FAILED: patch "[PATCH] scsi: virtio_scsi: let host do exception handling" failed to apply to 4.4-stable tree

FAILED: patch "[PATCH] scsi: virtio_scsi: let host do exception handling" failed to apply to 4.4-stable tree

[gregkh]

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 <stable@vger.kernel.org>.

thanks,

greg k-h

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

>From e72c9a2a67a6400c8ef3d01d4c461dbbbfa0e1f0 Mon Sep 17 00:00:00 2001
From: Paolo Bonzini <pbonzini@redhat.com>
Date: Wed, 21 Jun 2017 16:35:46 +0200
Subject: [PATCH] scsi: virtio_scsi: let host do exception handling

virtio_scsi tries to do exception handling after the default 30 seconds
timeout expires.  However, it's better to let the host control the
timeout, otherwise with a heavy I/O load it is likely that an abort will
also timeout.  This leads to fatal errors like filesystems going
offline.

Disable the 'sd' timeout and allow the host to do exception handling,
following the precedent of the storvsc driver.

Hannes has a proposal to introduce timeouts in virtio, but this provides
an immediate solution for stable kernels too.

[mkp: fixed typo]

Reported-by: Douglas Miller <dougmill@linux.vnet.ibm.com>
Cc: "James E.J. Bottomley" <jejb@linux.vnet.ibm.com>
Cc: "Martin K. Petersen" <martin.petersen@oracle.com>
Cc: Hannes Reinecke <hare@suse.de>
Cc: linux-scsi@vger.kernel.org
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

diff --git a/drivers/scsi/virtio_scsi.c b/drivers/scsi/virtio_scsi.c
index dc2e97c543a5..8b93197daefe 100644
--- a/drivers/scsi/virtio_scsi.c
+++ b/drivers/scsi/virtio_scsi.c
@@ -795,6 +795,16 @@ static int virtscsi_map_queues(struct Scsi_Host *shost)
 	return blk_mq_virtio_map_queues(&shost->tag_set, vscsi->vdev, 2);
 }
 
+/*
+ * The host guarantees to respond to each command, although I/O
+ * latencies might be higher than on bare metal.  Reset the timer
+ * unconditionally to give the host a chance to perform EH.
+ */
+static enum blk_eh_timer_return virtscsi_eh_timed_out(struct scsi_cmnd *scmnd)
+{
+	return BLK_EH_RESET_TIMER;
+}
+
 static struct scsi_host_template virtscsi_host_template_single = {
 	.module = THIS_MODULE,
 	.name = "Virtio SCSI HBA",
@@ -805,6 +815,7 @@ static struct scsi_host_template virtscsi_host_template_single = {
 	.change_queue_depth = virtscsi_change_queue_depth,
 	.eh_abort_handler = virtscsi_abort,
 	.eh_device_reset_handler = virtscsi_device_reset,
+	.eh_timed_out = virtscsi_eh_timed_out,
 	.slave_alloc = virtscsi_device_alloc,
 
 	.can_queue = 1024,
@@ -825,6 +836,7 @@ static struct scsi_host_template virtscsi_host_template_multi = {
 	.change_queue_depth = virtscsi_change_queue_depth,
 	.eh_abort_handler = virtscsi_abort,
 	.eh_device_reset_handler = virtscsi_device_reset,
+	.eh_timed_out = virtscsi_eh_timed_out,
 
 	.can_queue = 1024,
 	.dma_boundary = UINT_MAX,