nvme: get changed ns log once AER notice of ns changed received.

Each time the following file
"/sys/kernel/config/nvmet/subsystems/nqn_name/namespaces/ns_id/enable"
on the target side was changed, the SPDK initiator should receive an
async event (type: SPDK_NVME_ASYNC_EVENT_TYPE_NOTICE, info:
SPDK_NVME_ASYNC_EVENT_NS_ATTR_CHANGED).
But actually not.
Since for SPDK, when target sent the non-first event, the condition
"nvmet_aen_bit_disabled(ctrl, NVME_AEN_BIT_NS_ATTR)" that prevents
target from sending event was matched.
This commit fix this issue by issuing a get_log_page cmd for each async
event received, just as the kernel initiator does.

Fixes #1825.

Signed-off-by: tyler.sun <tyler.sun@dell.com>
Change-Id: I2973470a81893456ca12e86ac390ea1de0eed62c
Reviewed-on: https://review.spdk.io/gerrit/c/spdk/spdk/+/7107
Community-CI: Mellanox Build Bot
Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>
Reviewed-by: Shuhei Matsumoto <shuhei.matsumoto.xt@hitachi.com>
Reviewed-by: Changpeng Liu <changpeng.liu@intel.com>
Reviewed-by: Aleksey Marchuk <alexeymar@mellanox.com>
Reviewed-by: Ziye Yang <ziye.yang@intel.com>

include/spdk/nvme_spec.h

@@ -72,6 +72,11 @@ extern "C" {
  */
 #define SPDK_NVME_DATASET_MANAGEMENT_RANGE_MAX_BLOCKS	0xFFFFFFFFu
 
+/**
+ * Maximum number of entries in the log page of Changed Namespace List.
+ */
+#define SPDK_NVME_MAX_CHANGED_NAMESPACES 1024
+
 union spdk_nvme_cap_register {
 	uint64_t	raw;
 	struct {

lib/nvme/nvme_ctrlr.c

@@ -38,6 +38,7 @@
 
 #include "spdk/env.h"
 #include "spdk/string.h"
+#include "spdk/endian.h"
 
 struct nvme_active_ns_ctx;
 
@@ -2614,24 +2615,81 @@ fail:
 	return rc;
 }
 
+static int
+nvme_ctrlr_clear_changed_ns_log(struct spdk_nvme_ctrlr *ctrlr)
+{
+	struct nvme_completion_poll_status	*status;
+	int		rc = -ENOMEM;
+	char		*buffer = NULL;
+	uint32_t	nsid;
+	size_t		buf_size = (SPDK_NVME_MAX_CHANGED_NAMESPACES * sizeof(uint32_t));
+
+	buffer = spdk_dma_zmalloc(buf_size, 4096, NULL);
+	if (!buffer) {
+		NVME_CTRLR_ERRLOG(ctrlr, "Failed to allocate buffer for getting "
+				  "changed ns log.\n");
+		return rc;
+	}
+
+	status = calloc(1, sizeof(*status));
+	if (!status) {
+		NVME_CTRLR_ERRLOG(ctrlr, "Failed to allocate status tracker\n");
+		goto free_buffer;
+	}
+
+	rc = spdk_nvme_ctrlr_cmd_get_log_page(ctrlr,
+					      SPDK_NVME_LOG_CHANGED_NS_LIST,
+					      SPDK_NVME_GLOBAL_NS_TAG,
+					      buffer, buf_size, 0,
+					      nvme_completion_poll_cb, status);
+
+	if (rc) {
+		NVME_CTRLR_ERRLOG(ctrlr, "spdk_nvme_ctrlr_cmd_get_log_page() failed: rc=%d\n", rc);
+		free(status);
+		goto free_buffer;
+	}
+
+	rc = nvme_wait_for_completion_timeout(ctrlr->adminq, status,
+					      ctrlr->opts.admin_timeout_ms * 1000);
+	if (!status->timed_out) {
+		free(status);
+	}
+
+	if (rc) {
+		NVME_CTRLR_ERRLOG(ctrlr, "wait for spdk_nvme_ctrlr_cmd_get_log_page failed: rc=%d\n", rc);
+		goto free_buffer;
+	}
+
+	/* only check the case of overflow. */
+	nsid = from_le32(buffer);
+	if (nsid == 0xffffffffu) {
+		NVME_CTRLR_WARNLOG(ctrlr, "changed ns log overflowed.\n");
+	}
+
+free_buffer:
+	spdk_dma_free(buffer);
+	return rc;
+}
+
 void
 nvme_ctrlr_process_async_event(struct spdk_nvme_ctrlr *ctrlr,
 			       const struct spdk_nvme_cpl *cpl)
 {
 	union spdk_nvme_async_event_completion event;
 	struct spdk_nvme_ctrlr_process *active_proc;
+	bool				ns_changed = false;
 	int rc;
 
 	event.raw = cpl->cdw0;
 
 	if ((event.bits.async_event_type == SPDK_NVME_ASYNC_EVENT_TYPE_NOTICE) &&
 	    (event.bits.async_event_info == SPDK_NVME_ASYNC_EVENT_NS_ATTR_CHANGED)) {
-		rc = nvme_ctrlr_identify_active_ns(ctrlr);
+		/*
-		if (rc) {
+		 * apps (e.g., test/nvme/aer/aer.c) may also get changed ns log (through
-			return;
+		 * active_proc->aer_cb_fn). To avoid impaction, move our operations
-		}
+		 * behind call of active_proc->aer_cb_fn.
-		nvme_ctrlr_update_namespaces(ctrlr);
+		 */
-		nvme_io_msg_ctrlr_update(ctrlr);
+		ns_changed = true;
 	}
 
 	if ((event.bits.async_event_type == SPDK_NVME_ASYNC_EVENT_TYPE_NOTICE) &&
@@ -2647,6 +2705,22 @@ nvme_ctrlr_process_async_event(struct spdk_nvme_ctrlr *ctrlr,
 	if (active_proc && active_proc->aer_cb_fn) {
 		active_proc->aer_cb_fn(active_proc->aer_cb_arg, cpl);
 	}
+
+	if (ns_changed) {
+		/*
+		 * Must have the changed ns log cleared by getting it.
+		 * Otherwise, the target won't send
+		 * the subsequent ns enabling/disabling events to us.
+		 */
+		nvme_ctrlr_clear_changed_ns_log(ctrlr);
+
+		rc = nvme_ctrlr_identify_active_ns(ctrlr);
+		if (rc) {
+			return;
+		}
+		nvme_ctrlr_update_namespaces(ctrlr);
+		nvme_io_msg_ctrlr_update(ctrlr);
+	}
 }
 
 static void