[PATCH 1/2] nvme: add API of nvme_delete_dead_ctrl

[Ming Lei]

When driver confirms that the controller is dead, this controller should
be deleted with marking as DEAD. Otherwise, upper layer may wait forever
in __bio_queue_enter() since the disk won't be marked as DEAD.
Especially, in del_gendisk(), disk won't be marked as DEAD unless bdev
sync & invalidate returns. If any writeback IO waits in
__bio_queue_enter(), IO deadlock is caused.

Add nvme_delete_dead_ctrl() for avoiding such kind of io deadlock.

Signed-off-by: Ming Lei <ming.lei at redhat.com>
---
 drivers/nvme/host/core.c | 24 +++++++++++++++++++++++-
 drivers/nvme/host/nvme.h |  1 +
 2 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index ccb6eb1282f8..413213cfa417 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -227,16 +227,38 @@ static void nvme_delete_ctrl_work(struct work_struct *work)
 	nvme_do_delete_ctrl(ctrl);
 }
 
-int nvme_delete_ctrl(struct nvme_ctrl *ctrl)
+static int __nvme_delete_ctrl(struct nvme_ctrl *ctrl,
+			      enum nvme_ctrl_state state)
 {
+	if (state != NVME_CTRL_DELETING && state != NVME_CTRL_DEAD)
+		return -EINVAL;
+
 	if (!nvme_change_ctrl_state(ctrl, NVME_CTRL_DELETING))
 		return -EBUSY;
+	if (state == NVME_CTRL_DEAD) {
+		if (!nvme_change_ctrl_state(ctrl, NVME_CTRL_DEAD))
+			return -EBUSY;
+	}
 	if (!queue_work(nvme_delete_wq, &ctrl->delete_work))
 		return -EBUSY;
 	return 0;
 }
+
+int nvme_delete_ctrl(struct nvme_ctrl *ctrl)
+{
+	return __nvme_delete_ctrl(ctrl, NVME_CTRL_DELETING);
+}
 EXPORT_SYMBOL_GPL(nvme_delete_ctrl);
 
+/*
+ * Called when driver confirmed that the controller is really dead
+ */
+int nvme_delete_dead_ctrl(struct nvme_ctrl *ctrl)
+{
+	return __nvme_delete_ctrl(ctrl, NVME_CTRL_DEAD);
+}
+EXPORT_SYMBOL_GPL(nvme_delete_dead_ctrl);
+
 static void nvme_delete_ctrl_sync(struct nvme_ctrl *ctrl)
 {
 	/*
diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h
index bf46f122e9e1..8f62246a85be 100644
--- a/drivers/nvme/host/nvme.h
+++ b/drivers/nvme/host/nvme.h
@@ -828,6 +828,7 @@ void nvme_stop_keep_alive(struct nvme_ctrl *ctrl);
 int nvme_reset_ctrl(struct nvme_ctrl *ctrl);
 int nvme_reset_ctrl_sync(struct nvme_ctrl *ctrl);
 int nvme_delete_ctrl(struct nvme_ctrl *ctrl);
+int nvme_delete_dead_ctrl(struct nvme_ctrl *ctrl);
 void nvme_queue_scan(struct nvme_ctrl *ctrl);
 int nvme_get_log(struct nvme_ctrl *ctrl, u32 nsid, u8 log_page, u8 lsp, u8 csi,
 		void *log, size_t size, u64 offset);
-- 
2.40.1