[PATCHv2] nvme-tcp: Do not terminate i/o commands during RESETTING

[hare at kernel.org]

From: Hannes Reinecke <hare at suse.de>

Terminating commands from the timeout handler might lead
to a data corruption as the timeout might trigger before
KATO expired.
When several commands have been sent in a batch and
the command timeouts trigger just after the keep-alive
command has been sent then the first command will trigger
the error recovery. But all other commands will timeout
directly afterwards and will hit the timeout handler
before the err_work workqueue handler has started.
This results in these commands being aborted and
immediately retried without waiting for KATO.
So return BLK_EH_RESET_TIMER for I/O commands when
the controller is in 'RESETTING' or 'DELETING'
state to ensure that the commands will
be retried only after the KATO interval.

Signed-off-by: Hannes Reinecke <hare at suse.de>
---
 drivers/nvme/host/tcp.c | 22 ++++++++++++++++------
 1 file changed, 16 insertions(+), 6 deletions(-)

diff --git a/drivers/nvme/host/tcp.c b/drivers/nvme/host/tcp.c
index 08805f027810..9dcb2d3b123c 100644
--- a/drivers/nvme/host/tcp.c
+++ b/drivers/nvme/host/tcp.c
@@ -2431,17 +2431,27 @@ static enum blk_eh_timer_return nvme_tcp_timeout(struct request *rq)
 	struct nvme_tcp_cmd_pdu *pdu = nvme_tcp_req_cmd_pdu(req);
 	u8 opc = pdu->cmd.common.opcode, fctype = pdu->cmd.fabrics.fctype;
 	int qid = nvme_tcp_queue_id(req->queue);
+	enum nvme_ctrl_state state = nvme_ctrl_state(ctrl);
 
 	dev_warn(ctrl->device,
-		"queue %d: timeout cid %#x type %d opcode %#x (%s)\n",
+		"queue %d: timeout cid %#x type %d opcode %#x (%s) state %d\n",
 		nvme_tcp_queue_id(req->queue), nvme_cid(rq), pdu->hdr.type,
-		opc, nvme_opcode_str(qid, opc, fctype));
+		opc, nvme_opcode_str(qid, opc, fctype), state);
+
+	/*
+	 * If the controller is in state RESETTING or DELETING all
+	 * inflight commands will be terminated soon which in turn
+	 * may failover to a different path.
+	 */
+	if ((state == NVME_CTRL_RESETTING ||
+	     state == NVME_CTRL_DELETING) && qid > 0)
+		return BLK_EH_RESET_TIMER;
 
-	if (nvme_ctrl_state(ctrl) != NVME_CTRL_LIVE) {
+	if (state != NVME_CTRL_LIVE) {
 		/*
-		 * If we are resetting, connecting or deleting we should
-		 * complete immediately because we may block controller
-		 * teardown or setup sequence
+		 * If the controller is not live we should complete
+		 * immediately because we may block controller teardown
+		 * or setup sequence
 		 * - ctrl disable/shutdown fabrics requests
 		 * - connect requests
 		 * - initialization admin requests
-- 
2.35.3