bdev/nvme: Add active/active policy for multipath mode

The NVMe bdev module supported active-passive policy for multipath mode
first. By this patch, the NVMe bdev module supports active-active policy
for multipath node next. Following the Linux kernel native NVMe multipath,
the NVMe bdev module supports round robin algorithm for active-active
policy.

The multipath policy, active-passive or active-active, is managed per
nvme_bdev. The multipath policy is copied to all corresponding
nvme_bdev_channels.

Different from active-passive, active-active caches even non_optimized
path to provide load balance across multiple paths.

Signed-off-by: Shuhei Matsumoto <smatsumoto@nvidia.com>
Change-Id: Ie18b24db60d3da1ce2f83725b6cd3079f628f95b
Reviewed-on: https://review.spdk.io/gerrit/c/spdk/spdk/+/12001
Community-CI: Mellanox Build Bot
Community-CI: Broadcom CI <spdk-ci.pdl@broadcom.com>
Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>
Reviewed-by: Ben Walker <benjamin.walker@intel.com>
Reviewed-by: Aleksey Marchuk <alexeymar@nvidia.com>

CHANGELOG.md

@@ -26,6 +26,9 @@ A new RPC `bdev_nvme_get_io_paths` was added to get all active I/O paths.
 A new RPC `bdev_nvme_set_preferred_path` was added to set preferred I/O path for an NVMe bdev
 when in multipath mode. This RPC does not support NVMe bdevs in failover mode.
 
+A new RPC `bdev_nvme_set_multipath_policy` was added to set multipath policy of a NVMe bdev
+in multipath mode.
+
 ### idxd
 
 A new parameter `flags` was added to all low level submission and preparation

doc/jsonrpc.md

@@ -3433,6 +3433,43 @@ Example response:
 }
 ~~~
 
+### bdev_nvme_set_multipath_policy {#rpc_bdev_nvme_set_multipath_policy}
+
+Set multipath policy of the NVMe bdev in multipath mode.
+
+#### Parameters
+
+Name                    | Optional | Type        | Description
+----------------------- | -------- | ----------- | -----------
+name                    | Required | string      | Name of the NVMe bdev
+policy                  | Required | string      | Multipath policy: active_active or active_passive
+
+#### Example
+
+Example request:
+
+~~~json
+{
+  "jsonrpc": "2.0",
+  "method": "bdev_nvme_set_multipath_policy",
+  "id": 1,
+  "params": {
+    "name": "Nvme0n1",
+    "policy": "active_passive"
+  }
+}
+~~~
+
+Example response:
+
+~~~json
+{
+  "jsonrpc": "2.0",
+  "id": 1,
+  "result": true
+}
+~~~
+
 ### bdev_nvme_cuse_register {#rpc_bdev_nvme_cuse_register}
 
 Register CUSE device on NVMe controller.

module/bdev/nvme/bdev_nvme.c

@@ -825,6 +825,55 @@ nvme_ctrlr_is_available(struct nvme_ctrlr *nvme_ctrlr)
 	return true;
 }
 
+/* Simulate circular linked list. */
+static inline struct nvme_io_path *
+nvme_io_path_get_next(struct nvme_bdev_channel *nbdev_ch, struct nvme_io_path *prev_path)
+{
+	struct nvme_io_path *next_path;
+
+	next_path = STAILQ_NEXT(prev_path, stailq);
+	if (next_path != NULL) {
+		return next_path;
+	} else {
+		return STAILQ_FIRST(&nbdev_ch->io_path_list);
+	}
+}
+
+static struct nvme_io_path *
+bdev_nvme_find_next_io_path(struct nvme_bdev_channel *nbdev_ch,
+			    struct nvme_io_path *prev)
+{
+	struct nvme_io_path *io_path, *start, *non_optimized = NULL;
+
+	start = nvme_io_path_get_next(nbdev_ch, prev);
+
+	io_path = start;
+	do {
+		if (spdk_likely(nvme_io_path_is_connected(io_path) &&
+				!io_path->nvme_ns->ana_state_updating)) {
+			switch (io_path->nvme_ns->ana_state) {
+			case SPDK_NVME_ANA_OPTIMIZED_STATE:
+				nbdev_ch->current_io_path = io_path;
+				return io_path;
+			case SPDK_NVME_ANA_NON_OPTIMIZED_STATE:
+				if (non_optimized == NULL) {
+					non_optimized = io_path;
+				}
+				break;
+			default:
+				break;
+			}
+		}
+		io_path = nvme_io_path_get_next(nbdev_ch, io_path);
+	} while (io_path != start);
+
+	/* We come here only if there is no optimized path. Cache even non_optimized
+	 * path for load balance across multiple non_optimized paths.
+	 */
+	nbdev_ch->current_io_path = non_optimized;
+	return non_optimized;
+}
+
 static struct nvme_io_path *
 _bdev_nvme_find_io_path(struct nvme_bdev_channel *nbdev_ch)
 {
@@ -864,7 +913,11 @@ bdev_nvme_find_io_path(struct nvme_bdev_channel *nbdev_ch)
 		return _bdev_nvme_find_io_path(nbdev_ch);
 	}
 
+	if (spdk_likely(nbdev_ch->mp_policy == BDEV_NVME_MP_POLICY_ACTIVE_PASSIVE)) {
 		return nbdev_ch->current_io_path;
+	} else {
+		return bdev_nvme_find_next_io_path(nbdev_ch, nbdev_ch->current_io_path);
+	}
 }
 
 /* Return true if there is any io_path whose qpair is active or ctrlr is not failed,
@@ -2600,6 +2653,20 @@ nvme_namespace_info_json(struct spdk_json_write_ctx *w,
 	spdk_json_write_object_end(w);
 }
 
+static const char *
+nvme_bdev_get_mp_policy_str(struct nvme_bdev *nbdev)
+{
+	switch (nbdev->mp_policy) {
+	case BDEV_NVME_MP_POLICY_ACTIVE_PASSIVE:
+		return "active_passive";
+	case BDEV_NVME_MP_POLICY_ACTIVE_ACTIVE:
+		return "active_active";
+	default:
+		assert(false);
+		return "invalid";
+	}
+}
+
 static int
 bdev_nvme_dump_info_json(void *ctx, struct spdk_json_write_ctx *w)
 {
@@ -2612,6 +2679,7 @@ bdev_nvme_dump_info_json(void *ctx, struct spdk_json_write_ctx *w)
 		nvme_namespace_info_json(w, nvme_ns);
 	}
 	spdk_json_write_array_end(w);
+	spdk_json_write_named_string(w, "mp_policy", nvme_bdev_get_mp_policy_str(nvme_bdev));
 	pthread_mutex_unlock(&nvme_bdev->mutex);
 
 	return 0;
@@ -2884,6 +2952,7 @@ nvme_bdev_create(struct nvme_ctrlr *nvme_ctrlr, struct nvme_ns *nvme_ns)
 	}
 
 	bdev->ref = 1;
+	bdev->mp_policy = BDEV_NVME_MP_POLICY_ACTIVE_PASSIVE;
 	TAILQ_INIT(&bdev->nvme_ns_list);
 	TAILQ_INSERT_TAIL(&bdev->nvme_ns_list, nvme_ns, tailq);
 	bdev->opal = nvme_ctrlr->opal_dev != NULL;
@@ -3635,6 +3704,88 @@ err_alloc:
 	cb_fn(cb_arg, rc);
 }
 
+struct bdev_nvme_set_multipath_policy_ctx {
+	struct spdk_bdev_desc *desc;
+	bdev_nvme_set_multipath_policy_cb cb_fn;
+	void *cb_arg;
+};
+
+static void
+bdev_nvme_set_multipath_policy_done(struct spdk_io_channel_iter *i, int status)
+{
+	struct bdev_nvme_set_multipath_policy_ctx *ctx = spdk_io_channel_iter_get_ctx(i);
+
+	assert(ctx != NULL);
+	assert(ctx->desc != NULL);
+	assert(ctx->cb_fn != NULL);
+
+	spdk_bdev_close(ctx->desc);
+
+	ctx->cb_fn(ctx->cb_arg, status);
+
+	free(ctx);
+}
+
+static void
+_bdev_nvme_set_multipath_policy(struct spdk_io_channel_iter *i)
+{
+	struct spdk_io_channel *_ch = spdk_io_channel_iter_get_channel(i);
+	struct nvme_bdev_channel *nbdev_ch = spdk_io_channel_get_ctx(_ch);
+	struct nvme_bdev *nbdev = spdk_io_channel_get_io_device(_ch);
+
+	nbdev_ch->mp_policy = nbdev->mp_policy;
+	nbdev_ch->current_io_path = NULL;
+
+	spdk_for_each_channel_continue(i, 0);
+}
+
+void
+bdev_nvme_set_multipath_policy(const char *name, enum bdev_nvme_multipath_policy policy,
+			       bdev_nvme_set_multipath_policy_cb cb_fn, void *cb_arg)
+{
+	struct bdev_nvme_set_multipath_policy_ctx *ctx;
+	struct spdk_bdev *bdev;
+	struct nvme_bdev *nbdev;
+	int rc;
+
+	assert(cb_fn != NULL);
+
+	ctx = calloc(1, sizeof(*ctx));
+	if (ctx == NULL) {
+		SPDK_ERRLOG("Failed to alloc context.\n");
+		rc = -ENOMEM;
+		goto err_alloc;
+	}
+
+	ctx->cb_fn = cb_fn;
+	ctx->cb_arg = cb_arg;
+
+	rc = spdk_bdev_open_ext(name, false, dummy_bdev_event_cb, NULL, &ctx->desc);
+	if (rc != 0) {
+		SPDK_ERRLOG("bdev %s is not registered in this module.\n", name);
+		rc = -ENODEV;
+		goto err_open;
+	}
+
+	bdev = spdk_bdev_desc_get_bdev(ctx->desc);
+	nbdev = SPDK_CONTAINEROF(bdev, struct nvme_bdev, disk);
+
+	pthread_mutex_lock(&nbdev->mutex);
+	nbdev->mp_policy = policy;
+	pthread_mutex_unlock(&nbdev->mutex);
+
+	spdk_for_each_channel(nbdev,
+			      _bdev_nvme_set_multipath_policy,
+			      ctx,
+			      bdev_nvme_set_multipath_policy_done);
+	return;
+
+err_open:
+	free(ctx);
+err_alloc:
+	cb_fn(cb_arg, rc);
+}
+
 static void
 aer_cb(void *arg, const struct spdk_nvme_cpl *cpl)
 {

module/bdev/nvme/bdev_nvme.h

@@ -48,6 +48,11 @@ extern bool g_bdev_nvme_module_finish;
 
 #define NVME_MAX_CONTROLLERS 1024
 
+enum bdev_nvme_multipath_policy {
+	BDEV_NVME_MP_POLICY_ACTIVE_PASSIVE,
+	BDEV_NVME_MP_POLICY_ACTIVE_ACTIVE,
+};
+
 typedef void (*spdk_bdev_create_nvme_fn)(void *ctx, size_t bdev_count, int rc);
 typedef void (*spdk_bdev_nvme_start_discovery_fn)(void *ctx);
 typedef void (*spdk_bdev_nvme_stop_discovery_fn)(void *ctx);
@@ -171,6 +176,7 @@ struct nvme_bdev {
 	struct nvme_bdev_ctrlr		*nbdev_ctrlr;
 	pthread_mutex_t			mutex;
 	int				ref;
+	enum bdev_nvme_multipath_policy	mp_policy;
 	TAILQ_HEAD(, nvme_ns)		nvme_ns_list;
 	bool				opal;
 	TAILQ_ENTRY(nvme_bdev)		tailq;
@@ -207,6 +213,7 @@ struct nvme_io_path {
 
 struct nvme_bdev_channel {
 	struct nvme_io_path			*current_io_path;
+	enum bdev_nvme_multipath_policy		mp_policy;
 	STAILQ_HEAD(, nvme_io_path)		io_path_list;
 	TAILQ_HEAD(retry_io_head, spdk_bdev_io)	retry_io_list;
 	struct spdk_poller			*retry_io_poller;
@@ -333,4 +340,18 @@ typedef void (*bdev_nvme_set_preferred_path_cb)(void *cb_arg, int rc);
 void bdev_nvme_set_preferred_path(const char *name, uint16_t cntlid,
 				  bdev_nvme_set_preferred_path_cb cb_fn, void *cb_arg);
 
+typedef void (*bdev_nvme_set_multipath_policy_cb)(void *cb_arg, int rc);
+
+/**
+ * Set multipath policy of the NVMe bdev.
+ *
+ * \param name NVMe bdev name
+ * \param policy Multipath policy (active-passive or active-active)
+ * \param cb_fn Function to be called back after completion.
+ */
+void bdev_nvme_set_multipath_policy(const char *name,
+				    enum bdev_nvme_multipath_policy policy,
+				    bdev_nvme_set_multipath_policy_cb cb_fn,
+				    void *cb_arg);
+
 #endif /* SPDK_BDEV_NVME_H */

module/bdev/nvme/bdev_nvme_rpc.c

@@ -2196,3 +2196,90 @@ cleanup:
 }
 SPDK_RPC_REGISTER("bdev_nvme_set_preferred_path", rpc_bdev_nvme_set_preferred_path,
 		  SPDK_RPC_RUNTIME)
+
+struct rpc_set_multipath_policy {
+	char *name;
+	enum bdev_nvme_multipath_policy policy;
+};
+
+static void
+free_rpc_set_multipath_policy(struct rpc_set_multipath_policy *req)
+{
+	free(req->name);
+}
+
+static int
+rpc_decode_mp_policy(const struct spdk_json_val *val, void *out)
+{
+	enum bdev_nvme_multipath_policy *policy = out;
+
+	if (spdk_json_strequal(val, "active_passive") == true) {
+		*policy = BDEV_NVME_MP_POLICY_ACTIVE_PASSIVE;
+	} else if (spdk_json_strequal(val, "active_active") == true) {
+		*policy = BDEV_NVME_MP_POLICY_ACTIVE_ACTIVE;
+	} else {
+		SPDK_NOTICELOG("Invalid parameter value: policy\n");
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static const struct spdk_json_object_decoder rpc_set_multipath_policy_decoders[] = {
+	{"name", offsetof(struct rpc_set_multipath_policy, name), spdk_json_decode_string},
+	{"policy", offsetof(struct rpc_set_multipath_policy, policy), rpc_decode_mp_policy},
+};
+
+struct rpc_set_multipath_policy_ctx {
+	struct rpc_set_multipath_policy req;
+	struct spdk_jsonrpc_request *request;
+};
+
+static void
+rpc_bdev_nvme_set_multipath_policy_done(void *cb_arg, int rc)
+{
+	struct rpc_set_multipath_policy_ctx *ctx = cb_arg;
+
+	if (rc == 0) {
+		spdk_jsonrpc_send_bool_response(ctx->request, true);
+	} else {
+		spdk_jsonrpc_send_error_response(ctx->request, rc, spdk_strerror(-rc));
+	}
+
+	free_rpc_set_multipath_policy(&ctx->req);
+	free(ctx);
+}
+
+static void
+rpc_bdev_nvme_set_multipath_policy(struct spdk_jsonrpc_request *request,
+				   const struct spdk_json_val *params)
+{
+	struct rpc_set_multipath_policy_ctx *ctx;
+
+	ctx = calloc(1, sizeof(*ctx));
+	if (ctx == NULL) {
+		spdk_jsonrpc_send_error_response(request, -ENOMEM, spdk_strerror(ENOMEM));
+		return;
+	}
+
+	if (spdk_json_decode_object(params, rpc_set_multipath_policy_decoders,
+				    SPDK_COUNTOF(rpc_set_multipath_policy_decoders),
+				    &ctx->req)) {
+		SPDK_ERRLOG("spdk_json_decode_object failed\n");
+		spdk_jsonrpc_send_error_response(request, SPDK_JSONRPC_ERROR_INTERNAL_ERROR,
+						 "spdk_json_decode_object failed");
+		goto cleanup;
+	}
+
+	ctx->request = request;
+
+	bdev_nvme_set_multipath_policy(ctx->req.name, ctx->req.policy,
+				       rpc_bdev_nvme_set_multipath_policy_done, ctx);
+	return;
+
+cleanup:
+	free_rpc_set_multipath_policy(&ctx->req);
+	free(ctx);
+}
+SPDK_RPC_REGISTER("bdev_nvme_set_multipath_policy", rpc_bdev_nvme_set_multipath_policy,
+		  SPDK_RPC_RUNTIME)

python/spdk/rpc/bdev.py

@@ -840,6 +840,20 @@ def bdev_nvme_set_preferred_path(client, name, cntlid):
     return client.call('bdev_nvme_set_preferred_path', params)
 
 
+def bdev_nvme_set_multipath_policy(client, name, policy):
+    """Set multipath policy of the NVMe bdev
+
+    Args:
+        name: NVMe bdev name
+        policy: Multipath policy (active_passive or active_active)
+    """
+
+    params = {'name': name,
+              'policy': policy}
+
+    return client.call('bdev_nvme_set_multipath_policy', params)
+
+
 def bdev_nvme_cuse_register(client, name):
     """Register CUSE devices on NVMe controller.
 

scripts/rpc.py

@@ -779,6 +779,17 @@ if __name__ == "__main__":
     p.add_argument('-c', '--cntlid', help='NVMe-oF controller ID', type=int, required=True)
     p.set_defaults(func=bdev_nvme_set_preferred_path)
 
+    def bdev_nvme_set_multipath_policy(args):
+        rpc.bdev.bdev_nvme_set_multipath_policy(args.client,
+                                                name=args.name,
+                                                policy=args.policy)
+
+    p = subparsers.add_parser('bdev_nvme_set_multipath_policy',
+                              help="""Set multipath policy of the NVMe bdev""")
+    p.add_argument('-b', '--name', help='Name of the NVMe bdev', required=True)
+    p.add_argument('-p', '--policy', help='Multipath policy (active_passive or active_active)', required=True)
+    p.set_defaults(func=bdev_nvme_set_multipath_policy)
+
     def bdev_nvme_cuse_register(args):
         rpc.bdev.bdev_nvme_cuse_register(args.client,
                                          name=args.name)

test/unit/lib/bdev/nvme/bdev_nvme.c/bdev_nvme_ut.c

@@ -6200,6 +6200,58 @@ test_set_preferred_path(void)
 	CU_ASSERT(nvme_ctrlr_get_by_name("nvme0") == NULL);
 }
 
+static void
+test_find_next_io_path(void)
+{
+	struct nvme_bdev_channel nbdev_ch = {
+		.io_path_list = STAILQ_HEAD_INITIALIZER(nbdev_ch.io_path_list),
+		.mp_policy = BDEV_NVME_MP_POLICY_ACTIVE_ACTIVE,
+	};
+	struct spdk_nvme_qpair qpair1 = {}, qpair2 = {}, qpair3 = {};
+	struct spdk_nvme_ctrlr ctrlr1 = {}, ctrlr2 = {}, ctrlr3 = {};
+	struct nvme_ctrlr nvme_ctrlr1 = { .ctrlr = &ctrlr1, };
+	struct nvme_ctrlr nvme_ctrlr2 = { .ctrlr = &ctrlr2, };
+	struct nvme_ctrlr nvme_ctrlr3 = { .ctrlr = &ctrlr3, };
+	struct nvme_ctrlr_channel ctrlr_ch1 = {};
+	struct nvme_ctrlr_channel ctrlr_ch2 = {};
+	struct nvme_ctrlr_channel ctrlr_ch3 = {};
+	struct nvme_qpair nvme_qpair1 = { .ctrlr_ch = &ctrlr_ch1, .ctrlr = &nvme_ctrlr1, .qpair = &qpair1, };
+	struct nvme_qpair nvme_qpair2 = { .ctrlr_ch = &ctrlr_ch2, .ctrlr = &nvme_ctrlr2, .qpair = &qpair2, };
+	struct nvme_qpair nvme_qpair3 = { .ctrlr_ch = &ctrlr_ch3, .ctrlr = &nvme_ctrlr3, .qpair = &qpair3, };
+	struct nvme_ns nvme_ns1 = {}, nvme_ns2 = {}, nvme_ns3 = {};
+	struct nvme_io_path io_path1 = { .qpair = &nvme_qpair1, .nvme_ns = &nvme_ns1, };
+	struct nvme_io_path io_path2 = { .qpair = &nvme_qpair2, .nvme_ns = &nvme_ns2, };
+	struct nvme_io_path io_path3 = { .qpair = &nvme_qpair3, .nvme_ns = &nvme_ns3, };
+
+	STAILQ_INSERT_TAIL(&nbdev_ch.io_path_list, &io_path1, stailq);
+	STAILQ_INSERT_TAIL(&nbdev_ch.io_path_list, &io_path2, stailq);
+	STAILQ_INSERT_TAIL(&nbdev_ch.io_path_list, &io_path3, stailq);
+
+	/* nbdev_ch->current_io_path is filled always when bdev_nvme_find_next_io_path() is called. */
+
+	nbdev_ch.current_io_path = &io_path2;
+	nvme_ns1.ana_state = SPDK_NVME_ANA_INACCESSIBLE_STATE;
+	nvme_ns2.ana_state = SPDK_NVME_ANA_OPTIMIZED_STATE;
+	nvme_ns3.ana_state = SPDK_NVME_ANA_INACCESSIBLE_STATE;
+	CU_ASSERT(bdev_nvme_find_io_path(&nbdev_ch) == &io_path2);
+
+	nvme_ns1.ana_state = SPDK_NVME_ANA_NON_OPTIMIZED_STATE;
+	nvme_ns2.ana_state = SPDK_NVME_ANA_OPTIMIZED_STATE;
+	nvme_ns3.ana_state = SPDK_NVME_ANA_NON_OPTIMIZED_STATE;
+	CU_ASSERT(bdev_nvme_find_io_path(&nbdev_ch) == &io_path2);
+
+	nvme_ns1.ana_state = SPDK_NVME_ANA_OPTIMIZED_STATE;
+	nvme_ns2.ana_state = SPDK_NVME_ANA_OPTIMIZED_STATE;
+	nvme_ns3.ana_state = SPDK_NVME_ANA_NON_OPTIMIZED_STATE;
+	CU_ASSERT(bdev_nvme_find_io_path(&nbdev_ch) == &io_path1);
+
+	nbdev_ch.current_io_path = &io_path3;
+	nvme_ns1.ana_state = SPDK_NVME_ANA_INACCESSIBLE_STATE;
+	nvme_ns2.ana_state = SPDK_NVME_ANA_NON_OPTIMIZED_STATE;
+	nvme_ns3.ana_state = SPDK_NVME_ANA_NON_OPTIMIZED_STATE;
+	CU_ASSERT(bdev_nvme_find_io_path(&nbdev_ch) == &io_path2);
+}
+
 int
 main(int argc, const char **argv)
 {
@@ -6250,6 +6302,7 @@ main(int argc, const char **argv)
 	CU_ADD_TEST(suite, test_nvme_ns_cmp);
 	CU_ADD_TEST(suite, test_ana_transition);
 	CU_ADD_TEST(suite, test_set_preferred_path);
+	CU_ADD_TEST(suite, test_find_next_io_path);
 
 	CU_basic_set_mode(CU_BRM_VERBOSE);