[PATCH 2/2] nvmet: zns: return the namespace lookup error for Identify

[shao.mingyin at zte.com.cn]

From: Shao Mingyin <shao.mingyin at zte.com.cn>

nvmet_execute_identify_ns_zns() jumps to the done label when
nvmet_req_find_ns() fails, and that label unconditionally overwrites
status with the result of nvmet_copy_to_sgl():

	status = nvmet_req_find_ns(req);
	if (status)
		goto done;
	...
done:
	status = nvmet_copy_to_sgl(req, 0, id_zns, sizeof(*id_zns));

The identify command has already been checked to transfer exactly
NVME_IDENTIFY_DATA_SIZE bytes, so copying the zeroed id_zns always
succeeds.  An Identify command with CNS 05h and CSI 02h for a namespace
that does not exist therefore completes successfully with a zeroed
identify structure instead of returning Invalid Namespace, hiding the
error from the host.

Return the lookup error directly.  The other error paths in this
function already use the out label.

Fixes: aaf2e048af27 ("nvmet: add ZBD over ZNS backend support")
Cc: stable at vger.kernel.org
Signed-off-by: Shao Mingyin <shao.mingyin at zte.com.cn>
---
Tested on 7.3.0-next-20261030 (QEMU/TCG guest) with the loop transport
and CONFIG_BLK_DEV_ZONED.

An Identify with CNS 05h and CSI 02h for a namespace that does not
exist (NSID 100) completes successfully and returns a zeroed structure:

  unpatched                            patched
  ret=0, all 4096 bytes zero           ret=24587 (Invalid Namespace)

diff --git a/drivers/nvme/target/zns.c b/drivers/nvme/target/zns.c
index 92f5c1435582..cea05b4bc740 100644
--- a/drivers/nvme/target/zns.c
+++ b/drivers/nvme/target/zns.c
@@ -108,7 +108,7 @@ void nvmet_execute_identify_ns_zns(struct nvmet_req *req)
 
 	status = nvmet_req_find_ns(req);
 	if (status)
-		goto done;
+		goto out;
 
 	if (nvmet_ns_revalidate(req->ns)) {
 		mutex_lock(&req->ns->subsys->lock);
@@ -140,7 +140,6 @@ void nvmet_execute_identify_ns_zns(struct nvmet_req *req)
 		mar--;
 	id_zns->mar = cpu_to_le32(mar);
 
-done:
 	status = nvmet_copy_to_sgl(req, 0, id_zns, sizeof(*id_zns));
 out:
 	kfree(id_zns);