static int check_refcounts_l2(BlockDriverState *bs,
    uint16_t *refcount_table, int refcount_table_size, int64_t l2_offset,
    int check_copied)
{
    BDRVQcowState *s = bs->opaque;
    uint64_t *l2_table, offset;
    int i, l2_size, nb_csectors, refcount;
    int errors = 0;
    
    l2_size = s->l2_size * sizeof(uint64_t);
    l2_table = qemu_malloc(l2_size);
    if (bdrv_pread(s->hd, l2_offset, l2_table, l2_size) != l2_size)
        goto fail;
    
    for(i = 0; i < s->l2_size; i++) {
        offset = be64_to_cpu(l2_table[i]);
        if (offset != 0) {
            if (offset & QCOW_OFLAG_COMPRESSED) {
                
                if (offset & QCOW_OFLAG_COPIED) {
                    fprintf(stderr, "ERROR: cluster %" PRId64 ": "
                        "copied flag must never be set for compressed "
                        "clusters\n", offset >> s->cluster_bits);
                    offset &= ~QCOW_OFLAG_COPIED;
                
                nb_csectors = ((offset >> s->csize_shift) &
                               s->csize_mask) + 1;
                offset &= s->cluster_offset_mask;
                errors += inc_refcounts(bs, refcount_table,
                              refcount_table_size,
                              offset & ~511, nb_csectors * 512);
            } else {
                
                if (check_copied) {
                    uint64_t entry = offset;
                    offset &= ~QCOW_OFLAG_COPIED;
                    refcount = get_refcount(bs, offset >> s->cluster_bits);
                    if ((refcount == 1) != ((entry & QCOW_OFLAG_COPIED) != 0)) {
                        fprintf(stderr, "ERROR OFLAG_COPIED: offset=%"
                            PRIx64 " refcount=%d\n", entry, refcount);
                
                offset &= ~QCOW_OFLAG_COPIED;
                errors += inc_refcounts(bs, refcount_table,
                              refcount_table_size,
                              offset, s->cluster_size);
    qemu_free(l2_table);
    return errors;
fail:
    fprintf(stderr, "ERROR: I/O error in check_refcounts_l1\n");
    qemu_free(l2_table);
    return -EIO;