Method set_data_refcounts

block/src/qcow/mod.rs:1090–1140

Traverse the L1 and L2 tables to find all reachable data clusters.

(
            refcounts: &mut [u64],
            header: &QcowHeader,
            cluster_size: u64,
            raw_file: &mut QcowRawFile,
            max_refcount: u64,
            refcount_bits: u

        // Traverse the L1 and L2 tables to find all reachable data clusters.
        fn set_data_refcounts(
            refcounts: &mut [u64],
            header: &QcowHeader,
            cluster_size: u64,
            raw_file: &mut QcowRawFile,
            max_refcount: u64,
            refcount_bits: u64,
        ) -> Result<()> {
            let l1_table = raw_file
                .read_pointer_table(
                    header.l1_table_offset,
                    u64::from(header.l1_size),
                    Some(L1_TABLE_OFFSET_MASK),
                )
                .map_err(Error::ReadingPointers)?;
            for l1_index in 0..header.l1_size as usize {
                let l2_addr_disk = *l1_table.get(l1_index).ok_or(Error::InvalidIndex)?;
                if l2_addr_disk != 0 {
                    // Add a reference to the L2 table cluster itself.
                    add_ref(
                        refcounts,
                        cluster_size,
                        l2_addr_disk,
                        max_refcount,
                        refcount_bits,
                    )?;

                    // Read the L2 table and find all referenced data clusters.
                    let l2_table = raw_file
                        .read_pointer_table(
                            l2_addr_disk,
                            cluster_size / size_of::<u64>() as u64,
                            Some(L2_TABLE_OFFSET_MASK),
                        )
                        .map_err(Error::ReadingPointers)?;
                    for data_cluster_addr in l2_table {
                        if data_cluster_addr != 0 {
                            add_ref(
                                refcounts,
                                cluster_size,
                                data_cluster_addr,
                                max_refcount,
                                refcount_bits,
                            )?;
                        }
                    }
                }
            }

            Ok(())
        }

        // Add references to the top-level refcount table clusters.
        fn set_refcount_table_refcounts(