FAILED: patch "[PATCH] scsi: zfcp: fix reaction on bit error threshold notification" failed to apply to 4.4-stable tree

The patch below does not apply to the 4.4-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 2190168aaea42c31bff7b9a967e7b045f07df095 Mon Sep 17 00:00:00 2001
From: Steffen Maier <[email protected]>
Date: Tue, 1 Oct 2019 12:49:49 +0200
Subject: [PATCH] scsi: zfcp: fix reaction on bit error threshold notification

On excessive bit errors for the FCP channel ingress fibre path, the channel notifies us. Previously, we only emitted a kernel message and a trace record. Since performance can become suboptimal with I/O timeouts due to bit errors, we now stop using an FCP device by default on channel notification so multipath on top can timely failover to other paths. A new module parameter zfcp.ber_stop can be used to get zfcp old behavior.

User explanation of new kernel message:

* Description:
* The FCP channel reported that its bit error threshold has been exceeded.
* These errors might result from a problem with the physical components
* of the local fibre link into the FCP channel.
* The problem might be damage or malfunction of the cable or
* cable connection between the FCP channel and
* the adjacent fabric switch port or the point-to-point peer.
* Find details about the errors in the HBA trace for the FCP device.
* The zfcp device driver closed down the FCP device
* to limit the performance impact from possible I/O command timeouts.
* User action:
* Check for problems on the local fibre link, ensure that fibre optics are
* clean and functional, and all cables are properly plugged.
* After the repair action, you can manually recover the FCP device by
* writing "0" into its "failed" sysfs attribute.
* If recovery through sysfs is not possible, set the CHPID of the device
* offline and back online on the service element.

index 296bbc3c4606..cf63916814cc 100644
@@ -27,6 +27,11 @@
 
 struct kmem_cache *zfcp_fsf_qtcb_cache;
 
+static bool ber_stop = true;
+module_param(ber_stop, bool, 0600);
+MODULE_PARM_DESC(ber_stop,
+		 "Shuts down FCP devices for FCP channels that report a bit-error count in excess of its threshold (default on)");
+
 static void zfcp_fsf_request_timeout_handler(struct timer_list *t)
 {
 	struct zfcp_fsf_req *fsf_req = from_timer(fsf_req, t, timer);

@@ -236,10 +241,15 @@ static void zfcp_fsf_status_read_handler(struct zfcp_fsf_req *req)
 	case FSF_STATUS_READ_SENSE_DATA_AVAIL:
 		break;
 	case FSF_STATUS_READ_BIT_ERROR_THRESHOLD:
-		dev_warn(&adapter->ccw_device->dev,
-			 "The error threshold for checksum statistics "
-			 "has been exceeded\n");
 		zfcp_dbf_hba_bit_err("fssrh_3", req);
+		if (ber_stop) {
+			dev_warn(&adapter->ccw_device->dev,
+				 "All paths over this FCP device are disused because of excessive bit errors\n");
+			zfcp_erp_adapter_shutdown(adapter, 0, "fssrh_b");
+		} else {
+			dev_warn(&adapter->ccw_device->dev,
+				 "The error threshold for checksum statistics has been exceeded\n");
+		}
 		break;
 	case FSF_STATUS_READ_LINK_DOWN:
 		zfcp_fsf_status_read_link_down(req);