static int mirror_cow_align(MirrorBlockJob *s, int64_t *offset, uint64_t *bytes) { bool need_cow; int ret = 0; int64_t align_offset = *offset; unsigned int align_bytes = *bytes; int max_bytes = s->granularity * s->max_iov; assert(*bytes < INT_MAX); need_cow = !test_bit(*offset / s->granularity, s->cow_bitmap); need_cow |= !test_bit((*offset + *bytes - 1) / s->granularity, s->cow_bitmap); if (need_cow) { bdrv_round_to_clusters(blk_bs(s->target), *offset, *bytes, &align_offset, &align_bytes); } if (align_bytes > max_bytes) { align_bytes = max_bytes; if (need_cow) { align_bytes = QEMU_ALIGN_DOWN(align_bytes, s->target_cluster_size); } } /* Clipping may result in align_bytes unaligned to chunk boundary, but * that doesn't matter because it's already the end of source image. */ align_bytes = mirror_clip_bytes(s, align_offset, align_bytes); ret = align_offset + align_bytes - (*offset + *bytes); *offset = align_offset; *bytes = align_bytes; assert(ret >= 0); return ret; }