Split the 5369-line scanner_io.rs (39% inline tests) into a canonical
scanner_io.rs + scanner_io/ module tree with zero behavior change:
- scanner_io.rs (~660): constants, metadata-error constructors, the
bucket scan plan, cycle-status classification helpers, the ScannerIO /
ScannerIOCache / ScannerIODisk traits, and ScannerCycleResult
- scanner_io/dirty_usage.rs (~300): process-wide dirty-usage statics
and the acknowledgment protocol
- scanner_io/guards.rs (~270): concurrency gauges and RAII guards
- scanner_io/cache.rs (~410): scanner cache locks and the snapshot
persist/publish path
- scanner_io/io_cycle.rs (~390), io_cache.rs (~1160), io_disk.rs
(~230): the ECStore / SetDisks / Disk trait implementations
- scanner_io/publish_gate_tests.rs (~750) and tests.rs (~1340): the two
inline test modules as child modules
All crate paths are unchanged: the lib.rs scanner_io re-exports and
every crate::scanner_io:: consumer (scanner.rs, remote_scanner,
scanner_folder, and cross-crate rustfs users) resolve through root
re-exports with their original visibilities (pub stays pub, pub(crate)
stays pub(crate)). Cross-module items gain pub(super), whose scope
equals the old single-module privacy domain. Code is moved verbatim
apart from those markers, per-module import headers, and rustfmt
re-wraps.
The logging-guardrail nsscanner_disk skip-set_disks rule now points at
scanner_io/io_disk.rs where the function moved; the pattern and
thresholds are unchanged.
Co-authored-by: heihutu <heihutu@gmail.com>
houseme