[PATCH V2] nvme: mark ctrl as DEAD if removing from error recovery

[Ming Lei]

namespace's request queue is frozen and quiesced during error recovering,
writeback IO is blocked in bio_queue_enter(), so fsync_bdev() <- del_gendisk()
can't move on, and causes IO hang. Removal could be from sysfs, hard
unplug or error handling.

Fix this kind of issue by marking controller as DEAD if removal breaks
error recovery.

This ways is reasonable too, because controller can't be recovered any
more after being removed.

Cc: stable at vger.kernel.org
Reported-by: Chunguang Xu <brookxu.cn at gmail.com>
Closes: https://lore.kernel.org/linux-nvme/cover.1685350577.git.chunguang.xu@shopee.com/
Reported-by: Yi Zhang <yi.zhang at redhat.com>
Signed-off-by: Ming Lei <ming.lei at redhat.com>
---
V2:
	- patch style fix, as suggested by Christoph
	- document this handling

 drivers/nvme/host/core.c | 9 ++++++++-
 drivers/nvme/host/nvme.h | 1 +
 2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index fdfcf2781c85..1419eb35b47a 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -567,6 +567,7 @@ bool nvme_change_ctrl_state(struct nvme_ctrl *ctrl,
 	}
 
 	if (changed) {
+		ctrl->old_state = ctrl->state;
 		ctrl->state = new_state;
 		wake_up_all(&ctrl->state_wq);
 	}
@@ -4054,8 +4055,14 @@ void nvme_remove_namespaces(struct nvme_ctrl *ctrl)
 	 * disconnected. In that case, we won't be able to flush any data while
 	 * removing the namespaces' disks; fail all the queues now to avoid
 	 * potentially having to clean up the failed sync later.
+	 *
+	 * If this removal happens during error recovering, resetting part
+	 * may not be started, or controller isn't be recovered completely,
+	 * so we have to treat controller as DEAD for avoiding IO hang since
+	 * queues can be left as frozen and quiesced.
 	 */
-	if (ctrl->state == NVME_CTRL_DEAD) {
+	if (ctrl->state == NVME_CTRL_DEAD ||
+	    ctrl->old_state != NVME_CTRL_LIVE) {
 		nvme_mark_namespaces_dead(ctrl);
 		nvme_unquiesce_io_queues(ctrl);
 	}
diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h
index 9a98c14c552a..ce67856d4d4f 100644
--- a/drivers/nvme/host/nvme.h
+++ b/drivers/nvme/host/nvme.h
@@ -254,6 +254,7 @@ struct nvme_ctrl {
 	bool comp_seen;
 	bool identified;
 	enum nvme_ctrl_state state;
+	enum nvme_ctrl_state old_state;
 	spinlock_t lock;
 	struct mutex scan_lock;
 	const struct nvme_ctrl_ops *ops;
-- 
2.40.1