static int handle_dependencies(BlockDriverState *bs, uint64_t guest_offset, unsigned int *nb_clusters) { BDRVQcowState *s = bs->opaque; QCowL2Meta *old_alloc; 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; if (end < old_start || start > old_end) { /* No intersection */ } else { if (start < old_start) { /* Stop at the start of a running allocation */ *nb_clusters = old_start - start; } else { *nb_clusters = 0; } if (*nb_clusters == 0) { /* Wait for the dependency to complete. We need to recheck * the free/allocated clusters when we continue. */ qemu_co_mutex_unlock(&s->lock); qemu_co_queue_wait(&old_alloc->dependent_requests); qemu_co_mutex_lock(&s->lock); return -EAGAIN; } } } if (!*nb_clusters) { abort(); } return 0; }