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Chris LuandGitHub
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* ec: split the shard-interval recovery into a gather and a rebuild Recovering an interval is now one function doing the local seeding, the waved peer fetch, the shard accounting and the Reed-Solomon rebuild, under a memory budget. Splitting the gather from the rebuild makes the rebuild a plain function over a set of intervals, which is testable on its own and reusable by the parity checks a full scrub wants. The rebuild refuses a parity target, and the caller checks that before the gather so a doomed target costs no fan-out. ReconstructData rebuilds data shards only, so asking it for a parity shard returned no error and left the slot nil, and the caller copied that out as a successful read of zeroes. Only data shard ids reach here today, so this is a guard, not a live fix. Claude-Session: https://claude.ai/code/session_014yMNebkUjSbx9sfUCWJJtq * ec: rebuild only the EC shard the read asked for ReconstructData rebuilds every missing data shard. The gather stops as soon as DataShards intervals are in hand, so on a distributed volume it routinely finishes holding parity where data is missing -- and each of those data shards is then rebuilt into an interval-sized buffer, decoded, and never read. Ask for the one shard the read needs. The budget covers it now too: DataShards gathered plus the one the rebuild allocates. It never covered the rebuild's output, and with ReconstructData that output was up to ParityShards buffers. The required mask is Total() long rather than DataShards. reedsolomon documents both lengths, but its presence scan walks every shard and indexes the short mask past its end, so the documented short form panics whenever a parity shard is absent - which here it usually is. Claude-Session: https://claude.ai/code/session_014yMNebkUjSbx9sfUCWJJtq