feat(fs): extent_sharing reports reflink/snapshot block sharing (0.1.21) - #353
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A hard-link count cannot prove that deleting a file frees its space: reflinks and snapshots share blocks between files that each have one link (zackees/zccache#1673, where a retired-store sweep over-credited reclaimed bytes after reflink restores into target/). extent_sharing returns Exclusive, Shared, or Unknown. Linux reads the file's FIEMAP extent map and looks for FIEMAP_EXTENT_SHARED, falling back to the volume type (ext4/tmpfs/ramfs cannot share) when FIEMAP is unsupported. macOS and Windows answer from the volume's file system: HFS+/FAT/exFAT/NTFS are Exclusive, APFS and ReFS are Unknown. Verified on a loop-mounted btrfs volume: a reflinked pair reports Shared. Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
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kernal-api 0.1.21 (zackees/kernal-api#353) publishes the platform::fs::extent_sharing facade the retired-store sweep uses to credit only unshared blocks. Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
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kernal-api 0.1.21 (zackees/kernal-api#353) publishes the platform::fs::extent_sharing facade the retired-store sweep uses to credit only unshared blocks. Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
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…reflink-aware byte credit (#1673) (#1676) * fix(daemon): age-gate retired-store sweep and never sweep newer stores (#1673) Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com> * test(daemon): backdate retired-store victims past the #1673 grace period Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com> * style: rustfmt retired-store changes (#1673) Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com> * fix(core): credit retired-store bytes only for unshared blocks (#1673) A reflink restore into target/ (ReFS, btrfs, XFS, APFS) leaves the cache file at nlink == 1 while sharing every block, so the link count alone over-credited bytes_reclaimed and over-estimated the pressure decision's reclaimable retired bytes. file_frees_space_on_removal now also requires kernal_api::platform::fs::extent_sharing to report Exclusive; unknown sharing never counts. Verified RED -> GREEN on a loop-mounted btrfs volume: the old rule credited 262144 bytes for a reflinked entry, the fix credits 0. Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com> * style: rustfmt retired_store re-exports (#1673) Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com> * build(deps): pin kernal-api =0.1.21 for fs::extent_sharing (#1673) kernal-api 0.1.21 (zackees/kernal-api#353) publishes the platform::fs::extent_sharing facade the retired-store sweep uses to credit only unshared blocks. Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com> * fix(daemon): keep the #1659 pressure estimate alive on APFS/ReFS (#1673) extent_sharing reports Unknown on every APFS and ReFS volume, so requiring Exclusive in retired_store_bytes zeroed the pressure estimate on macOS and silently disabled the retired-store pressure valve there (macOS CI: issue_1659_retired_store_bytes_are_reclaimed_before_live_entries). Split the two rules: bytes_reclaimed (reported) still credits only a last link with proven-exclusive blocks, while the pressure estimate counts any last link not proven shared (file_may_free_space_on_removal), excluding only btrfs/XFS reflinks. The core sweep test now expects credit only where the temp volume proves exclusivity. Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com> * test(daemon): expect retired-byte credit only on exclusivity-proving volumes (#1673) On APFS/ReFS extent_sharing reports Unknown, so the pressure sweep removes retired files but credits no reclaimed bytes (macOS CI failure at disk_maintenance_unit.rs:1196). The re-plan already uses the recomputed estimate and fresh free space, so no live entry is evicted there; only the test's credit expectation was platform-blind. Also rustfmt the re-exports. Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com> --------- Co-authored-by: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
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Summary
Adds
kernal_api::platform::fs::extent_sharing(path) -> io::Result<ExtentSharing>(Exclusive/Shared/Unknown), and bumps the version to 0.1.21.A hard-link count can't prove that deleting a file frees its space: reflinks and snapshots share blocks between files that each have
nlink == 1. zackees/zccache#1673 needs this so the retired-store sweep'sbytes_reclaimedstops counting reflinked cache files.FS_IOC_FIEMAP, looking forFIEMAP_EXTENT_SHAREDin any extent; volumes without FIEMAP fall back to the volume type (ext4/tmpfs/ramfs →Exclusive, otherwiseUnknown)fstatfsf_fstypename: hfs/msdos/exfat →Exclusive, APFS and anything else →UnknownGetVolumeInformationByHandleWfile system name: NTFS/FAT/FAT32/exFAT →Exclusive, ReFS and anything else →UnknownThe OS-specific code lives only in
platform_{linux,macos,win}/fs_extent.rs; the neutral facade is inplatform/fs/materialize.rs.Tests
tests/fs/materialization.rs::extent_sharing_never_calls_a_reflinked_copy_exclusive: a fresh file is neverShared, a reflinked pair is neverExclusive, and a missing file returnsNotFound.Exclusive, and a reflinked pair is exactlyShared.fstest binaries were run in a privileged container withTMPDIRon a loop-mounted btrfs volume, and the reflink case printedreflink-shared-verified. Linux CI (ext4) can't reflink, so this path only runs where the volume supports it.-D warnings) is clean forx86_64-pc-windows-msvc,aarch64-apple-darwinand Linux, and the Python compatibility tests pass.Labelled
ci-fullbecause this is platform-sensitive code.🤖 Generated with Claude Code