Function read_buffer_from_extents 

pub fn read_buffer_from_extents(
    extents: &Extents,
    logical_offset: u64,
    dest_buffer: OwnedBuffer,
    service: &(impl BlockService + ?Sized),
    on_complete: impl FnOnce(Result<OwnedBuffer, Error>) + Send + 'static,
) -> Result<(), Error>

Reads data for dest_buffer starting at logical_offset according to extents from service.

If the range is contiguous within a single extent, issues a single read. If the range spans multiple extents or holes, splits dest_buffer across the extents and reconstructs the original buffer when all reads complete.