[PATCH] rbd: fix buffer size for writes to images with snapshots

[PATCH] rbd: fix buffer size for writes to images with snapshots

[Josh Durgin]

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@linaro.org>
Signed-off-by: Josh Durgin <josh.durgin@inktank.com>
---
 drivers/block/rbd.c |   10 +++++-----
 1 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
index f8fd7d3..80f787b 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
-- 
1.7.2.5

Re: [PATCH] rbd: fix buffer size for writes to images with snapshots

[Alex Elder]

On 08/27/2013 05:06 PM, Josh Durgin wrote:
> 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@linaro.org>

I must have suggested it in e-mail...  I guess I should have updated
the bug.

This looks good.

Reviewed-by: Alex Elder <elder@linaro.org>

> Signed-off-by: Josh Durgin <josh.durgin@inktank.com>
> ---
>  drivers/block/rbd.c |   10 +++++-----
>  1 files changed, 5 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
> index f8fd7d3..80f787b 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
>