[PATCH 1/2] nvmet: make MDTS value configurable

[hare@suse.de (Hannes Reinecke)]

For testing the bio splitting algorithm it's useful to be able to
modify the mdts value.

Signed-off-by: Hannes Reinecke <hare at suse.com>
---
 drivers/nvme/target/admin-cmd.c |  3 +--
 drivers/nvme/target/configfs.c  | 27 +++++++++++++++++++++++++++
 drivers/nvme/target/nvmet.h     |  2 ++
 3 files changed, 30 insertions(+), 2 deletions(-)

diff --git a/drivers/nvme/target/admin-cmd.c b/drivers/nvme/target/admin-cmd.c
index 76250181fee0..1c4cb371fac8 100644
--- a/drivers/nvme/target/admin-cmd.c
+++ b/drivers/nvme/target/admin-cmd.c
@@ -311,8 +311,7 @@ static void nvmet_execute_identify_ctrl(struct nvmet_req *req)
 	/* we support multiple ports, multiples hosts and ANA: */
 	id->cmic = (1 << 0) | (1 << 1) | (1 << 3);
 
-	/* no limit on data transfer sizes for now */
-	id->mdts = 0;
+	id->mdts = ctrl->subsys->mdts;
 	id->cntlid = cpu_to_le16(ctrl->cntlid);
 	id->ver = cpu_to_le32(ctrl->subsys->ver);
 
diff --git a/drivers/nvme/target/configfs.c b/drivers/nvme/target/configfs.c
index adb79545cdd7..63b9991de79e 100644
--- a/drivers/nvme/target/configfs.c
+++ b/drivers/nvme/target/configfs.c
@@ -859,10 +859,37 @@ static ssize_t nvmet_subsys_attr_serial_store(struct config_item *item,
 }
 CONFIGFS_ATTR(nvmet_subsys_, attr_serial);
 
+static ssize_t nvmet_subsys_attr_mdts_show(struct config_item *item,
+					   char *page)
+{
+	struct nvmet_subsys *subsys = to_subsys(item);
+
+	return snprintf(page, PAGE_SIZE, "%u\n", subsys->mdts);
+}
+
+static ssize_t nvmet_subsys_attr_mdts_store(struct config_item *item,
+					    const char *page, size_t count)
+{
+	struct nvmet_subsys *subsys = to_subsys(item);
+	unsigned int mdts;
+	int ret;
+
+	ret = kstrtou32(page, 0, &mdts);
+	if (ret)
+		return ret;
+	down_write(&nvmet_config_sem);
+	subsys->mdts = mdts;
+	up_write(&nvmet_config_sem);
+
+	return count;
+}
+CONFIGFS_ATTR(nvmet_subsys_, attr_mdts);
+
 static struct configfs_attribute *nvmet_subsys_attrs[] = {
 	&nvmet_subsys_attr_attr_allow_any_host,
 	&nvmet_subsys_attr_attr_version,
 	&nvmet_subsys_attr_attr_serial,
+	&nvmet_subsys_attr_attr_mdts,
 	NULL,
 };
 
diff --git a/drivers/nvme/target/nvmet.h b/drivers/nvme/target/nvmet.h
index 51e49efd7849..f05f069f83ea 100644
--- a/drivers/nvme/target/nvmet.h
+++ b/drivers/nvme/target/nvmet.h
@@ -217,6 +217,8 @@ struct nvmet_subsys {
 	bool			allow_any_host;
 
 	u16			max_qid;
+	u8			mdts;
+	u8			mpsmin;
 
 	u64			ver;
 	u64			serial;
-- 
2.16.4