pub fn fast_copy(src: &Path, dst: &Path) -> Result<u64>Expand description
Copy src to dst, preserving sparseness. Returns the apparent
size of the destination in bytes.
Tries reflink first (zero-copy COW); on filesystems without reflink
support, walks the source’s allocation map and copies only its
data extents into a ftruncate-established sparse destination.
Blocking. Callers in async contexts should wrap in
tokio::task::spawn_blocking.