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* volume server: read GET/HEAD needles off the store lock, and only once The GET/HEAD handler read the needle synchronously on the tokio worker while holding store.read(): first a stream-info read that loaded the whole record just to parse its meta, then, for every needle that was not streamed (small, compressed, chunk manifest, image ops), a second full read. For a tiered volume each read is an S3 GET under the store lock, and a writer queued behind it parks every other store reader. The regular-volume read now runs in spawn_blocking. Under the store guard it only resolves a NeedleReadPlan (index lookup, a freshly opened .dat handle or the remote backend, offset, size); the guard is dropped before any needle data I/O. No data-file lease is held across the read either, since a writer waits for one while holding the store write lock. The index size decides the read, as in Go's readNeedle: a HEAD, a ranged read or a needle above the stream threshold reads only its header and meta tail (ReadNeedleMeta) and hands off to StreamingBody or the range path; everything else is read in full once, with its checksum verified. A compressed or manifest needle found by the meta read is then read in full once. The range-from-source read also moves to spawn_blocking. Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com> * volume server: stream needle chunks without the store lock StreamingBody::poll_frame took store.read() and find_volume for every chunk to compare the volume's compaction revision, dup'd the source handle, and allocated a fresh chunk buffer. With -hasSlowRead=false the stream also holds a data-file read lease for its whole life, while a writer waits for that lease under store.write(): the next chunk's store.read() then waits for the writer and the writer for the stream. The per-chunk re-lookup was also wrong. The stream reads a handle opened at plan time, which pins the .dat inode the offset was resolved against; a vacuum commit renames a new file over .dat and leaves that inode untouched. The re-looked-up offset belongs to the new file but was read from the old inode, so a stream whose needle a vacuum moved ended in a checksum error. The pinned offset stays valid, so the check, and with it every store access, is dropped, along with the now unused re_lookup_needle_data_offset and the revision fields of the read plan. The source is shared as an Arc instead of dup'd per chunk, and the chunk buffer is a BytesMut that the blocking read hands back with its result, so its allocation is reclaimed once the previous frame has been written. Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com> * volume server: stop a needle stream once its volume becomes unavailable Taking the store lock out of StreamingBody also dropped its per-chunk unavailable_error() check. With -hasSlowRead a writer can take the data-file lease between chunks, fail its fsync and its truncate, and mark the volume unavailable; the stream then kept serving the rest of the needle from its pinned handle. The volume's io_unavailable reason is now an Arc-shared leaf mutex that the read plan hands to the stream. Each chunk checks it under its data-file lease, where the writer marks it, and fails with the same "volume is unavailable: <reason>" error the old check returned. Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com> --------- Co-authored-by: Claude Opus 5.5 (1M context) <noreply@anthropic.com> Co-authored-by: Chris Lu <chrislusf@users.noreply.github.com>