RE: [PATCH 4/6] scsi: storvsc: use correct defaults for values determined by protocol negotiation

[Long Li]

> -----Original Message-----
> From: devel [mailto:driverdev-devel-bounces@xxxxxxxxxxxxxxxxxxxxxx] On
> Behalf Of K. Y. Srinivasan
> Sent: Friday, May 29, 2015 1:29 PM
> To: gregkh@xxxxxxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx;
> devel@xxxxxxxxxxxxxxxxxxxxxx; ohering@xxxxxxxx; jbottomley@xxxxxxxxxxxxx;
> hch@xxxxxxxxxxxxx; linux-scsi@xxxxxxxxxxxxxxx; apw@xxxxxxxxxxxxx;
> vkuznets@xxxxxxxxxx; jasowang@xxxxxxxxxx
> Cc: Keith Mange
> Subject: [PATCH 4/6] scsi: storvsc: use correct defaults for values determined
> by protocol negotiation
> 
> From: keith.mange@xxxxxxxxxxxxx <keith.mange@xxxxxxxxxxxxx>
> 
> Use correct defaults for values determined by protocol negotiation, instead of
> resetting them with every scsi controller.
> 
Reviewed-by: Long Li <longli@xxxxxxxxxxxxx>
> Tested-by: Alex Ng <alexng@xxxxxxxxxxxxx>
> Signed-off-by: Keith Mange <keith.mange@xxxxxxxxxxxxx>
> Signed-off-by: K. Y. Srinivasan <kys@xxxxxxxxxxxxx>
> ---
>  drivers/scsi/storvsc_drv.c |   33 +++++++++++++++++++--------------
>  1 files changed, 19 insertions(+), 14 deletions(-)
> 
> diff --git a/drivers/scsi/storvsc_drv.c b/drivers/scsi/storvsc_drv.c index
> f29871e..6f38cdf 100644
> --- a/drivers/scsi/storvsc_drv.c
> +++ b/drivers/scsi/storvsc_drv.c
> @@ -151,19 +151,17 @@ struct hv_fc_wwn_packet {
> 
>  /*
>   * Sense buffer size changed in win8; have a run-time
> - * variable to track the size we should use.
> + * variable to track the size we should use.  This value will
> + * likely change during protocol negotiation but it is valid
> + * to start by assuming pre-Win8.
>   */
> -static int sense_buffer_size;
> +static int sense_buffer_size = PRE_WIN8_STORVSC_SENSE_BUFFER_SIZE;
> 
>  /*
> - * The size of the vmscsi_request has changed in win8. The
> - * additional size is because of new elements added to the
> - * structure. These elements are valid only when we are talking
> - * to a win8 host.
> - * Track the correction to size we need to apply.
> - */
> -
> -static int vmscsi_size_delta;
> + * The storage protocol version is determined during the
> + * initial exchange with the host.  It will indicate which
> + * storage functionality is available in the host.
> +*/
>  static int vmstor_proto_version;
> 
>  struct vmscsi_win8_extension {
> @@ -209,6 +207,17 @@ struct vmscsi_request {
> 
> 
>  /*
> + * The size of the vmscsi_request has changed in win8. The
> + * additional size is because of new elements added to the
> + * structure. These elements are valid only when we are talking
> + * to a win8 host.
> + * Track the correction to size we need to apply. This value
> + * will likely change during protocol negotiation but it is
> + * valid to start by assuming pre-Win8.
> + */
> +static int vmscsi_size_delta = sizeof(struct vmscsi_win8_extension);
> +
> +/*
>   * The list of storage protocols in order of preference.
>   */
>  struct vmstor_protocol {
> @@ -1810,14 +1819,10 @@ static int storvsc_probe(struct hv_device *device,
>  	 */
> 
>  	if (vmbus_proto_version < VERSION_WIN8) {
> -		sense_buffer_size = PRE_WIN8_STORVSC_SENSE_BUFFER_SIZE;
> -		vmscsi_size_delta = sizeof(struct vmscsi_win8_extension);
>  		max_luns_per_target =
> STORVSC_IDE_MAX_LUNS_PER_TARGET;
>  		max_targets = STORVSC_IDE_MAX_TARGETS;
>  		max_channels = STORVSC_IDE_MAX_CHANNELS;
>  	} else {
> -		sense_buffer_size =
> POST_WIN7_STORVSC_SENSE_BUFFER_SIZE;
> -		vmscsi_size_delta = 0;
>  		max_luns_per_target = STORVSC_MAX_LUNS_PER_TARGET;
>  		max_targets = STORVSC_MAX_TARGETS;
>  		max_channels = STORVSC_MAX_CHANNELS;
> --
> 1.7.4.1
> 
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