target: Fix SPC-2 RELEASE bug for multi-session iSCSI client setups

target: Fix SPC-2 RELEASE bug for multi-session iSCSI client setups

commit edc318d9fea6854df752ec8c645b960b0d5a1d23 upstream.

This patch addresses a bug in a special case for target core SPC-2 RELEASE
logic where the same physical client (eg: iSCSI InitiatorName) with
differing iSCSI session identifiers (ISID) is allowed to incorrectly release
the same client's SPC-2 reservation from the non reservation holding path.

Note this bug is specific to iscsi-target w/ SPC-2 reservations, and
with the default enforce_pr_isids=1 device attr setting in target-core
controls if a InitiatorName + different ISID reservations are handled
the same as a single iSCSI client entity.

Signed-off-by: Bernhard Kohl <bernhard.kohl@gmx.net>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>