Am 17.11.2011 14:40, schrieb Stefan Hajnoczi:
> Detect overlapping requests and remember to align to cluster boundaries
> if the image format uses them. This assumes that allocating I/O is
> performed in cluster granularity - which is true for qcow2, qed, etc.
>
> Signed-off-by: Stefan Hajnoczi <stefa...@linux.vnet.ibm.com>
> static void coroutine_fn wait_for_overlapping_requests(BlockDriverState *bs,
> int64_t sector_num, int nb_sectors)
> {
> BdrvTrackedRequest *req;
> + int64_t cluster_sector_num;
> + int cluster_nb_sectors;
> bool retry;
>
> + /* If we touch the same cluster it counts as an overlap */
> + round_to_clusters(bs, sector_num, nb_sectors,
> + &cluster_sector_num, &cluster_nb_sectors);
Is this really required? Image formats must be able to deal with two
concurrent write requests to the same cluster, and I don't think it
makes a difference whether it's a guest write request or a COR one.
Or does the queuing protect more than just that a COR never takes
precedence over a guest write?
Kevin
