[PATCHv2] nvme: disable namespaces with unsupported metadata

[PATCHv2] nvme: disable namespaces with unsupported metadata

[Keith Busch]

The only fabrics target that supports metadata is RDMA and usable only
if it is 8B per block, and formatted for protection information. If an
rdma target were to export a namespace with a different format (ex:
4k+64B), the driver will not be able to submit valid read/write commands
for that namespace.

Suppress setting the metadata feature in the namespace so that the
gendisk capacity will be set to 0. This will prevent read/write access.

Reviewed-by: Max Gurtovoy <mgurtovoy@nvidia.com>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Keith Busch <kbusch@kernel.org>
---
v1->v2: changelog and comment updates

 drivers/nvme/host/core.c | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index 4b5de8f5435a..47a941207058 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -1740,7 +1740,18 @@ static int nvme_configure_metadata(struct nvme_ns *ns, struct nvme_id_ns *id)
 		 */
 		if (WARN_ON_ONCE(!(id->flbas & NVME_NS_FLBAS_META_EXT)))
 			return -EINVAL;
-		if (ctrl->max_integrity_segments)
+
+		/*
+		 * The current fabrics transport drivers support namespace
+		 * metadata formats only if nvme_ns_has_pi() returns true.
+		 * Suppress setting the feature for all other formats so the
+		 * namespace will have a 0 capacity and not be usable through
+		 * the block stack.
+		 *
+		 * Note, this check will need to be modified if any drivers
+		 * gain the ability to use other metadata formats.
+		 */
+		if (ctrl->max_integrity_segments && nvme_ns_has_pi(ns))
 			ns->features |=
 				(NVME_NS_METADATA_SUPPORTED | NVME_NS_EXT_LBAS);
 	} else {
-- 
2.25.4

Re: [PATCHv2] nvme: disable namespaces with unsupported metadata

[Keith Busch]

On Mon, Nov 29, 2021 at 08:07:12AM -0800, Keith Busch wrote:
> +		if (ctrl->max_integrity_segments && nvme_ns_has_pi(ns))
>  			ns->features |=
>  				(NVME_NS_METADATA_SUPPORTED | NVME_NS_EXT_LBAS);

Apparently the passthrough interface works fine for any arbitrary
metadata format, so looks like we should leave NVME_NS_EXT_LBAS flag set
for all transports. I'll need to send a v3.