Deallocates a range of bytes. Full clusters are deallocated via metadata. Partial clusters need the caller to write zeros. This method returns a list of actions the caller should take.
(
&self,
address: u64,
length: usize,
sparse: bool,
virtual_size: u64,
cluster_size: u64,
backing_file: Option<&dyn BackingRead>,
)
| 273 | /// Partial clusters need the caller to write zeros. This method returns a |
| 274 | /// list of actions the caller should take. |
| 275 | pub(crate) fn deallocate_bytes( |
| 276 | &self, |
| 277 | address: u64, |
| 278 | length: usize, |
| 279 | sparse: bool, |
| 280 | virtual_size: u64, |
| 281 | cluster_size: u64, |
| 282 | backing_file: Option<&dyn BackingRead>, |
| 283 | ) -> io::Result<Vec<DeallocAction>> { |
| 284 | if address.checked_add(length as u64).is_none() { |
| 285 | return Ok(Vec::new()); |
| 286 | } |
| 287 | let mut inner = self.inner.write().unwrap(); |
| 288 | let mut actions = Vec::new(); |
| 289 | |
| 290 | let file_end = virtual_size; |
| 291 | let remaining_in_file = file_end.saturating_sub(address); |
| 292 | let write_count = min(length as u64, remaining_in_file) as usize; |
| 293 | |
| 294 | let mut nwritten = 0usize; |
| 295 | while nwritten < write_count { |
| 296 | let curr_addr = address + nwritten as u64; |
| 297 | let offset_in_cluster = inner.raw_file.cluster_offset(curr_addr) as usize; |
| 298 | let count = min( |
| 299 | write_count - nwritten, |
| 300 | cluster_size as usize - offset_in_cluster, |
| 301 | ); |
| 302 | |
| 303 | if count == cluster_size as usize { |
| 304 | let punch_offset = inner.deallocate_cluster(curr_addr, sparse)?; |
| 305 | if let Some(host_offset) = punch_offset { |
| 306 | actions.push(DeallocAction::PunchHole { |
| 307 | host_offset, |
| 308 | length: cluster_size, |
| 309 | }); |
| 310 | } |
| 311 | } else { |
| 312 | // Partial cluster - COW from backing to preserve non zeroed bytes, |
| 313 | // then the caller writes zeros to the partial range. |
| 314 | let backing_data = if let Some(backing) = backing_file { |
| 315 | let cluster_begin = curr_addr - offset_in_cluster as u64; |
| 316 | let mut data = vec![0u8; cluster_size as usize]; |
| 317 | backing.read_at(cluster_begin, &mut data)?; |
| 318 | Some(data) |
| 319 | } else { |
| 320 | None |
| 321 | }; |
| 322 | let mapping = inner.map_write(curr_addr, backing_data)?; |
| 323 | let ClusterWriteMapping::Allocated { offset } = mapping; |
| 324 | actions.push(DeallocAction::WriteZeroes { |
| 325 | host_offset: offset, |
| 326 | length: count, |
| 327 | }); |
| 328 | } |
| 329 | |
| 330 | nwritten += count; |
| 331 | } |
| 332 | Ok(actions) |
no test coverage detected