[3.13.y-ckt stable] Patch "storvsc: ring buffer failures may result in I/O freeze" has been added to staging queue

[Kamal Mostafa]

This is a note to let you know that I have just added a patch titled

    storvsc: ring buffer failures may result in I/O freeze

to the linux-3.13.y-queue branch of the 3.13.y-ckt extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.13.y-queue

This patch is scheduled to be released in version 3.13.11-ckt15.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.13.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

------

>From 83d91f4bcc7047f44c1c6334b0071529775450ee Mon Sep 17 00:00:00 2001
From: Long Li <longli at microsoft.com>
Date: Fri, 5 Dec 2014 19:38:18 -0800
Subject: storvsc: ring buffer failures may result in I/O freeze

commit e86fb5e8ab95f10ec5f2e9430119d5d35020c951 upstream.

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 at microsoft.com>
Reviewed-by: K. Y. Srinivasan <kys at microsoft.com>
Signed-off-by: Christoph Hellwig <hch at lst.de>
Signed-off-by: Kamal Mostafa <kamal at canonical.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 ed0f899..86b0515 100644
--- a/drivers/scsi/storvsc_drv.c
+++ b/drivers/scsi/storvsc_drv.c
@@ -1690,13 +1690,12 @@ 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;
--
1.9.1