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Omar ElsayedandZen Dodd
6cef370422
* Add 4 KiB logical block footprint tracking to stats This adds a 'Number of 4 KiB logical blocks touched' metric to the --stats output to decouple network delta payload from actual local file modifications. Previously, a small amount of literal data scattered across a file (especially with --inplace) could result in a massive number of local file write operations with no visibility, and large sparse files masked their true write opreations (ignoring punch holes). Technical details: - Implemented a stateful block tracker in the receiver that calculates touched 4K boundaries using file offsets and lengths, including strict lseek awareness to accurately skip sparse file holes. - Enforced strict per-file lifetime state with a reset hook inside receive_data(), successfully mitigating POSIX file descriptor (FD) recycling state leaks. - Created MSG_BLOCK_STATS multiplex message to tunnel the block footprint safely out of the isolated receiver process and relay it over the network. - Bumped PROTOCOL_VERSION to 33 and SUBPROTOCOL_VERSION to 8392 for safe PR testing. - Added test suite covering contiguous, scattered, zero-byte, sparse file (hole-skipping), multi-file (FD reuse), batch mode, and maximum-I/O boundary conditions. * io: fix block stats integration --------- Co-authored-by: Zen Dodd <mail@steadytao.com>