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Chris LuandGitHub
cdb60069a6
* filer: accept a WriteCondition on UpdateEntry, under the per-path lock UpdateEntry was a bare read-modify-write: the precondition check, the chunk garbage diff, and the store write could interleave with a concurrent update to the same path. Take the per-path lock CreateEntry already holds, and evaluate an optional CreateEntry-style WriteCondition under it, failing with FailedPrecondition like expected_extended. * filer: IF_CHUNKS_EQUAL write condition compares the stored chunk fid set A chunk-preserving read-modify-write (tagging, setattr, copy-in-place) races UpdateEntry's garbage diff: if a concurrent update empties the chunk list first, the stale writer's commit resurrects fids that are already queued for deletion, stranding the entry on a dead needle once vacuum reclaims it. The reverse also holds: a writer that read an empty chunk list can wipe chunks a concurrent update just added. IF_CHUNKS_EQUAL guards both: the stored chunk fid multiset must still equal what the caller read, order-independent, with an empty fids list expecting no chunks. Absent entry counts as no chunks for CreateEntry overwrites and transactions. * filer: delete and append serialize on the entry path lock DeleteEntry queues the entry's chunks for deletion and AppendToEntry rewrites the chunk list, but neither held the per-path lock, so either could interleave with a conditional update between its precondition check and its write — a passed IF_CHUNKS_EQUAL would then resurrect fids already on the deletion queue, or clobber a freshly appended chunk. AppendToEntry keeps the cluster lock for cross-filer append serialization; the path lock covers the local read-modify-write. * filer: reuse lockPath in UpdateEntry lookup