[PATCH] nvmet: implement unique discovery NQN

[Chaitanya Kulkarni]

On 12/11/23 00:10, hare at kernel.org wrote:
> From: Hannes Reinecke <hare at suse.de>
>
> Add a configfs attribute 'discovery_nqn' in the 'nvmet' configfs
> directory to specify the unique discovery NQN.
>
> Signed-off-by: Hannes Reinecke <hare at suse.de>
> ---
>   drivers/nvme/target/configfs.c | 45 ++++++++++++++++++++++++++++++++++
>   drivers/nvme/target/core.c     |  7 ++++++
>   2 files changed, 52 insertions(+)
>
> diff --git a/drivers/nvme/target/configfs.c b/drivers/nvme/target/configfs.c
> index d937fe05129e..88911d0cd057 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 +2136,47 @@ 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)
> +{
> +	size_t len;
> +	struct list_head *entry;
> +
> +	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;
> +}
> +
>

please consider something like following, it removes long line
re-structures the declaration totally untested :-

diff --git a/drivers/nvme/target/configfs.c b/drivers/nvme/target/configfs.c
index 88911d0cd057..05d67ddfe83e 100644
--- a/drivers/nvme/target/configfs.c
+++ b/drivers/nvme/target/configfs.c
@@ -2145,8 +2145,8 @@ static ssize_t 
nvmet_root_discovery_nqn_show(struct config_item *item,
  static ssize_t nvmet_root_discovery_nqn_store(struct config_item *item,
                 const char *page, size_t count)
  {
-       size_t len;
         struct list_head *entry;
+       size_t len;

         len = strcspn(page, "\n");
         if (!len || len > NVMF_NQN_FIELD_LEN - 1)
@@ -2154,7 +2154,9 @@ static ssize_t 
nvmet_root_discovery_nqn_store(struct config_item *item,

         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);
+               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);

-ck