[PATCH 2/3] nvmet: per-port discovery subsystem

[Hannes Reinecke <hare@suse.de>]

Add a 'disc_subsys' pointer to each port to specify which discovery
subsystem to use.
The pointer is set when a discovery subsystem is linked into a port,
and reset if that link is removed.

Signed-off-by: Hannes Reinecke <hare@suse.de>
---
 drivers/nvme/target/configfs.c  | 10 +++++++++
 drivers/nvme/target/core.c      | 15 ++++++++++---
 drivers/nvme/target/discovery.c | 39 ++++++++++++++++++++++-----------
 drivers/nvme/target/nvmet.h     |  1 +
 4 files changed, 49 insertions(+), 16 deletions(-)

diff --git a/drivers/nvme/target/configfs.c b/drivers/nvme/target/configfs.c
index 38b0ab9fb721..44573fe0dfe4 100644
--- a/drivers/nvme/target/configfs.c
+++ b/drivers/nvme/target/configfs.c
@@ -821,6 +821,12 @@ static int nvmet_port_subsys_allow_link(struct config_item *parent,
 	link->subsys = subsys;
 
 	down_write(&nvmet_config_sem);
+	if (subsys->type == NVME_NQN_CURR &&
+	    port->disc_subsys) {
+		pr_err("discovery subsystem already present\n");
+		ret = -EAGAIN;
+		goto out_free_link;
+	}
 	ret = -EEXIST;
 	list_for_each_entry(p, &port->subsystems, entry) {
 		if (p->subsys == subsys)
@@ -835,6 +841,8 @@ static int nvmet_port_subsys_allow_link(struct config_item *parent,
 
 	list_add_tail(&link->entry, &port->subsystems);
 	subsys->port_count++;
+	if (subsys->type == NVME_NQN_CURR)
+		port->disc_subsys = subsys;
 	nvmet_port_disc_changed(port, subsys);
 
 	up_write(&nvmet_config_sem);
@@ -866,6 +874,8 @@ static void nvmet_port_subsys_drop_link(struct config_item *parent,
 	subsys->port_count--;
 	nvmet_port_del_ctrls(port, subsys);
 	nvmet_port_disc_changed(port, subsys);
+	if (port->disc_subsys == subsys)
+		port->disc_subsys = NULL;
 
 	if (list_empty(&port->subsystems))
 		nvmet_disable_port(port);
diff --git a/drivers/nvme/target/core.c b/drivers/nvme/target/core.c
index 90e75324dae0..afd80999a335 100644
--- a/drivers/nvme/target/core.c
+++ b/drivers/nvme/target/core.c
@@ -1495,10 +1495,19 @@ static struct nvmet_subsys *nvmet_find_get_subsys(struct nvmet_port *port,
 	if (!port)
 		return NULL;
 
+	/*
+	 * As per spec discovery subsystems with a unique NQN
+	 * have to respond to both NQNs, the unique NQN and the
+	 * standard discovery NQN.
+	 */
 	if (!strcmp(NVME_DISC_SUBSYS_NAME, subsysnqn)) {
-		if (!kref_get_unless_zero(&nvmet_disc_subsys->ref))
-			return NULL;
-		return nvmet_disc_subsys;
+		struct nvmet_subsys *disc_subsys;
+
+		disc_subsys = port->disc_subsys ?
+			port->disc_subsys : nvmet_disc_subsys;
+		if (!kref_get_unless_zero(&disc_subsys->ref))
+				return NULL;
+		return disc_subsys;
 	}
 
 	down_read(&nvmet_config_sem);
diff --git a/drivers/nvme/target/discovery.c b/drivers/nvme/target/discovery.c
index b5012df790d5..6b8aa6c4e752 100644
--- a/drivers/nvme/target/discovery.c
+++ b/drivers/nvme/target/discovery.c
@@ -29,18 +29,22 @@ void nvmet_port_disc_changed(struct nvmet_port *port,
 			     struct nvmet_subsys *subsys)
 {
 	struct nvmet_ctrl *ctrl;
+	struct nvmet_subsys *disc_subsys;
 
 	lockdep_assert_held(&nvmet_config_sem);
 	nvmet_genctr++;
 
-	mutex_lock(&nvmet_disc_subsys->lock);
-	list_for_each_entry(ctrl, &nvmet_disc_subsys->ctrls, subsys_entry) {
+	disc_subsys = port->disc_subsys ?
+		port->disc_subsys : nvmet_disc_subsys;
+
+	mutex_lock(&disc_subsys->lock);
+	list_for_each_entry(ctrl, &disc_subsys->ctrls, subsys_entry) {
 		if (subsys && !nvmet_host_allowed(subsys, ctrl->hostnqn))
 			continue;
 
 		__nvmet_disc_changed(port, ctrl);
 	}
-	mutex_unlock(&nvmet_disc_subsys->lock);
+	mutex_unlock(&disc_subsys->lock);
 
 	/* If transport can signal change, notify transport */
 	if (port->tr_ops && port->tr_ops->discovery_chg)
@@ -48,19 +52,23 @@ void nvmet_port_disc_changed(struct nvmet_port *port,
 }
 
 static void __nvmet_subsys_disc_changed(struct nvmet_port *port,
-					struct nvmet_subsys *subsys,
 					struct nvmet_host *host)
 {
 	struct nvmet_ctrl *ctrl;
+	struct nvmet_subsys *disc_subsys;
+
+	disc_subsys = port->disc_subsys ?
+		port->disc_subsys : nvmet_disc_subsys;
 
-	mutex_lock(&nvmet_disc_subsys->lock);
-	list_for_each_entry(ctrl, &nvmet_disc_subsys->ctrls, subsys_entry) {
+	mutex_lock(&disc_subsys->lock);
+
+	list_for_each_entry(ctrl, &disc_subsys->ctrls, subsys_entry) {
 		if (host && strcmp(nvmet_host_name(host), ctrl->hostnqn))
 			continue;
 
 		__nvmet_disc_changed(port, ctrl);
 	}
-	mutex_unlock(&nvmet_disc_subsys->lock);
+	mutex_unlock(&disc_subsys->lock);
 }
 
 void nvmet_subsys_disc_changed(struct nvmet_subsys *subsys,
@@ -76,7 +84,7 @@ void nvmet_subsys_disc_changed(struct nvmet_subsys *subsys,
 		list_for_each_entry(s, &port->subsystems, entry) {
 			if (s->subsys != subsys)
 				continue;
-			__nvmet_subsys_disc_changed(port, subsys, host);
+			__nvmet_subsys_disc_changed(port, host);
 		}
 }
 
@@ -146,7 +154,10 @@ static size_t discovery_log_entries(struct nvmet_req *req)
 	struct nvmet_ctrl *ctrl = req->sq->ctrl;
 	struct nvmet_subsys_link *p;
 	struct nvmet_port *r;
-	size_t entries = 1;
+	size_t entries = 0;
+
+	if (!req->port->disc_subsys)
+		entries++;
 
 	list_for_each_entry(p, &req->port->subsystems, entry) {
 		if (!nvmet_host_allowed(p->subsys, ctrl->hostnqn))
@@ -208,10 +219,12 @@ static void nvmet_execute_disc_get_log_page(struct nvmet_req *req)
 
 	nvmet_set_disc_traddr(req, req->port, traddr);
 
-	nvmet_format_discovery_entry(hdr, req->port,
-				     nvmet_disc_subsys->subsysnqn,
-				     traddr, NVME_NQN_CURR, numrec);
-	numrec++;
+	if (!req->port->disc_subsys) {
+		nvmet_format_discovery_entry(hdr, req->port,
+				nvmet_disc_subsys->subsysnqn,
+				traddr, NVME_NQN_CURR, numrec);
+		numrec++;
+	}
 
 	list_for_each_entry(p, &req->port->subsystems, entry) {
 		if (!nvmet_host_allowed(p->subsys, ctrl->hostnqn))
diff --git a/drivers/nvme/target/nvmet.h b/drivers/nvme/target/nvmet.h
index ecba3890ce65..8df297a190bf 100644
--- a/drivers/nvme/target/nvmet.h
+++ b/drivers/nvme/target/nvmet.h
@@ -144,6 +144,7 @@ struct nvmet_port {
 	struct list_head		global_entry;
 	struct config_group		ana_groups_group;
 	struct nvmet_ana_group		ana_default_group;
+	struct nvmet_subsys		*disc_subsys;
 	enum nvme_ana_state		*ana_state;
 	void				*priv;
 	bool				enabled;
-- 
2.29.2