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[fix][client] Reset chunk_set last_write_length_ on O_TRUNC to fix ov… #861

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Merged
chuandew merged 1 commit into from
Apr 13, 2026
Merged

[fix][client] Reset chunk_set last_write_length_ on O_TRUNC to fix ov… #861

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9 changes: 9 additions & 0 deletions src/client/vfs/metasystem/mds/metasystem.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -712,6 +712,15 @@ Status MDSMetaSystem::DoOpen(ContextSPtr ctx, Ino ino, int flags, uint64_t fh,

// update chunk cache
auto& chunk_set = file_session->GetChunkSet();

// Reset the cached write length so that FlushFile sends the correct
// post-truncation length rather than the stale pre-truncation value.
// Without this, a fast close(fd1)+open(fd2,O_TRUNC) race leaves the
// shared chunk_set with last_write_length_ from fd1 (e.g. 4), and
// fd2's write of 2 bytes computes max(4,2)=4 → FlushFile(length=4).
if (flags & O_TRUNC) {
chunk_set->ResetLastWriteLength();
}
if (!chunks.empty()) chunk_set->Put(chunks, "open");

// update chunk memo
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