[PATCH 2/4] nvmet: per-port discovery subsystem

Hannes Reinecke
2022-04-20T09:28:01Z

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