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Commit 56b26e69 authored by K. Y. Srinivasan's avatar K. Y. Srinivasan Committed by Christoph Hellwig
Browse files

Drivers: scsi: storvsc: Implement a eh_timed_out handler 



On Azure, we have seen instances of unbounded I/O latencies. To deal with
this issue, implement handler that can reset the timeout. Note that the
host gaurantees that it will respond to each command that has been issued.

Signed-off-by: default avatarK. Y. Srinivasan <kys@microsoft.com>
Reviewed-by: default avatarHannes Reinecke <hare@suse.de>
Cc: <stable@vger.kernel.org>
[hch: added a better comment explaining the issue]
Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
parent adb6f9e1

drivers/scsi/storvsc_drv.c

+12 −0
Original line number Diff line number Diff line
@@ -33,6 +33,7 @@ 
#include <linux/device.h>

#include <linux/hyperv.h>

#include <linux/mempool.h>

#include <linux/blkdev.h>

#include <scsi/scsi.h>

#include <scsi/scsi_cmnd.h>

#include <scsi/scsi_host.h>
@@ -1518,6 +1519,16 @@ static int storvsc_host_reset_handler(struct scsi_cmnd *scmnd) 
	return SUCCESS;

}



/*

 * The host guarantees to respond to each command, although I/O latencies might

 * be unbounded on Azure.  Reset the timer unconditionally to give the host a

 * chance to perform EH.

 */

static enum blk_eh_timer_return storvsc_eh_timed_out(struct scsi_cmnd *scmnd)

{

	return BLK_EH_RESET_TIMER;

}



static bool storvsc_scsi_cmd_ok(struct scsi_cmnd *scmnd)

{

	bool allowed = true;
@@ -1697,6 +1708,7 @@ static struct scsi_host_template scsi_driver = { 
	.bios_param =		storvsc_get_chs,

	.queuecommand =		storvsc_queuecommand,

	.eh_host_reset_handler =	storvsc_host_reset_handler,

	.eh_timed_out =		storvsc_eh_timed_out,

	.slave_alloc =		storvsc_device_alloc,

	.slave_destroy =	storvsc_device_destroy,

	.slave_configure =	storvsc_device_configure,