[3.16.y-ckt stable] Patch "sunvdc: limit each sg segment to a page" has been added to staging queue

[Luis Henriques]

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

    sunvdc: limit each sg segment to a page

to the linux-3.16.y-queue branch of the 3.16.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-3.16.y-queue

This patch is scheduled to be released in version 3.16.7-ckt2.

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

For more information about the 3.16.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From 21a3064f80655bd5b4a83c9267c2cff45f437d7b Mon Sep 17 00:00:00 2001
From: Dwight Engen <dwight.engen at oracle.com>
Date: Fri, 19 Sep 2014 09:42:53 -0400
Subject: sunvdc: limit each sg segment to a page

commit 5eed69ffd248c9f68f56c710caf07db134aef28b upstream.

ldc_map_sg() could fail its check that the number of pages referred to
by the sg scatterlist was <= the number of cookies.

This fixes the issue by doing a similar thing to the xen-blkfront driver,
ensuring that the scatterlist will only ever contain a segment count <=
port->ring_cookies, and each segment will be page aligned, and <= page
size. This ensures that the scatterlist is always mappable.

Orabug: 19347817
OraBZ: 15945

Signed-off-by: Dwight Engen <dwight.engen at oracle.com>
Signed-off-by: David S. Miller <davem at davemloft.net>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 drivers/block/sunvdc.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/block/sunvdc.c b/drivers/block/sunvdc.c
index 1616ad091a5e..1a9360da1f54 100644
--- a/drivers/block/sunvdc.c
+++ b/drivers/block/sunvdc.c
@@ -747,6 +747,10 @@ static int probe_disk(struct vdc_port *port)

 	port->disk = g;

+	/* Each segment in a request is up to an aligned page in size. */
+	blk_queue_segment_boundary(q, PAGE_SIZE - 1);
+	blk_queue_max_segment_size(q, PAGE_SIZE);
+
 	blk_queue_max_segments(q, port->ring_cookies);
 	blk_queue_max_hw_sectors(q, port->max_xfer_size);
 	g->major = vdc_major;
--
2.1.0