Nicholas Dudfield 4c546e5d91 feat: enable metacopy=on to test metadata-only copy-up ...

Mount OverlayFS with metacopy=on option (kernel 4.2+, supported on ubuntu-22.04).
This prevents full file copy-up when files are opened with O_RDWR but not modified.

Expected behavior:
- ccache opens cache files with write access
- OverlayFS creates metadata-only entry in upper layer
- Full copy-up only happens if data is actually written
- Should dramatically reduce delta sizes from ~324 MB to ~KB

Re-enabled use-deltas for ccache to test this optimization.
Conan remains base-only (hash-based keys mean exact match most of the time).

If successful, deltas should be tiny for cache hit scenarios.

2025-10-31 09:36:09 +07:00

..

action.yml

feat: enable metacopy=on to test metadata-only copy-up

2025-10-31 09:36:09 +07:00