* [PATCHv3] nvmet: implement unique discovery NQN
@ 2023-12-17 15:58 Hannes Reinecke
0 siblings, 0 replies; only message in thread
From: Hannes Reinecke @ 2023-12-17 15:58 UTC (permalink / raw
To: Christoph Hellwig; +Cc: Sagi Grimberg, Keith Busch, linux-nvme, Hannes Reinecke
From: Hannes Reinecke <hare@suse.de>
Unique discovery NQNs allow to differentiate between discovery
services from (typically physically separate) NVMe-oF subsystems.
This allows to identify discovery connections to the same subsystem
and to minimize the number of discovery connections when
persistent discovery controllers are enabled.
This patch adda a configfs attribute 'discovery_nqn' in the 'nvmet'
configfs directory to specify the unique discovery NQN.
Signed-off-by: Hannes Reinecke <hare@suse.de>
---
drivers/nvme/target/configfs.c | 46 ++++++++++++++++++++++++++++++++++
drivers/nvme/target/core.c | 7 ++++++
2 files changed, 53 insertions(+)
diff --git a/drivers/nvme/target/configfs.c b/drivers/nvme/target/configfs.c
index d937fe05129e..456aa5e009cd 100644
--- a/drivers/nvme/target/configfs.c
+++ b/drivers/nvme/target/configfs.c
@@ -1587,6 +1587,11 @@ static struct config_group *nvmet_subsys_make(struct config_group *group,
return ERR_PTR(-EINVAL);
}
+ if (sysfs_streq(name, nvmet_disc_subsys->subsysnqn)) {
+ pr_err("can't create subsystem using unique discovery NQN\n");
+ return ERR_PTR(-EINVAL);
+ }
+
subsys = nvmet_subsys_alloc(name, NVME_NQN_NVME);
if (IS_ERR(subsys))
return ERR_CAST(subsys);
@@ -2131,7 +2136,48 @@ static const struct config_item_type nvmet_hosts_type = {
static struct config_group nvmet_hosts_group;
+static ssize_t nvmet_root_discovery_nqn_show(struct config_item *item,
+ char *page)
+{
+ return sprintf(page, "%s\n", nvmet_disc_subsys->subsysnqn);
+}
+
+static ssize_t nvmet_root_discovery_nqn_store(struct config_item *item,
+ const char *page, size_t count)
+{
+ struct list_head *entry;
+ size_t len;
+
+ len = strcspn(page, "\n");
+ if (!len || len > NVMF_NQN_FIELD_LEN - 1)
+ return -EINVAL;
+
+ down_write(&nvmet_config_sem);
+ list_for_each(entry, &nvmet_subsystems_group.cg_children) {
+ struct config_item *item =
+ container_of(entry, struct config_item, ci_entry);
+ if (!strncmp(config_item_name(item), page, len)) {
+ pr_err("duplicate NQN %s\n", config_item_name(item));
+ up_write(&nvmet_config_sem);
+ return -EINVAL;
+ }
+ }
+ memset(nvmet_disc_subsys->subsysnqn, 0, NVMF_NQN_FIELD_LEN);
+ memcpy(nvmet_disc_subsys->subsysnqn, page, len);
+ up_write(&nvmet_config_sem);
+
+ return len;
+}
+
+CONFIGFS_ATTR(nvmet_root_, discovery_nqn);
+
+static struct configfs_attribute *nvmet_root_attrs[] = {
+ &nvmet_root_attr_discovery_nqn,
+ NULL,
+};
+
static const struct config_item_type nvmet_root_type = {
+ .ct_attrs = nvmet_root_attrs,
.ct_owner = THIS_MODULE,
};
diff --git a/drivers/nvme/target/core.c b/drivers/nvme/target/core.c
index 3935165048e7..9c028bbedb45 100644
--- a/drivers/nvme/target/core.c
+++ b/drivers/nvme/target/core.c
@@ -1530,6 +1530,13 @@ static struct nvmet_subsys *nvmet_find_get_subsys(struct nvmet_port *port,
}
down_read(&nvmet_config_sem);
+ if (!strncmp(nvmet_disc_subsys->subsysnqn, subsysnqn,
+ NVMF_NQN_SIZE)) {
+ if (kref_get_unless_zero(&nvmet_disc_subsys->ref)) {
+ up_read(&nvmet_config_sem);
+ return nvmet_disc_subsys;
+ }
+ }
list_for_each_entry(p, &port->subsystems, entry) {
if (!strncmp(p->subsys->subsysnqn, subsysnqn,
NVMF_NQN_SIZE)) {
--
2.35.3
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