[PATCH 1/3] nvmet: allow user to set the ns readonly

[Chaitanya Kulkarni]

From: "Mark Ruijter" <mruijter at primelogic.nl>

User may want to export readonly ns to host in order to export
read-only snapshots. Right now we don't have configfs attribute to
allow user to mark readonly & export ns.

Add a configfs attribute such that user can set the ns and export ns
readonly when it is not enabled.

Signed-off-by: Mark Ruijter <mruijter at primelogic.nl>
Signed-off-by: Chaitanya Kulkarni <chaitanya.kulkarni at wdc.com>
---
 drivers/nvme/target/configfs.c | 29 +++++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)

diff --git a/drivers/nvme/target/configfs.c b/drivers/nvme/target/configfs.c
index 37e1d7784e17..90c55ffab802 100644
--- a/drivers/nvme/target/configfs.c
+++ b/drivers/nvme/target/configfs.c
@@ -570,6 +570,34 @@ static ssize_t nvmet_ns_buffered_io_store(struct config_item *item,
 
 CONFIGFS_ATTR(nvmet_ns_, buffered_io);
 
+static ssize_t nvmet_ns_readonly_show(struct config_item *item, char *page)
+{
+	return sprintf(page, "%d\n", to_nvmet_ns(item)->readonly);
+}
+
+static ssize_t nvmet_ns_readonly_store(struct config_item *item,
+		const char *page, size_t count)
+{
+	struct nvmet_ns *ns = to_nvmet_ns(item);
+	bool val;
+
+	if (strtobool(page, &val))
+		return -EINVAL;
+
+	mutex_lock(&ns->subsys->lock);
+	if (ns->enabled) {
+		pr_err("disable ns before setting readonly value.\n");
+		mutex_unlock(&ns->subsys->lock);
+		return -EINVAL;
+	}
+
+	ns->readonly = val;
+	mutex_unlock(&ns->subsys->lock);
+	return count;
+}
+
+CONFIGFS_ATTR(nvmet_ns_, readonly);
+
 static ssize_t nvmet_ns_revalidate_size_store(struct config_item *item,
 		const char *page, size_t count)
 {
@@ -602,6 +630,7 @@ static struct configfs_attribute *nvmet_ns_attrs[] = {
 	&nvmet_ns_attr_ana_grpid,
 	&nvmet_ns_attr_enable,
 	&nvmet_ns_attr_buffered_io,
+	&nvmet_ns_attr_readonly,
 	&nvmet_ns_attr_revalidate_size,
 #ifdef CONFIG_PCI_P2PDMA
 	&nvmet_ns_attr_p2pmem,
-- 
2.22.1