[PATCH 01/10] nvmet: zeroout id-ns buffer for invalid nsid

[Chaitanya Kulkarni]

According to spec :-
"5.15.2.7 Identify Namespace data structure for an Allocated Namespace
ID (CNS 11h) The Identify Namespace data structure (refer to Figure 245)
is returned to the host for the namespace specified in the Namespace
Identifier (NSID) field if it is an allocated NSID. If the specified
namespace is an unallocated NSID then the controller returns a zero
filled data structure."

Move call to nvmet_find_namespace() in nvmet_execute_identify_ns()
above the id-ns buffer allocation since there is no point in allocating
a buffer if namespace doesn't exist. Call nvmet_zero_sgl() when call to
nvmet_find_namespace() fails and add an explicit comment to specify the
reason for zeroing the buffer which is not common for the NVMe commands.
Remove the done label and we can directly jump to out label from
nvmet_find_namespace() error case.

Fixes: bffcd507780e ("nvmet: set right status on error in id-ns handler")
Signed-off-by: Chaitanya Kulkarni <chaitanya.kulkarni at wdc.com>
---
 drivers/nvme/target/admin-cmd.c | 22 ++++++++++++++--------
 1 file changed, 14 insertions(+), 8 deletions(-)

diff --git a/drivers/nvme/target/admin-cmd.c b/drivers/nvme/target/admin-cmd.c
index 613a4d8feac1..8cc7bb25d10d 100644
--- a/drivers/nvme/target/admin-cmd.c
+++ b/drivers/nvme/target/admin-cmd.c
@@ -476,19 +476,25 @@ static void nvmet_execute_identify_ns(struct nvmet_req *req)
 		goto out;
 	}
 
+	req->ns = nvmet_find_namespace(ctrl, req->cmd->identify.nsid);
+	if (!req->ns) {
+		status = NVME_SC_INVALID_NS;
+		/*
+		 * According to spec : If the specified namespace is
+		 * an unallocated NSID then the controller returns a zero filled
+		 * data structure. Also don't override the error status as invalid
+		 * namespace takes priority over the failed zeroout buffer case.
+		 */
+		nvmet_zero_sgl(req, 0, sizeof(*id));
+		goto out;
+	}
+
 	id = kzalloc(sizeof(*id), GFP_KERNEL);
 	if (!id) {
 		status = NVME_SC_INTERNAL;
 		goto out;
 	}
 
-	/* return an all zeroed buffer if we can't find an active namespace */
-	req->ns = nvmet_find_namespace(ctrl, req->cmd->identify.nsid);
-	if (!req->ns) {
-		status = NVME_SC_INVALID_NS;
-		goto done;
-	}
-
 	nvmet_ns_revalidate(req->ns);
 
 	/*
@@ -539,7 +545,7 @@ static void nvmet_execute_identify_ns(struct nvmet_req *req)
 
 	if (req->ns->readonly)
 		id->nsattr |= (1 << 0);
-done:
+
 	if (!status)
 		status = nvmet_copy_to_sgl(req, 0, id, sizeof(*id));
 
-- 
2.22.1