RE: drivers:scsi:storvsc: Fix a bug in handling ring buffer failures that may result in I/O freeze

[KY Srinivasan]

> -----Original Message-----
> From: Long Li [mailto:longli@xxxxxxxxxxxxx]
> Sent: Friday, December 5, 2014 7:38 PM
> To: linux-scsi@xxxxxxxxxxxxxxx
> Cc: KY Srinivasan; Haiyang Zhang; JBottomley@xxxxxxxxxxxxx;
> devel@xxxxxxxxxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; Long Li
> Subject: drivers:scsi:storvsc: Fix a bug in handling ring buffer failures that may
> result in I/O freeze
> 
> When ring buffer returns an error indicating retry, storvsc may not return a
> proper error code to SCSI when bounce buffer is not used. This has
> introduced I/O freeze on RAID running atop storvsc devices. This patch fixes
> it by always returning a proper error code.
> 
> Signed-off-by: Long Li <longli@xxxxxxxxxxxxx>
> Reviewed-by: K. Y. Srinivasan <kys@xxxxxxxxxxxxx>
Signed-off-by: K. Y. Srinivasan <kys@xxxxxxxxxxxxx>
cc: stable@xxxxxxxxxxxxxxx

> ---
>  drivers/scsi/storvsc_drv.c | 7 +++----
>  1 file changed, 3 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/scsi/storvsc_drv.c b/drivers/scsi/storvsc_drv.c index
> e3ba251..4cff0dd 100644
> --- a/drivers/scsi/storvsc_drv.c
> +++ b/drivers/scsi/storvsc_drv.c
> @@ -1688,13 +1688,12 @@ static int storvsc_queuecommand(struct
> Scsi_Host *host, struct scsi_cmnd *scmnd)
>  	if (ret == -EAGAIN) {
>  		/* no more space */
> 
> -		if (cmd_request->bounce_sgl_count) {
> +		if (cmd_request->bounce_sgl_count)
>  			destroy_bounce_buffer(cmd_request->bounce_sgl,
>  					cmd_request->bounce_sgl_count);
> 
> -			ret = SCSI_MLQUEUE_DEVICE_BUSY;
> -			goto queue_error;
> -		}
> +		ret = SCSI_MLQUEUE_DEVICE_BUSY;
> +		goto queue_error;
>  	}
> 
>  	return 0;
> --
> 2.1.0

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