Archipelago » qemu

    QCowL2Meta *old_alloc;

    /*

     * 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.

     */

    LIST_FOREACH(old_alloc, &s->cluster_allocs, next_in_flight) {

        uint64_t end_offset = offset + nb_clusters * s->cluster_size;

        uint64_t old_offset = old_alloc->offset;

        uint64_t old_end_offset = old_alloc->offset +

            old_alloc->nb_clusters * s->cluster_size;

        if (end_offset < old_offset || offset > old_end_offset) {

            /* No intersection */

        } else {

            if (offset < old_offset) {

                /* Stop at the start of a running allocation */

                nb_clusters = (old_offset - offset) >> s->cluster_bits;

            } else {

                nb_clusters = 0;

            }

            if (nb_clusters == 0) {

                /* Set dependency and wait for a callback */

                m->depends_on = old_alloc;

                m->nb_clusters = 0;

                *num = 0;

                return 0;

            }

        }

    }

    if (!nb_clusters) {

        abort();

    }

    LIST_INSERT_HEAD(&s->cluster_allocs, m, next_in_flight);