drbd: remove DRBD_GENLA_F_MANDATORY flag handling

DRBD used a custom mechanism to mark netlink attributes as "mandatory":
bit 14 of nla_type was repurposed as DRBD_GENLA_F_MANDATORY. Attributes
sent from userspace that had this bit present and that were unknown
to the kernel would lead to an error.

Since commit ef6243acb478 ("genetlink: optionally validate strictly/dumps"),
the generic netlink layer rejects unknown top-level attributes when
strict validation is enabled. DRBD never opted out of strict
validation, so unknown top-level attributes are already rejected by
the netlink core.

The mandatory flag mechanism was required for nested attributes, because
these are parsed liberally, silently dropping attributes unknown to the
kernel.

This prepares for the move to a new YNL-based family, which will use the
now-default strict parsing.
The current family is not expected to gain any new attributes, which
makes this change safe.

Old userspace that still sets bit 14 is unaffected: nla_type()
strips it before __nla_validate_parse() performs attribute validation,
so the bit never reaches DRBD.

Remove all references to the mandatory flag in DRBD.

Cc: Johannes Berg <johannes.berg@intel.com>
Cc: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Christoph Böhmwalder <christoph.boehmwalder@linbit.com>
Link: https://patch.msgid.link/20260403132953.2248751-1-christoph.boehmwalder@linbit.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

0 files changed, 0 insertions, 0 deletions