[RFC PATCH 12/14] nvme-fc: Decouple error recovery from controller reset

[Mohamed Khalfella <mkhalfella@purestorage.com>]

nvme_fc_error_recovery() called from nvme_fc_timeout() while controller
in CONNECTING state results in deadlock reported in link below. Update
nvme_fc_timeout() to schedule error recovery to avoid the deadlock.

Previous to this change, if controller was LIVE, error recovery resets
the controller. This did not match nvme-tcp and nvme-rdma. Decouple
error recovery from controller reset to match other fabric transports.

Link: https://lore.kernel.org/all/20250529214928.2112990-1-mkhalfella@purestorage.com/
Signed-off-by: Mohamed Khalfella <mkhalfella@purestorage.com>
---
 drivers/nvme/host/fc.c | 94 ++++++++++++++++++------------------------
 1 file changed, 41 insertions(+), 53 deletions(-)

diff --git a/drivers/nvme/host/fc.c b/drivers/nvme/host/fc.c
index 03987f497a5b..8b6a7c80015c 100644
--- a/drivers/nvme/host/fc.c
+++ b/drivers/nvme/host/fc.c
@@ -227,6 +227,8 @@ static DEFINE_IDA(nvme_fc_ctrl_cnt);
 static struct device *fc_udev_device;
 
 static void nvme_fc_complete_rq(struct request *rq);
+static void nvme_fc_start_ioerr_recovery(struct nvme_fc_ctrl *ctrl,
+					 char *errmsg);
 
 /* *********************** FC-NVME Port Management ************************ */
 
@@ -786,7 +788,7 @@ nvme_fc_ctrl_connectivity_loss(struct nvme_fc_ctrl *ctrl)
 		"Reconnect", ctrl->cnum);
 
 	set_bit(ASSOC_FAILED, &ctrl->flags);
-	nvme_reset_ctrl(&ctrl->ctrl);
+	nvme_fc_start_ioerr_recovery(ctrl, "Connectivity Loss");
 }
 
 /**
@@ -983,7 +985,7 @@ fc_dma_unmap_sg(struct device *dev, struct scatterlist *sg, int nents,
 static void nvme_fc_ctrl_put(struct nvme_fc_ctrl *);
 static int nvme_fc_ctrl_get(struct nvme_fc_ctrl *);
 
-static void nvme_fc_error_recovery(struct nvme_fc_ctrl *ctrl, char *errmsg);
+static void nvme_fc_error_recovery(struct nvme_fc_ctrl *ctrl);
 
 static void
 __nvme_fc_finish_ls_req(struct nvmefc_ls_req_op *lsop)
@@ -1563,9 +1565,8 @@ nvme_fc_ls_disconnect_assoc(struct nvmefc_ls_rcv_op *lsop)
 	 * for the association have been ABTS'd by
 	 * nvme_fc_delete_association().
 	 */
-
-	/* fail the association */
-	nvme_fc_error_recovery(ctrl, "Disconnect Association LS received");
+	nvme_fc_start_ioerr_recovery(ctrl,
+				     "Disconnect Association LS received");
 
 	/* release the reference taken by nvme_fc_match_disconn_ls() */
 	nvme_fc_ctrl_put(ctrl);
@@ -1867,7 +1868,7 @@ nvme_fc_ctrl_ioerr_work(struct work_struct *work)
 	struct nvme_fc_ctrl *ctrl =
 			container_of(work, struct nvme_fc_ctrl, ioerr_work);
 
-	nvme_fc_error_recovery(ctrl, "transport detected io error");
+	nvme_fc_error_recovery(ctrl);
 }
 
 /*
@@ -1888,6 +1889,17 @@ char *nvme_fc_io_getuuid(struct nvmefc_fcp_req *req)
 }
 EXPORT_SYMBOL_GPL(nvme_fc_io_getuuid);
 
+static void nvme_fc_start_ioerr_recovery(struct nvme_fc_ctrl *ctrl,
+					 char *errmsg)
+{
+	if (!nvme_change_ctrl_state(&ctrl->ctrl, NVME_CTRL_RESETTING))
+		return;
+
+	dev_warn(ctrl->ctrl.device, "NVME-FC{%d}: starting error recovery %s\n",
+		 ctrl->cnum, errmsg);
+	queue_delayed_work(nvme_reset_wq, &ctrl->ioerr_work, 0);
+}
+
 static void
 nvme_fc_fcpio_done(struct nvmefc_fcp_req *req)
 {
@@ -2045,9 +2057,8 @@ nvme_fc_fcpio_done(struct nvmefc_fcp_req *req)
 		nvme_fc_complete_rq(rq);
 
 check_error:
-	if (terminate_assoc &&
-	    nvme_ctrl_state(&ctrl->ctrl) != NVME_CTRL_RESETTING)
-		queue_work(nvme_reset_wq, &ctrl->ioerr_work);
+	if (terminate_assoc)
+		nvme_fc_start_ioerr_recovery(ctrl, "io error");
 }
 
 static int
@@ -2497,39 +2508,6 @@ __nvme_fc_abort_outstanding_ios(struct nvme_fc_ctrl *ctrl, bool start_queues)
 		nvme_unquiesce_admin_queue(&ctrl->ctrl);
 }
 
-static void
-nvme_fc_error_recovery(struct nvme_fc_ctrl *ctrl, char *errmsg)
-{
-	enum nvme_ctrl_state state = nvme_ctrl_state(&ctrl->ctrl);
-
-	/*
-	 * if an error (io timeout, etc) while (re)connecting, the remote
-	 * port requested terminating of the association (disconnect_ls)
-	 * or an error (timeout or abort) occurred on an io while creating
-	 * the controller.  Abort any ios on the association and let the
-	 * create_association error path resolve things.
-	 */
-	if (state == NVME_CTRL_CONNECTING) {
-		__nvme_fc_abort_outstanding_ios(ctrl, true);
-		dev_warn(ctrl->ctrl.device,
-			"NVME-FC{%d}: transport error during (re)connect\n",
-			ctrl->cnum);
-		return;
-	}
-
-	/* Otherwise, only proceed if in LIVE state - e.g. on first error */
-	if (state != NVME_CTRL_LIVE)
-		return;
-
-	dev_warn(ctrl->ctrl.device,
-		"NVME-FC{%d}: transport association event: %s\n",
-		ctrl->cnum, errmsg);
-	dev_warn(ctrl->ctrl.device,
-		"NVME-FC{%d}: resetting controller\n", ctrl->cnum);
-
-	nvme_reset_ctrl(&ctrl->ctrl);
-}
-
 static enum blk_eh_timer_return nvme_fc_timeout(struct request *rq)
 {
 	struct nvme_fc_fcp_op *op = blk_mq_rq_to_pdu(rq);
@@ -2538,24 +2516,14 @@ static enum blk_eh_timer_return nvme_fc_timeout(struct request *rq)
 	struct nvme_fc_cmd_iu *cmdiu = &op->cmd_iu;
 	struct nvme_command *sqe = &cmdiu->sqe;
 
-	/*
-	 * Attempt to abort the offending command. Command completion
-	 * will detect the aborted io and will fail the connection.
-	 */
 	dev_info(ctrl->ctrl.device,
 		"NVME-FC{%d.%d}: io timeout: opcode %d fctype %d (%s) w10/11: "
 		"x%08x/x%08x\n",
 		ctrl->cnum, qnum, sqe->common.opcode, sqe->fabrics.fctype,
 		nvme_fabrics_opcode_str(qnum, sqe),
 		sqe->common.cdw10, sqe->common.cdw11);
-	if (__nvme_fc_abort_op(ctrl, op))
-		nvme_fc_error_recovery(ctrl, "io timeout abort failed");
 
-	/*
-	 * the io abort has been initiated. Have the reset timer
-	 * restarted and the abort completion will complete the io
-	 * shortly. Avoids a synchronous wait while the abort finishes.
-	 */
+	nvme_fc_start_ioerr_recovery(ctrl, "io timeout");
 	return BLK_EH_RESET_TIMER;
 }
 
@@ -3347,6 +3315,26 @@ nvme_fc_reset_ctrl_work(struct work_struct *work)
 	}
 }
 
+static void
+nvme_fc_error_recovery(struct nvme_fc_ctrl *ctrl)
+{
+	nvme_stop_keep_alive(&ctrl->ctrl);
+	nvme_stop_ctrl(&ctrl->ctrl);
+
+	/* will block while waiting for io to terminate */
+	nvme_fc_delete_association(ctrl);
+
+	/* Do not reconnect if controller is being deleted */
+	if (!nvme_change_ctrl_state(&ctrl->ctrl, NVME_CTRL_CONNECTING))
+		return;
+
+	if (ctrl->rport->remoteport.port_state == FC_OBJSTATE_ONLINE) {
+		queue_delayed_work(nvme_wq, &ctrl->connect_work, 0);
+		return;
+	}
+
+	nvme_fc_reconnect_or_delete(ctrl, -ENOTCONN);
+}
 
 static const struct nvme_ctrl_ops nvme_fc_ctrl_ops = {
 	.name			= "fc",
-- 
2.51.2