nvmet: fix Reservation Register Replace for unregistered host with IEKEY

When a host sends a Reservation Register command with RREGA=Replace
and IEKEY=1 without being previously registered, nvmet returns
Reservation Conflict.

The NVMe specification states:

  "A host may replace its reservation key without regard to its
   registration status or current reservation key value by setting
   the Ignore Existing Key (IEKEY) bit to '1' in the Reservation
   Register command."

Fix nvmet_pr_replace() to add a new registrant when the host is not
found in the registrant list and IEKEY is set with a non-zero NRKEY.
If IEKEY is set but NRKEY is zero, return Invalid Field since there
is no valid reservation key to register.

Tested with nvme-cli against nvmet-tcp:

  # no prior registration
  nvme resv-register /dev/nvmeXn1 -n 1 --rrega=2 --iekey --nrkey=0x9999

  Before: RESERVATION_CONFLICT (0x4083)
  After:  success, registrant created with rkey 0x9999

Fixes: 5a47c2080a73 ("nvmet: support reservation feature")
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Guixin Liu <kanie@linux.alibaba.com>
Signed-off-by: Zhengrong Li <zhengrong_li@linux.alibaba.com>
Signed-off-by: Keith Busch <kbusch@kernel.org>

0 files changed, 0 insertions, 0 deletions