CA-134864: Fix plugin call for SXM.

Signed-off-by: Siddharth Vinothkumar <siddharth.vinothkumar@citrix.com>
Reviewed-by: Chandrika Srinivasan <chandrika.srinivasan@citrix.com>

GitHub: closes #175 on xapi-project/sm
CA-130987: Forward any exceptions thrown inside _snapshot

Signed-off-by: Vineeth Raveendran <vineeth.thampi@citrix.com>
Reviewed-by: Chandrika Srinivasan <chandrika.srinivasan@citrix.com>
Imported-by: Siddharth Vinothkumar <siddharth.vinothkumar@citrix.com>
Reviewed-by: Mate Lakat <mate.lakat@citrix.com>

(cherry picked from commit 6d7cf76dc400fbc4c8ccafddf72131c65724da67)

GitHub: closes #195 on xapi-project/sm
CA-142451: Failed to report all LUNs advertised on targets sharing the same IQN

If a multicontroller array advertises its targets using the same IQN
but different IPs and the LUNs in those targets are distinct,
we are able to show only LUNs coming from the first IP address.

The fix reinstates a line that was removed in commit 391bdf055dff
in our old sm.hg repository.
The purporse of the line is to first check that we have
a valid active iscsi connection using the original pair IP,IQN.
Only if it fails (it should not in my opinion) we fall back to
other ip addresses.

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

GitHub: closes #207 on xapi-project/sm
CA-141002: Enable ALUA auto-detection for DGC arrays

We have seen quite a few incidents where a configuration mismatch (ALUA vs.
DGC) between XS and the array caused confusion and got escalated: SCTX-1780,
SCTX-1333, CA-112771, CA-124429. This updated configuration will prevent such
misconfiguration incidents from reocurring, as XS will dynamically adapt to the
configuration on the array.

The partner has completed the qualification of the updated multipath
configuration with their storage arrays.

Signed-off-by: Robert Breker <robert.breker@citrix.com>
Acked-by: Germano Percossi <germano.percossi@citrix.com>

GitHub: closes #214 on xapi-project/sm