feat(fast_io): add Windows ReFS reflink via FSCTL_DUPLICATE_EXTENTS (#1389)#3997
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…1389) Add partial-file reflink support via FSCTL_DUPLICATE_EXTENTS_TO_FILE alongside the existing whole-file reflink. The new try_refs_reflink_range() accepts source offset, destination offset, and byte count, enabling block-level CoW clones of file subranges on ReFS. Extract compute_duplicate_extents_params() to encapsulate cluster alignment arithmetic, making parameter construction testable without requiring a ReFS volume. Nine pure-logic tests verify alignment for various cluster sizes (4KB, 64KB), boundary conditions, and edge cases. Platform-specific tests validate graceful fallback on NTFS (CI) and Unsupported on non-Windows. ReFS reflink added to platform_io_capabilities() output.
Add #[cfg(any(target_os = "windows", test))] to DuplicateExtentsParams and compute_duplicate_extents_params so they compile on all platforms for tests but don't trigger dead_code errors in production builds on Linux/macOS. Replace manual ((x + n - 1) / n) * n with .div_ceil(n).
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…1389) (#3997) * feat(fast_io): add Windows ReFS reflink via FSCTL_DUPLICATE_EXTENTS (#1389) Add partial-file reflink support via FSCTL_DUPLICATE_EXTENTS_TO_FILE alongside the existing whole-file reflink. The new try_refs_reflink_range() accepts source offset, destination offset, and byte count, enabling block-level CoW clones of file subranges on ReFS. Extract compute_duplicate_extents_params() to encapsulate cluster alignment arithmetic, making parameter construction testable without requiring a ReFS volume. Nine pure-logic tests verify alignment for various cluster sizes (4KB, 64KB), boundary conditions, and edge cases. Platform-specific tests validate graceful fallback on NTFS (CI) and Unsupported on non-Windows. ReFS reflink added to platform_io_capabilities() output. * fix: gate ReFS reflink helpers with cfg(windows|test) and use div_ceil Add #[cfg(any(target_os = "windows", test))] to DuplicateExtentsParams and compute_duplicate_extents_params so they compile on all platforms for tests but don't trigger dead_code errors in production builds on Linux/macOS. Replace manual ((x + n - 1) / n) * n with .div_ceil(n).
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Summary
try_refs_reflink_range()for partial-file CoW block cloning viaFSCTL_DUPLICATE_EXTENTS_TO_FILEon Windows ReFS volumes, complementing the existing whole-filetry_refs_reflink()compute_duplicate_extents_params()to encapsulate cluster alignment arithmetic (offsets rounded down, byte count rounded up to cluster boundary), making the logic testable without ReFS hardwareReFS reflinktoplatform_io_capabilities()output on WindowsTest plan
ErrorKind::Unsupportedfor both range and zero-byte callsOk(())on Windows (no ioctl issued)cargo fmt --all -- --check