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

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

[Long Li]

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@microsoft.com>
Reviewed-by: K. Y. Srinivasan <kys@microsoft.com>
---
 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

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@microsoft.com]
> Sent: Friday, December 5, 2014 7:38 PM
> To: linux-scsi@vger.kernel.org
> Cc: KY Srinivasan; Haiyang Zhang; JBottomley@parallels.com;
> devel@linuxdriverproject.org; linux-kernel@vger.kernel.org; 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@microsoft.com>
> Reviewed-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
cc: stable@vger.kernel.org

> ---
>  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