Method map_cluster_for_write

block/src/qcow/metadata.rs:230–237

Maps a guest write address to a write mapping. Always takes a write lock since writes may need to allocate clusters, update L2 entries and update refcounts. The backing_data parameter is the COW source. If the cluster is unallocated and a backing file exists, the caller should have already read the backing cluster data and pass it here. If None, the new cluster is zeroed.

(
        &self,
        address: u64,
        backing_data: Option<Vec<u8>>,
    )

    /// read the backing cluster data and pass it here. If None, the new
    /// cluster is zeroed.
    pub fn map_cluster_for_write(
        &self,
        address: u64,
        backing_data: Option<Vec<u8>>,
    ) -> io::Result<ClusterWriteMapping> {
        let mut inner = self.inner.write().unwrap();
        inner.map_write(address, backing_data)
    }

    pub fn flush(&self) -> io::Result<()> {
        let mut inner = self.inner.write().unwrap();