[PATCH 2/3] nvmet: make the subsystem type configurable

[Hannes Reinecke <hare@suse.de>]

Make the subsystem type configurable to allow for unique
discovery subsystems by changing the subsystem type to
'discovery'.

Signed-off-by: Hannes Reinecke <hare@suse.de>
---
 drivers/nvme/target/configfs.c  | 65 +++++++++++++++++++++++++++++++++
 drivers/nvme/target/core.c      |  3 ++
 drivers/nvme/target/discovery.c | 20 +++++++++-
 drivers/nvme/target/nvmet.h     |  3 ++
 4 files changed, 89 insertions(+), 2 deletions(-)

diff --git a/drivers/nvme/target/configfs.c b/drivers/nvme/target/configfs.c
index 57a6795a2d8d..ae6815b72d7d 100644
--- a/drivers/nvme/target/configfs.c
+++ b/drivers/nvme/target/configfs.c
@@ -930,6 +930,9 @@ static void nvmet_port_subsys_drop_link(struct config_item *parent,
 
 found:
 	list_del(&p->entry);
+	/* Reset to static discovery controller */
+	if (nvmet_disc_subsys == subsys)
+		nvmet_set_disc_subsys(NULL);
 	nvmet_port_del_ctrls(port, subsys);
 	nvmet_port_disc_changed(port, subsys);
 
@@ -1302,6 +1305,67 @@ static ssize_t nvmet_subsys_attr_model_store(struct config_item *item,
 }
 CONFIGFS_ATTR(nvmet_subsys_, attr_model);
 
+static const struct nvmet_type_name_map nvmet_subsys_type_map[] = {
+	{ NVME_NQN_DISC,	"referral" },
+	{ NVME_NQN_NVME,	"nvme" },
+	{ NVME_NQN_CURR,	"discovery" },
+};
+
+static ssize_t nvmet_subsys_attr_type_show(struct config_item *item,
+						 char *page)
+{
+	u8 type = to_subsys(item)->type;
+	int i;
+
+	for (i = 1; i < ARRAY_SIZE(nvmet_subsys_type_map); i++) {
+		if (nvmet_subsys_type_map[i].type == type)
+			return snprintf(page, PAGE_SIZE, "%s\n",
+					nvmet_subsys_type_map[i].name);
+	}
+
+	return snprintf(page, PAGE_SIZE, "\n");
+}
+
+static ssize_t nvmet_subsys_attr_type_store(struct config_item *item,
+					    const char *page, size_t count)
+{
+	struct nvmet_subsys *subsys = to_subsys(item);
+	int i;
+
+	if (subsys->subsys_discovered)
+		return -EACCES;
+
+	for (i = 0; i < ARRAY_SIZE(nvmet_subsys_type_map); i++) {
+		if (sysfs_streq(page, nvmet_subsys_type_map[i].name))
+			goto found;
+	}
+
+	pr_err("Invalid value '%s' for subsystem type\n", page);
+	return -EINVAL;
+
+found:
+	down_write(&nvmet_config_sem);
+	if (nvmet_subsys_type_map[i].type == NVME_NQN_CURR) {
+		if (nvmet_has_unique_disc_subsys()) {
+			pr_err("unique discovery subsystem already present\n");
+			return -EINVAL;
+		}
+		if (!xa_empty(&subsys->namespaces)) {
+			pr_err("discovery subsystem cannot have namespaces\n");
+			return -EINVAL;
+		}
+		nvmet_subsys_del_ctrls(nvmet_disc_subsys);
+		nvmet_set_disc_subsys(subsys);
+	} else if (subsys->type == NVME_NQN_CURR)
+		nvmet_set_disc_subsys(NULL);
+
+	subsys->type = nvmet_subsys_type_map[i].type;
+	up_write(&nvmet_config_sem);
+
+	return count;
+}
+CONFIGFS_ATTR(nvmet_subsys_, attr_type);
+
 #ifdef CONFIG_BLK_DEV_INTEGRITY
 static ssize_t nvmet_subsys_attr_pi_enable_show(struct config_item *item,
 						char *page)
@@ -1331,6 +1395,7 @@ static struct configfs_attribute *nvmet_subsys_attrs[] = {
 	&nvmet_subsys_attr_attr_cntlid_min,
 	&nvmet_subsys_attr_attr_cntlid_max,
 	&nvmet_subsys_attr_attr_model,
+	&nvmet_subsys_attr_attr_type,
 #ifdef CONFIG_BLK_DEV_INTEGRITY
 	&nvmet_subsys_attr_attr_pi_enable,
 #endif
diff --git a/drivers/nvme/target/core.c b/drivers/nvme/target/core.c
index 83eba511d098..a9d03dfe547e 100644
--- a/drivers/nvme/target/core.c
+++ b/drivers/nvme/target/core.c
@@ -1527,6 +1527,9 @@ static struct nvmet_subsys *nvmet_find_get_subsys(struct nvmet_port *port,
 	}
 	up_read(&nvmet_config_sem);
 
+	if (nvmet_has_unique_disc_subsys())
+		return NULL;
+
 	if (!strcmp(NVME_DISC_SUBSYS_NAME, subsysnqn)) {
 		if (!kref_get_unless_zero(&nvmet_disc_subsys->ref))
 			return NULL;
diff --git a/drivers/nvme/target/discovery.c b/drivers/nvme/target/discovery.c
index c2162eef8ce1..bceeec00099a 100644
--- a/drivers/nvme/target/discovery.c
+++ b/drivers/nvme/target/discovery.c
@@ -9,9 +9,23 @@
 #include "nvmet.h"
 
 struct nvmet_subsys *nvmet_disc_subsys;
+static struct nvmet_subsys *_nvmet_disc_subsys;
 
 static u64 nvmet_genctr;
 
+bool nvmet_has_unique_disc_subsys(void)
+{
+	return (_nvmet_disc_subsys != nvmet_disc_subsys);
+}
+
+void nvmet_set_disc_subsys(struct nvmet_subsys *subsys)
+{
+	if (subsys)
+		nvmet_disc_subsys = subsys;
+	else
+		nvmet_disc_subsys = _nvmet_disc_subsys;
+}
+
 static void __nvmet_disc_changed(struct nvmet_port *port,
 				 struct nvmet_ctrl *ctrl)
 {
@@ -393,12 +407,14 @@ u16 nvmet_parse_discovery_cmd(struct nvmet_req *req)
 
 int __init nvmet_init_discovery(void)
 {
-	nvmet_disc_subsys =
+	_nvmet_disc_subsys =
 		nvmet_subsys_alloc(NVME_DISC_SUBSYS_NAME, NVME_NQN_CURR);
+	nvmet_disc_subsys = _nvmet_disc_subsys;
 	return PTR_ERR_OR_ZERO(nvmet_disc_subsys);
 }
 
 void nvmet_exit_discovery(void)
 {
-	nvmet_subsys_put(nvmet_disc_subsys);
+	nvmet_disc_subsys = NULL;
+	nvmet_subsys_put(_nvmet_disc_subsys);
 }
diff --git a/drivers/nvme/target/nvmet.h b/drivers/nvme/target/nvmet.h
index 81061aa8c6d3..658e3fd81f06 100644
--- a/drivers/nvme/target/nvmet.h
+++ b/drivers/nvme/target/nvmet.h
@@ -556,6 +556,9 @@ void nvmet_exit_discovery(void);
 extern struct nvmet_subsys *nvmet_disc_subsys;
 extern struct rw_semaphore nvmet_config_sem;
 
+bool nvmet_has_unique_disc_subsys(void);
+void nvmet_set_disc_subsys(struct nvmet_subsys *subsys);
+
 extern u32 nvmet_ana_group_enabled[NVMET_MAX_ANAGRPS + 1];
 extern u64 nvmet_ana_chgcnt;
 extern struct rw_semaphore nvmet_ana_sem;
-- 
2.29.2