[3.11.y.z extended stable] Patch "rbd: fix buffer size for writes to images with snapshots" has been added to staging queue

[Luis Henriques]

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

    rbd: fix buffer size for writes to images with snapshots

to the linux-3.11.y-queue branch of the 3.11.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.11.y-queue

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

For more information about the 3.11.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From 57037041dc451ad62559317282510ad7c73551a4 Mon Sep 17 00:00:00 2001
From: Josh Durgin <josh.durgin at inktank.com>
Date: Tue, 27 Aug 2013 14:45:46 -0700
Subject: rbd: fix buffer size for writes to images with snapshots

commit 03507db631c94a48e316c7f638ffb2991544d617 upstream.

rbd_osd_req_create() needs to know the snapshot context size to create
a buffer large enough to send it with the message front. It gets this
from the img_request, which was not set for the obj_request yet. This
resulted in trying to write past the end of the front payload, hitting
this BUG:

libceph: BUG_ON(p > msg->front.iov_base + msg->front.iov_len);

Fix this by associating the obj_request with its img_request
immediately after it's created, before the osd request is created.

Fixes: http://tracker.ceph.com/issues/5760
Suggested-by: Alex Elder <alex.elder at linaro.org>
Signed-off-by: Josh Durgin <josh.durgin at inktank.com>
Reviewed-by: Alex Elder <alex.elder at linaro.org>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 drivers/block/rbd.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
index 45aa20a..0ab2829 100644
--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -2203,6 +2203,11 @@ static int rbd_img_request_fill(struct rbd_img_request *img_request,
 		rbd_segment_name_free(object_name);
 		if (!obj_request)
 			goto out_unwind;
+		/*
+		 * set obj_request->img_request before creating the
+		 * osd_request so that it gets the right snapc
+		 */
+		rbd_img_obj_request_add(img_request, obj_request);

 		if (type == OBJ_REQUEST_BIO) {
 			unsigned int clone_size;
@@ -2244,11 +2249,6 @@ static int rbd_img_request_fill(struct rbd_img_request *img_request,
 					obj_request->pages, length,
 					offset & ~PAGE_MASK, false, false);

-		/*
-		 * set obj_request->img_request before formatting
-		 * the osd_request so that it gets the right snapc
-		 */
-		rbd_img_obj_request_add(img_request, obj_request);
 		if (write_request)
 			rbd_osd_req_format_write(obj_request);
 		else
--
1.8.3.2