On Wed, Feb 13, 2013 at 02:21:53PM +0100, Kevin Wolf wrote:
> Signed-off-by: Kevin Wolf <kw...@redhat.com>
> ---
> block/qcow2-cluster.c | 40 ++++++++++++++++++++++++++++------------
> block/qcow2.h | 11 +++++++++++
> 2 files changed, 39 insertions(+), 12 deletions(-)
>
> diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c
> index 0e804ba..a3b2447 100644
> --- a/block/qcow2-cluster.c
> +++ b/block/qcow2-cluster.c
> @@ -756,31 +756,41 @@ out:
> * Check if there already is an AIO write request in flight which allocates
> * the same cluster. In this case we need to wait until the previous
> * request has completed and updated the L2 table accordingly.
> + *
> + * Returns:
> + * 0 if there was no dependency. *cur_bytes indicates the number of
> + * bytes from guest_offset that can be read before the next
> + * dependency must be processed (or the request is complete)
s/read/accessed/
IMO "read" is too specific, the doc comment doesn't need to contain
knowledge of what the caller will do at guest_offset.
> + *
> + * -EAGAIN if we had to wait for another request, previously gathered
> + * information on cluster allocation may be invalid now. The caller
> + * must start over anyway, so consider *cur_bytes undefined.
> */
> static int handle_dependencies(BlockDriverState *bs, uint64_t guest_offset,
> - unsigned int *nb_clusters)
> + uint64_t *cur_bytes)
> {
> BDRVQcowState *s = bs->opaque;
> QCowL2Meta *old_alloc;
> + uint64_t bytes = *cur_bytes;
>
> QLIST_FOREACH(old_alloc, &s->cluster_allocs, next_in_flight) {
>
> - uint64_t start = guest_offset >> s->cluster_bits;
> - uint64_t end = start + *nb_clusters;
> - uint64_t old_start = old_alloc->offset >> s->cluster_bits;
> - uint64_t old_end = old_start + old_alloc->nb_clusters;
> + uint64_t start = guest_offset;
I'm not sure this is safe. Previously the function caught write
requests which overlap at cluster granularity, now it will allow them?
Stefan
