Re: [PATCH 2/4] rbd: encapsulate submission of image object requests

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

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

On 04/19/2013 03:50 PM, Alex Elder wrote:
> Object requests that are part of an image request are subject to
> some additional handling.  Define rbd_img_obj_request_submit() to
> encapsulate that, and use it when initially submitting an image
> object request, and when re-submitting it during callback of
> an object existence check.
>
> Signed-off-by: Alex Elder <elder@inktank.com>
> ---
>   drivers/block/rbd.c |   65
> ++++++++++++++++++++++++++++++++++-----------------
>   1 file changed, 43 insertions(+), 22 deletions(-)
>
> diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
> index a185239..894af4f 100644
> --- a/drivers/block/rbd.c
> +++ b/drivers/block/rbd.c
> @@ -423,6 +423,7 @@ void rbd_warn(struct rbd_device *rbd_dev, const char
> *fmt, ...)
>   #endif /* !RBD_DEBUG */
>
>   static void rbd_img_parent_read(struct rbd_obj_request *obj_request);
> +static int rbd_img_obj_request_submit(struct rbd_obj_request *obj_request);
>
>   static int rbd_dev_refresh(struct rbd_device *rbd_dev, u64 *hver);
>   static int rbd_dev_v2_refresh(struct rbd_device *rbd_dev, u64 *hver);
> @@ -1874,8 +1875,6 @@ out_unwind:
>
>   static void rbd_img_obj_exists_callback(struct rbd_obj_request
> *obj_request)
>   {
> -	struct rbd_device *rbd_dev;
> -	struct ceph_osd_client *osdc;
>   	struct rbd_obj_request *orig_request;
>   	int result;
>
> @@ -1901,8 +1900,6 @@ static void rbd_img_obj_exists_callback(struct
> rbd_obj_request *obj_request)
>
>   	rbd_assert(orig_request);
>   	rbd_assert(orig_request->img_request);
> -	rbd_dev = orig_request->img_request->rbd_dev;
> -	osdc = &rbd_dev->rbd_client->client->osdc;
>
>   	/*
>   	 * Our only purpose here is to determine whether the object
> @@ -1923,7 +1920,7 @@ static void rbd_img_obj_exists_callback(struct
> rbd_obj_request *obj_request)
>   	 * Resubmit the original request now that we have recorded
>   	 * whether the target object exists.
>   	 */
> -	orig_request->result = rbd_obj_request_submit(osdc, orig_request);
> +	orig_request->result = rbd_img_obj_request_submit(orig_request);
>   out_err:
>   	if (orig_request->result)
>   		rbd_obj_request_complete(orig_request);
> @@ -1987,32 +1984,56 @@ out:
>   	return ret;
>   }
>
> +static int rbd_img_obj_request_submit(struct rbd_obj_request *obj_request)
> +{
> +	struct rbd_img_request *img_request;
> +
> +	rbd_assert(obj_request_img_data_test(obj_request));
> +
> +	img_request = obj_request->img_request;
> +	rbd_assert(img_request);
> +
> +	/* (At the moment we don't care whether it exists or not...) */
> +	(void) obj_request_exists_test;
> +
> +	/*
> +	 * Only layered writes need special handling.  If it's not a
> +	 * layered write, or it is a layered write but we know the
> +	 * target object exists, it's no different from any other
> +	 * object request.
> +	 */
> +	if (!img_request_write_test(img_request) ||
> +		!img_request_layered_test(img_request) ||
> +		obj_request_known_test(obj_request)) {
> +
> +		struct rbd_device *rbd_dev;
> +		struct ceph_osd_client *osdc;
> +
> +		rbd_dev = obj_request->img_request->rbd_dev;
> +		osdc = &rbd_dev->rbd_client->client->osdc;
> +
> +		return rbd_obj_request_submit(osdc, obj_request);
> +	}
> +
> +	/*
> +	 * It's a layered write and we don't know whether the target
> +	 * exists.  Issue existence check; once that completes the
> +	 * original request will be submitted again.
> +	 */
> +
> +	return rbd_img_obj_exists_submit(obj_request);
> +}
> +
>   static int rbd_img_request_submit(struct rbd_img_request *img_request)
>   {
> -	struct rbd_device *rbd_dev = img_request->rbd_dev;
> -	struct ceph_osd_client *osdc = &rbd_dev->rbd_client->client->osdc;
>   	struct rbd_obj_request *obj_request;
>   	struct rbd_obj_request *next_obj_request;
> -	bool write_request = img_request_write_test(img_request);
> -	bool layered = img_request_layered_test(img_request);
>
>   	dout("%s: img %p\n", __func__, img_request);
>   	for_each_obj_request_safe(img_request, obj_request, next_obj_request) {
> -		bool known;
> -		bool object_exists;
>   		int ret;
>
> -		/*
> -		 * We need to know whether the target object exists
> -		 * for a layered write.  Issue an existence check
> -		 * first if we need to.
> -		 */
> -		known = obj_request_known_test(obj_request);
> -		object_exists = known && obj_request_exists_test(obj_request);
> -		if (!write_request || !layered || object_exists)
> -			ret = rbd_obj_request_submit(osdc, obj_request);
> -		else
> -			ret = rbd_img_obj_exists_submit(obj_request);
> +		ret = rbd_img_obj_request_submit(obj_request);
>   		if (ret)
>   			return ret;
>   	}
>