[PATCH 3/4] nvmet: include all configured ports in the discovery log page

[Hannes Reinecke <hare@suse.de>]

When a per-port discovery subsystem is used we should include
all configured ports in the discovery log page, not just that one
through which the controller was connected.

- /
  o- ports
  | o- 1 .. [trtype=tcp, traddr=127.0.0.1, trsvcid=8009]
  | | o- subsystems
  | |   o- nqn.discovery
  | o- 2 .. [trtype=tcp, traddr=127.0.0.1, trsvcid=4420]
  | | o- subsystems
  | |   o- nqn.discovery
  | |   o- nqn.io-1
  | o- 3 .. [trtype=tcp, traddr=127.0.0.1, trsvcid=4421]
  |   o- subsystems
  |     o- nqn.io-2
  o- subsystems
    o- nqn.discovery
    o- nqn.io-1
    | o- namespaces
    o- nqn.io-2
      o- namespaces

A discovery on port 8009 will return information about
- nqn.discovery at port 8009
- nqn.discovery at port 4420
- nqn.io-1 at port 4420
A discovery on port 4420 will return the same information.
A discovery on port 4421 will return information about
- standard discovery subsystem on port 4421
- nqn.io-2 on port 4421

Signed-off-by: Hannes Reinecke <hare@suse.de>
---
 drivers/nvme/target/discovery.c | 53 +++++++++++++++++++++++++++------
 1 file changed, 44 insertions(+), 9 deletions(-)

diff --git a/drivers/nvme/target/discovery.c b/drivers/nvme/target/discovery.c
index 6b8aa6c4e752..ea8fce538342 100644
--- a/drivers/nvme/target/discovery.c
+++ b/drivers/nvme/target/discovery.c
@@ -149,6 +149,30 @@ static void nvmet_set_disc_traddr(struct nvmet_req *req, struct nvmet_port *port
 		memcpy(traddr, port->disc_addr.traddr, NVMF_TRADDR_SIZE);
 }
 
+/*
+ * discovery_port_match - filter eligible ports for discovery log page
+ *
+ * If the port through which the controller is connected has no discovery
+ * subsystem linked, use the original behaviour of just including information
+ * about that port in the discovery log page.
+ * Otherwise include information about all ports into which the specified
+ * discovery subsystem is linked.
+ */
+
+static bool discovery_port_match(struct nvmet_req *req, struct nvmet_port *r)
+{
+	struct nvmet_ctrl *ctrl = req->sq->ctrl;
+
+	if (!req->port->disc_subsys) {
+		if (r != req->port)
+			return false;
+	} else {
+		if (ctrl->subsys != r->disc_subsys)
+			return false;
+	}
+	return true;
+}
+
 static size_t discovery_log_entries(struct nvmet_req *req)
 {
 	struct nvmet_ctrl *ctrl = req->sq->ctrl;
@@ -159,10 +183,14 @@ static size_t discovery_log_entries(struct nvmet_req *req)
 	if (!req->port->disc_subsys)
 		entries++;
 
-	list_for_each_entry(p, &req->port->subsystems, entry) {
-		if (!nvmet_host_allowed(p->subsys, ctrl->hostnqn))
+	list_for_each_entry(r, nvmet_ports, global_entry) {
+		if (!discovery_port_match(req, r))
 			continue;
-		entries++;
+		list_for_each_entry(p, &r->subsystems, entry) {
+			if (!nvmet_host_allowed(p->subsys, ctrl->hostnqn))
+				continue;
+			entries++;
+		}
 	}
 	list_for_each_entry(r, &req->port->referrals, entry)
 		entries++;
@@ -226,14 +254,21 @@ static void nvmet_execute_disc_get_log_page(struct nvmet_req *req)
 		numrec++;
 	}
 
-	list_for_each_entry(p, &req->port->subsystems, entry) {
-		if (!nvmet_host_allowed(p->subsys, ctrl->hostnqn))
+	list_for_each_entry(r, nvmet_ports, global_entry) {
+		nvmet_set_disc_traddr(req, r, traddr);
+
+		if (!discovery_port_match(req, r))
 			continue;
 
-		nvmet_format_discovery_entry(hdr, req->port,
-				p->subsys->subsysnqn, traddr,
-				p->subsys->type, numrec);
-		numrec++;
+		list_for_each_entry(p, &r->subsystems, entry) {
+			if (!nvmet_host_allowed(p->subsys, ctrl->hostnqn))
+				continue;
+
+			nvmet_format_discovery_entry(hdr, r,
+					p->subsys->subsysnqn, traddr,
+					p->subsys->type, numrec);
+			numrec++;
+		}
 	}
 
 	list_for_each_entry(r, &req->port->referrals, entry) {
-- 
2.29.2