Re: [PATCH 5/7] Drivers: scsi: storvsc: Implement a timedout handler

[Hannes Reinecke]

On 07/12/2014 06:48 PM, K. Y. Srinivasan wrote:
> 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: K. Y. Srinivasan <kys@xxxxxxxxxxxxx>
> Cc: <stable@xxxxxxxxxxxxxxx>
> ---
>   drivers/scsi/storvsc_drv.c |   10 ++++++++++
>   1 files changed, 10 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/scsi/storvsc_drv.c b/drivers/scsi/storvsc_drv.c
> index 7e8a642..3516761 100644
> --- a/drivers/scsi/storvsc_drv.c
> +++ b/drivers/scsi/storvsc_drv.c
> @@ -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 +1519,14 @@ static int storvsc_host_reset_handler(struct scsi_cmnd *scmnd)
>   	return SUCCESS;
>   }
>
> +static enum blk_eh_timer_return storvsc_timeout_handler(struct scsi_cmnd *scmnd)
> +{
> +	/*
> +	 * The host will respond; ask for more time.
> +	 */
> +	return BLK_EH_RESET_TIMER;
> +}
> +
>   static bool storvsc_scsi_cmd_ok(struct scsi_cmnd *scmnd)
>   {
>   	bool allowed = true;
> @@ -1697,6 +1706,7 @@ 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_timeout_handler,
>   	.slave_alloc =		storvsc_device_alloc,
>   	.slave_destroy =	storvsc_device_destroy,
>   	.slave_configure =	storvsc_device_configure,
Reviewed-by: Hannes Reinecke <hare@xxxxxxx>

Cheers,

Hannes
--
Dr. Hannes Reinecke		      zSeries & Storage
hare@xxxxxxx			      +49 911 74053 688
SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: J. Hawn, J. Guild, F. Imendörffer, HRB 16746 (AG Nürnberg)
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