nvme: add a quirk to disable namespace identifiers

Add a quirk to disable using and exporting namespace identifiers for
controllers where they are broken beyond repair.

The most directly visible problem with non-unique namespace identifiers
is that they break the /dev/disk/by-id/ links, with the link for a
supposedly unique identifier now pointing to one of multiple possible
namespaces that share the same ID, and a somewhat random selection of
which one actually shows up.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Keith Busch <kbusch@kernel.org>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>

drivers/nvme/host/core.c

@@ -1288,6 +1288,8 @@ static int nvme_process_ns_desc(struct nvme_ctrl *ctrl, struct nvme_ns_ids *ids,
 				 warn_str, cur->nidl);
 			return -1;
 		}
+		if (ctrl->quirks & NVME_QUIRK_BOGUS_NID)
+			return NVME_NIDT_EUI64_LEN;
 		memcpy(ids->eui64, data + sizeof(*cur), NVME_NIDT_EUI64_LEN);
 		return NVME_NIDT_EUI64_LEN;
 	case NVME_NIDT_NGUID:
@@ -1296,6 +1298,8 @@ static int nvme_process_ns_desc(struct nvme_ctrl *ctrl, struct nvme_ns_ids *ids,
 				 warn_str, cur->nidl);
 			return -1;
 		}
+		if (ctrl->quirks & NVME_QUIRK_BOGUS_NID)
+			return NVME_NIDT_NGUID_LEN;
 		memcpy(ids->nguid, data + sizeof(*cur), NVME_NIDT_NGUID_LEN);
 		return NVME_NIDT_NGUID_LEN;
 	case NVME_NIDT_UUID:
@@ -1304,6 +1308,8 @@ static int nvme_process_ns_desc(struct nvme_ctrl *ctrl, struct nvme_ns_ids *ids,
 				 warn_str, cur->nidl);
 			return -1;
 		}
+		if (ctrl->quirks & NVME_QUIRK_BOGUS_NID)
+			return NVME_NIDT_UUID_LEN;
 		uuid_copy(&ids->uuid, data + sizeof(*cur));
 		return NVME_NIDT_UUID_LEN;
 	case NVME_NIDT_CSI:
@@ -1400,12 +1406,18 @@ static int nvme_identify_ns(struct nvme_ctrl *ctrl, unsigned nsid,
 	if ((*id)->ncap == 0) /* namespace not allocated or attached */
 		goto out_free_id;
 
-	if (ctrl->vs >= NVME_VS(1, 1, 0) &&
-	    !memchr_inv(ids->eui64, 0, sizeof(ids->eui64)))
-		memcpy(ids->eui64, (*id)->eui64, sizeof(ids->eui64));
-	if (ctrl->vs >= NVME_VS(1, 2, 0) &&
-	    !memchr_inv(ids->nguid, 0, sizeof(ids->nguid)))
-		memcpy(ids->nguid, (*id)->nguid, sizeof(ids->nguid));
+
+	if (ctrl->quirks & NVME_QUIRK_BOGUS_NID) {
+		dev_info(ctrl->device,
+			 "Ignoring bogus Namespace Identifiers\n");
+	} else {
+		if (ctrl->vs >= NVME_VS(1, 1, 0) &&
+		    !memchr_inv(ids->eui64, 0, sizeof(ids->eui64)))
+			memcpy(ids->eui64, (*id)->eui64, sizeof(ids->eui64));
+		if (ctrl->vs >= NVME_VS(1, 2, 0) &&
+		    !memchr_inv(ids->nguid, 0, sizeof(ids->nguid)))
+			memcpy(ids->nguid, (*id)->nguid, sizeof(ids->nguid));
+	}
 
 	return 0;
 

drivers/nvme/host/nvme.h

@@ -144,6 +144,11 @@ enum nvme_quirks {
 	 * encoding the generation sequence number.
 	 */
 	NVME_QUIRK_SKIP_CID_GEN			= (1 << 17),
+
+	/*
+	 * Reports garbage in the namespace identifiers (eui64, nguid, uuid).
+	 */
+	NVME_QUIRK_BOGUS_NID			= (1 << 18),
 };
 
 /*