On 03/12/2014 10:21 PM, Guangliang Zhao wrote:
> It need to copyup the parent's content when layered writing,
> but an entire object write would overwrite it, so skip it.
>
> Signed-off-by: Guangliang Zhao <lucienchao@xxxxxxxxx>
> ---
> drivers/block/rbd.c | 49 ++++++++++++++++++++++++++++++++++---------------
> 1 file changed, 34 insertions(+), 15 deletions(-)
>
> diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
> index b365e0d..2d48858 100644
> --- a/drivers/block/rbd.c
> +++ b/drivers/block/rbd.c
> @@ -2624,34 +2624,53 @@ out:
> return ret;
> }
>
> -static int rbd_img_obj_request_submit(struct rbd_obj_request *obj_request)
> +static bool rbd_obj_request_simple(struct rbd_obj_request *obj_request)
The only objects that will be passed to this functions will
be associated with images. That fact can be reinforced by
naming it rbd_img_obj_request_simple().
Other than that suggestion, this looks good.
Reviewed-by: Alex Elder <elder@xxxxxxxxxx>
> {
> struct rbd_img_request *img_request;
> struct rbd_device *rbd_dev;
> - bool known;
> + u64 obj_size;
>
> rbd_assert(obj_request_img_data_test(obj_request));
>
> img_request = obj_request->img_request;
> rbd_assert(img_request);
> rbd_dev = img_request->rbd_dev;
> + obj_size = (u64) 1 << rbd_dev->header.obj_order;
>
> + /* Read requests didn't need special handling */
> + if (!img_request_write_test(img_request))
> + return true;
> + /* No-layered writes are simple requests*/
> + if (!img_request_layered_test(img_request))
> + return true;
> /*
> - * Only writes to layered images need special handling.
> - * Reads and non-layered writes are simple object requests.
> * Layered writes that start beyond the end of the overlap
> - * with the parent have no parent data, so they too are
> - * simple object requests. Finally, if the target object is
> - * known to already exist, its parent data has already been
> - * copied, so a write to the object can also be handled as a
> - * simple object request.
> + * with the parent have no parent data, so they are simple
> + * object requests.
> */
> - if (!img_request_write_test(img_request) ||
> - !img_request_layered_test(img_request) ||
> - rbd_dev->parent_overlap <= obj_request->img_offset ||
> - ((known = obj_request_known_test(obj_request)) &&
> - obj_request_exists_test(obj_request))) {
> + if (rbd_dev->parent_overlap <= obj_request->img_offset)
> + return true;
> + /*
> + * If the obj_request aligns with the boundary and equals
> + * to the size of an object, it doesn't need copyup, because
> + * the obj_request will overwrite it finally.
> + */
> + if ((!obj_request->offset) && (obj_request->length == obj_size))
> + return true;
> + /*
> + * If the target object is known to already exist, its parent
> + * data has already been copied, so a write to the object can
> + * also be handled as a simple object request
> + */
> + if (obj_request_known_test(obj_request) &&
> + obj_request_exists_test(obj_request))
> + return true;
> + return false;
> +}
>
> +static int rbd_img_obj_request_submit(struct rbd_obj_request *obj_request)
> +{
> + if (rbd_obj_request_simple(obj_request)) {
> struct rbd_device *rbd_dev;
> struct ceph_osd_client *osdc;
>
> @@ -2667,7 +2686,7 @@ static int rbd_img_obj_request_submit(struct rbd_obj_request *obj_request)
> * start by reading the data for the full target object from
> * the parent so we can use it for a copyup to the target.
> */
> - if (known)
> + if (obj_request_known_test(obj_request))
> return rbd_img_obj_parent_read_full(obj_request);
>
> /* We don't know whether the target exists. Go find out. */
>
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