nvme: Eliminate identify errors to Discovery ctrlr

The nvme/identify cmd issued some cmds to a ctrlr irrespective
of its type, and when the target was a Discovery ctrlr which only
accepts a very limited cmd set, that would result in errors observable
both on the initiator side (from nvme/identify) and in the output on
the target (nvmf_tgt).  Introduce new API, spdk_nvme_ctrlr_is_discovery(),
and alter identify to make use of that in determining which commands
to send to the target.

Change-Id: I974a569843f1d2b9e1ece7bd3bf9ceee1bfae872
Signed-off-by: Lance Hartmann <lance.hartmann@oracle.com>
Reviewed-on: https://review.gerrithub.io/436225
Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>
Reviewed-by: Jim Harris <james.r.harris@intel.com>
Reviewed-by: Shuhei Matsumoto <shuhei.matsumoto.xt@hitachi.com>
Reviewed-by: Ben Walker <benjamin.walker@intel.com>
Chandler-Test-Pool: SPDK Automated Test System <sys_sgsw@intel.com>

CHANGELOG.md

@@ -18,6 +18,9 @@ Add a new TCP/IP transport(located in lib/nvme/nvme_tcp.c) in nvme driver. With
 this new transport, it can be used to connect the NVMe-oF target with the
 same TCP/IP support.
 
+Added API, spdk_nvme_ctrlr_is_discovery(), to indicate whether the ctrlr
+arg refers to a Discovery Controller or not.
+
 ### NVMe-oF Target
 
 The `spdk_nvmf_tgt_opts` struct has been deprecated in favor of `spdk_nvmf_transport_opts`.

examples/nvme/identify/identify.c

@@ -405,25 +405,34 @@ get_log_pages(struct spdk_nvme_ctrlr *ctrlr)
 {
 	const struct spdk_nvme_ctrlr_data *cdata;
 	outstanding_commands = 0;
+	bool is_discovery = spdk_nvme_ctrlr_is_discovery(ctrlr);
 
 	cdata = spdk_nvme_ctrlr_get_data(ctrlr);
 
-	if (get_error_log_page(ctrlr) == 0) {
-		outstanding_commands++;
-	} else {
-		printf("Get Error Log Page failed\n");
-	}
+	if (!is_discovery) {
+		/*
+		 * Only attempt to retrieve the following log pages
+		 * when the NVM subsystem that's being targeted is
+		 * NOT the Discovery Controller which only fields
+		 * a Discovery Log Page.
+		 */
+		if (get_error_log_page(ctrlr) == 0) {
+			outstanding_commands++;
+		} else {
+			printf("Get Error Log Page failed\n");
+		}
 
-	if (get_health_log_page(ctrlr) == 0) {
-		outstanding_commands++;
-	} else {
-		printf("Get Log Page (SMART/health) failed\n");
-	}
+		if (get_health_log_page(ctrlr) == 0) {
+			outstanding_commands++;
+		} else {
+			printf("Get Log Page (SMART/health) failed\n");
+		}
 
-	if (get_firmware_log_page(ctrlr) == 0) {
-		outstanding_commands++;
-	} else {
-		printf("Get Log Page (Firmware Slot Information) failed\n");
+		if (get_firmware_log_page(ctrlr) == 0) {
+			outstanding_commands++;
+		} else {
+			printf("Get Log Page (Firmware Slot Information) failed\n");
+		}
 	}
 
 	if (cdata->lpa.celp) {
@@ -459,7 +468,7 @@ get_log_pages(struct spdk_nvme_ctrlr *ctrlr)
 
 	}
 
-	if (get_discovery_log_page(ctrlr) == 0) {
+	if (is_discovery && (get_discovery_log_page(ctrlr) == 0)) {
 		outstanding_commands++;
 	}
 
@@ -867,7 +876,15 @@ print_controller(struct spdk_nvme_ctrlr *ctrlr, const struct spdk_nvme_transport
 	cap = spdk_nvme_ctrlr_get_regs_cap(ctrlr);
 	vs = spdk_nvme_ctrlr_get_regs_vs(ctrlr);
 
-	get_features(ctrlr);
+	if (!spdk_nvme_ctrlr_is_discovery(ctrlr)) {
+		/*
+		 * Discovery Controller only supports the
+		 * IDENTIFY and GET_LOG_PAGE cmd set, so only
+		 * attempt GET_FEATURES when NOT targeting a
+		 * Discovery Controller.
+		 */
+		get_features(ctrlr);
+	}
 	get_log_pages(ctrlr);
 
 	cdata = spdk_nvme_ctrlr_get_data(ctrlr);

include/spdk/nvme.h

@@ -183,6 +183,15 @@ struct spdk_nvme_ctrlr_opts {
 	bool data_digest;
 };
 
+/**
+ * Indicate whether a ctrlr handle is associated with a Discovery controller.
+ *
+ * \param ctrlr Opaque handle to NVMe controller.
+ *
+ * \return true if a discovery controller, else false.
+ */
+bool spdk_nvme_ctrlr_is_discovery(struct spdk_nvme_ctrlr *ctrlr);
+
 /**
  * Get the default options for the creation of a specific NVMe controller.
  *

lib/nvme/nvme_ctrlr.c

@@ -2733,3 +2733,12 @@ spdk_nvme_ctrlr_free_cmb_io_buffer(struct spdk_nvme_ctrlr *ctrlr, void *buf, siz
 		nvme_robust_mutex_unlock(&ctrlr->ctrlr_lock);
 	}
 }
+
+bool
+spdk_nvme_ctrlr_is_discovery(struct spdk_nvme_ctrlr *ctrlr)
+{
+	assert(ctrlr);
+
+	return !strncmp(ctrlr->trid.subnqn, SPDK_NVMF_DISCOVERY_NQN,
+			strlen(SPDK_NVMF_DISCOVERY_NQN));
+}