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perf(copy): skip redundant chmod after reflink on macOS #3149

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Merged
max-sixty merged 2 commits into from
Jun 21, 2026
Merged

perf(copy): skip redundant chmod after reflink on macOS #3149

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perf(copy): skip redundant chmod after reflink on macOS
max-sixty Jun 21, 2026
e53924c
Merge remote-tracking branch 'origin/main' into copy-skip-macos-chmod
max-sixty Jun 21, 2026
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9 changes: 7 additions & 2 deletions src/copy.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -80,15 +80,20 @@ pub fn copy_leaf(
} else {
match reflink_copy::reflink_or_copy(src, dest) {
Ok(_) => {
// Preserve file permissions (especially the execute bit).
// Preserve file permissions (especially the execute bit) —
// needed on Linux, skipped on macOS.
//
// On btrfs/XFS, reflink (FICLONE ioctl) clones data extents
// only — the destination gets umask-based permissions, losing
// execute bits. std::fs::copy's fallback preserves permissions
// via fchmod, creating an asymmetry in reflink_or_copy.
//
// On macOS/APFS, clonefile() already preserves the source's
// mode bits, so this chmod is redundant — skip it to save a
// syscall per file.
//
// Refs: ioctl_ficlonerange(2), LWN Articles/331808
#[cfg(unix)]
#[cfg(all(unix, not(target_os = "macos")))]
{
fs::set_permissions(dest, src_meta.permissions())
.context("setting destination file permissions")?;
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