch ensures that, if the root disk is multipathed, it is
never blacklisted.

This patch can only guarantee that multipath is not broken for
the root disk but it is not responsible for making it multipathed
in the first place.

To make it working at installation time, dracut or mkinitrd should
call it explicitly.

Signed-off-by: Germano Percossi <germano.percossi@citrix.com>
Reviewed-by: Chandrika Srinivasan <chandrika.srinivasan@citrix.com>
CA-121481: No need to use the daemon

The script does not need the daemon to get the needed info.
This script is executed both as a standard boot script and
during the installation ensure the root disk is whitelisted.
In the latter case the daemon is not supposed to be running
but the root disk can be managed by the device mapper.

Signed-off-by: Germano Percossi <germano.percossi@citrix.com>
Reviewed-by: Chandrika Srinivasan <chandrika.srinivasan@citrix.com>
CA-121481: Improved wwid_conf script

Added the following:
- usage message
- command line options
- ability to both add and remove
- force addition or removal

Signed-off-by: Germano Percossi <germano.percossi@citrix.com>
Reviewed-by: Chandrika Srinivasan <chandrika.srinivasan@citrix.com>
CA-121481: make sure 'stat' follows symlinks

Signed-off-by: Germano Percossi <germano.percossi@citrix.com>
Reviewed-by: Chandrika Srinivasan <chandrika.srinivasan@citrix.com>
CA-121481: /dev/root does not exist at installation time

sm-multipath was meant to start at run time only.
We use this function to fix boot from SAN at installation time, too.
We cannot rely on /dev/root so we borrowed some utility functions
from dracut with a slight modification

Signed-off-by: Germano Percossi <germano.percossi@citrix.com>
Signed-off-by: Frediano Ziglio <frediano.ziglio@citrix.com>
Reviewed-by: Chandrika Srinivasan <chandrika.srinivasan@citrix.com>
Merge changes for CA-121481

Signed-off-by: Chandrika Srinivasan <chandrika.srinivasan@citrix.com>

GitHub: closes #56 on xapi-project/sm