Re: [PATCH 2/5] rbd: support data returned from OSD methods

[Josh Durgin <josh.durgin@inktank.com>]

Reviewed-by: Josh Durgin <josh.durgin@inktank.com>

On 09/07/2012 11:19 AM, Alex Elder wrote:
> An OSD object method call can be made using rbd_req_sync_exec().
> Until now this has only been used for creating a new RBD snapshot,
> and that has only required sending data out, not receiving anything
> back from the OSD.
>
> We will now need to get data back from an OSD on a method call, so
> add parameters to rbd_req_sync_exec() that allow a buffer into which
> returned data should be placed to be specified, along with its size.
>
> Previously, rbd_req_sync_exec() passed a null pointer and zero
> size to rbd_req_sync_op(); change this so the new inbound buffer
> information is provided instead.
>
> Rename the "buf" and "len" parameters in rbd_req_sync_op() to
> make it more obvious they are describing inbound data.
>
> Signed-off-by: Alex Elder <elder@inktank.com>
> ---
>   drivers/block/rbd.c |   19 +++++++++++--------
>   1 file changed, 11 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
> index 4e84f99..ba68566 100644
> --- a/drivers/block/rbd.c
> +++ b/drivers/block/rbd.c
> @@ -1098,8 +1098,8 @@ static int rbd_req_sync_op(struct rbd_device *rbd_dev,
>   			   int flags,
>   			   struct ceph_osd_req_op *ops,
>   			   const char *object_name,
> -			   u64 ofs, u64 len,
> -			   char *buf,
> +			   u64 ofs, u64 inbound_size,
> +			   char *inbound,
>   			   struct ceph_osd_request **linger_req,
>   			   u64 *ver)
>   {
> @@ -1109,13 +1109,13 @@ static int rbd_req_sync_op(struct rbd_device
> *rbd_dev,
>
>   	rbd_assert(ops != NULL);
>
> -	num_pages = calc_pages_for(ofs , len);
> +	num_pages = calc_pages_for(ofs, inbound_size);
>   	pages = ceph_alloc_page_vector(num_pages, GFP_KERNEL);
>   	if (IS_ERR(pages))
>   		return PTR_ERR(pages);
>
>   	ret = rbd_do_request(NULL, rbd_dev, snapc, snapid,
> -			  object_name, ofs, len, NULL,
> +			  object_name, ofs, inbound_size, NULL,
>   			  pages, num_pages,
>   			  flags,
>   			  ops,
> @@ -1125,8 +1125,8 @@ static int rbd_req_sync_op(struct rbd_device *rbd_dev,
>   	if (ret < 0)
>   		goto done;
>
> -	if ((flags & CEPH_OSD_FLAG_READ) && buf)
> -		ret = ceph_copy_from_page_vector(pages, buf, ofs, ret);
> +	if ((flags & CEPH_OSD_FLAG_READ) && inbound)
> +		ret = ceph_copy_from_page_vector(pages, inbound, ofs, ret);
>
>   done:
>   	ceph_release_page_vector(pages, num_pages);
> @@ -1445,6 +1445,8 @@ static int rbd_req_sync_exec(struct rbd_device
> *rbd_dev,
>   			     const char *method_name,
>   			     const char *outbound,
>   			     size_t outbound_size,
> +			     char *inbound,
> +			     size_t inbound_size,
>   			     int flags,
>   			     u64 *ver)
>   {
> @@ -1478,7 +1480,8 @@ static int rbd_req_sync_exec(struct rbd_device
> *rbd_dev,
>   	ret = rbd_req_sync_op(rbd_dev, NULL,
>   			       CEPH_NOSNAP,
>   			       flags, ops,
> -			       object_name, 0, 0, NULL, NULL, ver);
> +			       object_name, 0, inbound_size, inbound,
> +			       NULL, ver);
>
>   	rbd_destroy_ops(ops);
>
> @@ -1789,7 +1792,7 @@ static int rbd_header_add_snap(struct rbd_device
> *rbd_dev,
>
>   	ret = rbd_req_sync_exec(rbd_dev, rbd_dev->header_name,
>   				"rbd", "snap_add",
> -				data, (size_t) (p - data),
> +				data, (size_t) (p - data), NULL, 0,
>   				CEPH_OSD_FLAG_WRITE | CEPH_OSD_FLAG_ONDISK,
>   				NULL);
>