By redirecting VHDx I/O through the AlignedFile the required RMW
semantics can be achieved for writes less than the logical block size
whilt reusing the same logic used for other backend implementations.
Assisted-by: Claude:Opus-4.8
Signed-off-by: Rob Bradford <rbradford@meta.com>
Reuse the functionality in the AlignedFile wrapper for the QCOW RawFile
wrapper. This makes alignment handling more transparent.
Assisted-by: Claude:Opus-4.8
Signed-off-by: Rob Bradford <rbradford@meta.com>
Provide a single home for O_DIRECT alignment and RMW behavior behind an
std::os::unix::fs::FileExt implementation built on AlignedBuffer.
Unaligned requests are bounced through an AlignedBuffer (applying RMW
for writes) and aligned requests pass straight through to the inner
File.
Assisted-by: Claude:Opus-4.8
Signed-off-by: Rob Bradford <rbradford@meta.com>
