From: "Ewan D. Milne" <emilne@redhat.com>
Date: Wed, 11 Mar 2020 10:39:30 -0400
Subject: scsi: core: avoid repetitive logging of device offline messages
Patch-mainline: v5.7-rc1
Git-commit: b0962c53bde9a485c8ebc401fa1dbe821a76bc3e
References: bsc#1145929

Large queues of I/O to offline devices that are eventually submitted when
devices are unblocked result in a many repeated "rejecting I/O to offline
device" messages.  These messages can fill up the dmesg buffer in crash
dumps so no useful prior messages remain.  In addition, if a serial console
is used, the flood of messages can cause a hard lockup in the console code.

Introduce a flag indicating the message has already been logged for the
device, and reset the flag when scsi_device_set_state() changes the device
state.

Link: https://lore.kernel.org/r/20200311143930.20674-1-emilne@redhat.com
Reviewed-by: Bart van Assche <bvanassche@acm.org>
Signed-off-by: Ewan D. Milne <emilne@redhat.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Acked-by: Daniel Wagner <dwagner@suse.de>
---
 drivers/scsi/scsi_lib.c    |    9 ++++++---
 include/scsi/scsi_device.h |    3 +++
 2 files changed, 9 insertions(+), 3 deletions(-)

--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -1266,9 +1266,11 @@ scsi_prep_state_check(struct scsi_device
 			 * commands.  The device must be brought online
 			 * before trying any recovery commands.
 			 */
-			sdev_printk(KERN_ERR, sdev,
-				    "rejecting I/O to offline device\n");
-			ret = BLKPREP_KILL;
+			if (!sdev->offline_already) {
+				sdev->offline_already = true;
+				sdev_printk(KERN_ERR, sdev,
+					"rejecting I/O to offline device\n");
+			}
 			break;
 		case SDEV_DEL:
 			/*
@@ -2680,6 +2682,7 @@ scsi_device_set_state(struct scsi_device
 		break;
 
 	}
+	sdev->offline_already = false;
 	sdev->sdev_state = state;
 	return 0;
 
--- a/include/scsi/scsi_device.h
+++ b/include/scsi/scsi_device.h
@@ -203,6 +203,9 @@ struct scsi_device {
 	struct work_struct event_work;
 
 	unsigned int max_device_blocked; /* what device_blocked counts down from  */
+
+	bool offline_already;		/* Device offline message logged */
+
 #define SCSI_DEFAULT_DEVICE_BLOCKED	3
 
 	atomic_t iorequest_cnt;