[PATCH v7 02/17] nvmet/debugfs: Export controller CIU and CIRN via debugfs

[Mohamed Khalfella <mkhalfella@purestorage.com>]

Export ctrl->ciu and ctrl->cirn as debugfs files under controller
debugfs directory. The values are useful in matching host controller
with the corresponding target controller.

While tools like nvme-cli can parse and dump these values during normal
operation via identify commands, having these attributes exported in
debugfs is essential when a controller is stuck in a state where it
cannot process standard admin commands. Exposing these values directly
ensures administrators and diagnostic scripts can always retrieve CIU
and CIRN for manual Cross-Controller Reset (CCR) operations or path
correlations.

Signed-off-by: Mohamed Khalfella <mkhalfella@purestorage.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Daniel Wagner <dwagner@suse.de>
---
 drivers/nvme/target/debugfs.c | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/drivers/nvme/target/debugfs.c b/drivers/nvme/target/debugfs.c
index e85fe1d4c9f8..221fa81e124f 100644
--- a/drivers/nvme/target/debugfs.c
+++ b/drivers/nvme/target/debugfs.c
@@ -153,6 +153,24 @@ static int nvmet_ctrl_tls_concat_show(struct seq_file *m, void *p)
 NVMET_DEBUGFS_ATTR(nvmet_ctrl_tls_concat);
 #endif
 
+static int nvmet_ctrl_instance_ciu_show(struct seq_file *m, void *p)
+{
+	struct nvmet_ctrl *ctrl = m->private;
+
+	seq_printf(m, "%02x\n", ctrl->ciu);
+	return 0;
+}
+NVMET_DEBUGFS_ATTR(nvmet_ctrl_instance_ciu);
+
+static int nvmet_ctrl_instance_cirn_show(struct seq_file *m, void *p)
+{
+	struct nvmet_ctrl *ctrl = m->private;
+
+	seq_printf(m, "%016llx\n", ctrl->cirn);
+	return 0;
+}
+NVMET_DEBUGFS_ATTR(nvmet_ctrl_instance_cirn);
+
 static const char *const nvmet_pr_type_names[] = {
 	[NVME_PR_WRITE_EXCLUSIVE]		= "write_exclusive",
 	[NVME_PR_EXCLUSIVE_ACCESS]		= "exclusive_access",
@@ -287,6 +305,10 @@ int nvmet_debugfs_ctrl_setup(struct nvmet_ctrl *ctrl)
 	debugfs_create_file("tls_key", S_IRUSR, ctrl->debugfs_dir, ctrl,
 			    &nvmet_ctrl_tls_key_fops);
 #endif
+	debugfs_create_file("ciu", S_IRUSR, ctrl->debugfs_dir, ctrl,
+			    &nvmet_ctrl_instance_ciu_fops);
+	debugfs_create_file("cirn", S_IRUSR, ctrl->debugfs_dir, ctrl,
+			    &nvmet_ctrl_instance_cirn_fops);
 	return 0;
 }
 
-- 
2.56.0