nvmet: enable Discovery Controller AENs

Add functions to find connections requesting Discovery Change events
and send a notification to hosts that maintain an explicit persistent
connection and have and active Asynchronous Event Request pending.
Only Hosts that have access to the Subsystem effected by the change
will receive notifications of Discovery Change event.

Call these functions each time there is a configfs change that effects
the Discover Log Pages.

Set the OAES field in the Identify Controller response to advertise the
support for Asynchronous Event Notifications.

Signed-off-by: Jay Sternberg <jay.e.sternberg@intel.com>
Reviewed-by: Phil Cayton <phil.cayton@intel.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

1 files changed, 65 insertions, 3 deletions

diff --git a/drivers/nvme/target/discovery.c b/drivers/nvme/target/discovery.c
index 5fbb1bb2c4fc..eb45ebc3ac2c 100644
--- a/drivers/nvme/target/discovery.c
+++ b/drivers/nvme/target/discovery.c
@@ -20,24 +20,82 @@ struct nvmet_subsys *nvmet_disc_subsys;
 
 u64 nvmet_genctr;
 
+static void __nvmet_disc_changed(struct nvmet_port *port,
+				 struct nvmet_ctrl *ctrl)
+{
+	if (ctrl->port != port)
+		return;
+
+	if (nvmet_aen_bit_disabled(ctrl, NVME_AEN_BIT_DISC_CHANGE))
+		return;
+
+	nvmet_add_async_event(ctrl, NVME_AER_TYPE_NOTICE,
+			      NVME_AER_NOTICE_DISC_CHANGED, NVME_LOG_DISC);
+}
+
+void nvmet_port_disc_changed(struct nvmet_port *port,
+			     struct nvmet_subsys *subsys)
+{
+	struct nvmet_ctrl *ctrl;
+
+	nvmet_genctr++;
+
+	list_for_each_entry(ctrl, &nvmet_disc_subsys->ctrls, subsys_entry) {
+		if (subsys && !nvmet_host_allowed(subsys, ctrl->hostnqn))
+			continue;
+
+		__nvmet_disc_changed(port, ctrl);
+	}
+}
+
+static void __nvmet_subsys_disc_changed(struct nvmet_port *port,
+					struct nvmet_subsys *subsys,
+					struct nvmet_host *host)
+{
+	struct nvmet_ctrl *ctrl;
+
+	list_for_each_entry(ctrl, &nvmet_disc_subsys->ctrls, subsys_entry) {
+		if (host && strcmp(nvmet_host_name(host), ctrl->hostnqn))
+			continue;
+
+		__nvmet_disc_changed(port, ctrl);
+	}
+}
+
+void nvmet_subsys_disc_changed(struct nvmet_subsys *subsys,
+			       struct nvmet_host *host)
+{
+	struct nvmet_port *port;
+	struct nvmet_subsys_link *s;
+
+	nvmet_genctr++;
+
+	list_for_each_entry(port, nvmet_ports, global_entry)
+		list_for_each_entry(s, &port->subsystems, entry) {
+			if (s->subsys != subsys)
+				continue;
+			__nvmet_subsys_disc_changed(port, subsys, host);
+		}
+}
+
 void nvmet_referral_enable(struct nvmet_port *parent, struct nvmet_port *port)
 {
 	down_write(&nvmet_config_sem);
 	if (list_empty(&port->entry)) {
 		list_add_tail(&port->entry, &parent->referrals);
 		port->enabled = true;
-		nvmet_genctr++;
+		nvmet_port_disc_changed(parent, NULL);
 	}
 	up_write(&nvmet_config_sem);
 }
 
-void nvmet_referral_disable(struct nvmet_port *port)
+void nvmet_referral_disable(struct nvmet_port *parent, struct nvmet_port *port)
 {
 	down_write(&nvmet_config_sem);
 	if (!list_empty(&port->entry)) {
 		port->enabled = false;
 		list_del_init(&port->entry);
-		nvmet_genctr++;
+		nvmet_port_disc_changed(parent, NULL);
 	}
 	up_write(&nvmet_config_sem);
 }
@@ -136,6 +194,8 @@ static void nvmet_execute_get_disc_log_page(struct nvmet_req *req)
 	hdr->numrec = cpu_to_le64(numrec);
 	hdr->recfmt = cpu_to_le16(0);
 
+	nvmet_clear_aen_bit(req, NVME_AEN_BIT_DISC_CHANGE);
+
 	up_read(&nvmet_config_sem);
 
 	status = nvmet_copy_to_sgl(req, 0, hdr, data_len);
@@ -174,6 +234,8 @@ static void nvmet_execute_identify_disc_ctrl(struct nvmet_req *req)
 	if (req->port->inline_data_size)
 		id->sgls |= cpu_to_le32(1 << 20);
 
+	id->oaes = cpu_to_le32(NVMET_DISC_AEN_CFG_OPTIONAL);
+
 	strlcpy(id->subnqn, ctrl->subsys->subsysnqn, sizeof(id->subnqn));
 
 	status = nvmet_copy_to_sgl(req, 0, id, sizeof(*id));