nvmet: fix Identify Namespace handling

nvmet: fix Identify Namespace handling

[ Upstream commit 8c098aa00118c35108f0c19bd3cdc45e11574948 ]

The identify command with cns set to NVME_ID_CNS_NS does not directly
depend on the command set. The NVMe specifications is rather confusing
here as it appears that this command only applies to the NVM command
set. However, footnote 8 of Figure 273 in the NVMe 2.0 base
specifications clearly state that this command applies to NVM command
sets that support logical blocks, that is, NVM and ZNS. Both the NVM and
ZNS command set specifications also list this identify as mandatory.

The command handling should thus not look at the csi field since it is
defined as unused for this command. Given that we do not support the
KV command set, simply remove the csi switch-case for that command
handling and call directly nvmet_execute_identify_ns() in
nvmet_execute_identify().

Fixes: 72d47ff18071 ("nvmet: add Command Set Identifier support")
Signed-off-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Tested-by: Chaitanya Kulkarni <kch@nvidia.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>