fix: false hdd detection on virtual devices#352
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KSXGitHub merged 81 commits intoMar 15, 2026
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The sysinfo crate reads /sys/block/*/queue/rotational to determine disk type, but virtual block devices (VirtIO, Xen, VMware PVSCSI, Hyper-V) default to rotational=1 because the kernel doesn't know the backing storage type. This caused pdu to falsely detect virtual disks as HDDs and unnecessarily limit threads to 1. The fix adds a secondary check on Linux: when sysinfo reports HDD, we read the block device's driver via /sys/block/<dev>/device/driver and reclassify known virtual drivers (virtio_blk, xen_blkfront, vmw_pvscsi, hyperv_storvsc) as Unknown instead of HDD. https://claude.ai/code/session_01MHKaZm6DcA9kjBPnW3KN5K
Apply rustfmt formatting and replace map_or with is_some_and per clippy. https://claude.ai/code/session_01MHKaZm6DcA9kjBPnW3KN5K
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Pull request overview
This PR adjusts HDD detection on Linux to avoid misclassifying virtual block devices as HDDs when sysinfo reports DiskKind::HDD due to the kernel’s rotational=1 default on some virtual devices.
Changes:
- Intercept
DiskKind::HDDon Linux and reclassify known virtual block-device drivers toDiskKind::Unknown(-1). - Add Linux-only helpers to extract a base block device name and check the sysfs driver symlink.
- Add Linux-specific tests for device-name extraction and virtual-driver detection.
Reviewed changes
Copilot reviewed 2 out of 2 changed files in this pull request and generated 5 comments.
| File | Description |
|---|---|
| src/app/hdd.rs | Adds Linux-only correction path for HDD detection via /sys/block/<dev>/device/driver, plus device-name extraction. |
| src/app/hdd/test.rs | Adds Linux-only tests around extraction and virtual device detection (currently environment-dependent). |
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- Fix Hyper-V driver name: use 'hv_storvsc' (actual kernel name) instead of 'hyperv_storvsc' - Split extract_block_device_name into parse_block_device_name (pure parsing, no I/O) and validate_block_device (sysfs check), making the parsing logic independently testable - Update doc comments to document /dev/root handling - Make tests hermetic: test_parse_block_device_name asserts deterministically on all cases without depending on sysfs availability - Improve test_extract_and_check_real_disks to validate all disk types, not just VirtIO https://claude.ai/code/session_01MHKaZm6DcA9kjBPnW3KN5K
On macOS and FreeBSD, sysinfo reports DiskKind::Unknown because there is no reliable OS API for rotational vs solid-state detection. The HDD code path is never reached on those platforms today. Added a doc comment explaining this and noting the fragility if sysinfo improves detection. https://claude.ai/code/session_01MHKaZm6DcA9kjBPnW3KN5K
The Api trait's purpose is to enable dependency injection by delegating to sysinfo::Disk methods. get_disk_kind should only call disk.kind(), not apply platform-specific corrections. - RealApi::get_disk_kind now purely delegates to disk.kind() - Added get_disk_name to Api trait (delegates to disk.name()) - correct_hdd_detection takes (DiskKind, &str) instead of &Disk - Correction is applied in new is_in_hdd helper called from path_is_in_hdd - Updated MockedApi to implement get_disk_name https://claude.ai/code/session_01MHKaZm6DcA9kjBPnW3KN5K
Add the hyphenated `virtio-blk` driver name alongside the existing `virtio_blk` for consistency with the Xen dual-name treatment. Add a comment clarifying why the recursive `extract_block_device_name` call is safe (canonicalize resolves all symlinks). https://claude.ai/code/session_01MHKaZm6DcA9kjBPnW3KN5K
Replace all occurrences of `DiskKind::Unknown(-1)` with a named constant to make the intent explicit and avoid coupling to a specific numeric value across implementation and tests. https://claude.ai/code/session_01MHKaZm6DcA9kjBPnW3KN5K
…ariable `is_in_hdd` checks whether a disk IS an HDD, not whether something is IN an HDD — rename to `is_hdd`. Also rename the leftover `$mount` macro capture variable to `$disk_name` to match its parameter name. https://claude.ai/code/session_01MHKaZm6DcA9kjBPnW3KN5K
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Pull request overview
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Pull request overview
Copilot reviewed 5 out of 5 changed files in this pull request and generated no new comments.
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Summary
Fixes virtual block devices (VirtIO, Xen, Hyper-V, VMware) on Linux being misclassified as HDDs. The kernel's
rotationalsysfs flag defaults to1for virtual devices, causingsysinfoto report them as HDDs. This PR checks the block device's driver via/sys/block/<dev>/device/driverand reclassifies known virtual drivers asDiskKind::Unknown(-1).Key Changes
Apitrait withDiskApi(&selfmethods, impl'd directly on disk types) +FsApi(static filesystem operations) for fine-grained test mockingreclassify_virtual_hdd()— checks sysfs driver and reclassifies virtual devices (Linux-only; no-op on other platforms)extract_block_device_name()— resolves/dev/mapper/,/dev/rootsymlinks and parses device paths (sd*,vd*,xvd*,nvme*,mmcblk*)is_virtual_block_device()— matches drivers:virtio_blk,xen_blkfront,xen-blkfront,vbd,vmw_pvscsi,hv_storvscpath_is_in_hddto filter by mount point first, then check disk kind/dev/dm-*) volumes are not traced to backing deviceshttps://claude.ai/code/session_01MHKaZm6DcA9kjBPnW3KN5K